AQA GCSE biology Unit 2!!

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Cells

All plant and animals cells have :

  • Mitochondria : where respiration takes place
  • Ribosomes : where proteins are made
  • Cytoplasm: where chemical reactions in a cell occur
  • Nucleus: controls the cell's activities and contains DNA
  • Cell membrane: semi permeable and it controls what goes in and out of cells.

Plant Cells have:

  • A cell wall: this makes sure the cell doesn't burst and also controls what goes in and out of cells, made of cellulose.
  • A permanent vacuole :This is made of cell sap.
  • Chloroplasts: contains chlorophyll which is used to make food for the plant from sunlight (photosynthesis)

How are cells adapted to specific functions?

Some cells e.g the cells in the small intestine have a LARGE SURFACE AREA and are one cell thick, this allows more food to be absorbed through the small intestine and into the bloodstream.

Palisade cells are the cells on the top part of the leaf, they have a large supply of chloroplasts so as much photosynthesis can take place as possible. they are also tightly packed together so many palisade cells can fit into one area. 

Cells in the pancreas have a large supply of ribosomes, this helps make hormones and enzymes (which are made of proteins)

Root hair cells in plants also have a large surface area, this is so it can absorb more water and nutrients from the soil.

Red blood cells are biconcave (you can just say concave in the exam), they have no nucleus so there is more room for oxygen.

Transporting materials in animal cells:

Diffusion: when particles move from an area of high concentration to an area of low concentration

Osmosis: the movement of water particles from an area of high concentration to an area of low concentration through a semi/partially permeable membrane.

Different types…

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