Size and Surface Area 3A

Question 1

Why do cells need exchange surfaces

Answer 1

Cells need to take in oxygen and nutrients
Need to excrete waste products like carbon dioxide and urea
Heat needs to be exchanged so that organisms are able to stay at roughly the same temperature

Question 2

How to calculate volume

Answer 2

Measure each side of the object or cube and times them by each other

Question 3

How to calculate surface area

Answer 3

Find the area of each face and add them together

Question 4

Larger the organism

Answer 4

smaller the surface area to volume ratio

Question 5

Define Size

Answer 5

Rate of heat loss depending on surface area smaller animals need a relatively high metabolic rate in order to generate enough energy to stay warm

Question 6

Define shape

Answer 6

Compact shape - small surface area relative to volume reducing heat loss
Less compact increases heat loss

Question 7

Arctic Fox Adaptations

Answer 7

Body temp 37 degrees Celsius
Average outside temp 0 degrees Celsius

Small ears and a round head to reduce SA:V ratio and reduce heat loss

Question 8

African bat-eared fox Adaptations

Answer 8

Body temp 37 degrees Celsius
Average outside temp 25 degrees Celsius
Large ears and more pointed nose to increase SA:V ratio and heat loss

Question 9

European Fox

Answer 9

Body temp 37 degrees Celsius
Average outside temp 12 degrees Celsius
Intermediate between two other foxes matching the temperature of its environment

Question 10

Why do multicellular organisms need transport systems

Answer 10

Diffusion across outer membrane too slow big distance between cells and environment
low SA: Vol ratio - difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface

Question 11

Behavioural and physical adaptations to aid exchange

Answer 11

Some animals which lose a lot of water due to high SA: Vol ratio have kidney structural adaptations so they produce less urine to compensate

Small animals living in cold regions need a large amount of high energy foods to maintain their high metabolic rates

Smaller mammals tend to hibernate or have thick fur when the weather turns cold

Elephants have developed large flat ears to increase their SA allowing them to lose more heat.
Hippos spend much of the day in water - behavioural adaptation to help them lose heat