3.3.1 Surface area to Volume Ratio

Question 1

Which out of smaller and larger organisms has a higher surface area to volume ratio

Answer 1

Smaller
(They have more surface area relative to their volume)

Question 2

Examples of substances exchanged between an organism and its environment

Answer 2

Oxygen, Carbon dioxide (gases)
Glucose, amino acids (nutrients)
Heat
Urea, ammonia (Nitrogen waste)

Question 3

Single- celled and very small multicellular organisms are very small so have a short…and a large…

Answer 3

Diffusion pathway
Surface area to volume ratio

Therefore they all carry out gas exchange in the same way (across their surface)

Question 4

Why do smaller mammals have a higher metabolic rate than larger mammals

Answer 4

Smaller mammals have a higher surface area to volume ratio so lose heat more quickly. Therefore they have a higher metabolic rate in order to maintain their body temperature

Question 5

Which size of mammals have a higher metabolic rate and why

Answer 5

Smaller mammals
They have a higher surface area to volume ratio so lose more heat so have a higher metabolic rate in order to maintain body temperature

Question 6

Larger mammals like elephants are at risk of over-heating due to heaving a very low surface area to volume ratio so not losing much heat. Therefore why do elephants have large ears

Answer 6

To increase heat loss as their ears have a higher surface area to volume ratio than the rest of their body

Question 7

What is one key adaptation of elephants to increase heat loss and help prevent them from overheating (as their low surface area to volume ratio means they lose less heat compared to smaller mammals)

Answer 7

Large ears