Biology B1 - Summary Notes

B1 Revision notes

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  • Created by: Hugo
  • Created on: 11-05-12 17:40
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Biology 2-Life processes
Plant and animal cells
plant cell
Has all the bits that the animal cell has plus:
Permanent Vacuole- contains cell sap, weak solution of sugar and salts.
Nucleus-contains genetic material and controls activities of cells
Cytoplasm-gel like substance where all the chemical reactions take place
Cell membrane- holds cell together and controls what goes IN and OUT
Mitochondria- reactions for respiration takes place Ribosomes-proteins are made here

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Lots of cells= tissues = organs = organ systems
Specialised cells-Palisade cells, Guard cells,Red blood cells and sperm and egg cell
-Palisade cells are packed with chloroplasts for photosynthesis.
- Crammed at top of cell so are near light.
-Tall shape means lots of surface area for absorption of Carbon dioxide.
-Thin shape means that you can pack lots of them at the top of the leaf.
Red Blood cells
Concave shape gives big surface area for aborption of oxygen and can pass
through capillaries.…read more

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No nuclues- so have enough room for the haemoglobin, important part of blood, blood is a tissue.
Sperm and egg cell
Main functions of an egg cell are to carry the female DNA and nourish the developing embryo in the
early stages.
When sperm fuses with egg, the eggs membrane changes its structure to stop any sperm
from getting in. This is so the offspring end up with the right amount of DNA.…read more

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Only small molecules can diffuse e.g. glucose,amino acids, water and oxygen.
big molecules like starch and proteins and starch cant fit through the membarne.
Three things which the rate of diffusion depends on-
-Distance- substances diffuse more quickly when they havent got far to move.
- Concentration difference-substances duffuse faster if theres a big difference in
concentration.
-Surface area- the more surface there is available for molecules to move across, the faster
they can get from one side to another side.…read more

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Minerals for healthy growth
Nitrates- needed for amino acids which are used to make proteins.
Magnesium needed to make chlorophyll, which is needed for photosynthesis.
other minerals such as potassium and phosphates and needed for things like making
DNA and cell membranes.
Lack of these nutrients can cause deficiency symptoms
Lack of nitrates ­ the plant has STUNTED growth, because proteins are needed
for growth,
Lack of Magnesium- the leaves start to turn YELLOW because chlorophyll in
needed to make the plants green in colour.…read more

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All the important elements are recycyled, ready to make
new plants and put back into the food chain.
Managing food production
The efficiency of food production can be improved.
By reducing the nbumber of stgaes in the food chain
You can grow crops on the field for humans rather than grazing the animals.
People need a varied diet to stay healthy and there is a lot of demand for meat
products Only 10% of what beef cattle eat becomes useful meat for people to
eat.…read more

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