Exchange and transport systems: Size and surface area

Question 1

Do smaller organisms have a high or low surface area : volume ratio

Answer 1

High

Question 2

Do larger organisms have a higher or low surface area : volume ratio

Answer 2

Lower

Question 3

What does FICKS law state

Answer 3

It states that the rate of diffusion across an exchange surfaces is = (surface area x difference in concentration gradient) / thickness of surface

Question 4

How does the exchange and transport of substances like oxygen occur in single celled organisms and why

Answer 4

• Substances diffuse directly into and out of the cell across the cell-surface membrane
• Bc single-celled organisms have a higher SA:V ratio meaning their is a large surface for exchange to occur

Question 5

How does the exchange and transport of substances like glucose and oxygen occur in multicellular organisms and why

Answer 5

• Substances are transported and exchanged through a mass transport system that consist of specialised organs
  *Bc large multicellular organisms have a smaller SA:V ratio which means there is less surface area fir exchange to occur

Question 6

Define metabolic rate/activity

Answer 6

Organism is the amount of energy expended by that organism within a given period of time

Question 7

Explain how body shape and size impacts the rate if heat loss from an organism

Answer 7

• Smaller organisms have a higher SA:V ratio meaning that heat loss increased because there is a late surface (relative to the volume) which heat can escape

Question 8

Why do smaller organisms need to have a higher metabolic rate

Answer 8

So they are able to regulate thermal temperatures and keep up with the constant heat loss
(This req a high rate of oxygen too - via respiration)

Question 9

List and describe adaptations some animals have to aid exchange (Behavioural and physiological)

Answer 9

• Thick layers of fur - protect against the cold
• Eating high energy foods - to support high metabolic rates

Question 10

Name the variables in FICKS ;aw

Answer 10

• Concentration gradient
• Distance (Diffusion pathway)
• Surface area

Question 11

What is a specialised exchange surface

Answer 11

They are surfaces that allow the efficient transport of material across them via mechanisms such as active transport and diffusion