gas exchange

Question 1

explain two ways in which the structure of fish gills are adapted for efficient gas exchange

Answer 1

-many lamellae for large surface area
-lamellae are thin for shorter diffusion distance

Question 2

a fish uses its gills to absorb oxygen from water. explain how the gills of a fish are adapted for efficient gas exchange

Answer 2

-many lamellae for larger surface area
-thin lamellae for shorter diffusion distance
- water and blood flow in opposite directions to maintain a concentration gradient
- water has low o2 concentration when next to blood
-circulation replaces saturated blood with oxygen
-ventilation replaces water (as oxygen is removed)

Question 3

explain how the counter current mechanism in fish gills ensures the maximum amount of oxygen passes into the blood flowing through the gills.

Answer 3

water flows in opposite direction to blood so blood always passes water with a high concentration of o2. so maintains a concentration gradient

Question 4

what are the adaptations of leaf’s for gas exchange:

Answer 4

-flat -for larger surface area
-many stomata - pores to allow air to move in and out of leaf
-air spaces in leaf so shorter diffusion distance

Question 5

describe diffusion of CO2 for photosynthesis

Answer 5

-mesophyll cells photosynthesis co2 so reduce the concentration of co2 in cells
-co2 diffuses from the air spaces into the cell.
-this reduces the concentration of co2 in the air space. causing the co2 to move from the air outside the leaf into the air spaces inside the spongy mesopyll cell and eventually diffuse into palisade mesophyll where most photosynthesis occurs

Question 6

describe diffusion of o2

Answer 6

-mesophyll cells produce o2 in photosynthesis. resulting in an increase in o2 in the cells
- o2 diffuses from the cell into the air spaces
-this is leads to an increase in concentration in o2 in the air spaces. causing o2 from the air spaces to move out into the air outside the leaf

Question 7

give the adaptations of xerophytic plants to reduce water loss

Answer 7

-less stomata: less surface area
-pits in the stomata: reduce the concentration gradient
-rolled leaves: to reduce concentration gradient
-long hairs to trap water vapor : reduce the concentration gradient
-thick waxy walls on cuticles to increase diffusion distance