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B3, C3, P3 Revision

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					Living and growing

 Respiration happens in   

 Diffusion eg molecules

  

mitochondria DNA is a double helix, A-T, C-G DNA replicates and controls protein synthesis DNA fingerprint – Isolation, fragmentation, separation and comparison Each protein = different no. aa=different shaped molecules Enzymes = catalyst = optimum pH, temp = lock and key Enzymes used in respiration, photosynthesis & protein synthesis

move in and out of cells through cell membrane  High concentration to low, faster if short distance, high concentration gradient and large surface area  Happens in alveoli, small intestine – villi and placenta (H & synapse)  Plant Leaves – carbon dioxide and oxygen, water loss

 Red blood cell contains

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haemoglobin & no nucleus White blood cell , flexible shape to engulf bacteria Plasma transports, food, hormones, antibodies, water, waste products Arteries away, Veins to the heart and Capillaries exchange material Heart – ventricles pump blood, atria receive blood, semilunar, bicuspid (L) and tricuspid (R) valves prevent backflow Cholesterol builds up in arteries to form a plaque – due to diet. Transplants – need a tissue match problems of rejection, use of pacemaker or valves instead

 Multicellular= large, cell

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differentiation, more complex, large surface area:volume ratio Grow by mitosis = genetically identical, diploid number Gametes combine to form diploid zygote Gametes produced by meiosis, they are haploid Meiosis produces variation, each cell is different, there are two divisions First division pairs of chromosomes separate to opposite poles, second chromosomes split to opposite poles Sperm cells have mitochondria and an acrosome

 Animal and plant cells = 

 Plant hormones are auxins, they

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nucleus, cell membrane & cytoplasm Plants only = cell wall, large vacuole & chloroplasts Plants keep growing animals stop at a finite size, plants grow by cells getting larger, cell division is at root & shoot tips only and plant cells can differentiate Animal cells that are undifferentiated are stem cells – stem cell research issues Gestation periods differ, and different parts of a baby/foetus grow at different rates Human growth phases are, infancy, childhood, adolescence. Maturity and old age

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   

are made in the tips Shoots are +phototropic and – geotropic Roots are –phototropic and +geotropic Plant hormones are carried through the plant in solution Auxin causes the shoot to curve due to cell elongation Plant hormones are used commercially for – weedkillers, rooting powder, fruit ripening, dormancy/germination

 Mutations are changes to

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genes (DNA base sequence) they are usually harmful but can be beneficial They are caused by radiation, chemicals or spontaneously Selective breeding – select characteristic, cross breed & select suitable offspring – reduces gene pool = less variation Genetic engineering – adv = new features disadv =harmful effects (moral & ethical issues) Examples include beta-carotene from carrots into rice, human insulin from bacteria, resistance to weedkillers, frost or disease in crops

 Cloning produces genetically identical copies & is a form of asexual reproduction  Cows cloned by artificial insemination, embryo collected, embryo split, clones put into   

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surrogate cows Method of producing organs for transplantation H only – cloning dolly Cloning plants – adv – know the characteristics, produce plants difficult to grow from seed, disadv – disease, lack of variation Tissue culture – large number made from small pieces of tissue , aseptic technique, growth medium & suitable conditions Plants can differentiate unlike animals

Chemistry

Atomic Structure
    

Atoms are made of protons, neutrons and electrons. Protons and neutrons are found in the nucleus. Protons are positively charged and have a mass of 1. Neutrons have no charge and a mass of 1. Electrons have a charge of -1 and a very low mass, 0.

Periodic Table
 The rows are called periods.  The columns are called groups.  The large number in each box is the mass number.  The small number is called the atomic number.  The atomic number is equal to the number of protons and also the number of electrons.  The number of neutrons is the difference between the atomic and mass numbers.  Group one is called the alkali metals.  Group seven is called the halogens.

Bonding
 There are two types of bonding, ionic and covalent.  In covalent bonding electrons are SHARED, forming molecules.  In ionic bonding electrons are given away or received forming positive and negative ions.  Ionic substances are formed between metals and non metals and are always SOLIDS at room temperature.  Covalent substances are formed from non metals

and are usually liquids or gases.

GROUP 1 – ALKALI METALS
 Group 1 consists of –lithium-Li, sodium- Na, potassium-K,     

rubidium-Rb, Caesium Cs, and francium-Fr. They are all low density and float on water. They are all very reactive but lithium is the least reactive. They react with water to form the metal hydroxide and the gas hydrogen. The metal hydroxide is an alkali and turns universal indicator purple. They react with chlorine forming chlorides such as sodium chloride.

GROUP 7 – THE HALOGENS
 Fluorine, chlorine, bromine and iodine are in group 7.  They are coloured and have different states of matter, F

yellow gas, Cl green gas, Br red liquid, I grey solid.  Displacement reactions occur when fluorine reacts with sodium chloride forming chlorine and sodium fluoride.

Transition metals
 Transition metals form the middle section of the periodic table and include copper, zinc, nickel, silver mercury and gold.  All form coloured compounds.  All are dense, conduct heat and electricity, malleable, sonorous, and ductile.  Copper is used to make wires and pipes because it conducts electricity and is flexible  Superconductors have zero resistance at very low temperatures.

Forces for Transport

Speed
 Measuring Speed – trundle wheels, speed cameras  Speed = Distance /Time  Distance/Time graphs  Calculating speed from a DT graph – slope of graph –

(unit m/s)

horizontal line = at rest!

Distance Time Graphs
Gentle slope = slow constant speed

Horizontal line = NOT MOVING, AT REST, STATIONARY

Steep slope = fast constant speed Moving backwards with a constant speed

Acceleration on a Distance Time Graph
Downwards curve = DECELERATING

Upwards curve = ACCELERATING

Changing Speed
 Speed Time graphs  Calculating Acceleration from a SpT graph  Calculating Distance travelled from a SpT graph  Calculating Acceleration from formula  Unit of Acceleration is ms-2  Objects travelling in a circle are always accelerating

Speed Time Graphs
Acceleration = Change in speed ÷ Time

Unit = m/s2
A-B uniform acceleration B-C constant speed C-D non-uniform acceleration D-E constant speed E-F uniform deceleration AREA UNDER GRAPH = DISTANCE TRAVELLED DURING JOURNEY!

D

E

B C

A

F

Forces & Motion
 Newton’s 2nd Law  Large mass

F=mxa

small acceleration  Small mass greater acceleration  Forces always occur in pairs
 Stopping Distance = Thinking Distance + Braking Distance

 Factors affecting Thinking Distance  Factors affecting Braking Distance

Work, Energy & Power
 Work is done when energy is transferred  Power is the rate at which work is done (or energy is

transferred)  Work = Force x Distance (Unit = Joules)  Power = Work Done / Time taken (Watts)

Energy on the move
 Kinetic Energy KE = ½ mv2  Fuels are burned so that vehicles gain KE  Different fuels – petrol, diesel – fossil fuels  Fossil fuels – non-renewable

 Renewable energy sources – biofuels
 Pollution?

Car & Road Design
 Collisions – KE has to be absorbed!  Crumple zones  Brakes get hot  Seat belts stretch a little

 Air bags inflate and squash
 Roads – crash barriers, escape lanes, road markings  Active and Passive safety features

Falling
 Terminal Speed  Gravity and weight  Air Resistance or Drag  Balanced Forces cause terminal speed

Energy of Games and Theme Rides
 Gravitational Potential Energy GPE = m x g x h  g is always 10N/kg on Earth

 GPE at top becomes KE at bottom and energy lost to the

surroundings by heat and sound  Weight = mass x gravitational constant. Eg 2kg has a weight of 20N.


				
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