Surface area and metabolism

Describe and explain the relationship between surface area to volume ratio

of the human body and metabolic rate.

1. As surface area to volume ratio increases, metabolic rate

increases

OR

(Humans with) a large surface area to volume ratio have

a high/fast metabolic rate;

Accept the converse for all marking points

Accept the relationship is proportional

Ignore ‘directly’ if prefixing proportional

Accept the relationship is positively correlated

2. (A large(r) surface area to volume ratio will) lose more heat;

Accept lose heat faster/more easily

3. (A high(er) rate of metabolism/respiration)

releases/provides/replaces heat

OR

(A high(er) rate of metabolism/respiration) maintains body

temperature;

Accept (a higher rate of metabolism/ respiration)

releases energy OR produces /generates hea

Name two structural features of the gills of a fish that increase their surface

area.

(Gill) lamella(e) and (gill) filament(s);

The damage to the gills causes uncontrolled cell division in the cells around

the capillaries in the gill filaments.

Other than surface area:volume ratio, describe one way this uncontrolled

cell division changes the gills, as shown in Figure 1.

Explain how this difference would affect gas exchange.

More cells (between water and capillary/ blood)

OR

Wider/thicker filament/lamella;

2. Longer diffusion pathway

OR

Longer diffusion distance;

3. (So) slower gas exchange

OR

(So) slower absorption of oxygen

OR

(So) slower release of carbon dioxide

OR

(So) slower rate of diffusion;