B2 bullet points

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  • Created by: Aya
  • Created on: 27-11-10 02:03

Animal cells

- every cell is surrounded by a cell membrane that controls what goes in and out if the cell.

- organelles such as nucleus controls the cell's activity and chemical reactions occuring in the cytoplasm.

- mitochondria use glucose to release energy.

- ribosomes synthesis (make) protein.

- all ells in the body differ from one another. These specialise cells have features that help them to do their jobs successfully.

=> sperm cell: has a tail and lots of mitochondria because they move continuously looking for and egg.

=> epithelial cell: has cilia moving constantly to move particles along.

=> muscle cell: have fibrils that can shorten.

=> nerve cell: has fibers to carry electrical impulses.

Plant cells

- plant cells are the only cells that have cell walls giving them support and strenght.

- in the cytoplasm is found an organelle called chloroplast and it contains the green pigment chlorophyll.

- chlorophyll is a chemical used in photosynthesis to produce glucose.

- the vacuole contains cell sap which is salt, sugar and water.

- plant cells are specialised for specific jobs

=> palisade cells: are found in the leaf and packed with chloroplast.

they help in absorbing the maximised amount of sunlight during photosynthesis.

=> root hair cells: have extentions to absorb water and dissolved mineral ions.

=> xylem vessels: are dead cells arranged in tubes with no end walls between them. They transport water from roots through the stem to the leaves.

::: each root hair is only 0.1 mm long.

Cells make tissues make organs

- some organisms are uni-cellular and others are multi-cellular.

- specialised cells group together to form tissues.

=> epithelial tissues: cover the surface of organs as skin and lines all tubes.

- groups of tissues group together to make the complex organs.

=> arteries: are aogans lined with epithelial tissues and surrounded by muscle tissues and fibrous tissues.

- plant cells group together to make tissues like epidermal, photosynthetic and vascular.

- plant organs are root, stem and leaves.

=> vascular tissue: transport water and sugar.

=> epidermal tisse: protects the tissue.

=> photosythetic tissue: produce glucose.


- smelly particles spread through the air. It can spread many meters.

- diffusion is the movement of particles from area of high concentration to area of low concentration. As particles diffuse their concentration decrease.

- diffusion happens also in liquid. The difference in concetration is the " concentration gradient ".

- the greater the concentration gradient the faster the rate of diffusion.

- particles in liquid diffuse through a partially permeable membrane.


- a dilute solution contains more water particles than a concentrated one.

- osmosis is the diffusion of water across a partially permeable membrane.

- in osmosis there is always a net movement from dilute to concentrated solutions.

::: water moves from soil to root hair cells to stem cells then to leaves by osmosis. From the dilute solution to  the concentrated step by step.

- if too…


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