revison cards for section B3 in science

  • Created by: Elise
  • Created on: 22-11-11 20:40


The movement of particles (molecules or ions) from an area of high concentration to an area of low concentration.

Example where diffusion occurs:

  • gut
  • lungs
  • villi of small intestine
  • the placenta
  • leaf of a plant
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Alveoli are tiny air sacs in the lungs.

 In the alveoli, oxygen and carbon dioxide are exchanged in the blood, getting rid of the carbon dioxide and giving the oxygen to the red blood cells to be delivered to all of the muscles and organs.

Alveoli are elastic, which means that they can stretch when they are filled with air.

The singular of alveoli is one alveolus.

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Animal and Plant Cells/ Omosis

Animal cells and plant cells have features in common, such as a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.

Dissolved substances pass into and out of cells by diffusion. Water passes into and out of cells by osmosis.

nucleus:   contains genetic material, which controls the activities of the cell cytoplasm:   most chemical processes take place here, controlled by enzymes cell membrane: controls the movement of substances into and out of the cell mitochondria:   most energy is released by respiration here ribosomes: protein synthesis happens here

extra parts of a plant

cell wall : strengthens the cell chloroplasts: contain chlorophyll which absorbs light energy for photosynthesis

permanent vacuole: filled with cell sap to help keep the cell turgid.

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Picture Of Labelled Plant And Animal Cell


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Plasma, Cytoplasm Nucleoplasm; Protoplasm.

Plasma: the yellow coloured liquid compounent of blood in which blood cells are suspended.   Contains dissolved proteins, glucose, clotting factors, mineral ions, hormones and carbon dioxide. Plasma also serves as the protein reserve of the human body. It plays a vital role in intravascular osmotic effect that keep electrolyte in balance form and protects the body from infection and other blood disorders.

Cytoplasm: a water like substance that fills cells.The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cells internal sub-structures, except for the necleus.  

Nucleoplasm: a highly viscous liqud that surround the chromosomes and nucleoli.

Protoplasm: the living substance inside the cell. It is a general term of the Cytoplasm. Protoplasm is composed of a mixture of small molecules such as ions, amino acidsmonosaccharides and water, and macromolecules such as nucleic acids, protiens, lipids and polysaccharides.

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