B2 revision

just a few revision topics in biology unit 2

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Osmosis and diffusion

The movement of water from a dilute solution (lots of water) to a concentrated solution (less water) through a partially permeable membrane.

High concentration -------------------> low concentration

Used in lungs oxygen diffuses into the blood and carbon dioxide diffuses into the lungs.

Photosynthesis equation

Carbon Dioxide + Water ----> Glucose + Oxygen

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Cells and mitosis

Parts of a cell

Cytoplasm, Chloroplast, Vacuole, Nucleus, Cell membrane, Cell Wall

A cell nucleus contains 46 Chromosomes, which carry genes. Different versions of genes are called allels.

Mitosis: used for normal cell growth

  • Parent cell
  • chromosomes make identical copies of themselves
  • They line up along the centre
  • They move apart
  • two daughter cells form each with 46 identical chromosomes to the parent cell
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Temperature about the body

Too Hot:

-hair lies flat

-blood vessels dialate so heat is lost through the skin

-sweat is produced

Too Cold:

-goosebumps and hairs trap air

-blood vessels constrict and no sweat is produced

-shiver, respiration, releases heat.

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Enzymes and controlling blood sugar levels

Blood levels are controlled by the pancreas, diabetics do not produce enough insulin. Treatments are injections or a monitoring diet.

Enzymes have an optimum temperature and pH.

Changes in pH/temperature can denature  the enzyme so it's shape changes and the substrate can't bind to the active site.

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