Flashcards in 3.3.1 Surface area to volume ratio Deck (22):

1

## The name given to the environment surrounding a cell

### tissue fluid

2

## Single celled organisms can match their metabolic demands by

### simple diffusion

3

## Exchange of materials in living organisms occurs at ..

### exchange surfaces e.g. lungs, intestine

4

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

###
its size and its metabolic rate

5

## Substances a cell exchanges with its environment include

### oxygen, carbon dioxide, nutrients (glucose)

6

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

###
simple diffusion

facilitated diffusion

osmosis

active transport

7

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

###
its gets smaller - less efficient exchange.

Special exchange surfaces therefore required i.e. lungs

8

## How do larger organisms cope with their increasing size?

###
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

## What is ficks law?

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

10

## How are specialised exchange surfaces adapted?

###
1. Large surface area to volume ratio

2. Thin - short diffusion pathway

3. Selectively permeable

4. Extensive blood supply to maintain concentration gradient

11

## single celled organisms SA: volume ratio is described as

### large surface area to volume ratio

12

## single celled organisms obtain their nutrients via..

### simple diffusion

13

## Why are insects usually small

### 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

##
Maths Skills:

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

### 6 cm2

15

##
Maths Skills:

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

### 1 cm3

16

##
Maths Skills:

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

### 6:1

17

##
Maths Skills:

How do you calculate the volume of a sphere?

###
4/3 x 3.14 x r3

(3.14 = pi, r = radius)

18

##
Maths skills:

How do you calculate the surface area of a sphere?

###
4 x 3.14 x r2

(3.14 = pi, r = radius)

19

## List 4 features of specialised exchange surfaces

###
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

##
Remember substances not only have to move into cells, they have to move into organelles too.

What would move into mitochondria and why?

### Oxygen and glucose for (aerobic) respiration

21

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

### as size increases, SA:volume ratio decreases

22