Flashcards in Organism Exchange - 3.3.1 Surface area to volume ratio Deck (22)
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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
