Course Content
TRANSPORT IN PLANTS AND ANIMALS
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EXCRETION AND HOMEOSTASIS
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Biology Form 2
About Lesson

Excretion in Unicellular organisms (Amoeba)

Have a large surface area to volume ratio with a thin cell membrane.

Excretion occurs in two major ways;

  • By simple diffusion

Carbon (IV) oxide and nitrogenous wastes diffuse from the cell cytoplasm across the cell membrane to the surrounding water where they are lowly concentrated.

  • Use of contractile vacuole

Excess water and mineral salts accumulate in the contractile vacuoles, which enlarge to reach maximum volume. The enlarged contractile vacuoles move to the cell surface where they burst releasing the contents back into the surrounding.

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