# Organism Exchange - 3.3.1 Surface area to volume ratio Flashcards

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1
Q

The name given to the environment surrounding a cell

A

tissue fluid

2
Q

Single celled organisms can match their metabolic demands by

A

simple diffusion

3
Q

Exchange of materials in living organisms occurs at ..

A

exchange surfaces e.g. lungs, intestine

4
Q

How much material that needs to be exchanged in an organism depends on

A

its size and its metabolic rate

5
Q

Substances a cell exchanges with its environment include

A

oxygen, carbon dioxide, nutrients (glucose)

6
Q

Exchange of materials in living organisms takes place via (4 types of transport)..

A

simple diffusion
facilitated diffusion
osmosis
active transport

7
Q

As an organism gets larger what happens to its surface area to volume ratio?

A

its gets smaller - less efficient exchange.

Special exchange surfaces therefore required i.e. lungs

8
Q

How do larger organisms cope with their increasing size?

A

They have specialised exchange surfaces - which have large surface area:volume ratio!

OR

they are flat and thin therefore no cell is too far away from the surface

9
Q

What is ficks law?

A

diffusion rate is directly proportional to surface area x difference in concentration divided by length of the diffusion pahway

10
Q

How are specialised exchange surfaces adapted?

A
1. Large surface area to volume ratio
2. Thin - short diffusion pathway
3. Selectively permeable
4. Extensive blood supply to maintain concentration gradient
11
Q

single celled organisms SA: volume ratio is described as

A

large surface area to volume ratio

12
Q

single celled organisms obtain their nutrients via..

A

simple diffusion

13
Q

Why are insects usually small

A

their tracheal system relies on diffusion, for this to be efficient the diffusion path needs to be short and this is only achieved if the insects are small

14
Q

Maths Skills:

If a cube had a side length of 1cm, what would it’s SA be?

A

6 cm2

15
Q

Maths Skills:

If a cube had a side length of 1cm, what would it’s volume be?

A

1 cm3

16
Q

Maths Skills:

What is the SA:V ratio of a cube with a side of 1cm

A

6:1

17
Q

Maths Skills:

How do you calculate the volume of a sphere?

A

4/3 x 3.14 x r3

3.14 = pi, r = radius

18
Q

Maths skills:

How do you calculate the surface area of a sphere?

A

4 x 3.14 x r2

3.14 = pi, r = radius

19
Q

List 4 features of specialised exchange surfaces

A
1. Large SA - increases rate of exchange
2. Thin - short diffusion distance
3. Selectively permeable - allows selected materials to cross
4. Diffusion gradient maintained - eg by movement of medium - blood, air
20
Q

Remember substances not only have to move into cells, they have to move into organelles too.
What would move into mitochondria and why?

A

Oxygen and glucose for (aerobic) respiration

21
Q

explain the relationship between size and surface area to volume ratio in organisms

A

as size increases, SA:volume ratio decreases

22
Q

explain why oxygen uptake is a measure of metabolic rate in organisms

A

oxygen used in respiration which is chemical process