Biology

revise for wednesday 8th december.

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  • Created by: Ella
  • Created on: 07-12-10 18:58

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CARBOHYDRATES: potatoes, pasta, bread, bananas, sugar and rice

A source of energy for other life processes. Sometimes referred to as fibre, which is actually just one - very common - type of carbohydrate.

 

FATS: cheese, butter, margarine and oils

Fats are needed to make cell membranes and to insulate our bodies. They also contain important fat-soluble vitamins.

 

PROTEINS: meat, fish, eggs and cheese

Growth and repair. 

FIBRE: wholemeal bread, fruit, vegetables and pulses The fibre or roughage in our diet is not digested, but is important because it allows the muscles in our intestines to move food through our system by peristalsis.

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enzyme

use protease used to pre-digest proteins during the manufacture of baby foods lipase used - together with protease - in biological detergents to break down - digest - the substances in stains into smaller, water soluble substances carbohydrase    used to convert starch syrup, which is relatively cheap, into sugar    syrup, which is more valuable - for example, as an ingredient in sports drinks isomerase used to convert glucose syrup into fructose syrup - fructose is sweeter than glucose, so it can be used in smaller amounts in slimming foods

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2Function of cells which animal and plant cells have in common

partfunction 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

Plant cells also have extra parts:

Extra parts of plant cells

partfunction 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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photosynthesis

The carbon dioxide needed for photosynthesis enters the leaf through tiny pores called stomata, which are mainly in the lower surface of the leaf.  The leaves are thin, so diffusion happens quickly, because the distance through which the gases have to diffuse is short. This ensures that carbon dioxide continues to enter the leaf by the passive process of diffusion. The carbon dioxide in the air spaces of the leaf is quickly absorbed into the cells and used for photosynthesis. Therefore a concentration gradient is maintained between the air outside the leaf and the air in the spaces between the leaf cells. Oxygen, which is produced as a by-product of photosynthesis, is also released into the atmosphere via diffusion through the open stomata.

6H2O + 6CO2 ----------> C6H12O6+ 6O2

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micro-organisms

There are five types of micro organisms; fungi, viruses, bacteria, algae and protozoa.

Bacteria: single cell spherical, spiral or rod shaped. Example include salmonella which causes food poisoning.

Fungi: Different sizes ranging from microscopic single celled yeasts used in bread and beer making to the macroscopic fungi which contain many cells such as moulds, mushrooms and toadstools.

Viruses: Are parasites which means that they can only survive inside cells of other living things. They cause infectious diseases like chicken pox, measles and conjunctivitis. They are the smallest of the micro organisms and can only be seen with a very powerful microscope.

Algae: Vary sizes: Single cell used in toothpaste to microscopic algae which contain many cells like seaweed.

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