OCR B4 the processes of life notes part 1

  • Created by: Edd
  • Created on: 10-06-12 13:35

All living things carry out a number of processes. Without the right body conditions, certain processes (eg osmosis) and proteins (eg enzymes) will not function properly.

Processes of life.

The processes of life carried out by all living things depend on chemical reactions within cells. These reactions need energy released by respiration. Respiration is one of seven major life processes. The phrase MRS GREN is a way to remember them:

M Movement All living things move - to find food, escape predators or find better growing conditions. R Respiration Getting energy from food to carry out cell processes. S Sensitivity Detecting changes in the surroundings such as light levels. G Growth All living things grow. R Reproduction Making new generations of a species. E Excretion Getting rid of waste - including carbon dioxide from respiration. N Nutrition Taking in and using food as a supply of energy.

Processes in plants.

The cytoplasm of every cell in a plant contains a biological chemical factory. Different chemical reactions occur that serve different purposes. Some reactions help the plant to repair itself, some to copy itself and some to help it grow. Other reactions allow the plant to break down large food molecules to release energy in respiration.


Enzymes are proteins that speed up chemical reactions in our cells.

Enzymes work best at their optimum temperature. This is why homeostasis is important - to keep our body temperature at a constant 37°C.

As the temperature increases, so does the rate of chemical reaction. This is because heat energy causes more collisions, with more energy, between the enzyme molecules and other molecules. However, if the temperature gets too high, the enzyme is denatured and stops working.



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