Size and Surface Area

Why do cells need to take in oxygen and nutrients?

For aerobic respiration.

What do cells need to excrete?

Carbon dioxide and urea.

What does the rate of heat exchange depend on?

Surface area to volume ratio.

How does the surface area to volume ratio relate to smaller animals?

Smaller animals have larger surface area to volume ratios.

How does the surface area to volume ratio relate to larger animals?

Larger animals have smaller surface area to volume ratios.

Why do multicellular organisms require exchange organs?

Diffusion across outer membranes is too slow for adequate substance exchange.

What is an example of an exchange organ in multicellular organisms?

Lungs.

What is the effect of size on heat loss?

Large volume equals small surface area, making it harder to lose heat.

What do smaller organisms require to stay warm?

A high metabolic rate to generate enough heat.

How does shape affect heat loss?

Compact shapes minimize heat loss while less compact shapes increase heat loss.

What adaptations do small desert animals have to reduce water loss?

Kidney structure adaptations to produce less urine.

What do small mammals in cold areas need to support their high metabolic rate?

Large amounts of high energy food like seeds and nuts.

How do large organisms in hot areas manage heat loss?

They have adaptations like large flat ears (elephants) to increase surface area or spend time in water (hippos).