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[AQA BIOLOGY 1 REVISION] September 17, 2010


Desert Animals:
They live in hot, dry conditions needed to keep cool, and are adapted to save water.
Large surface area compared to volume- Lets them lose more body heat, which helps to
stop them overheating.
Efficient with water- They lose less…

Page 2

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[AQA BIOLOGY 1 REVISION] September 17, 2010

Population and Competition

The size of population depends on three main factors:
Competition- Organisms compete with other species for the same resources.
Plants compete for light, water and nutrients from the soil.
Animals compete for territory (space), food, water and mates.

Page 3

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[AQA BIOLOGY 1 REVISION] September 17, 2010

Variation in Plants and Animals

Organisms of same species have differences:
Different species look different
Even organisms of the same species will usually look slightly different. For example; in a room
full of people, you'll see different colour hair, individually shaped noses etc.…

Page 4

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[AQA BIOLOGY 1 REVISION] September 17, 2010

Genes, Chromosomes and DNA

Genes, Chromosomes and DNA
Most cells in our body have a nucleus- which contains our genetic material.
The human cell nucleus contains 23 pairs of chromosomes.
Chromosomes carry genes. Different genes control the development of different
characteristics. E.g. hair…

Page 5

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[AQA BIOLOGY 1 REVISION] September 17, 2010


Asexual reproduction produces Genetically Identical Cells:
An ordinary cell can make a new cell by simply dividing in two. The new cell has exactly the
same genetic information as the parent cell. This is known as asexual reproduction.
This is how it…

Page 6

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[AQA BIOLOGY 1 REVISION] September 17, 2010


Plants can be cloned from Cuttings and by Tissue Culture:
Gardeners can take cuttings from good parent plants, and
then plant them to produce genetically identical copies
(clones) of the parent plant.
These plants can be produced quickly and cheaply.


Page 7

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[AQA BIOLOGY 1 REVISION] September 17, 2010

Some people think it's unethical to do this as embryos genetically identical to the sufferer
are created and then destroyed.
Fusion cloning will avoid this problem. Here, an adult cell is fused to an already existing but
genetically different embryonic stem cell.

Page 8

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[AQA BIOLOGY 1 REVISION] September 17, 2010

Genetic Engineering

Genetic engineering uses enzymes to cut and paste genes:
A useful gene is "cut" from one organism's chromosomes using
Enzymes are then used to cut another organism's chromosomes
and then to insert the useful gene. This technique is called gene…

Page 9

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[AQA BIOLOGY 1 REVISION] September 17, 2010


No one knows how life began:
There are various theories suggesting how life came into being, but no one really knows.
Could be from a primordial swamp or under the sea here on Earth. Maybe from simple
organic molecules brought by comets.…

Page 10

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[AQA BIOLOGY 1 REVISION] September 17, 2010


Mutations are when DNA changes:
An organism's DNA can change through everyday wear and tear, e.g. from coming into
contact with nasty chemicals. Most of the time mutations have no effect.
But, if the mutation happens within a gene AND it's passed…


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