Transport in Animals Flashcards

All 6 cards in this deck

Name four substances that must be transported into an organism's cells.

Oxygen, water, dissolved food molecules and mineral ions.

Name two waste substances that must be transported out of an organism to be removed.

Carbon dioxide and urea.

Why can a single-celled organism rely on diffusion across its surface alone?

It has a large surface area : volume ratio and a short diffusion distance, so substances reach all of the cell fast enough.

True or false? As an organism gets larger, its surface area : volume ratio gets smaller.

True. Volume increases faster than surface area as size increases.

Why do multicellular organisms need specialised exchange surfaces and a transport system?

Their surface area : volume ratio is too small and diffusion distances to inner cells are too long, so diffusion alone is too slow.

Give four general features of an efficient exchange surface.

Large surface area, thin (short diffusion distance), good blood supply and moist.