Biological Science:
Characteristics of living things

Mrs Gren
Living things have certain characteristics that make them easy to classify as living.

All living things:-

M = move
R = reproduce
S = are sensitive to changes in the internal and external environment

G = grow
R = respire (see right)
E = eliminate waste products
N = nutrition is required to produce energy to maintain life

This is known as MRS GREN to biologists.

Respiration is the chemical process that takes place in all living cells to make energy. Carbohydrates react with oxygen to produce carbon dioxide and water. This process should not be confused with breathing, which is the physical process of taking in oxygen through lungs, gills or absorption through the skin.

Mrs Gren and plants
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Sometimes people doubt whether plants show the characteristics of living things but they do. Movement, sensitivity and respiration are the characteristics that are the most difficult to justify.

Plants do move as demonstrated by geranium leaves that rotate to follow the Sun and pea plant tentacles that coil around a branch.

Plants do respond to changes in their environment as their shoots grow towards light and their roots grow downwards.

Plants carry out two main chemical processes, photosynthesis and respiration. Photosynthesis is the process by which plants make their own food which is then broken down by respiration to produce energy. People often do not realise that plant cells need to make energy to keep the plant working and hence staying alive.

Characteristics of living things Needs of living things
Animal, plant or fungi? - A simplified classification system
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