Mass Flow in Animals

Question 1

What type of ratio do multicultural organisms have ?

Answer 1

• Small surface are to volume ratio

Question 2

Why do multicellular organisms have a circulatory system ?

Answer 2

• They have a small SA:Vol ratio
• And a higher metabolic rate
• So transport of oxygen is inefficient by diffusion alone.

Question 3

Small animals

Answer 3

• They have a high surface area to volume ratio
• Its cells are very close to the blood/heart
• So diffusion is fast enough for exchange of nutrients/gases/waste.

Question 4

Describe the circulation of blood in a fish.

Answer 4

• Single circulatory system.

Question 5

Suggest some advantages that the human circulatory system has compared with that of a fish.

Answer 5

Question 6

Give features of a mass transport system.

Answer 6

• A network to move through (Vessels)
• A medium for movement (a fluid e.g blood)
• Maintains speed (e.g contraction of the heart + elastic recoil of the arteries helps to maintain the pressure gradient, thus speed)

Question 7

How does public perception of risk differ from actual risk ?

Answer 7

• People may overestimate risk if something is not under their control, is unfanmiliar or has particularly severe consequences.
• People underestimate risk if something only has an effect in the long term.

Question 8

Give some ethical issues surrounding the use of interverterbrates in research.

Answer 8

Some consider it wrong to harm any living creature. However others argue that intervertabrates are not complex enough to suffer stress or pain.

Question 9

Answer 9

Question 10

Explain why a snake needs a heart.
in other words explain the role of the heart

Answer 10

• To pump blood
• Which which will supply oxygen to body cells
• By mass transport
• As the sa to vol ratio is too small to allow difussion to occur at a sufficent rate.

Question 11

Answer 11

Hearts are an example of a mass transport system.

Animals need mass transport systems as their SA:V ratio is too small

Having a heart allows oxygen to be transported.

Improving gas exchange as blood is flowing faster through the body with a mass transport system.

Question 12

Model answer for what happens when the size of an organism increases

Answer 12

• Surface area to volume ratio decreases.
• Diffusion distance increases.
• Metabolic rate increases.

Question 13

What are the effects of damage to a mass transport system

Answer 13

• There will be smaller surface area to volume ratio.
• As well as a greater diffusion distance
• This will reduce the rate of diffusion.
• So there will be a reduction in rate of gas exchange.