Biology B1 notes - Pretty much everything you need to know

This is everything that I needed for my B1 exam, I got an A so I guess it was allright. It's the WJEC spec, hope it helps someone :3

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  • Created by: Becky
  • Created on: 04-04-12 22:53
Preview of Biology B1 notes - Pretty much everything you need to know

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Adaptation and competition
Animals have a common name and a Latin scientific name so that scientists recognise
the Latin name, regardless of their language and common name for it.
Size of a population may be affected by competition for food, space + light; predators,
disease, pollution, temperature, amount of water and availability of minerals.
Changes in pH + Oxygen levels can be used as signs of pollution. Lichens are also
indicators of air pollution, there are usually very few lichen species in industrial towns
where pollution is high.
Variation
Sexual reproduction leads to offspring that are genetically different from the parents.
Asexual reproduction means that the offspring are genetically identical offspring, called
clones, and are produced from a single parent. Sexual production therefore gives rise to
increased variation.
A mutation is a change to a gene or several genes. It is a change in one or more of the
chromosomes. A mutation starts in the nucleus of one particular cell. New genes result
from changes, mutations in existing genes. Mutations occur naturally at random.
Mutations may be beneficial or harmful and are increased by exposure to radiation and
some toxic chemicals.
Variation can either be genetic variation, or environmental variation. Genetic being the
genes and environmental being the way you were brought up etc. Eye/hair colour,
inherited diseases and your blood group are not affected by environment. Body weight,
height, skin colour, condition of teeth, academic or athletic powers however, are a mix of
the two.
Environmental variation in plants is much greater as they are strongly affected by
temperature, sunlight, the moisture level and soil composition.
Variation is the basis of evolution.
Evolution
All organisms produce more offspring than could possibly survive, yet the numbers tend to
remain fairly constant of long periods of time. Organisms in a species show wide variation,
and some of these variations are inherited and passed on to the next generation. The
ones that survive, due to having better genes than the others, will reproduce passing on
their genes.
Warfarin is a good example of inheriting genes. They used to drug rats with warfarin, and
it got rid of them. However they kept putting it down, so gradually some of the rats got
used to it. The rats that had no resistance to the drug died off, which left the bigger rats
that had enough resistance to reproduce, passing on their resistance to their offspring.
This meant that the rats had evolved to be warfarin resistant.
Variations of species may become extinct due to being the less developed variation. For

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So the lesser hearing rabbits will become extinct, due to being caught first etc.
Inheritance
Chromosomes are strands of DNA. DNA contains coded information that determines
how cells function. Short sections of a chromosome are called genes (Alleles). Genes
determine inherited characteristics, and are in pairs.
XX is female and XY is male.
Mitosis- Cells asexually reproduces itself, by splitting to form two identical offspring called
clones. This is done in the whole body, to replace original cells.…read more

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This is called vasoconstriction.
The hairs on the body stick up. This happens because the tiny erector muscles contract.
Warm air circulates between the hairs, and forms a layer of insulation.
If the temperature is hot outside- The body sweats. The sweat is released from the
sweat gland and travels along the sweat duct. As the sweat evaporates from the skin, it
conducts heat away.
The capillaries expand. They carry more blood and therefore lose more heat. This is called
vasodilatation.…read more

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