3.1 Surface Area to Volume Ratio

Question 1

How is SA:V calculated?

Answer 1

Divide surface area (l x w x number of sides) by volume (l x w x h)

Question 2

What is the relationship between size an SA:V?

Answer 2

• As size increases, SA:V decreases
• Thinner structures increase SA:V

Question 3

What is the relationship between SA:V and metabolic rate?

Answer 3

• As SA:V ratio increases metabolic rate increases (more energy used within given time)
• As rate of heat loss per unit body mass increases
• So organisms need a higher rate of respiration
• To release enough heat energy to maintain a constant body temperature