gas exchange exam questions

Question 1

describe a method you could use to find the surface area of a leaf. (4)

Answer 1

-draw around l eaf
-count boxes
-multiply by 2- for upper and lower surface of leaf

Question 2

adaptations of xerophytes.

Answer 2

hairy leaves
sunken stomata
curled leaves

increases humidity

Question 3

ii) The estimate does not provide a reliable value for the mean breathing rate of all insect species in the meadow.
Other than being an estimate, suggest and explain three reasons why this value would not be reliable.
1 ……………………………………………………………………………………………… (3)

Answer 3

-only 3 grasshoppers- small scale- unrepresentative
-grasshoppers are not the only insect in the meadow
-movement not restricted in meadow- rate of respiration is higher in meadow

Question 4

Describe and explain how the structure of the mammalian breathing system enables
efficient uptake of oxygen into the blood. (6)

Answer 4

-many alveoli- large surface area
-alveoli are thin- short diffusion pathway
-cartilidge rings keep trachea open
-cell membrane permeable to gases
-walls of capilleries are thin

Question 5

Explain how oxygen is loaded, transported and unloaded in the blood.
___________________________________________________________________
(6)

Answer 5

haemoglobin has high oxygen affinity
-loads in lungs
-at high partial pressures
-unloads at lower partial pressures
-in respiring cells
-unloading linked to high carbon dioxide concentration