Core Science- Biology 1b

Revision Notes for GCSE Biology 1b


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  • Created on: 22-02-11 13:33
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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 water by producing small amounts of concentrated
They make very little sweat. Camels are able to do this by accepting big changes in body
Good in hot, sandy conditions- They have thin layers of body fat to help them lose body
heat. Camels keep all their fat in their humps.
Large feet spread their weight across soft sand, making it to get around easily.
A sandy colour gives good camouflage, so they're not easily seen by their predators.
Arctic Animals:
They live in cold conditions needed to keep warm, and are adapted to reduce heat loss.
Small surface area compared to volume- They have a compact (round) shape to keep their
surface area to a minimum- this reduces heat loss.
Well insulated- They have a thick layer of blubber for insulation, which acts as an energy
store when food is scarce.
Thick hairy coats keep body heat in, and greasy fur sheds water- this prevents cooling due to
Good in snowy conditions- White fur for camouflage.
Big feet to help spread weight, which stops animals sinking in snow, or breaking thin ice.
Some plants are adapted to living in a desert.
Minimise water loss- Cacti have spines instead of leaves to reduce water loss.
They also have a small surface area compared to their size, which reduces water loss.
A cactus stores water in its stem.
Maximise water absorption- Some cacti have shallow but extensive roots to absorb water
quickly over a large area. Others have deep roots to access underground water.
Plants and Animals
Some plants and animals are adapted to deter (prevent) predators.
Some plants and animals have armour- like roses with thorns, cacti with sharp spines and
tortoises with hard shells.
Others produce poisons- like bees and poison ivy.
And some have warning colours to scare of predators, like wasps.

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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.
Disease- Infectious diseases caused by bacteria and viruses can kill members of a
population- but organisms that are fit and healthy stand the best chance of survival.…read more

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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.
These differences are called the variation within species, and there are two types of
variation: genetic variation and environmental variation.…read more

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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 colour or eye colour.
A gene- a short length of the chromosomes, which is quite a long length of DNA.
The DNA is coiled up to form the arms of the chromosome.…read more

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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 works:
This is how all plants and animals grow and produce replacement cells.
Some organisms also produce offspring using asexual reproduction, e.g. bacteria and
certain plants.…read more

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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.
Tissue culture:
This is where a few plant cells are put in a growth medium
with hormones, and they then grow into new plants- clones of
the parent plant.…read more

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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.…read more

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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
Scientists use this method to do different things. E.g. the human
insulin gene can be inserted into bacteria to produce human
insulin.…read more

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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.
The fossil record shows that organisms have evolved:
A fossil fuel is any evidence of an animal or plant that lived ages ago.…read more

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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 on to the next generation it can
cause new characteristics. Very occasionally, it can give the organism a better chance of
survival (e.g. warmer fur, longer legs, larger leaves etc.).…read more


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