Chapter 1 - Principles Of Exchange And Transport

Question 1

What do animal tissues obtain?

Answer 1

Oxygen form the air
Glucose, fatty acids and amino acids from ingested food
Water

Question 2

What do plant tissues obtain?

Answer 2

Oxygen form air
Carbon dioxide from air
Inorganic ions from soil solution
Water

Question 3

What does a surface need to have to exchange substances?

Answer 3

It needs to be moist and permeable

Question 4

Why do mammals and plants require specialised exchange surfaces?

Answer 4

It depends on the size and shape of an organism, because both these factors affect the surface area-to-volume ratio

Question 5

What is surface area?

Answer 5

Represented as the total number of cells in direct contact with the surrounding environment

Question 6

What is volume?

Answer 6

The total three dimensional space occupied by metabolically active tissues

Question 7

Is it better to have a small or large surface area-to-volume ratio?

Answer 7

Large

Question 8

What reasons would an organism need a specialised exchange/absorptive surface?

Answer 8

It has an impermeable surface,
Large,
Small SA-V ratio,
High metabolic rate

Question 9

Methods of increasing absorptive surface

Answer 9

Evagination (outfolding) of the surface
Invagination (infolding) of the suface
Flattening if the organism

Question 10

Where can the specialised surfaces be?

Answer 10

They can be internal exchange surfaces e.g. Fish gills and alveoli
They can be external exchange surfaces e.g. Folded external membranes of the external gills of young tadpoles

Question 11

Why are exchange surfaces thin?

Answer 11

So that the rate of diffusion is maximised

Question 12

Why does there need to be a large concentration gradient?

Answer 12

Diffusion will only occur across a surface if there is a concentration gradient.

Question 13

What is mass flow?

Answer 13

It is brought about by pressure differences existing within the organism.
Materials are moved by the pressure differences between the area where pressure is generated(source) and the area where the pressure is much less(sink)

Question 14

What are some examples of mass flow systems

Answer 14

Xylem tissue,
Phloem tissue,
Circulation in mammals,
Ventilation in mammals.

Question 15

What does the xylem do?

Answer 15

Transports water and mineral ions fro the roots to the leaves

Question 16

What does the phloem do?

Answer 16

Transport of sucrose(translocation) to roots and to growing regions.

Question 17

What does circulation in mammals do?

Answer 17

Transport of substances including oxygen, carbon dioxide, glucose, amino acids, lipids, and urea in the blood system around the body

Question 18

What happens during ventilation in mammals?

Answer 18

The bringing fresh air into the lungs and removing air with raised carbon dioxide levels and low oxygen levels,
It ensures that diffusion if respiratory gases can take place between the alveoli and the capillaries

Question 19

How do you maximise the rate of exchange?

Answer 19

Have a large surface area,
Have a moist surface, 
Have diffusion gradients for both oxygen and carbon dioxide,
Must be permeable,
Thin exchange surface.

Question 20

What is Ficks law?

Answer 20

Surface area x difference in concentration
___________________________________________
Rate of diffusion=. thickness of membrane

Question 21

Leaf adaptations for gas exchange

Answer 21

Leaves are thin,
Large and moist gas exchange surfaces of the spongy mesophyll,
Intercellular air spaces of the spongy mesophyll,
Stomata and two guard cells,
Waxy cuticle to reduce water loss