1. Most organisms are active in a limited temperature range
DP1 “identify the role of enzymes in metabolism, describe their chemical
composition and use a simple model to describe their specificity on substrates”
o Enzymes are biological catalysts. This means that they lower the energy
required to start a chemical reaction within a cell but do not get used up
by that reaction. Every reaction and process within a cell (metabolism) is
controlled by a specific enzyme.
o Enzymes are globular proteins whose shapes are specialised so that other
chemicals (substrates) can form a temporary bond with them. There are
two models used to show how an enzyme work:
o One model used to illustrate the action of an enzyme is the lock-key
model. This is where only one small part of the enzyme molecule can form
a complex with the substrate. This part of the molecule is called the active
site. Only a specific substrate(s) can bond in that site and this makes the
enzyme specific to that substrate.
o The induced fit model, a more recent modification on the lock-key model,
proposes that the active site slightly changes its shape to accommodate
the substrate perfectly.
DP2 “identify the pH as a way of describing the acidity of a substance”
The pH of blood is between 7.2 and 7.4 (neutral)
DP3 “explain why the maintenance of a constant internal environment is
important for optimal metabolic efficiency”
The following adaptations are common to Endo and Ectotherms.
1. Migration – Animals can move to avoid temperature extremes. Behavioural.
2. Hibernation – Some animals remain in a sheltered spot, their metabolism slows,
and in endotherms their body temperature drops.
3. Shelter – Animals seek shelter from extreme conditions. They may dig burrows
or hide in caves. For Ectotherms such as lizards, basking in the sun and
sheltering in shade may both be part of regular daily activity to keep the body
temperature reasonably constant.
4. Nocturnal activity – The brown snake is usually active during the day, but when
it gets very hot they become nocturnal and their active period is at night time.
5. Controlling exposure – Ectotherms such as lizards may alter their posture to
gain as much access to sunlight as possible through increasing their surface area.
Endotherms may cuddle up or huddle together to reduce heat loss.
Structural And Physiological Adaptations Of Endotherms
1. Insulation – Fur in mammals and feathers in birds maintain an insulating layer
of trapped air that slows down heat exchange with the environment.
2. Metabolic activity – Endotherms generate heat as a result of their metabolic
activity. In cold conditions this keeps the body warm; one of these means is
shivering which drastically reduces heat loss.
3. Control of blood flow – Endotherms may increase or decrease heat exchange
with the environment by controlling the blood flow to their skin and extremities.
This enables the skin temperature to be lowered while maintaining a normal
internal body temperature.
4. Counter-current exchange – Is used by some endotherms in cold conditions.
Blood vessels leading to and from the extremities of the body (E.G. the tail and
the legs) are placed close together and chilled blood returning in the veins picks
up heat from the arteries going to extremities.
5. Evaporation – By controlling the rate of evaporation of water from their bodies,
endotherms can help keep themselves cool. E.G. Humans sweat, dogs pant and
bird flutter a membrane in their throat.
DP4 “describe homeostasis as the process by which organisms maintain a
relatively stable internal environment”
Homeostasis is the maintenance of a balanced or stable internal environment.
Examples of conditions or features maintained by this process include:
o Water Concentration
o Blood Pressure
o Oxygen Concentration
o Blood Sugar Level
o Carbon Dioxide Concentration
o Salt Concentration
o Urea Concentration
o pH Level
A feedback mechanism is one in which the response alters the original stimulus.
o If the response causes an increase in the stimulus, it is said to be positive
feedback. E.g. Oxytocin is produced in women during childbirth to expand
the cervix, this is done even though it is defies homeostasis.
o If the response opposes or counteracts the stimulus, it is called negative
DP5 “explain that homeostasis consists of two stages:”
detecting changes from the stable state
counteracting changes from the stable state
Homeostasis involves two key steps:
o Detection of any change within the internal environment.
o Counteract the change that has taken place.
DP6 “outline the role of the nervous system in detecting and responding to
environmental changes” DO 16 WORK
These are highly specialised cells found throughout the body. They are
responsible for detecting stimuli or change.
Touch, movement and vibration Mechanoreceptors
Chemical Concentrations Chemoreceptors
Receptor cells also convert the stimulus in formation into electrochemical
impulses that the nerve cells and brain can understand and interpret.
Nerve cells or neurones:
These cells carry the information, in the form of impulses, to and from the central
Central Nervous System:
The brain receives information regarding any change and formulates an
DP7 “identify the broad range of temperatures over which life is found compared
with the narrow limits for individual species”
Habitats that offer temperature conditions that are fairly stable and those that
fall within a relatively narrow range are highly sought after and result in much
competition. Most living things live at a temperature between 10 and 35 degrees
Celsius. Active growth in most plants occurs between 5 and 40 degrees Celsius.
The diverse number of living things on Earth are found across a broad range of
temperatures. Some can survive in temperatures as low as -70 Celsius, others as
high as 56 Celsius in deserts and 350 Celsius in Thermal vents. However,
individual species cannot survive in this large temperature range, they need
Species have an optimal range of temperatures at which they can function. The
temperatures range in which they can survive is termed its tolerance range. The
tolerance range for the platypus is -8 to 34, the Sydney blue gum is -1 to 34.
Endotherms – These organisms are able to maintain a constant, stable internal
Ectotherms – These organisms are able to change their internal temperature in
relation to the external or ambient temperature.
Methods of mammalian temperature regulation:
Observation Type of Adaptation Explanation
(structural, behavioural, (how it relates to temperature
An echidna living in cold Behavioural They will move where it is
regions hibernates during the cold so their body
winter. temperature will drop and
they can hibernate.
Your skin often looks flushed Physiological The body does this to regulate
on a hot day. heat temperature.
Many Australian marsupials Behavioural They choose to lick their fur
salivate and lick their fur on a because they want their body
hot day. temperature to lower.
Whales have a thick layer of Structural The whales are born with a
blubber or fat under their thick layer of blubber.
You tend to feel cooler on a Physiological Your body functions better
hot dry day than on a humid without humidity.
day of temperature.
A small mammal, with the Structural Their smaller body size
same body temperature and prevents them from insulating
insulating mechanisms as a the heat, even though it is the
larger mammal, loses more same principle as the larger
heat than a larger mammal. mammal.
DP8 “compare responses of named Australian ectothermic and endothermic
organisms to changes in the ambient temperature and explain how these
responses assist temperature regulation”
Animal Environment Adaptations for heat control
Structural Behavioural Physiological
Thorny Devil Desert Flattened body Lays in the warm sand Absorbs water
to increase with its body flattened. through skin.
surface area of It remains motionless
Mitchell’s Desert - Sweat Is active from the late Fluffs up fur.
Hopping Glands afternoon to the early
Mouse - Fur morning
Corroboree Alpine Wet, slimy skin It is only active on It feeds on small
Frog warm days in summer. insects and other
It basks in the sun arthropods to
during the morning to accumulate fat tissue
warm up. for winter.
Mountain Alpine Thick fur and a When hibernating It doubles its body
Pigmy round stocky during winter it rolls weight through
Possum body. itself up into a furry spring, summer and
ball, tucking its nose, autumn to double its
ears, tail and feet into body weight so it can
its body. It also slows survive hibernation
down its metabolic in winter.
DP9 “identify some responses of plants to temperature change”
Plant response to high temperature:
o Evaporative cooling (transpiration), exposure to heat (and light) causes
the stomata in plants to open, leading to a loss of water by transpiration
(evaporation of water from the stomata of leaves). The advantage of this
water loss is that it decreases the internal temperature in plants by
evaporating cooling. However, the plants run the risk of dehydration due
to water loss and so excessive heat in plants will cause stomata to close.
This poses the threat of overheating. Plants have developed adaptations
to cope with this.
o Turgor response – wilting some plants respond with changes in turgor
pressure, which allows them to reduce the exposure of their surface area
to the sun and its associated heat and light, for example a wilting
response. In extreme heat, plants transpire and lost turgor in the palisade
cells of leaves, as a result the leaves wilt, reducing the surface area that is
exposed to the sun.
o Leaf orientation – to overcome the problems of overheating and excessive
water loss, some plant for example eucalypts are able to change the
concentration of their leaves so that they hang vertically downwards in
hot weather. This reduced the surface area that is exposed to the sun
during the heat of the noonday sun. The flat part of the leaf blade, with its
large surface area, is exposed to the less intense rays of the early morning
and late afternoon sun, but in the middle of the day when the sun is at its
hottest, the sun’s rays strike the thin edge neat the leaf stalk of the vertical
o Leaf fall – many trees lose their leaves during the cold winter months, but
eucalypts are evergreen trees that drop some of their leaves during the
dry season in hot climates to reduce the surface area exposed to absorb
heat. This also reduces the risk of loosing too much water by
o Reseeding and resprouting (germination) in response to extreme high
temperatures – fire:
In Australia, one of the extreme temperature changes plants have to
respond to is caused by bushfires. Plants have two general responses that
ensure their survival after the fire – they may resprout or release seeds.
Resprouters, such as the bottle brush, tea trees and eucalypts.
o Plants have several responses to cold temperatures:
Dormancy – in response to cold temperatures, deciduous trees
(those who drop their leaves annually) lose their leaves in winter
(leaf fall) and undergo a period of dormancy, which allows them to
survive not only the extremely low temperatures, but also the
water shortages and lower availability of sunlight. For example,
the deciduous beech (Nothofagus gunnii), found in Tasmania, is
the only indigenous Australian deciduous tree.
Vernalisation – some plants flower in response to low
temperatures; for example, tulip bulbs must be exposed to
between 6 weeks and 3 months of intense cold before they will
SC2 DP1 “identify data sources, plan, choose , equipment or resources and
perform a first-hand investigation to test the effect of:”
Procedures to investigate the activity of an enzyme:
A. To demonstrate the effect of increased temperature:
1. Make a rennin solution by dissolving a junket tablet in distilled water.
2. Add the same amount of rennin solution to a number of test tubes of milk, eg 7 test
3. Place test tubes in different water baths at temperature ranges such as 0oC, 10oC,
20oC, 30oC, 40oC, 50oC and 60oC. Make sure each water bath is kept at the
temperature it has been allocated.
4. Time the interval between adding the rennin and curdling of the milk for each
5. Note that the variables kept constant in each test tube are the junket solution, the
pH of the solution, the type of milk and the quantity of milk in each test tube.
6. Comment on which temperature is the most effective in curdling the milk. Could a
different temperature be better?
B. To demonstrate the effect of change in pH:
1. Make a rennin solution the same as was done in A and add pH solution to each with
known concentrations of pH solutions from for example pH 3, pH 4, pH 5, pH 6, pH
7 and pH 8.
2. Add the same amount of rennin solution with the varying pH to six test tubes of
3. Place in a water bath kept at a constant temperature of 37oC.
4. Time the interval between adding the rennin and curdling of the milk in each test
5. Note that the variables kept constant in each test tube are the junket solution, the
type of milk, the temperature of 37oC, and the quantity of milk in each test tube.
6. Comment on which pH is the most effective in curdling the milk.
C. To demonstrate the effect of change in substrate concentration:
1. Make different concentrations of the substrate by diluting the milk using different
amounts of powdered milk to get different concentrations.
2. Add the same amount of rennin solution to each test tube of milk.
3. Place in a water bath kept at a constant temperature of 37oC.
4. Time the interval between adding the rennin and curdling of the milk.
5. Note that the variables kept constant in each test tube are the type of milk, the
temperature of 37oC, and the quantity of milk in each test tube.
6. Should smaller increments of milk concentrations have been used?
SC2 DP2 “gather, process and analyse information from secondary sources and
use available evidence to develop a model of a feedback mechanism”
The body has some effective mechanisms to alter body temperature. To reduce
temperature, heat can be expelled by sweating or radiation of heat from the skin. To
increase heat, the body can respond by shivering or by contracting the skin. These
responses can be activated by heat receptors. If a mechanism is activated, it will operate
until receptors indicate that the optimum temperature has been reached.
If receptors in the skin detect heat, they relay information via the nerves to the
hypothalamus, which also contains receptors sensitive to the heat of passing blood. This
triggers the sympathetic nervous system to dilate skin capillaries and activate sweat
glands. When receptors in the skin detect a low temperature, a negative feedback
mechanism is activated to stop the original action. If skin temperature is still low, the
hypothalamus may activate thyroid hormones to increase metabolic rate, activate the
sympathetic nervous system to shut down skin capillaries and sweat glands and
activate food metabolism in the liver to produce heat. In this way, the body can maintain
a stable body temperature.
Gather samples of feedback mechanisms from biology texts, from scientific
journals or from the Internet. Often, analogies, such as the operation of a
thermostat in a refrigerator or an air conditioning system, are used.
Process the samples to identify the common elements of each system. Evaluate
the validity of your sources by checking the reputation of the sources and by
looking to see how consistently the information compares.
Analyse and use the information to design a creative model to represent a
feedback mechanism. The model might be a physical model, e.g. may be based on
a see-saw action, or it might be a conceptual model, based on an analogy.
SC2 DP3 “analyse information from secondary sources to describe adaptations
and responses that have occurred in Australian organisms to assist temperature
Endotherms derive most of their body heat from cell metabolism. Mammals and birds
are endothermic animals. Australian endotherms include: the kangaroos and the
platypus (temperate regions); the rabbit-eared bandicoot (desert dweller); and the
alpine pygmy possum (alpine dweller)
Ectotherms derive most of their body heat from their surroundings. All invertebrates
and fish, reptiles and amphibians are ectothermic. Australian ectotherms include the
blue-tongued lizard, the green tree frog and barramundi.
2. Plants and animals transport dissolved nutrients and gases in a fluid medium
DP1 “identify the form(s) in which each of the following is carried in mammalian
o Red blood cells
o Carbon dioxide
o Dissolved in plasma
o Hydrogen carbonate ions
o The form that oxygen is attached to is called oxyhaemoglobin which is
contained in the red blood cells.
o It transported through blood plasma and water molecules.
o Dissolved in plasma
o Fatty acids and glycerol
Other Products Of Digestion
o Amino acids
DP2 “explain the adaptive advantage of haemoglobin:”
The red colour of the blood is due to the presence of a protein molecule called
haemoglobin, which is made up of four long amino acid chains, each assembled
around an atom of iron.
Haemoglobin has a strong affinity for (great ability to pick up) oxygen when it is
in higher concentrations that it is in the blood. This happens at the lungs.
Haemoglobin can also release oxygen when it is in lower concentration than it is
in the blood and this is why it is dropped off at body cells.
When haemoglobin picks up oxygen it becomes bright red, but changes back to
purple once it has given it up. Oxygen chemically combines with haemoglobin to
form oxyhaemoglobin. Each haemoglobin molecule combines with four
molecules of oxygen. When all four binding sites are carrying oxygen, the oxygen
saturation is said to be 100%.
Because it is released at the tissues, the haemoglobin can be used over and over
again. The shape of the haemoglobin molecule changes slightly each time it binds
to an oxygen molecule. The attachment of the first molecule makes the second
easier and so on.
There are approximately 280 million haemoglobin molecules in each red blood
DP3 “compare the structure of arteries, capillaries and veins in relation to their
Arteries carry blood away from the heart under high pressure and so must have
a structure that can withstand the pressure. They have thick, but elastic walls,
made up of three tissue layers: endothelium as a lining, smooth muscle to
contract the vessel and connective tissue to allow for expansion. Arteries do not
Veins carry blood back toward the heart. They carry the same quantity of blood
as the arteries but not at the same high pressures. Veins have the same three
layers as the arteries: endothelium, smooth muscle and connective tissue.
However, the layers are not as thick. The veins also contain valves that prevent
the backflow of blood.
Capillaries have walls that are only one endothelium cell thick, as they have to
allow diffusion of materials through their wall to reach the cells found in the
tissues in which the capillary is located.
DP4 “describe the main changes in the chemical composition of the blood as it
moves around the body and identify tissues in which these changes occur”
Tissue Chemical Change Why the change occurs?
Lungs - Increase in oxygen - Needed by cells for
- Decrease in carbon dioxide respiration
-Removal of waste (carbon
dioxide has to be removed
from the body)
Liver - Increase in nitrogenous - Deamination (breakdown) of
waste (urea) amino acids
- Increase or decrease in - Change blood sugar level
glucose (the liver can store or
insert glucose into the blood)
Small Intestine - Increase in dissolved - Broken down and absorbed
minerals, glucose, vitamins, by the small intestine
protein (amino acids) as being
Kidney - Decrease in urea - Urea is toxic
- Decrease in water - Filtration
Body Cells - Decrease in oxygen (when Respiration
blood gives away
- Decrease in glucose (when
blood gives away)
- Increase in CO2
All tissues have a small decrease in oxygen because of respiration and in turn a
small increase of carbon dioxide. Also all tissues use glucose to respirate.
DP5 “outline the need for oxygen in living cells and explain why removal of
carbon dioxide from cells is essential”
Cells require oxygen in the process of respiration: Glucose + oxygen Right arrow
carbon dioxide + water + energy (in the form of ATP)
Carbon dioxide is a waste product and must be removed to maintain the normal
pH balance of the blood. By removing excess carbon dioxide, it prevents a build
up of carbonic acid, which causes the lowering of the pH, and therefore
increasing breathing rate and depth. Carbonic acid forms when carbon dioxide
dissolves in water. At normal levels, (after excess removal of carbon dioxide) the
carbon dioxide - bicarbonate ion (HCO3-) equilibrium is an important
mechanism for buffering the blood to maintain a constant pH.
DP6 “describe current theories about processes responsible for the movement of
materials through plants in xylem and phloem tissue”
The transpiration stream in xylem occurs due to physical forces that result from
water and ions being moved by passive transport. A column of water is sucked up
the stream by the evaporative pull of transpiration and is known as
transpiration water mineral ions) are carried by xylem tissue from the roots
(the site of absorption) up to the leaves where they will be used for the
manufacture of food (photosynthesis).
Most photosynthesis in plants occurs in the leaves. Phloem vessels are involved
in the transport of organic nutrient products (particularly sugars, amino acids
and plant hormones) to all parts of the plant. Movement occurs in two directions
– up towards the flowers and down the roots.
The transpiration stream in xylem occurs due to physical forces that result from
water (and ions) being moved by passive transport. A column of water is sucked
up the stem by the evaporative pull of transpiration and is known as the
Chemical substances that are needed for photosynthesis (such as water mineral
ions) are carried by xylem tissue from the roots (the site of absorption) up to the
leaves where they will be used for the manufacture of food (photosynthesis).
Xylem tissue consists of xylem vessels, tracheids, fibres and parenchyma cells.
SC DP1 “perform a first-hand investigation to demonstrate the effect of dissolved
carbon dioxide on the pH of water”
Perform your investigation, making sure you take readings of the initial pH of the
Using a data logger with a pH probe, take readings of the change in pH of 100 mL of
distilled water as exhaled air is bubbled through it over a two-minute period. This
experiment can also be performed using universal indicator paper and an indicator
colour chart to estimate the pH at various stages of the experiment.
SC DP2 “perform a first-hand investigation using the light microscope and
prepared slides to gather information to estimate the size of red and white blood
cells and draw scaled diagrams of each”
SC DP3 “analyse information from secondary sources to identify current
technologies that allow measurement of oxygen saturation and carbon dioxide
concentrations in blood and describe and explain the conditions under which
these technologies are used”
One method used by hospitals to monitor blood oxygen and carbon dioxide levels in
patient's blood is to use a pulse oximeter. A small clip with a sensor is attached to the
person's finger, earlobe or toe. A cable connects the sensor to the pulse oximeter
machine. The colour of the blood changes according to the amount of oxygen that is
dissolved in the blood. Blood that is high in oxygen is bright red while blood low in
oxygen is a darker colour. The sensor emits a light signal that passes through the skin.
The sensor measures the amount of light absorbed as it passes through the tissue and
blood, and transmits the information to the pulse oximeter. A reading is given in a
Pulse oximetry is used to monitor the level of oxygen in a person's blood during heavy
sedation or anesthesia. This device is also used when a person is on a ventilator,
artificial breathing machine, during stress testing, in sleep laboratories, when checking
the body's response to different medications or to monitor a person with asthma or who
is having trouble breathing.
Another method of analysing blood gases is with arterial blood gas (ABG) analysis
machines. These can measure the amount of oxygen and carbon dioxide in a sample of
blood by monitoring the rate of diffusion of these gases through artificial membranes
which are permeable to these gases. When moving through a membrane, oxygen in the
blood produces an electrical current while carbon dioxide changes the pH of the
SC DP4 “analyse information from secondary sources to identify the products
extracted from donated blood and discuss the uses of these products”
When blood is donated, it can be used almost immediately as whole blood or it can be
separated into its components. Whole blood is given to patients where major functions
of the blood, such as oxygen carrying capacity, are impaired, or where more than 20%
of blood has been lost and there is a decrease in blood pressure.
Some blood products:
Red blood cells (RBCs)
o RBCs help patients who need to be able to carry more oxygen. RBCs may
also be used to help replace cells lost following significant bleeding.
o Platelets are essential for the coagulation of blood and are used to treat
bleeding caused by conditions or diseases where the platelets are not
Fresh frozen plasma (FFP)
o FFP is used mainly to provide blood components that coagulate the blood.
FFP contains all coagulation factors in normal amounts and is free of red
cells, white blood cells and platelets. It is used for patients who require
immediate clotting effects, such as those undergoing warfarin therapy
(blood thinning) or when massive transfusions have taken place.
Cryoprecipitate anti-haemophilic factor
o Cryoprecipitate AHF is a concentrate of clotting proteins and is used for
the treatment of von Willebrand disease (similar to haemophilia),
replacement of the clotting proteins, fibrinogen, Factor XIII and Factor
VIII when no other option is successful.
SC DP5 “analyse and present information from secondary sources to report on
progress in the production of artificial blood and use available evidence to
propose reasons why such research is needed”
Blood transfusions have been the subject of medical research for centuries. In the early
1900s, successful transfusions were carried out as an understanding of blood
components were understood. Up until the HIV crisis in the 1980s, there was little
interest in artificial blood as there did not seem a great need. With the transmission of
the virus during transfusions, there was nothing to replace donor blood, so artificial
blood became a priority for research. Sensitive screening tests have now been
developed for potential infective organisms, such as HIV and hepatitis, making donor
blood much safer. There are now available safe and effective blood substitutes for
certain applications, although they are still not ready for widespread use. Better blood
substitutes are still needed. There is a continuing shortage of donor blood to help the
victims of emergencies, civil and international conflicts and natural disasters.
Furthermore, there is no guarantee that something similar to the HIV crisis will not
occur in the future.
Why research on artificial blood is needed
Some advantages of artificial blood could include the following:
Pasteurisation could be used to remove all pathogens.
There would be no need for cross-matching and typing as the artificial blood
contains no blood-group antigens. This saves time and allows on-the-spot
Artificial blood can be stored for more than one year, compared with about one
month for donor blood using standard methods.
SC DP6 “choose equipment or resources to perform a first-hand investigation to
gather first-hand data to draw transverse and longitudinal sections of phloem and
Xylem transports water and mineral ions upward only, from roots toward leaves.
Phloem transports organic materials, in particular sugars, up and down to where the
material is needed or for storage.
Xylem: The transpiration-cohesion-tension mechanism is currently the theory
that accounts for the ascent of xylem sap. This sap is mainly pulled by
transpiration rather than pushed by root pressure. Cohesion is the “sticking”
together of water molecules so that they form a continuous stream of molecules
extending from the leaves down to the roots. Water molecules also adhere to the
cellulose molecules in the walls of the xylem. As water molecules are removed by
transpiration in the leaf, the next molecule moves upwards to take its place,
pulling the stream of molecules continuously along. This is passive transport.
Phloem: The pressure-flow mechanism (or Source to Sink) is a model for phloem
transport now widely accepted.
The model has the following steps:
1. Step 1: Sugar is loaded into the phloem tube from the sugar source, e.g. the leaf
2. Step 2: Water enters by osmosis due to a high solute concentration in the phloem
tube. Water pressure is now raised at this end of the tube.
3. Step 3: At the sugar sink, where sugar is taken to be used or stored, it leaves the
phloem tube. Water follows the sugar, leaving by osmosis and thus the water
pressure in the tube drops.
The building up of pressure at the source end, and the reduction of pressure at the sink
end, causes water to flow from source to sink. As sugar is dissolved in the water, it flows
at the same rate as the water. Sieve tubes between phloem cells allow the movement of
the phloem sap to continue relatively unimpeded.
3. Plants and animals regulate the concentration of gases, water and waste
products of metabolism in cells and in interstitial fluid
DP1 “explain why the concentration of water in cells should be maintained within
a narrow range for optimal function”
The concentration of water in the cells of the body should be maintained within a
narrow range because it is essential to have water in your body so you can
homeostaticly function. These include having enough water to transport
substances around your body because water can act like a solvent, the right mix
is essential to produce lubricating fluids such as mucous which is in your nose
and stomach to help protect the body from unwanted substances. Water is also
used for heat control and a watery substance surrounds the brain and protects it
from colliding with the skull. Without the right concentrations of water none of
this would be possible.
Solvent – transport substances
Lubricating fluids – mucous
Heat – not being able to control temperature
Cushioning – water based liquid in the brain
DP2 “explain why the removal of wastes is essential for continued metabolic
It is essential to remove wastes such as carbon dioxide and nitrogenous wastes
from the body because it can affect metabolic activity, if they are left in the body
for a prolonged period of time the pH of the cells would increase to an extent
where the blood would become to acidic and damage cells.
DP3 “identify the role of the kidney in the excretory system of fish and mammals”
The kidney is an organ of the excretory system of both fish and mammals. It
plays a central role in homeostasis, forming and excreting urine while regulating
water and salt concentration in the blood. It maintains the precise balance
between waste disposal and the animal's needs for water and salt.
The role of the kidney in fish is dependant on the environment of the fish:
o In marine (salt water) environments, the kidneys excrete small quantities
of isotonic (same concentration as sea water) urine. This helps conserve
water and excrete the excess salt they gain from their hyperosmotic
o In freshwater fish, the kidneys work continuously to excrete copious
quantities of dilute urine, which also has a very low salt concentration.
This helps to remove excess water gained from the hypo-osmotic
Excretion – This is the removal of metabolic waste. The kidneys remove
nitrogenous wastes in the form of ammonia, urea, or uric acid.
Osmoregulation – This is the regulation of balanced water concentrations within
DP4 “explain why the processes of diffusion and osmosis are inadequate in
removing dissolved nitrogenous wastes”
Diffusion and osmosis are both examples of passive transport, relying on random
movements of molecules. Diffusion is too slow for the normal functioning of the
body and does not select for useful solutes. Osmosis only deals with the
movement of water and thus would only allow water to move out of the body,
not the nitrogenous wastes.
DP5 “distinguish between active and passive transport and relate these to
processes occurring in the mammalian kidney”
Active transport involves an expenditure of energy on the part of the organism,
usually because the substance is moving against the concentration gradient, i.e.
when a salt moves to an area of high salt concentration from an area of low salt
concentration. Passive transport involves no expenditure of energy as the
materials follow the natural concentration gradient, i.e. movement from an area
of high concentration to an area of low concentration. Both diffusion and osmosis
are examples of passive transport.
In the mammalian kidney, both active and passive transport processes occur.
o Passive transport: Once filtration has occurred in Bowman's capsule,
water returns via the interstitial fluid from the tubule to the capillary in
the process of osmosis. This occurs along the length of the tubule.
o Active transport: Depending on their concentration, the ions in the blood
(Na+, K+, Cl- , H+ and HCO3) can be transported to cells in the nephron
tubule and then secreted by the cells into the tubule. Some poisons and
certain drugs are eliminated from the body in this manner.
DP6 “explain how the processes of filtration and reabsorption in the mammalian
nephron regulate body fluid composition”
Filtration of the blood occurs in Bowman's capsule where high blood pressure in
the glomerulus forces all small molecules out of the blood into the capsule.
Water, urea, ions (Na+, K+, Cl- , Ca2+, HCO3- ), glucose, amino acids and vitamins
are all small enough to be moved into the glomerular filtrate. Blood cells and
proteins are too large to be removed. This filtering process is non-selective and
therefore many valuable components of the blood must be recovered by
Reabsorption takes place selectively at various points along the proximal tubule,
loop of Henle and distal tubule.
All glucose molecules, amino acids and most vitamins are recovered, although
the kidneys do not regulate their concentrations. The reabsorption of the ions
Na+, K+, Cl- , Ca2+ and HCO3- occurs at different rates depending on feedback
from the body. In some cases, active transport is required. Water is reabsorbed
in all parts of the tubule except the ascending loop of Henle. The amount of water
reabsorbed depends on feedback from the hypothalamus. If no water were
reabsorbed human would soon dehydrate, losing water at a rate of around 7.5 L
The chemical composition of the body fluids is precisely regulated by the control
of solute reabsorption from the glomerular filtrate.
DP7 “outline the role of the hormones, aldosterone and ADH (anti-diuretic
hormone), in the regulation of water and salt levels in blood”
Aldosterone is a steroid hormone secreted by the adrenal gland. Its function is to
regulate the transfer of sodium and potassium ions in the kidney. When sodium
levels are low, aldosterone is released into the blood causing more sodium to
pass from the nephron to the blood. Water then flows from the nephron into the
blood by osmosis. This results in the homeostatic balance of blood pressure.
Antidiuretic hormone (ADH or vasopressin) controls water reabsorption in the
nephron. When levels of fluid in the blood drop, the hypothalamus causes the
pituitary to release ADH. This increases the permeability of the collecting ducts
to water, allowing more water to be absorbed from the urine into the blood. The
resulting urine is more concentrated. When there is too much fluid in the blood,
sensors in the heart cause the hypothalamus to reduce the production of ADH in
the pituitary, decreasing the amount of water reabsorbed in the kidney. This
results in a lower blood volume and larger quantities of more dilute urine.
DP8 “define enantiostasis as:”
The maintenance of metabolic and physiological functions in response to variations in
the environment and discuss its importance to estuarine organisms in maintaining
appropriate salt concentrations
DP9 “describe adaptations of a range of terrestrial Australian plants that assist in
minimising water loss”
Plant and feature Diagram How feature minimises water loss
If the leaves hang vertically they are reducing how much sunlight they
Eucalypts receive therefore water will evaporate from the plant.
Spinifex grass The grass leafs curl around leaving the stomates on the underside in turn
Leaf can coil around reducing water loss.
Hakea multilineata They are long and thin reducing the surface area in the sun there reducing
(grass-leaf hakea) the rate of evaporation.
Leaves are long, thin
Carpobrotus rossii Water will store water in the leaf and it takes longer to evaporate because it
(pigface) is thicker.
Leaves are thick,
Actinotus spp The hairs on the leaf trap water, and as long as there is water on the top of
(flannel flower) the leaf the plant doesn’t have to evaporate any of it’s own water, so this is
Leaves have dense it’s water conservation technique.
covering of pale
Acacia spp Collects water in a larger area and greater rate of osmosis to cool nodules.
Have extensive root
system with root
Oleander Gets water at a lower level where other plants cannot get to.
Deep root system
below the water table
SC DP1 “perform a first-hand investigation of the structure of a mammalian
kidney by dissection, use of a model or visual resource and identify the regions
involved in the excretion of waste products”
SC DP2 “gather, process and analyse information from secondary sources to
compare the process of renal dialysis with the function of the kidney”
Dialysis means separation in Greek, and, like the nephrons of the kidney, the dialysis
machine separates molecules from the blood removing some and returning others. The
patient's blood is pumped from an artery through tubes made of selectively permeable
membrane. The artificial tubing allows only water and small solute molecules to pass
through it into a dialysing solution that surrounds the tube. This dialysing solution is
similar to the interstitial fluid found around nephrons. As the blood circulates through
the dialysis tubing, urea and excess salts diffuse out of it instead of leaving by pressure
filtration, as in the nephron. Those substances needed by the body, such as bicarbonate
ions (HCO3-) diffuse from the dialysing solution into the blood (reabsorption). The
machine continually discards used dialysing solution as wastes build up in it.
Two healthy kidneys filter the blood volume about once every half-hour. Dialysis is a
much slower and less efficient process than the natural processes found in a healthy
kidney but it is a lifesaver for those people with damaged kidneys.
SC DP3 “present information to outline the general use of hormone replacement
therapy in people who cannot secrete aldosterone”
Hypoaldosteronism is a condition where people fail to secrete aldosterone. Addison's
disease is the name of a disease with these symptoms which include high urine output
with a resulting low blood volume. Eventually, as blood pressure falls, this can result in
heart failure. A replacement hormone, fludrocortisone (Florinef), is used to treat this
condition but a careful monitoring must be maintained to avoid fluid retention and high
SC DP4 “analyse information from secondary sources to compare and explain the
differences in urine concentration of terrestrial mammals, marine fish and
Terrestrial mammals must work to find water and they are surrounded by air into
which water quickly evaporates. Water conservation is of prime concern and these
animals cannot afford to excrete large quantities of water in the removal of metabolic
The loss of water to the external environment is a problem that all marine fish must
deal with. The marine environment in which the fish lives is hyperosmotic to the
internal environment, i.e. there is a higher salt concentration in the water than inside
the cells. This results in an osmotic gradient in which water is lost from the fish to the
environment while ions are gained by diffusion. Ions are excreted by specialised glands.
The freshwater environment is hypo-osmotic to the internal environment of fish, i.e.
there is a lower salt concentration in the water than inside the cells. This results in an
osmotic gradient in which water is gained by the fish from the environment without
drinking and salts are lost by diffusion. Ions are absorbed in the gut and by active
uptake across the gills.
SC DP5 “use available evidence to explain the relationship between the
conservation of water and the production and excretion of concentrated
nitrogenous wastes in a range of Australian insects and terrestrial mammals”
SC DP6 “process and analyse information from secondary sources and use
available evidence to discuss processes used by different plants for salt regulation
in saline environments”
Coping with salt:
Most plants cannot tolerate high salt concentrations in the root zone as it leads to water
stress. The salt accumulates in the leaves and is toxic. Enzymes are inhibited by Na+
ions. Halophytes are plants that can tolerate higher levels of salt in their environment.
The grey mangrove, Avicennia marina, has special salt glands in its leaves that excrete
salt. Other mangroves exclude salts at their roots through ultrafiltration and a third
mechanism is to store salt in leaves and then drop the leaves.
Another mechanism involves the efficient control of transpiration. Some mangroves
have small leaves hanging vertically to reduce the surface presented to the sun and thus
Salt marsh plants also have mechanisms for salt regulation. For example, Sarcocornia
quinqueflora accumulates salt in the swollen leaf bases which fall off, thus removing
excess salt and Sporobolus virginicus has salt glands on its leaves.
Another form of salt stress can occur in salt laden air such as in coastal environments.
Some coastal plants, such as the Norfolk Island pine, have a mesh of cuticle over their
stomates, which prevents small water droplets from entering the leaf.
SC DP7 “perform a first-hand investigation to gather information about structures
in plants that assist in the conservation of water”
Blueprint of Life – Syllabus
1. Evidence of evolution suggests that the mechanisms of inheritance, accompanied by
selection, allow change over many generations.
DP1 “outline the impact on the evolution of plants and animals of:”
changes in physical conditions in the environment
changes in chemical conditions in the environment
competition for resources
Changes in physical conditions in the environment
These include natural conditions, such as temperature and the availability of
The Australia landmass has become drier over time and this has lead to changes
in the species of kangaroos that are present today. Approximately 25 million
years ago, Australia was considerably wetter than today with large areas of
rainforest. During this time, kangaroos were small and omnivorous, with
unspecialised teeth, eating a variety of foods from the forest floor. Food was
nutritious and abundant; there was no need for specialised grinding teeth.
As Australia became more arid and grass became the dominant vegetation in
some areas, environmental selective pressure resulted in larger kangaroos
favouring teeth suitable for grass. These teeth, high-crested molars, efficiently
grind low-nutrition grass into a more easily digestible paste. Slicing pre-molars
are of little use and so became much reduced from the ancestral kangaroos.
Changes in chemical conditions in the environment
Chemicals that can affect the evolution of species include salts and elements,
such as iron. For example, many parts of Australia have soils that have a high
salinity. There are a range of salt tolerant plants that have evolved to inhabit
those areas. The animals that feed from these plants have also evolved to inhabit
The sheep blowfly, Lucilia cuprina, is a major problem to the Australian sheep
industry. It stresses, weakens and can be lethal to sheep when larvae, laid by
females, burrows into wounds and wet wool. Chemicals, such as dieldrin and
organophosphates, have been used extensively to control the blowfly. However,
genetic resistance has occurred within the fly population that has made these
chemicals ineffective. Withholding a particular insecticide for a time allowed the
resistance of this particular blowfly population to drop. Continued use of the
insecticide has resulted in the mutation of a modifier gene that increases and
maintains the resistance. Thus, the insecticides can never be effective again,
regardless of the number of blowfly generations that pass.
Competition for resources
This occurs within a species and between species. If a new species is introduced
into an area then the competition may lead to different species using different
Resources can include food, space or mates. If populations that live in the same
area could specialise on slightly different resources or breed at different times,
they would avoid direct competition.
Some species of fruit fly have evolved into different species with each confined to
a different type of fruit tree. This is possible if there are different flowering and
fruiting times on each tree type suited for different breeding cycles in the fruit
flies. Eventually, two distinct species can result.
DP2 “describe, using specific examples, how the theory of evolution is supported by the
following areas of study:”
The fossil record provides a time line of evolution of life engraved in the order in
which the fossils appear in rock layers. Some parts of the fossil record show a
gradual change in life forms over millions of years.
Of particular interest are transitional fossils that have characteristics belonging
to ancestral and descendant groups. The most famous transitional form is
Archaeopteryx. This is a fossil first thought to be a therapsid reptile. Its reptilian
features include teeth and a reptilian-like skeleton. However, Archaeopteryx also
had feathers and a wishbone sternum used to attach flight muscles. This
provides evidence of an evolutionary pathway from dinosaurs to birds.
Charles Darwin and Alfred Russell Wallace both observed the distribution of
species into different biogeographic regions and saw this as major evidence to
support the theory of evolution. They argued that animals in different regions
had come from ancestors in that region and had adapted over time to the
conditions there. Special Creation, the prevailing religious-based explanation of
the time, did not explain why islands with similar conditions did not contain the
same flora and fauna. Darwin proposed that migration and evolution were much
more satisfactory explanations for the unique flora found in places such as
There is an obvious similarity between embryos of fish, amphibians, reptiles,
birds and mammals. A comparison of embryos of vertebrates shows that all have
gill slits, even though they do not remain later in life, except in fish. This indicates
a fundamental step that is common to all vertebrates and supports the idea of a
Anatomical structures on different organisms that have the same basic plan but
perform different functions are called homologous structures. Homologous
structures are evidence for evolution. The structures are shared by related
species because they have been inherited in some way from a common ancestor.
An example of an homologous structure is the pentadactyl limb found in
amphibians, reptiles, birds and mammals. The basic plan consists of one bone in
the upper limb, two in the lower limb leading to five fingers or toes. In bats, the
limb is modified to form a wing with the fingers extended and skin stretched
between each finger. Whales have within their single paddle-like fin a fully
formed pentadactyl limb.
Recent advances in technology have allowed comparison of organisms on a
molecular basis rather than simply comparing structures. This was previously
impossible between such distantly related organisms as an orchid and a mouse.
The study of amino acid sequences shows that more closely related species share
more common sequences than do unrelated species. Particular evidence has
been derived from the amino acid sequence in haemoglobin, showing that
humans and rhesus monkeys share all but eight amino acid sequences whereas
there are 125 amino acid differences between humans and lampreys. This
supports the fossil, embryological and anatomical evidence that humans are
more closely related to rhesus monkeys than they are to lampreys.
DP3 “explain how Darwin/Wallace's theory of evolution by natural selection and isolation
accounts for divergent evolution and convergent evolution”
Divergent evolution occurs when closely related species experience quite
different environments and as a result vastly different characteristics will be
selected. The species, over time, will evolve differently and will eventually
appear quite different. For example, elephants are large plains-dwelling animals
that are closely related to a small guinea pig-like animal called a hyrax. Hyraxes
live amongst rocky outcrops on mountains. Comparison of skeletons indicates
the close relationship between the two groups.
Convergent evolution occurs when two relatively unrelated species develop
similar structures, physiology or behaviours in response to similar selective
pressures from similar environments. For example, dolphins (mammals) and
sharks (cartilaginous fish) have evolved a streamlined body shape and fins that
enable them to move efficiently through their aquatic environment, yet they are
only remotely related as vertebrates. Communal social behaviour has developed
independently in ants, termites and bees.
SC DP1 “plan, choose equipment or resources and perform a first-hand investigation to
model natural selection”
Toothpicks are mixed and scattered randomly over a measured grassed area. Stick birds
(students) are later brought to that area and remain outside a 'fence'. They are told to prey
on the 'worms' in the field (collect as many toothpicks as they can) in a given time. After 3
minutes, the 'stick-birds' are driven from the field by the 'farmer' (teacher). They escape
back to the classroom.
Tally and compare the numbers of green and cream toothpicks recovered. Calculate
percentages recovered of each colour.
SC DP2 “analyse information from secondary sources to prepare a case study to show how
an environmental change can lead to changes in a species”
Starting information: Possible case studies of changes in a species
Changes in physical conditions in the environment
The teeth of kangaroos have evolved in response to changes in physical conditions in
Australia over the last 25 million years.
Changes in chemical conditions
Chemicals, such as dieldrin and organophosphates, have been used extensively to control
the sheep blowfly, Lucilia cuprina. Genetic resistance has occurred within the fly population
in response to these chemicals.
Competition for resources
Some species of fruit fly have evolved into different species with each confined to a
different type of fruit tree.
SC DP3 “perform a first-hand investigation or gather information from secondary sources
(including photographs/ diagrams/models) to observe, analyse and compare the structure
of a range of vertebrate forelimbs”
Perform a first-hand investigation by observing a range of vertebrate forelimbs to compare
their structures. Use at least three different types of vertebrates.
SC DP4 “use available evidence to analyse, using a named example, how advances in
technology have changed scientific thinking about evolutionary relationships”
Until the 1950s, the relationships between organisms were worked out by similarities in
anatomical features. At this time, it became possible to analyse protein sequence data and
DNA sequence data. Proteins, such as haemoglobin, could now be compared and similarities
worked out based on biochemical similarity. If the rate of change is approximated, it is
possible to work out a molecular clock that estimates the time since two organisms shared a
SC DP5 “analyse information from secondary sources on the historical development of
theories of evolution and use available evidence to assess social and political influences
on these developments”
By the beginning of the 19th century, a great deal of evidence was available to the scientific
community that supported evolution. What was missing was a plausible mechanism to
explain how evolution was occurring. Charles Darwin and Alfred Wallace independently
arrived at evolution as a result of natural selection. Darwin gathered evidence after sailing
on the HMS Beagle to South America and the Galapagos Islands. By the early 1840s, he had
documented the main points of his theory.
Wallace was a British naturalist working in Indonesia in the mid-1850s. In 1858, Wallace sent
a copy of his work to Darwin. Darwin's colleagues encouraged him to publish The Origin of
Species at the same time and so receive the credit for his years of work and insight. The
Origin of Species included overwhelming evidence to support Darwin's conclusions. Even
though the Darwin/Wallace theory of natural selection caused a furore amongst Victorian
society in England when published, scientific thinking was gaining respectability and
becoming an important mechanism for change.
The theory of evolution has encountered opposition since it was first introduced. This is
because it can be seen as a threat to religious and social beliefs.
2. Gregor Mendel’s experiments helped advance our knowledge of the inheritance of
DP1 “outline the experiments carried out by Gregor Mendel”
Genetics is the study of heredity. Heredity is the transfer of characteristics from one
generation to the next. Its origins can be attributed to Gregor Mendel. Mendel was an
Austrian monk born 1822. He studied the inheritance of characteristics in pea plants.
He bred two groups of pea plants, over many generations until the offspring showed no
variation from the parents.
DP2 “describe the aspects of the experimental techniques used by Mendel that led to his
He bred two groups of pea plants, over many generations until the offspring showed no
variation from the parents. This ensured he had pure-breeding plants. This group became
known as the P generation.
He crossed these two groups by manually transferring pollen grains from one flower to
another. He prevented self-pollination by removing the stamens of one pea plant. The
offspring became known as the F1 generation(first filial generation). Mendel then allowed
the F1 generation to interbreed to obtain the F2 generation.
Why was he Successful?
Mendel designed his experiments in such away to ensure successful accurate results.
1. He studied a large number of characteristics in the plants.(Form of
2. He carried out a large number of crossed.
3. He used pure-breeding lines. (Form of accuracy)
4. He made exact counts of characteristics. (Form of accuracy)
He studied separate identifiable characteristics that occurred in pairs.
DP4 “distinguish between homozygous and heterozygous genotypes in monohybrid
When both alleles are the same e.g. BB (both dominant) this is called homozygous
When the alleles are different not carrying the same information e.g. Bb this is called
BB = homozygous dominant
Bb = heterozygous
bb = homozygous recessive
DP5 “distinguish between the terms allele and gene, using examples”
Hair colour is gene, brown is the allele.
DP6 “explain the relationship between dominant and recessive alleles and phenotype
Dominant allele means it will show through in the persons physical appearance
Recessive allele will turn up only if no dominant allele is present.
Dominant alleles are always shown as a capital letter e.g. B = black
Recessive alleles are always shown as a lower case letter e.g. b = blonde
Genotype – This is a persons genetic makeup (use letters big B, little b)
Phenotype – This is your physical appearance (physical description 50% of babies will have
brown hair) If dominant will show through, if not dominant it will not show through unless
there is 2 recessive alleles.
DP7 “outline the reasons why the importance of Mendel’s work was not recognized until
some time after it was published”
- lack of formal education/scientific training
- lack of public understanding
- timing coincided with Darwin (was overshadowed by evolution)
- publication (published in a very small scientific journal with very small audience)
SC DP1 “perform an investigation to construct pedigrees or family trees, trace the
inheritance of selected characteristics and discuss their current use”
A pedigree is a family tree showing a line of descent. It can be used to trace the occurrence
of inherited traits in parents and offspring through a number of generations.
By convention, circles represent females and squares, males. A line between a square and a
circle represents a union and a line down indicates offspring from the union.Filled in
symbols represent individuals displaying the phenotype being studied. For example:
Pedigrees are valuable tools in genetic counselling. It allows a pattern of inheritance to be
traced throughout generations of a family. This can allow identification of the genetic
disease and advice can be made available on the probability of a couple having an affected
child. Cystic fibrosis is an example of a recessive genetic disease. Huntington's chorea is an
example of a dominant genetic disease.
SC DP2 “solve problems involving monohybrid crosses using Punnett squares or other
A monohybrid cross involves the inheritance of one characteristic. All problems apply
Mendel's basic laws of inheritance. The following is typical of a problem that uses Punnett
squares to solve problems involving monohybrid crosses.
SC DP3 “process information from secondary sources to describe an example of
hybridisation within a species and explain the purpose of this hybridization”
Hybridisation means the breeding of two different types of plants or animals. For example, a
mule is the result of the union between a horse and a donkey, two different species. The
resulting animal has desirable characteristics from both parents but all mules are sterile and
cannot produce any offspring. Hybridisation also occurs between different varieties or
breeds within a species, such as dog, cattle or sheep breeds. Many, probably most
agricultural animals and plants are the result of hybridisation. This results in offspring with
desirable characteristics e.g. cross breeding cattle to produce better meat or to be tick
resistant and Triticale a grain that is a cross between wheat and rye, two different species.
Hybridisation is a good way of producing new commercial plants and animals.
3. Chromosomal structure provides the key to inheritance.
DP1 “outline the roles of Sutton and Boveri in identifying the importance of
Boveri and Sea Urchins
Betwenn 1896 and 1904, he carried out experiments on sea urchin eggs, studying the
behavior of the cell nucleus and chromosomes during meiosis and after fertilization. Sea
urchin eggs were ideally suited for study because they could be easily fertilized in a
laboratory and have a quick (48 hour) time frame for larval development.
It was already known at the time that each species of living organism has a set number of
chromosomes and that, during fertilisation, an egg cell and a sperm cell fuse. Boveri's
experimental work with sea urchins showed that the nucleus of the egg and sperm each
contribute the same amount (50%) of chromosomes to the zygote (fertilised egg), making a
connection between chromosomes and heredity.
His experiments showed:
when a normal egg and sperm fused, the resulting offspring showed characteristics of
if the nucleus of only one parent was present, the larvae resembled that parent, but
showed abnormalities. When an egg, whose nucleus had 'been removed, was fertilised
with a sperm, the resulting sea urchin larvae showed characteristics similar to the male
parent. However, they were smaller, had only half the normal number of chromosomes
and showed some abnormalities.
From this he deduced that:
—a complete set of chromosomes (that is, chromosomes in pairs) is needed for normal
—the inheritance 'factors' are found on chromosomes within the nucleus—that is,
chromosomes are the carriers of heredity.
Sutton and grasshoppers
Walter Sutton (1877-1916), an American cytologist, studied meiosis in cells of
grasshoppers (Brachystola magna). In contrast to the eminent Boveri, Sutton was a
young, unknown graduate student who produced remarkable and detailed drawings of
his findings in cytology. As a result of his observations, he made the connection between
the behaviour of chromosomes during meiosis and Mendel's laws of heredity. His
independent findings (1902-4), together with those of Boveri (1902), formed the basis of
the chromosome theory of inheritance.
Sutton's observations of meiosis in grasshoppers revealed that:
chromosomes occur in distinct pairs, visible during meiosis in grasshopper cells; one
chromosome of each pair is paternal and the other maternal (today termed
homologous pairs) and the chromosomes in each pair have the same size and shape
during meiosis (reduction division), the chromosome number of a cell is halved: the
chromosomes in each pair of chromosomes separate (just like Mendel's factors
segregate—his law of dominance and segregation) and each gamete receives one
chromosome from each pair
fertilisation restores the full number of chromosomes in the zygote.
He concluded that chromosomes were the carriers of heredity units and behaved in
the same manner as Mendel's 'factors of inheritance' (genes).
In addition, Sutton stated that:
Chromosomes arrange themselves independently along the middle of the cell just
before it divides—that is, they assort independently of each other during
segregation, like Mendel's factors (evidence for Mendel's law of independent
Chromosomes are units involved in inheritance. Sutton, like Boveri, also
believed that several Mendelian`factors' must be present in one chromosome and
could therefore be inherited as a unit. (This'is what we term 'linkage' today. It will
be dealt with in more detail on page 173—sex-linkage).
DP2 “describe the chemical nature of chromosomes and genes”
Chromosomes are compact tread-like molecules made up of 40% DNA and 60% histone
protein. Chemically each gene is made up of a portion or section of DNA that codes for
particular information. DNA consists of sugar phosphate and nitrogen bases arranged in
DP3 “identify that:”
DNA is a double-stranded molecule twisted into a helix with each strand comprised of a
sugar-phosphate backbone and attached bases adenine (A), thymine (T), cytosine (C) and
guanine (G) connected to a complementary strand by pairing the bases, A-T and G-C.”
DP4 “explain the relationship between the structure and behaviour of chromosomes
during meiosis and the inheritance of genes”
Chromosomes are made of DNA. Genes are coded within the DNA on the
chromosomes. During division each chromosome (which therefore includes the genes)
makes a complete copy of itself. The new chromosome is attached to the original
chromosome by a centromere. In the initial division of meiosis the homologous
chromosomes line up in matching pairs and one of each pair of homologous
chromosomes moves into a new cell. Next the duplicated chromosomes separate to
single strands resulting in four sex cells that are haploid, (ie contain half the
chromosome number of the original cell).
The genes are located on the chromosomes. They are duplicated during the first stage
of meiosis and are then randomly assorted depending on which chromosomes from
each pair enters which new haploid cell during the first and second division.
DP5 “explain the role of gamete formation and sexual reproduction in variability of
Gamete formation results in the halving of the chromosome number (n) (diploid to
haploid) and sexual reproduction results in combining gametes (haploid to diploid)
to produce a new diploid organism (2n). The processes involved in forming this new
organism result in variability of the offspring.
Gametes are formed during the process of meiosis. In meiosis there are two stages
that lead to variability. These are:
o random segregation of individual chromosomes with treir associated genes
ie, different new combinations of the original maternal and paternal
o the process of crossing over where the maternal and paternal chromosomes
of each pairmay exchange segments of genes making new combinations of
genes on the chromosomes.
In sexual reproduction each female or male cell produces 4 sex cells (gametes) from
the process of meiosis. Each of these sex cells is haploid (has half the normal
chromosome number) and has a random assortment of genes from the parent. The
genes (Mendel's alleles) are separated and the sex cells have a random assortment
of dominant and recessive genes. More variability is introduced depending on which
sex cells are successful in fertilisation. The resulting embryo has a completely
different set of genes from either of the parents.
DP6 “describe the inheritance of sex-linked genes, and genes that exhibit co-dominance
and explain why these do not produce simple Mendelian ratios”
Mendel was fortunate in his choice of factors as they all showed dominant/recessive
characteristics. However, sex-linked genes and genes that are co-dominant do not display
the phenotype ratioos predicted by Mendel's laws.
An example of sex-linked inheritance is red-green colour blindness in humans. The gene is
carried on the X chromosome and there is no corresponding gene on the Y chromosome.
Therefore males need only one allele for colour blindness on the X chromosome while
females require two. This results in many more males being colour blind than females
because the father would have to be colour blind and the mother either colour blind or be a
carrier for colour blindness. As you would expect the sex of offspring to be 50% male and
50% female the occurrence of colour blindness is higher in males than would be expected
from a simple pair of dominant and recessive genes. Take the cross between a normal
female XN XN and a colour-blind male X n Y.
All offspring have normal sight. But if the female is a carrier for colour blindness and crosses
with a normal male then 50 % of the males will be colour blind and none of the females.
Human blood types are another example of co-dominance. Human blood types give
different results from Mendelian ratios. When a homozygous male with AA alleles crosses
with a homozygous female with BB alleles then all of the offspring will be a different
phenotype from the parents (group AB).
DP7 “describe the work of Morgan that led to the understanding of sex linkage”
Thomas Hunt Morgan studied the fruit fly, Drosophila melanogaster, in genetic experiments.
After a year of breeding flies, looking for new characteristics, Morgan found a male fly with
white eyes in his breeding stock. The normal or ‘wild’ eye colour is red. The white-eyed
individual was probably a mutant.
He mated this white-eyed male with a red-eyed female and all F1 had red eyes, showing that
red eyes are dominant over white.
When Morgan crossed two of the F1 generation the offspring had a phenotypic ratio of 3
red-eyed offspring : 1 white-eyed offspring. However, the white-eyed trait was only present
in the males, with half the males having white eyes and half having red eyes
DP8 “explain the relationship between homozygous and heterozygous genotypes and the
resulting phenotypes in examples of co-dominance”
In genetic traits that show co-dominant inheritance, heterozygous individuals show both the
dominant and recessive trait in their phenotype.
– AB blood group in humans
– Roan cattle (referred to as red alleles if it crossed with a white cattle you get patched
red and white cows, both show through in phenotype)
– Andalusian chickens (black feathers crossed with white feathers appears to be blue,
both show through in phenotype)
Give the genotypic ratio of a cross between two roan cattle
Gametes R W
R RR RW
W RW WW
1 RR : 1 WW : 2 RW
Give the phenotypic ratio of the cross between a roan cow and a white bull.
Gametes R W
W RW WW
W WW WW
1 Roan : 3 White
Give the phenotypes and genotypes of the offspring between 1 pink snapdragon and 1 red
Gametes R W
R RR RW
R RR RW
Phenotypes are 50% red and 50% pink
Genotypes are 50% RR and 50% RW
DP9 “outline ways in which the environment may affect the expression of a gene in an
- The appearance of an individual is not based solely on their genetic information. The
environment of the organism also plays a part.
- Hydrangeas are plants that have different flower colour (pink or blue) depending on the
pH of the soil they are grown in. In acid soils (less than pH 5) Hydrangeas are blue. In soils
that have a pH greater than 7 Hydrangeas are pink. The pH has an effect on the
availability of other ions in the soil and it is these ions that are responsible for the colour
Sex Linkage Patterns
All the sons of an affected female will be affected
All the daughters of an affected male will be carriers
All children of two affected parents will have the trait
In a large sample, more males than females will show the trait
A male with the trait passed it onto all of his daughters and none of his sons
A female with the trait may pass it onto her daughters and sons
Every affected person has at least one person with the trait
In a large sample size, there are more affected females than males
SC DP1 “process information from secondary sources to construct a model that
demonstrates meiosis and the processes of crossing over, segregation of chromosomes
and the production of haploid gametes”
Use plasticine or pipe cleaners to model the process of meiosis to demonstrate crossing
over, segregation of chromosomes and the production of haploid gametes. Or use prepared
slides showing meiosis.
SC DP2 “solve problems involving co-dominance and sex linkage”
1. A man with haemophilia marries a woman with no family history. What % chance do they
have of having a haemophiliac child?
Alleles X X
X XX XXh
Y XY XY
2. A woman who carries the gene for haemophilia marries a man without haemophilia.
What % chance of a haemophiliac child?
Alleles X Xh
X XX XXh
Y XY XhY
25% chance of a haemophiliac child.
3. A haemophiliac male marries a carrier female. What % chance of a haemophiliac child?
Alleles X Xh
Xh XXh Xh Xh
Y XY XhY
50% chance of a haemophiliac child
4. A woman with haemophilia marries a normal man. What % chance of a haemophiliac
Alleles Xh Xh
X XX XXh
Y XhY XhY
50% chance of haemophiliac child. If a woman has haemophilia all of her sons
will have it, if a man has haemophilia he has inherited it from Mum.
SC DP3 “identify data sources and perform a first-hand investigation to demonstrate the
effect of the environment on phenotype”
Studies on identical twins separated at birth are useful to determine how much the
phenotype is determined by the environment. Identical twins have the same genotype, so
any differences in phenotype could be determined by the environment.
Other studies that are useful are long-term studies on height of individuals. For example,
Japanese people who grew up in America on average were taller than Japanese people who
grew up in Japan. Better nutrition was responsible for the Japanese people to reach their
genetic potential. This has been shown in an increase in the height of the average Japanese
person over the last fifty years as nutrition has improved.
4. The structure of DNA can be changed and such changes may be reflected in the
phenotype of the affected organism.
DP1 “describe the process of DNA replication and explain its significance”
1. Double helix unwinds
2. The two strands begin to separate
3. Free nucleotides attach to the exposed bases (maintaining base pairing rule A-T,
T-A, G-C, C-G)
4. Weak hydrogen bonds bands reform between the bases and the strands begin to
5. Each DNA molecule re-twists back into the double helix
It is significant because you do not want any change, you want the new cell to do it’s
intended job, whether it be a skin cell, nerve cell etc.
Ability to exactly copy information to be passed onto offspring, to make sure they receive
the correct phenotypic characteristics.
DP2 “outline, using a simple model, the process by which DNA controls the production of
DNA stores genetic information. The sequence of bases determines the sequence of amino
acids in protein molecules. The smallest unit that can code for an amino acid is a codon, or
triplet of bases. For example, the DNA code CCA codes for an amino acid called glycine.
Protein synthesis involves the transcription of the code from DNA to mRNA and then the
translation of the code from mRNA to tRNA.
The first step in polypeptide synthesis involves the unwinding of the DNA, and the copying
of one strand by mRNA. Once the mRNA has the code for the protein, it moves from the
nucleus into the cytoplasm.
In the cytoplasm the mRNA moves to a ribosome where it binds to the ribosome at the end
with a ‘start’ codon. In translation, a tRNA in the cytoplasm moves to the codon on the
ribosome. At one end of the tRNA there is an anticodon that matches the codon of the
mRNA, and at the other end of the tRNA is an amino acid. Once the first amino acid is
attached, the second tRNA brings in its amino acid to attach to the next codon and this
slowly builds up the sequence of amino acids.
Note: mRNA does not have a T it has a U
DNA A T G C C T G A C A T G
mRNA U A C G G A C U G U A C
tRNA A U G C C U G A C A U G
Codon = block of 3
Anticodon = Codon but once it is tRNA
DP3 “explain the relationship between proteins and polypeptides”
A protein is made up of one or more polypeptides. A polypeptide is made up of a chain of
many amino acids.
DP4 “explain how mutations in DNA may lead to the generation of new alleles”
Any change in the base sequence in DNA results in changes to the polypeptides that
are produced and is a source of new alleles.
To produce changes in alleles, the mutation must occur in the sex cells of the
organism which are then passed on to the next generation.
DP5 “discuss evidence for the mutagenic nature of radiation”
Evidence for radiation as a mutagen:
- Worked with radioactive substances
- Died of cancer
- Leaking of radioactive waste
- Cancer, birth defects
- Worked with X-Rays
- Died of cancer
- Radiation from bombs
- Cancers, birth defects
Beadle and Tatum
- X-rays bread mould
- Mould mutated and was unable to produce a specific enzyme
- UV radiation
- Skin cancer rates
- Agent Orange
DP6 “explain how an understanding of the source of variation in organisms has provided
support for Darwin’s theory of evolution by natural selection”
One of the foundation pillars for the theory of evolution is the variation that
occurs among individual members of a species. The basis of this variation is the
genetic makeup of the individuals in a species. It is this variation that selection
acts upon. Mutation of DNA provides a source of new variations thus supporting
Darwin's theory of evolution.
DP7 “describe the concept of punctuated equilibrium in evolution and how it differs from
the gradual process proposed by Darwin”
Punctuated equilibrium differs from Darwin's gradual evolution in that evolution
is seen as long periods where there is little change in organisms, followed by a
shorter period where there are rapid changes. Evolution is a sudden process
rather than slow gradual change. The evidence for this comes from the fossil
record where there are mass extinctions of organisms followed by the
appearance of new species.
SC DP1 “perform a first-hand investigation or process information from secondary sources
to develop a simple model for polypeptide synthesis”
You could choose to perform a first hand investigation using beads and plasticine to model
polypeptide synthesis. Include in your model the transfer of information from DNA to
messenger RNA (mRNA). You will also need to make a model of transfer RNA and of several
amino acids. Alternatively, you could process information from an animation, such as those
indicated below. When doing this activity, evaluate the relevance of first-hand and
secondary information in relation to the understanding of the process of polypeptide
SC DP2 “analyse information from secondary sources to outline the evidence that led to
Beadle and Tatum’s ‘one gene – one protein’ hypothesis and to explain why this was
altered to the ‘one gene – one polypeptide’ hypothesis”
Beadle and Tatum used bread mould to investigate nutritional mutations. Using X-rays, they
produced mould that was unable to produce a specific amino acid. The mould was unable
to grow unless the amino acid was added. They showed that genes controlled biochemical
processes. Their hypothesis was that for each gene there was one enzyme or protein. The
enzymes that they studied consisted of one polypeptide but many enzymes consist of chains
of polypeptides. Therefore, the hypothesis has been changed to the “one – gene one –
SC DP3 “process information to construct a flow chart that shows that changes in DNA
sequences can result in changes in cell activity”
SC DP4 “process and analyse information from secondary sources to explain a modern
example of ‘natural’ selection”
Some organisms, such as bacteria and insects, produce large numbers of offspring.
Amongst large numbers of bacteria offspring, some individuals may carry genes that give
them resistance to antibiotics. These individuals are then able to survive and reproduce with
reduced competition from other members of the same species. Each generation will
produce a higher percentage of individuals containing the resistant genes. This has been the
story for antibiotics since they were first used. The initial use of an antibiotic results in good
protection from bacteria. Over time the chemicals become less and less effective. A case
study provides a good example of how natural selection occurs. A similar situation occurs in
the resistance of insects to insecticides.
Selecting those individuals that are able to survive and reproduce increases the frequencies
of those genes in the population. This is “survival of the fittest” where the fittest are those
that have a natural resistance to a selecting factor, which in the case of bacteria described
above, is antibiotics.
SC DP5 “process information from secondary sources to describe and analyse the relative
importance of the work of:
o James Watson
o Francis Crick
o Rosalind Franklin
o Maurice Wilkins
in determining the structure of DNA and the impact of collaboration and communication
in scientific research”
James Watson – Worked together with Crick in finding the Double Helix
Francis Crick – Worked together with Watson in finding the Double Helix
Maurice Wilkins – Worked together with Franklin with photographs – stole Franklins Photo
Rosalind Franklin – Worked together with Wilkins with photographs
The communication between Watson/Crick and Wilkins was important because without
Wilkins giving them the photograph their timeframe in discovering the double helix would
be extremely held back. Also if Franklin and Wilkins were working in the same place and
they both knew what each other worked on, so if Wilkins never worked with Franklin, he
never would have found the photograph to give to Watson/Crick and they progress would
have been delayed.
5. Current reproductive technologies and genetic engineering have the
potential to alter the path of evolution.
DP1 “identify how the following current reproductive techniques may alter the genetic
composition of a population:”
o artificial insemination
o artificial pollination
In the case of all the technologies mentioned, the donor gametes or body cells have been
carefully selected for predetermined characteristics – or artificially selected. In most cases,
one exemplary donor contributes all the genetic material and this results in uniform
offspring. Over generations, genetic variability within the species has been reduced.
DP2 “outline the processes used to produce transgenic species and include examples of
this process and reasons for its use”
Transgenic organisms contain a gene (transgene) from another species. This is
acheived through recombinant DNA technology. Recombinant DNA technology
manipulates DNA by the use of restriction enzymes, ligases and PCR (polymerase
chain reaction). Restriction enzymes are used to cut DNA in specific places.
These enzymes are also known as gene scissors or gene shears. Different
restriction enzymes cut DNA in specific parts. The cut ends are known as 'sticky
ends'. Ligases are used to repair and strengthen DNA especially after it has been
cut by restriction enzymes. PCR is used to produce many copies of the
recombinant DNA formed by the previous processes.
Once the recombinant DNA is produced there are processes used to insert the
DNA into the host species. These processes include microinjection, Ti plasmid
insertion, gene gun and electroporation.
In microinjection a fine glass needle is used to insert the recombinant DNA into
the nucleus of the host cell.
Ti (tumour inducing) plasmid insertion uses a bacterium called Agrobacterium
tumefaciens. These bacteria produce crown gall in plants by inserting some of
their own DNA into the host DNA causing the plant to produce a gall in which the
bacteria live. The ability of the bacteria to insert DNA is used to transfer DNA into
the host species.
The gene gun blasts small metal pieces coated with DNA into the nucleus of the
Electroporation uses electric pulses to create small pores in the nuclear
membrane through which DNA is inserted.
Examples of transgenic species are genetically engineered salmon which have
the gene coding for the protein, bGH (bovine growth hormone), and potato
plants which have a pea gene for lectin inserted.
DP3 “discuss the potential impact of the use of reproduction technologies on the genetic
diversity of species using a named plant and animal example that have been genetically
Reproductive technologies, such as cloning, and the engineering of transgenic
species have the potential to both increase and decrease genetic diversity. By
moving genes from species to species, the genetic diversity is being increased.
Crops, such as rice, have been genetically engineered to suit a particular climate
and topography, making then resistant to herbicides and pesticides commonly
used in a particular region.
Transgenic animals present greater problems with lower success rates so far.
One important use is seen to be the preservation of numbers of endangered
species. The first cloned endangered mammal was a guar (an endangered wild
ox from SE Asia), but unfortunately it did not survive. It is hoped that
reproductive technologies such as cloning and sperm and embryo banks can be
used to preserve stocks of threatened species.
SC DP1 “process information from secondary sources to describe a methodology used in
Recently, plants have been cloned using tissue culture propagation. Tissue from the roots is
taken and the root cells separated. These cells are then grown (cultured) in a nutrient-rich
medium where they become unspecialised. The unspecialised cells are called calluses. After
treatment with the appropriate plant hormones, the calluses are able to develop into
seedlings, that go on to grow into fully mature plants. These plants are genetically identical
to the original ‘parent’ plant. Rare orchids have been cultured and grown in this manner. A
more recent example, has been the cloning of tissue from the Wollemi Pine. This rare pine,
thought to be extinct but now has been discovered in the Blue Mountains region of NSWand
successfully cloned. These cloned offspring are being cultivated in the Royal Botanic
Gardens in Sydney and sold to the public for planting in gardens. Thus, the species, which
has few numbers in the wild, can be preserved.
In animals, progress in cloning species has not been as rapid. Current techniques require an
unfertilised egg to act as a ‘host’ for genetic material from a specialised cell. The donor egg
has had its nucleus physically removed, and the nucleus from a cell of the species to be
cloned is inserted. An electrical stimulus is used to fuse the nucleus with the egg cell and to
stimulate cell division. At a certain stage in cell division, the embryo is introduced into a
surrogate mother where it continues its development. When born the clone is genetically
identical to the animal that donated the original nucleus. Cloning of animals was first
performed with tadpoles by John Gurdon in the 1970’s. The tadpoles did not survive to grow
into adult frogs. Dolly the sheep was the first successfully cloned mammal in 1997. Since
then, other species have been cloned.
SC DP2 “analyse information from secondary sources to identify examples of the use of
transgenic species and use available evidence to debate the ethical issues arising from the
development and use of transgenic species”
Some ethical issues arising from the development and use of transgenic species
Transgenic organisms are those that have DNA derived from another species incorporated
into their genetic complement. This is done by genetic engineering techniques. Both plants
and animals have been genetically modified to create ‘improved’ strains of a particular
The following are two examples:
Genetically engineered salmon:
The gene coding for the protein, bGH (bovine growth hormone), is incorporated into the
genes of salmon.
Outcome – larger, faster growing fish
Evaluation – Possible farmed source of fish as food. However, the fish are kept in
ponds that offer no escape to the wild because there is much concern that they
will upset or destroy natural ecosystems.
A pea gene for lectin has been incorporated into potato plants.
Outcome – protection against insect attack. Lectin is a protein which interferes
with digestion in insects. It is termed an ‘antifeedant’.
Evaluation – As potatoes are a staple food source for many populations
throughout the world, it is important to maintain and increase production.
Protection against insect attack improves the success of growing potatoes.
Concerns exist about controlling the ‘escape’ of these transgenic potatoes into
the wild as the technology is only recent and long-term impacts on the
environment have yet to be observed or evaluated.
1. What is a healthy organism?
DP1 “discuss the difficulties of defining the terms 'health' and 'disease'”
1. The definition of disease above is very broad. Disease can cover a wide range of
conditions that fit the above definition including minor conditions, such as a cut
finger or an ant bite, as well as the more obvious diseases.
2. Health varies on a daily basis and is not just the absence of disease. Health varies
with age and the susceptibility to disease. It is a state of physical, mental and social
3. The difficulties of defining the terms health and disease include that:
1. it is possible for a person to be healthy and have a disease at the same time
2. the terms are used in general conversation and have different meaning to the
DP2 “outline how the function of genes, mitosis, cell differentiation and specialisation
assist in the maintenance of health”
Gene expression is essential for the maintenance of health.
1. Genes are the units of inheritance. They control the process of protein synthesis.
They assist the maintenance of health by regulating the cell cycle and limiting the
growth and reproduction of cells. Genes provide the code for proteins that are
needed for growth and repair. Enzymes, which control all body processes, are
proteins and thus have been produced from the codes of genes.
2. Mitosis is cell division that produces identical cells. These cells are important for
growth and reproduction. Each day millions of cells die and are replaced by the
process of mitosis.
3. Cell differentiation is the process undergone by the cells that are formed after
mitosis. Each cell has the genetic information necessary to produce all types of cells.
However, each cell normally differentiates to become a specialised cell, with a
specialised structure and function. Undifferentiated cells form tumours.
4. Many types of cells have specialised roles in maintaining the health of an organism.
For example, there are specialised blood cells that produce antibodies to attack a
disease causing micro-organism.
SC DP1 “use available evidence to analyse the links between gene expression and
maintenance and repair of body tissues”
Gene expression refers to the transfer of information from a gene to produce a protein or
RNA. If you cut yourself, the genetic code contained in all your cells is used to form the new
tissue to repair the damage from the cut
2. Infectious and non-infectious diseases
DP1 “distinguish between infectious and non-infectious disease”
An infectious disease is one that is caused by an organism and that can be transferred from
one person to another. The transfer may be direct, where the disease-causing organisms,
such as viruses or bacteria, pass directly from person to person, or it may be carried out by
an intermediary (called a vector), such as a blood-sucking insect. Examples of infectious
diseases are colds, influenza, chicken pox, herpes and measles.
Non-infectious diseases are diseases that are not due to disease-causing organisms. They
include genetic diseases, such as Down syndrome, haemophilia, and those that are related
to lifestyle or environment, such as cardiovascular disease and skin cancer.
DP2 “explain why cleanliness in food, water and personal hygiene practices assist in
control of disease”
1. Cleanliness in Food
Washing hands before preparing food
Clean surfaces after each item has
Washing equipment to minimise cross
2. Cleanliness in Water
Boil the water, freeze and un-freeze it
Not using bore water
3. Personal Hygiene Practices
Non-sharing of cigarettes, needles
DP3 “identify the conditions under which an organism is described as a pathogen.”
1. A pathogen is any organism that can produce a disease. Pathogens range
from viruses so small that thousands will fit side by side in one millimetre to
tapeworms that can be several metres long. They are all infectious.
2. Pathogens may live outside the body, such as the fungus that causes
ringworm, inside particular organs, such as parasitic worms in the intestine,
in tissues or inside cells. Some information on water pathogens is found
SC DP1 “identify data sources, plan and choose equipment or resources to perform
a first-hand investigation to identify microbes in food or in water”
Agar is a jelly-like substance obtained from seaweed. When it is dissolved in water,
nutrients suitable for microbes can be added to it before it sets to form a gel. If a
microbe makes contact with the agar and if conditions are suitable, the microbe will
grow and reproduce to form a visible colony. You will need to decide on which
nutrients you will add to the agar, what food and water samples you will test and
how you will expose the agar to the microbes that may be present in your food and
water samples. Decide on the temperature you will provide for microbial growth.
SC DP2 “gather, process and analyse information from secondary sources to
describe ways in which drinking water can be treated and use available evidence
to explain how these methods reduce the risk of infection from pathogens”
There are a number of stages or processes involved in ensuring Sydney has a safe
and healthy water supply. The first involves removing particulate matter, the second
killing or inactivation of microbiological organisms, and the third addition of
chemicals for fluoridation and water corrosivity control.
First Stage - Removal of particulate matter:
The first stage involves the removal of particulate matter through filtration. The
filtration process involves the addition of one or more coagulants to the water. The
primary coagulant used by Sydney Water is Ferric Chloride. Sufficient ferric chloride
is added to overcome the naturally occurring surface charges of particles in the
water, and in most cases, to also form a “floc”. This floc is a ferric hydroxide
precipitate that helps collect the neutralised particles into bigger masses, which in
turn assists the filtering out of this material.
Second stage - Inactivation of Microbiological Organisms:
The second stage involves the inactivation of microbiological organisms (disinfection)
and the provision of a disinfection residual to protect the water from potential
recontamination as it travels from the water filtration plant through the distribution
system to consumers taps. This is normally achieved by the addition of a strong
Sydney Water uses chlorine for disinfection. Various forms of chlorine are used
including chlorine gas, liquid sodium hypochlorite and calcium hypochlorite tablets.
Sufficient chlorine is added to the filtered water to ensure effective primary
disinfection as well as an appropriate chlorine residual entering the distribution
Third stage - Fluoridation and corrosivity control:
In accordance with the Fluoridation of Public Water Supplies Act 1957, Sydney Water
adds fluoride, in the form of sodium silicofluoride or hydrofluosilicic acid to achieve a
fluoride content of one milligram per litre. Lime and carbon dioxide are added at
some water filtration plants where the water is very soft to adjust and buffer the pH
of the treated water. The carbon dioxide reacts with the lime to form calcium
bicarbonate which buffers the water (increases the resistance to changes in pH),
increases hardness and reduces the general corrosivity of the water. The addition of
lime and carbon dioxide have no adverse health effects.
3. Identifying microbes that cause disease
DP1 “describe the contribution of Pasteur and Koch to our understanding of
Louis Pasteur was a French chemist, born in 1825. In 1856, he was asked by the
father of one of his students for help with his wine business. Some of the alcohol
was going sour and turning to vinegar.
At the time, it was believed that fermentation was caused by the chemical
breakdown of sugar into alcohol. They knew that yeast cells were living organisms,
but thought that they were a product of fermentation. (Spontaneous Generation)
Using a microscope, Pasteur discovered that vats with good alcohol contained yeast
cells that were round and budding. When lactic acid formed instead of alcohol,
lactobacilli were mixed with the yeast. He concluded that the yeast caused the
fermentation of sugar into alcohol and that contaminating microorganisms turned
the fermentations sour.
He referred to the spoilage of wine as a ‘disease’ and infectious diseases caused by
microorganisms became known as the germ theory of disease. After further study,
Pasteur suggested that makers heat wine, beer or milk first, to moderately high
temperatures (50-60oc) for a few minutes to kill the microorganisms. This process
became known as Pasteurisation.
Robert Koch was a German physician born in 1843. After military service, he became
a country doctor in an area where many sheep and cattle died of anthrax. Learning
of Pasteur’s theory that microorganisms caused disease, he investigated, and in 1876
discovered the anthrax bacilli.
He isolated these bacteria from others and injected into healthy mice. The mice
developed anthrax similar to the sick sheep. In 1884, he made a list of criteria
needed to prove that a particular organism causes a particular disease. These are
known as Koch’s Postulates.
In 1892, he and his pupils found the agents causing diphtheria, typhoid, tetanus and
tuberculosis. In 1905, he was awarded the Nobel Prize for medicine for developing
tuberculin to test for tuberculosis.
The basic bacteriological technique used in his postulates is still used today to
identify the pathogen of an infectious disease.
1. The organisms believed to cause the disease must always be present when
the disease occurs.
2. The organism must be isolated from the host and grown in a pure culture.
3. Organisms from the pure culture, when placed into healthy hosts, must
produce the disease.
4. The organism must be re-isolated, grown in a pure culture and compared
with the organism first injected.
DP2 “distinguish between: prions, viruses, bacteria, protozoans, fungi and macro-
parasites, and name one example of a disease caused by each type of pathogen”
DP3 “identify the role of antibiotics in the management of infectious disease”
Antibiotics are used in the management of bacterial diseases. They are chemicals
that either destroy the bacteria or inhibit the growth of the bacteria. They do not
affect the host and are not effective against viruses. Broad-spectrum antibiotics are
effective against a range of bacteria (eg. Penicillin) whilst narrow-spectrum work
against 1 or 2 bacteria.
Remember antibiotics is only for bacteria. Antiviral medication is for viruses.
DP(SC)3 identify data sources, gather process and analyse information from
secondary sources to describe one named infectious disease in terms of its:
cause, transmission, host response, major symptoms, treatment, prevention &
1. Chicken Pox:
1. Chicken Pox is caused by the Herpes varicella-zoster virus
2. Chicken Pox has an incubation period of 14-21 days
It is transmitted by direct skin contact with lesions, indirect contact with
articles or by inhaling viral particles
3. It is also transmitted via the placenta of an infected mother or during birth.
4. Host Response: The host’s immune system produces specific antibodies,
which generally provide lifelong immunity.
5. Symptoms: The virus enters the nervous system. Small, raised pink spots
develop on the scalp, face, torso, limbs and inside the mouth.
These are followed by itchy blisters which form crusts.
6. Treatment: Calamine lotion, anti-histamines and creams can reduce itchiness.
Isolation and rest is needed.
Infected people should be isolated
A vaccine is available but is not widely used.
Contaminated articles should be disinfected
1. Cause: Syphilis is caused by a Bacteria called Treponema pallidum
Syphilis has an incubation period of 2-6 weeks
It is transmitted during sexual contact with an infected person through tiny
breaks in the skin. It is also transmitted via the placenta of an infected
3. Host Response: The host’s immune system is not effective against syphilis.
2-6 weeks – an ulcer or lesion appears on the penis or cervix
2-12 weeks – a rash develops over the body
Late – up to 15 years, the pathogen is damaging the brain, heart and blood
vessels. Blindness can occur.
An infected person is usually contagious for the first 2 years.
It is treated with antibiotics such as Penicillin.
This is best done early for best chance of a cure.
The spread of the disease is prevented by avoiding sexual contact with
Condoms may reduce risk, but will not eliminate it.
Pregnant women should have a blood test.
SC DP1 “perform an investigation to model Pasteur's experiment to identify the
role of microbes in decay”
Pasteur's experiment that showed that something from the air causes meat broth to
go bad. As you conduct your experiment consider which variables need to be kept
constant and be able to explain which are the dependent and which are
1. Use a meat extract cube to make a clear broth.
2. Use two conical flasks instead of Pasteur's balloon flasks. Fit the flasks
with one-holed stoppers. Use glass tubing bent into an S-shape to
replace Pasteur's swan-necked flask. Place a straight piece of glass
tubing in the other flask.
3. Put some broth into both flasks and boil gently for fifteen minutes.
4. Leave both flasks, not in direct sunlight for several weeks. Every two
or three days compare the contents of the two flasks. Look for
cloudiness, scum, bubbles and mould colonies. Record your results.
7. When Pasteur did his experiment, the broth in the swan-necked flask
remained clear for several weeks, while that in the open flask quickly became
cloudy and smelly.
8. Both flasks were open to the air. In the swan-necked flask, air could move
freely through the neck of the flask just as it did in the straight-necked flask,
but the much heavier micro-organisms, in the air, were trapped in the
bottom part of the S-curve.
9. This experiment showed that for the broth to grow micro-organisms and
start to decay, there had to be access to air containing the spores of micro-
SC DP2 “gather and process information to trace the historical development of our
understanding of the cause and prevention of malaria”
18 BC The disease malaria was described by the
Romans. Malaria was thought to come from
swamps so the name means 'bad air'
1820 Quinine used to prevent the disease
1880 Charles Laveran a French army doctor
observed the malarial parasite
1886 Golgi observed asexual reproduction in the
protozoan Plasmodium and identified two
1898 Giovanni Grassi named the Anopheles
mosquito as the carrier of the malarial
1897 Ronald Ross discovered that Plasmodium was
the protozoan that caused the disease
1940 Chloroquinine the first synthetic anti-malarial
drug was used
SC DP3 “identify data sources, gather process and analyse information from
secondary sources to describe one named infectious disease in terms of its:
12. host response
13. major symptoms
SC DP4 “process information from secondary sources to discuss problems relating
to antibiotic resistance”
Unfortunately, the overuse of antibiotics has led to the selection of more virulent
bacteria that are resistant to antibiotics.
When antibiotics were first introduced, they had a dramatic effect on the pathogens
that cause disease. Over time, it became apparent that the effects of the antibiotics
were beginning to become less potent. This was because of the development of drug
resistance in the pathogen. Each time an antibiotic is used, there may be some
individual pathogens that have a natural resistance to the drug. These naturally
resistant individuals are left to breed the next generation and pass on the genetic
information that made them resistant. The next time the drug is used, it will have no
effect. Overuse of antibiotics has resulted in "superbugs". These strains are resistant
to antibiotics and include vancomycin resistant golden staph (Staphylococcus
aureus). These organisms are not destroyed by our strongest antibiotics. Scientists
are developing new antibiotics such as Zyvox to deal with multi-resistant bacteria. In
the future, unless new antibiotics are produced, common infections will once again
be responsible for many deaths.
Many household products and cleaning agents now contain antibiotics. These do not
kill all bacteria so act as a selecting agent for antibiotic resistant bacteria. These can
increase in number without competing with other bacteria.
The use of antibiotics in farm animals also has the same effect of selecting for
antibiotic resistant bacteria. Some farm industries put human antibiotics into the
feed of their animals. Thus increasing the build up of antibiotic resistant bacteria.
During the production of meat, animals are given antibiotics to prevent infections.
When the meat reaches the table, it may still contain these animal antibiotics. This
could lead to more antibiotic resistant bacteria.
It is important to complete a course of antibiotics even when the symptoms are
gone. This will ensure that the bacteria have been completely destroyed. Not
finishing antibiotics can lead to the selection of antibiotic resistant strains.
4.Defence against disease
DP1 “identify defence barriers to prevent entry of pathogens in humans:”
1. Skin – openings have of weakness nose, mouth, ears, and urinal genital
The skin is largest organ of the human body and forms a tough outer barrier
that covers the body and prevents penetration by microbes.
2. Mucous Membranes - the mucous traps the pathogen ready for removal
The respiratory, digestive, reproductive and urinary tracts are covered with
membranes that produce a thick layer of mucus which traps the entering
3. Cilia (Nose Hair) – to trap foreign substances
Cilia are tiny ‘hairs’ that line the respiratory surfaces of the trachea and
4. Chemical Barriers
Different types of chemicals secreted in different parts of the body act as
barrier to the invading pathogens. In the alimentary canal, pathogens
entering with food or drink, or swallowed with mucus, will be destroyed by
the acidic conditions of the stomach or the alkaline conditions in the
5. Other Body Secretions – tears
- Urine is sterile and slightly acidic and flushes and cleans the ureters, bladder
and urethra. It helps to prevent the growth of microorganisms
- Tears contain lysozymes that destroy the cell walls of some bacteria. As the
tears are produced and the eyelid blinks, the surface of the eye is cleaned
and the pathogens are washed away.
- Saliva also contains lysozymes and washes micro-organisms from the teeth
and the lining of the mouth
DP2 “identify antigens”
As molecules that trigger the immune response
DP3 “explain why organ transplants should trigger an immune response”
The organ received during a transplant has MHC marker molecules on its cells that
differ from the marker molecules on the bodies’ own cells. These foreign marker
molecules are recognised as antigenic and the immune response will result in the
attacking of the transplanted organ. The closer the chemistry of the marker
molecules between donor organs and recipient, the less likely the immune response
DP4 “identify defence adaptations, including:”
Internal - non-specific
1. Inflammation – like mossie bite will swell become warm
2. Phagocytosis – the process of the phagocytes (a type of white blood cell)
being sent to engulf the antigen and the lysosome inside them will draw in
and destroy the antigen.
3. Lymph System – the lymph glands are where white blood cells are produced,
if sick will be inflamed because they are being used a lot.
4. Cell Death to seal off pathogens – the cell can suicide itself to kill of the
pathogen, this is a last resort if a virus is reproducing inside it and the
phagocytes can not notice this, it will burst it’s own lysosome.
The Second Line of Defense: - Within the tissues consists:
1. Inflammation Response – When any body tissue is damaged, such as by the
invasion of a pathogen, the area becomes red, hot, swollen and painful. The
blood circulation to that part is increased, and the blood vessels dilate and
2. Phagocytosis – Phagocytes are white blood cells which can actively move
from the blood to the tissues where they ingest and destroy any foreign
material including pathogens.
3. Lymph System – within the tissues consists of lymph capillaries which unite to
form larger vessels similar to veins. These vessels transport tissue fluid away
from the cells towards the heart.
4. Sealing off pathogens – When the body is unable to neutralize an antigen, a
particular type of chronic inflammation involving both macrophages and
lymphocytes may occur. This reaction forms a cluster of cells called a
granuloma in which a central core of dead tissue is surrounded by layers of
macrophages, then lymphocytes, then fibrolasts which produce a tough outer
wall. Granulomas are produced in tuberculosis and leprosy.
5. Triggering the immune response – The body’s immune response is its
reaction to invasion by foreign materials. These may be viruses, bacteria,
toxins or other foreign proteins. These substances are identified as foreign by
the body, which then responds by trying to destroy them. Substances which
trigger this reaction are known as antigens. Transplants are being used more
and more to treat people whose own tissues are diseased, particularly
kidneys, liver, heart, lung and bone marrow. However, an introduced organ
contains proteins (antigens) that are recognized as foreign to the patient and
so stimulates the production of antibodies that attack and possibly destroy
the new tissue. In the early days of organ transplants, rejection was a
constant problem. Nowadays, new drugs have overcome many of these
3rd Line of Defence
Lymphocytes = white blood cells
B-cells or B-lymphocytes (Bone marrow -> produced and matured)
T-cells or T-lymphocytes (Thymus gland -> matured in thymus gland -> produced in
1. Plasma B-cells – Produce antibodies
1. 1 type of antibody for every antigen
2. Memory B-cells
1. remember the antigen
2. remember the plasma B-cell
3. Helper T-cells
1. inform the plasma B-cells and cytotoxic T-cells that an antigen is
4. Cytotoxic T-cells – killer T-cells
1. Directly destroy the antigen
2. Specific to the antigen
5. Suppressor T-cells
1. Stop reproduction of T-cells
6. Memory T-cells
SC DP1 “gather, process and present information from secondary sources to show
how a named disease results from an imbalance of microflora in humans”
Thrush – Candidiasis
- Genital Surfaces
- Fungi (Candida Albicans)
- Bacteria (Lactobacilli)
- Balanced by competition
- Contraceptive Pill
- IV drug use
- Steroid use
- Increase always in fungal population
- Decrease in bacteria
- White discharge
- Stop antibiotics
- Anti-fungal creams
- Wear loose, cotton underwear
5. The immune response
DP1 “identify the components of the immune response:”
o Antibodies are proteins produced by plasma B-cells that bind to the
antigen or infected cell and destroy it only if it is floating alone
through the bloodstream. Their function in the immune response is to
combat foreign cells in the system.
o T-cells is also a type of lymphocyte that is sent to the thymus gland.
They usually destroy cells infected by a virus.
o B-cells are white blood cells, formed in the bone marrow. They
provide what is called ‘antibody-mediated immunity’. So their
function is to provide antibodies to help fight off unwanted antigens.
DP2 “describe and explain the immune response in the human body in terms of:”
interaction between B and T lymphocytes
o B and T lymphocytes interact as they are both attacking the same
antigen. They both are told to produce by the Helper T-cell secreting
the mechanisms that allow interaction between B and T lymphocytes
o Macrophage presents the antigen which locks with a helper T-cell,
which works out how to defend against the antigen, which causes the
creation of Interleukin-2
o The mechanism that allows interaction between B and T lymphocytes,
is when the helper t-cell secretes interleukin-2 to allow them to start
cloning themselves, so they can fight off the unwanted antigen.
the range of T lymphocyte types and the difference in their roles
Type of T cell Roles
killer T cells (Tc cells) attack and destroy macrophages that have engulfed an antigen.
They produce cytotoxins.
helper T cells (Th secrete chemicals that stimulate cloning in B and T cells
memory T cells remain in the body and reactivate quickly with subsequent
infections by the same antigen
suppressor T cells stop the reaction when the antigen is destroyed
DP3 “outline the way in which vaccinations prevent infection”
A vaccine is a serum of either weaken, dead, low concentration or toxoid, that is
injected into the body, to in-turn give you immunological memory.
A vaccination prevents infection because it causes the body to create immunological
memory. This is when the antigen has been introduced to the body and the body has
built up it’s own defence by creating and in turn making memory B and T cells.
Therefore the second time the body can immediately make the B and T cells.
DP4 “outline the reasons for the suppression of the immune response in organ
The organ received during a transplant has MHC marker molecules on its cells that
differ from the marker molecules on the bodies’ own cells. These foreign marker
molecules are recognised as antigenic and the immune response will result in the
attacking of the transplanted organ. The closer the chemistry of the marker
molecules between donor organs and recipient, the less likely the immune response
Even similar marker molecules will trigger some kind of response. This is why
immune suppressive drugs are used to prevent the organ from being recognised as
foreign. These drugs primarily reduce the activity of the T-cells. These drugs are
needed in large doses initially and can be reduced over time. They will make the
recipient more susceptible to other infections, however newer medications suppress
T-cells whilst allowing B-cells to function. In other words they do not shut down the
entire immune response.
SC DP1 “process, analyse and present information from secondary sources to
evaluate the effectiveness of vaccination programs in preventing the spread and
occurrence of once common diseases, including small pox, diphtheria and polio”
Vaccination gives artificially acquired immunity from a disease. Once common
diseases, such as small pox, diphtheria and polio, are now uncommon because of
successful vaccination programs. Smallpox was the first disease for which a vaccine
was developed. Edward Jenner did this in 1796. The vaccination program that was
started in the 1960s was so successful that the World Health Organisation (WHO)
has declared it eradicated. Diphtheria vaccine is given as part of a triple antigen
injection that protects against diphtheria, tetanus and whooping cough. In 1990,
WHO stated that 80% of children had been vaccinated against this disease. There
continues to be outbreaks of this disease and continued vaccination is
recommended. It is no longer thought of as a major child killer. Polio caused
thousands of children to become paralysed every year. A vaccine was introduced in
1955. It became available as an oral vaccine in the 1960s. Worldwide, the number of
cases is down by 80%.
6. Epidemiological Studies
DP1 “identify and describe the main features of epidemiology using lung cancer as
Epidemiology is the study of disease and its prevalence in the community. Epidemics
occur when there is a rapid spread of the pathogen and large amounts of people are
infected. Epidemics can be pandemic, spread to many countries of the world,
endemic, always present in particular parts of the world, or sporadic occurring in
different places at different times. The main features of epidemiology are to
understand the reasons for the epidemic, study these issues, then ensure suitable
procedures be set in place. Epidemiology studied helped to identify the risk factors
that could lead to lung cancer. As lung cancer is not caused by only one factor, the
epidemiologists had to research lifestyles, environmental factors and genetic history
of people who suffered from lung cancer.
Epidemiological studies need to investigate cause and effects of a disease. To be
valid they must:
focus on large groups of people rather than individuals and relate to a target
population that can be identified. This allows statistics to be used to identify
trends and possible causative factors.
use populations where there is occurrence of the disease and where there
are unequal exposures to the suspected or possible causes. No conclusions
about the effect of smoking could be drawn from a group of people who each
smoke 20 cigarettes a day
allow for analysis of factors that might contribute to the occurrence of the
disease among those afflicted, such as age, sex, ethnic group, and
DP2 “identify causes of non-infectious disease using an example from each of the
1. Inherited diseases result from mutations that lead to the production of
different or faulty enzymes, resulting in impaired body function.
2. Down syndrome is an inherited disease that is caused by the non-disjunction
of chromosome 21. This results in three chromosomes and not the usual two
(trisomy 21). People with Down syndrome have a characteristic appearance
and may have a shortened life span. Mothers who have children later in life
are more prone to produce Down syndrome children.
1. The effect of nutritional deficiencies depends on the kind of deficiency. In
some parts of the world diets may be deficient in certain elements, such as
iodine, copper, iron or zinc.
2. Scurvy is caused by a deficiency in vitamin C. Symptoms include bleeding
gums and tooth loss. It is treated by increasing the intake of food and drinks
containing vitamin C, such as citrus fruit.
1. Environmentally caused diseases include those due to lifestyle, such as
smoking-related diseases, as well as those caused by something in the
environment, such as lead or substances that cause allergies.
2. Mesothelioma is caused by exposure to asbestos and patients don't get any
symptoms until 20 to 30 years after exposure. There is no cure and treatment
can only slow down the progression of the disease.
SC DP1 “gather, process and analyse information to identify the cause and effect
relationship of smoking and lung cancer”
Cause and effect is difficult to establish. For example, it is one thing to say that
everyone with a certain disease also watches television, but to make the next step,
and say that television caused the disease, is not possible. There could be any
number of other possible causes for the disease. This difficulty arises with
epidemiological studies. Smoking and lung cancer have been linked by research time
after time but it is difficult to get the manufacturers of tobacco products to accept
that it is a direct cause and effect relationship, that is, smoking causes lung cancer.
SC DP2 “identify data sources, plan and perform a first-hand investigation or
gather information from secondary sources to analyse and present information
about the occurrence, symptoms, cause, treatment/management of a named non-
7. Modern strategies
DP1 “discuss the role of quarantine in preventing the spread of disease, plants and
animals into Australia or across regions of Australia”
Australia has generally been fortunate in preventing the spread of plant and animal
disease from other parts of the world because of its geographical isolation.
Quarantine seeks to prevent the entry of harmful diseases into Australia and to stop
the spread of diseases within Australia. These diseases cause huge financial losses to
farmers in other countries. Australia is able to sell its products to overseas markets
because of the absence of diseases, like mad cow disease and foot-and-mouth.
Australia also has declared fruit-fly free areas where the produce is sold with a
guarantee of no fruit fly. This can be done by having inspections and bins to put fruit
in when entering particular fruit growing areas.
DP2 “explain how the following strategy has controlled and/or prevented disease:”
Public health programs:
– mobile van visiting schools
- Health (obesity, diabetes, heart disease, lung cancer, STI’s)
- Eat healthy, exercise, anti-smoking
Slip, Slop, Slap
- TV, newspaper, posters
- Skin cancer
- Cover up from Sun (hat, sunscreen, T-shirt)
- TV, newspaper, packets, posters
- Lung Cancer
- Stop smoking
Cancer Screening Programs
- Newspaper, TV
- Breast cancer, prostate cancer, cervical cancer (Cervical cancer vaccine –
free, in schools, 15-29, HPV Human Papilloma Virus)
- Get checked regularly
- TV, posters, newspapers
- Condoms, no needle sharing
SC DP1 “perform an investigation to examine plant shoots and leaves and gather
first-hand information of evidence of pathogens and insect pests”
When you know what several plant diseases look like, go to an area of vegetation
(such as a garden, park or area of bush) and examine plant shoots and leaves to
gather evidence of plant diseases caused by pathogens or insect pest attack. You
should aim to identify at least two examples of pathogens and insect pests if
possible. Look for black patches on the leaves, white powdery residue or other spots
that indicate a pathogen such as a fungus, or holes in the leaves caused by insect
pests such as catepillars. Use a hand lens to observe the symptoms. For each
example, record observations systematically and use the evidence to suggest what
kind of organism has caused the disease.
SC DP2 “process and analyse information from secondary sources to evaluate the
effectiveness of quarantine in preventing the spread of plant and animal disease
into Australia or across regions of Australia”
SC DP3 “gather and process information and use available evidence to discuss the
changing methods of dealing with plant and animal diseases, including the shift in
emphasis from treatment and control to management or prevention of disease”