Size + Surface Area

Question 1

What is the relationship between size and SA:Vol of organisms?

Answer 1

As the size of an organism increases, its SA:Vol decreases

Question 2

What is the SA:Vol of small organisms?
What does this mean?

Answer 2

• have a high SA:Vol
• big surface area for exchange of substances and smaller distance from the outside of the organism to the middle of it
• can exchange substances across their surface

Question 3

What is the SA:Vol of larger organisms?
What does this mean?

Answer 3

• have low SA:Vol
• longer distance from outer to middle
• have higher metabolic rate → demands efficient transport of waste out of cells and reactants into cells →must have adaptations

Question 4

What are the two types of adaptations?

Answer 4

Physiological
Behavioural

Question 5

What are examples of physiological adaptations?

Answer 5

• layers of fur for insulation
• eating high energy food to support high metabolic rates
• migration
• adapted kidneys to produce less urine (when water is easily evaporated)

Question 6

What are examples of behavioural adaptations?

Answer 6

• hippos spending all day in water to prevent overheating
• lizards laying in the sun to warm up

Question 7

How do single cell organisms exchange substances?

Answer 7

diffuse substances directly into/ out of cell by membrane

Question 8

How do multicellular organisms exchange substances?

Answer 8

have speacialised exchange surfaces → can’t exchange by diffusion quickly enough

Question 9

What is the rate of heat loss dependent on?

Answer 9

An organisms surface area
→body size
→ shape

Question 9

What is the rate of heat loss like in smaller animals?

Answer 9

• heat is lost easily due to large SA:Vol

Question 10

What is the rate of heat loss like in larger animals?

Answer 10

• heat is lost less easily due to small SA:Vol

Question 11

How does shape effect rate of heat loss?

Answer 11

compact → small SA:Vol = minimises heat loss
less compact → larger SA:Vol = increases heat loss