E&T: Size and Surface Area

Question 1

Describe the SA:V ratio for smaller animals:

Answer 1

Higher

Question 2

Why do multicellular organisms need exchange organs + mass transport systems?

Answer 2

Diffusion across outer membrane is too slow as:

• Some cells are deep within body = large diffusion pathway
• Low SA:V ratio = difficult to exchange enough substances

Question 3

How does body size affect heat exchange?

Answer 3

• Large volume = relatively small surface area = harder to lose heat

Question 4

How does body shape affect heat exchange?

Answer 4

• Compact shape = small SA relative to volume = minimal heat loss

Question 5

Apart from physical, what other adaptations can an animal have with its environment?

Answer 5

Behavioural

Physiological

Question 6

Give examples of physiological adaptions to an environment:

Answer 6

• Small desert mammals have kidney structure adaptions to produce less urine
• Elephants have large flat ears to increase SA = more heat loss

Question 7

Give examples of behavioural adaptions to an environment:

Answer 7

• Small mammals in cold regions = eat large amounts of high energy foods, eg. nuts + seeds
• Hippos spend most of day in water = aids heat loss.