L3 - Biogeochemical Cycles

Question 1

What are the unique properties of water?

Answer 1

1. Forces of attraction - hydrogen bonding
   
   2. Water exists as liquid over range of temps
   3. Liquid water slowly changes temp
   4. Takes a lot of energy for water to evaporate
   5. Liquid water can dissolve compounds
      Water expands when It freezes

Question 2

Residence time

Answer 2

average length of time a substance spends in a reservoir under steady state conditions

Question 3

Saturation

Answer 3

all pores are full of water and gravitational water is lost

Question 4

Field capacity

Answer 4

when water is not flowing out but there is still water in the soil

Question 5

Wilting point

Answer 5

no more water can be removed

Question 6

What accounts for difference between PET and AET?

Answer 6

PET is high at equator however in some regions such as north Africa there is no water for evaporation

Question 7

What are the photosynthetic pathways?

Answer 7

1. C3 (Calvin cycle)
2. C4 (Hatch-Slack_)
3. Crassulacean Acid Metabolism (CAM)

Question 8

C3 plants:

Answer 8

Open stomata and co2 diffuses into mesophyll cell
Rubisco is in leaf and mesophyll cells

Question 9

C4 plants:

Answer 9

Co2 pumped to mesophyll cell
Fast diffusion and stomata does not mean to open as much - loses less water
Diffusion larger and faster

Question 10

Enhanced carbon uptake due to?

Answer 10

1. Co2 fertilization - mostly impacts C3 plants (C4 already optimised)
2. Longer growing season
3. Nutrient availability increase

Question 11

CAM:

Answer 11

Temporal separation
Carbon fixation at night and Calvin cycle during the day
Stomata closed during the day