Additional Science Biology Revison

Here is a great revison resource. The whole of the biology course for AQA additional science. 

Chemistry and Physics will be coming soon!!!

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  • Created by: Sophie
  • Created on: 07-04-14 21:17
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{Animal & Plant cells, diffusion, organs and organ systems, plant organs, photosynthesis,
limiting factors, distribution of organisms, transect sampling, proteins, digestives enzymes,
microbial enzymes, aerobic and anaerobic respiration, mitosis, meiosis, stem cells, genes
and alleles, genetic diagrams, Mendel's work, Punnett squares, family trees, embryo
screening, fossils, extinction, new species.}
Animal and plant cells:
Animal Cells:
· Nucleus: A large structure that contains genes that control the activities of the cell.
· Cell Membrane: Controls what enters and leaves the cell.
· Cytoplasm: Many reactions that place here.
· Mitochondria: Respiration takes place and energy is released for cell processes.
· Ribosomes: Where proteins are made.
Plant Cells:
· Nucleus: A large structure that contains genes that control the activities of the cell.
· Cell Membrane: Controls what enters and leaves the cell.
· Cytoplasm: Many reactions that place here.
· Mitochondria: Respiration takes place and energy is released for cell processes.
· Ribosomes: Where proteins are made.
· Chloroplasts: Absorbs light energy to make food.
· Cell Wall: Helps keep the plant structure and gives support.
· Permanent Vacuole: Helps to keep the plant rigid.
Diffusion is the spreading out of particles in a gas, or of the particles of a substance in a
solution. Particles are always moving. Where there is a concentration gradient:
More particles will be moving from the area of higher concentration.
Fewer particles will be moving from the area of lower concentration.
Many dissolved substances (such as glucose) and gases (such as oxygen) can cross cell
membrane by diffusion. The greater the difference in concentration between the two areas
the faster the rate of diffusion.

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Organisation of the body:
During development, cells specialise to perform different function. A tissue is a group of
specialised cells that have a similar structure and function.
Nerve tissue: Carries electrical impulses around the body and in the brain. Made of
nerve cells that often have long fibres to carry the electric impulses.
Epithelial tissue: Covers the surface (skin) and lines all tubes. Made from epithelial
cells that make a continuous surface.
Skeletal tissue: Supports and protects the body.…read more

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Limiting Factors:
Limiting factors:
A shortage of light,
Low temperature,
A shortage of carbon dioxide,
Limiting factors in greenhouse:
Some crops, such as tomatoes, can be grown in greenhouse. This can help the grower earn
more money than growing the crops outside.
The environment in a greenhouse is changed by: keeping lights on when outside is dark,
heating the air when it is cold and adding carbon dioxide to the air.…read more

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Distribution Of Organisms:
The distribution of a species is how the individuals of that species are spread out within an
area. Physical factors of the environment may limit where organisms can live. This affects
the distribution of the organisms.
Physical factors that affect organisms:
Too hot or too cold can kill,
Adaptions needed to survive extreme heat or cold.…read more

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Transect Sampling:
A transect is used to sample the distribution of organisms as it changes between two
neighbouring areas. Changes in physical factors (such as temperature, light intensity,
trampling) are also recorded at each quadrat position. This means that it is easier to link a
change in distribution with a change in a physical factor.
There are many different kinds of proteins in the body (structural proteins in the muscles,
hormones, antibodies and enzymes).…read more

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Microbial Enzymes:
Some microorganisms produce enzymes, which then pass out of the cell into the surrounding
environment. We use some of these enzymes in the house and in industry.
Uses of enzymes:
Advantages of enzymes in industry:
Bring about reactions at lower temperatures and pressures,
Avoid need for expensive equipment that uses a lot of energy,
Disadvantages of enzymes in industry:
Denature if the temperature is too high, which means reactions must be carefully
Are in many cases costly to produce.…read more

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Aerobic Respiration:
The chemical reactions inside cells, including those of aerobic respiration, are controlled by
enzymes. Aerobic respiration is a series of chemical reaction that take place mostly inside
mitochondria in the cell.
Use of energy from respiration:
In animals:
To build larger molecules from smaller ones e.g: proteins from amino acids, large
carbohydrates (e.g: starch, glycogen) from small sugars (e.g: glucose), fats from fatty
acids and glycerol.…read more

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The chromosomes in the nucleus of a body cell contain the genetic information (genes) of
the cell. The chromosomes of body cells come in pairs. Mitosis is one kind of cell division. It
o During growth ­ to produce more body cells,
o To produce replacement cells ­ when body cells are damged,
o During asexual reproduction,
Body Cells divide by mitosis:
The first cell has one large pair and one small pair of
Each chromosome is than copied.…read more

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Stem Cell:
Cell differentiation:
Most cells in growing organism differentiate into cells that are specialised for a
particular function.
Cells that remain able to divide
to form different specialised cells
are called stem cells.
New techniques are developing
other sources of stem cells
from human tissue.
Molecular biologists can make
human stem cells differentiate
into many kinds of specialised cell.
Genes and Alleles:
Each gene codes for a particular
combination of amino acids that
make a specific protein.…read more

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Some characteristics are controlled y a single gene. This is monohybrid inheritance.
Phenotype Genotype Note
Purple Flower RR R is dominant to r ­ only one cope needed to
Rr make the flower purple, RR, is the
homozygous dominant genotype, Rr is the
heterozygous genotype.
White Flower rr r is recessive to R ­ both alleles must be r to
make the flower white, rr is the homozygous
recessive genotype.…read more


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