Lesson 1 - Specialised Exchange structures Flashcards
1
Q
Why can single-celled organisms use diffusion alone to survive?
A
- Low metabolic rate, so O2 and CO2 demand is low
- High SA:V ratio
2
Q
Why do larger organisms need specialised exchange systems?
A
- Made up of millions/billions of cells, arranged into tissues, organs and organ systems. This causes a higher metabolic rate.
- Cells deep in the body, so large distance for mineral ions to diffuse.
- Low SA:V ratio, so gases couldn’t be exchanged fast enough for the organisms to survive.
3
Q
Volume of a sphere equation
A
4/3 x pi x r3
4
Q
Surface Area of a sphere equation
A
4 x pi x r2
5
Q
Features of specialist exchange surfaces
A
- Increased surface area
- Area needed for exchange and overcomes SA:V ratio limitations on larger organisms
- Thin layers
- Distance substances have to diffuse are short, process is fast and efficient
- Good blood supply (pump)
- Creates a steeper concentration gradient, so diffusion is faster. Substances are constantly delivered & removed from the exchange surface.
- Ventilation
- For gases, a ventilator system maintains a high concentration gradient.
6
Q
from mm to nm
A
x 1,000,000
7
Q
from m to nm
A
x 1,000,000,000
8
Q
from cm to um
A
x 10,000
9
Q
from nm to mm
A
/ 1,000,000
10
Q
from nm to um
A
/ 1,000
