OESWTE: Surface area to volume ratio

Question 1

Give the equation to calculate surface area to volume ratio:

Answer 1

Surface area: volume = surface area / volume

Question 2

Why is it a benefit for very small organisms to have a very large surface area to volume ratio?

Answer 2

• Dont require adaptations for substance exchange
• Substances can be exchanged across their surface

Question 3

How does substance exchange occur in single-celled organisms?

Answer 3

Substances can diffuse directly in and out of the cell across the cell-surface membrane.

Question 4

Give two reasons why gas exchange by diffusion is inappropriate for multicellular organisms:

Answer 4

1) Some cells are deep within the body
2) Larger animals have a low SA:V

Question 5

Explain why some cells being deep within the body makes gas exchange by diffusion is inappropriate for multicellular organisms:

Answer 5

There is a large distance between them and the outside environment.

Question 6

Explain why larger animals having a low SA:V makes gas exchange by diffusion is inappropriate for multicellular organisms:

Answer 6

It is difficult to exchange sufficient substances through a small outer surface.

Question 7

The rate of heat loss from an organism depends on its ________.

Answer 7

Surface area.

Question 8

Animals in a warm climate will have a _______ SA:V.

Answer 8

Large

Question 9

Animals in a cold climate will have a _______ SA:V.

Answer 9

Small

Question 10

A large SA:V ________ the rate of heat loss.

Answer 10

Increases

Question 11

A small SA:V _______ the rate of heat loss.

Answer 11

Decreases

Question 12

Why do animals with a large SA:V lose more water than animals with a small SA:V?

Answer 12

Increased rate of evaporation as there is more surface

Question 13

Why do small mammals living in cold climates need to eat large amounts of high energy food?

Answer 13

Maintain their high metabolic rates.