What do you know about

							 B3 Revision


Life on
 Earth
      What do you know about
•   Evolution of organisms
•   Mutations
•   Darwin
•   Evolution of humans
•   Biodiversity
•   Extinction
•   Sustainability
•   Nervous and hormonal communication

• Work with the person next to you to write
  down as many things as you can.
  Which is the odd one out, and
              why?
• Darwin, Mendel, Lamarck.

• Wild boar, wolf, Labrador.

• Vasodilation, sweat, shivering.

• Accent, scar, blood type.
       Which is the odd one out, and why?

   There may be more than 1 correct answer
• Darwin, Mendel, Lamarck.
• Lamarck did not believe in natural selection.

• Wild boar, wolf, Labrador.
• The Labrador is a domesticated species, the others
  are not.

• Vasodilation, sweat, shivering.
• Shivering warms the body up, the others cool it down.

• Accent, scar, blood type.
• Blood type is inherited, the others are environmental.
    Where Did it All Begin?
• There are two main theories of where
  life began. What are they?

• Is there any evidence to support
  either?

• Can we say either one is fact? Justify
  your answer.
              Where Did it All Begin?


There are two main theories of where life began.
1) It started at hot air vents under the sea.
2) It started in Outer Space and came to Earth on a
   meteorite.

Is there any evidence to support either?
Different people may believe different things, as there
  is some evidence for both, but no conclusive proof

THEREFORE WE CAN’T SAY EITHER ONE IS FACT.
     Unicellular to multicellular
• As living things became more complex
  they developed communication systems
  to be able to keep in touch.

•   Nervous system.
•   Fast, electrical impulses, short lasting.
•   Hormonal system.
•   Slower, chemical messengers, long
    lasting.
         Data or Explanation?
• It is important to be able to tell the difference!

• There are many varieties of domestic cattle.
• Ducks have webbed feet.
• The fossil record shows how organisms have changed
  over time.
• Characteristics of cattle have been chosen for
  different reasons, so there are many varieties.
• Individuals most adapted to their environment will
  survive to breed and pass on their characteristics.
             How did you do?
• There are many varieties of domestic cattle. D

• Ducks have webbed feet. D

• The fossil record shows how organisms have changed
  over time. D

• Characteristics of cattle have been chosen for
  different reasons, so there are many varieties. E

• Individuals most adapted to their environment will
  survive to breed and pass on their characteristics. E
Charles Darwin suggested the theory of
Natural Selection. Put these statements
                in order.

• They survive and breed.
• The beneficial characteristics are passed on
  to the offspring.
• All living things show variation.
• Some are better adapted to their
  environment than others.
• They compete for food, space, and mates.
• There are always too many individuals to
  survive.
Charles Darwin suggested the theory of
Natural Selection. Put these statements
                in order.

• All living things show variation.
• There are always too many individuals to
  survive.
• They compete for food, space, and mates.
• Some are better adapted to their
  environment than others.
• They survive and breed.
• The beneficial characteristics are passed on
  to the offspring.
• This is NATURAL SELECTION.

• Remember that organisms don’t
  CHOOSE to mutate or have a good
  feature.

• What is the term used when humans
  pick characteristics and breed
  individuals together to get these traits?
• This is NATURAL SELECTION.

• Remember that organisms don’t
  CHOOSE to mutate or have a good
  feature.

• What is the term used when humans
  pick characteristics and breed
  individuals together to get these traits?

• ARTIFICIAL SELECTION
• Darwin collected lots of observations and data
  before publishing his theory of Natural Selection.

• He had some evidence for it, but also had to be
  very creative to come up with his theory.


• Darwin’s theory was unpopular at first. Why was
  this?

• Can you remember what Lamarck’s theory was?
• That living things have an ‘inner urge’ to improve, and
  if they need something (e.g. wings, or a longer neck),
  they will develop it.
Variation can be caused by genetic differences
  (through sexual reproduction, or a mutation)
  or the environment. Make sure you can give
  examples of these.

If these differences are great enough, over
  time a new species may emerge.

Members of a species can breed together to
 produce fertile offspring. How do we know
 that horses and donkeys are separate
 species?
Because a mule is infertile.
   We are not descended from
           monkeys!
• Explain in 35 words or less why this is
  the case.

• You should have included
• There was 1 common ancestor.
• This split into different species,
  including monkeys, apes and hominids.
• All hominids except homo sapiens (us!)
  died out. Why did this happen?
                                     What would be
                                     affected if
                                     the number of
                     Otter           crayfish
Trout                                decreased?
                                     Remember to
                                     look at both
                                     immediate
                   White clawed
                    crayfish
                                     effects and
Small                                knock-on
fish                                 effects.


         Water
         boatman

                             Algae
 Plant
    What Causes Extinction?
• Extinction can be caused by many things, e.g.
  disease, loss of habitat, over hunting, a new
  member of the food chain….

• Give an example of extinctions caused
  indirectly by humans.
• E.g. bat – loss of habitat.
• Give an example of extinctions caused
  directly by humans.
• E.g. Wolf in Britain – hunting.
 Why is Biodiversity Important?
• We depend on plants and animals for many
  things e.g. fuel, food, materials, medicines,
  etc., etc.

• There are still many undiscovered species;
  these may be useful to us so it is important
  they don’t become extinct before we even
  find them.

• Almost all plants and animals depend on each
  other, so if one becomes endangered or
  extinct it will have an effect on others.