Excretion

Excretion

The removal of waste products of metabolism from the body

Metabolism

The chemical reactions that take place in cells to maintain life

Waste products of metabolism in plants

Oxygen, carbon dioxide and excess water

Source of oxygen waste in plants

Oxygen is produced during photosynthesis

Where oxygen is lost from plants

Oxygen diffuses out of the leaves through stomata

Source of carbon dioxide waste in plants

Carbon dioxide is produced during respiration

Where carbon dioxide is lost from plants

Carbon dioxide diffuses out of leaves and stems through stomata

Source of excess water in plants

Excess water is produced during respiration

Where excess water is lost from plants

Excess water is lost from leaves as water vapour during transpiration through stomata

Excretion in plants

Plants do not have specialised excretory organs; wastes diffuse out of the plant

Excretory organs in humans

Lungs, kidneys and skin

Role of the lungs in excretion

The lungs remove carbon dioxide and water vapour from the blood

Role of the kidneys in excretion

The kidneys remove urea, excess water and excess ions from the blood

Role of the skin in excretion

The skin removes excess water, salts and small amounts of urea in sweat

where is urea produced

in the liver from the breakdown of excess amino acids