Biology

1.1 - Characteristics of Living Organisms

7 min

Intro & MRS GREN

Movement, respiration and sensitivity

Growth, reproduction and excretion

Nutrition & summary

note 1 of 1

The seven characteristics of living organisms

All living organisms - from a single bacterium to a blue whale - share seven life processes.
The first letters spell out MRS GREN, a way of remembering them: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.

What each characteristic means

Movement - An action by an organism, or part of one, that causes a change of place or position. Animals move their whole bodies towards things they need (water, food) and away from danger (predators); even plants can move parts of themselves a little, e.g. by growing in a particular direction.
Respiration - The chemical reactions in cells that break down nutrient molecules and release the energy needed for the organism's metabolism (all the chemical reactions happening in an organism's cells). Respiration supplies energy for the rest of them.
Sensitivity - The ability to detect and respond to changes in the internal or external environment. This covers responding to surroundings (a plant growing towards light, an animal reacting to a sound) and keeping internal conditions steady, such as body temperature and water content - e.g. sweating when too hot.
Growth - A permanent increase in the size and dry mass of an organism. Dry mass is the mass not counting the water in the tissues, so growth measured this way reflects a real, lasting increase in living material rather than a temporary change in water content.
Reproduction - The processes that produce more of the same kind of organism, so the species continues from one generation to the next.
Excretion - The removal of the waste products of metabolism, plus any substances in excess of what the organism needs. Waste products removed include carbon dioxide from respiration and urea in urine.
Nutrition - The taking in of materials used for energy, growth, and development. These include nutrients such as proteins, fats, and carbohydrates, along with vitamins and minerals.

key terms

TermDefinition

MovementAn action by an organism, or part of an organism, that causes a change of place or position.

RespirationThe chemical reactions in cells that break down nutrient molecules, such as glucose, to release energy for metabolism (all the chemical reactions in an organism).

MetabolismThe sum of all the chemical reactions that happen in a cell or in the whole organism.

SensitivityThe ability to detect and respond to changes in the internal or external environment.

GrowthA permanent increase in the size and dry mass of an organism.

Dry massThe mass of an organism not counting the water in its tissues.

ReproductionThe processes that produce more of the same kind of organism.

ExcretionThe removal of waste made by an organism's chemical reactions (metabolism), and of substances it has more of than it needs.

NutritionThe taking in of materials used for energy, growth, and development.

end of notes

Key points to remember

Take a quiz View flashcards

1.2 - Variety of Living OrganismsNext up

The seven characteristics of living organisms

All living organisms - from a single bacterium to a blue whale - share seven life processes.

The first letters spell out MRS GREN, a way of remembering them: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.

What each characteristic means

Movement - An action by an organism, or part of one, that causes a change of place or position. Animals move their whole bodies towards things they need (water, food) and away from danger (predators); even plants can move parts of themselves a little, e.g. by growing in a particular direction.

Respiration - The chemical reactions in cells that break down nutrient molecules and release the energy needed for the organism's metabolism (all the chemical reactions happening in an organism's cells). Respiration supplies energy for the rest of them.

Sensitivity - The ability to detect and respond to changes in the internal or external environment. This covers responding to surroundings (a plant growing towards light, an animal reacting to a sound) and keeping internal conditions steady, such as body temperature and water content - e.g. sweating when too hot.

Growth - A permanent increase in the size and dry mass of an organism. Dry mass is the mass not counting the water in the tissues, so growth measured this way reflects a real, lasting increase in living material rather than a temporary change in water content.

Reproduction - The processes that produce more of the same kind of organism, so the species continues from one generation to the next.

Excretion - The removal of the waste products of metabolism, plus any substances in excess of what the organism needs. Waste products removed include carbon dioxide from respiration and urea in urine.

Nutrition - The taking in of materials used for energy, growth, and development. These include nutrients such as proteins, fats, and carbohydrates, along with vitamins and minerals.