Gas Exchange Flashcards
1
Q
what are common features that increase the rate of diffusion?
A
- large surface area
- short diffusion pathway
- steep concentration gradient
2
Q
explain gas exchange of single celled organisms.
A
- absorb and release gases by simple diffusion through their cell surface membrane
- large surface area
- short diffusion pathway
3
Q
which has a lower concentration of oxygen? water or air?
A
water
4
Q
where does water go in a fish?
A
enter the fish through its mouth and passes out through its gils
5
Q
what are gills made of?
A
gill filaments
6
Q
what covers the gill filaments?
A
lamellae
7
Q
what gives fish a large surface area?
A
many gill filaments and many lamellae covering these filaments
8
Q
what do lamellae have?
A
- lots of blood capillaries
- thin layer of cells
= speeds up the diffusion rate
9
Q
explain the counter current system.
A
- in gills of fish water flows in one direction and blood flows in another direction
- steep concentration gradient is maintained across the whole length of the lamellae
- so more oxygen diffuses from the water into the blood
10
Q
what are the organisms that require a specialised gas exchange system?
A
- in the leaves of dicotyledonous plants
- across the gills of fish
- tracheal system of an insect
11
Q
what is the main gas exchange surface for plants?
A
- mesophyll cells
12
Q
where do gases move in and out for plants?
A
stomata
13
Q
when does stomata open and close?
A
- stomata open when there is gas exchange
- stomata close when plant is losing too much water
14
Q
A
