Lec 3 - Essential resources

Question 1

The 5 essential resources:

Answer 1

• Light
• Water
• CO2
• Mineral nutrients
• Temperature

Question 2

Limiting resource:

Answer 2

something that if it were in greater

supply would increase growth

Question 3

photosynthetically active radiation:

Answer 3

Wavelengths between
350 and 700 nm.
Driven by absorbance
spectrum of chlorophyll.
Chlorophyll is a
photoreceptor, it absorbs
light energy.

Question 4

Photorespiration occurs when

Answer 4

O2 binds with rubisco (enzyme)

Question 5

Water is required for:

Answer 5

Photosynthesis
Structural integrity (turgor)
Transport

Question 6

C3 photosynthesis:

Answer 6

ordinary photosynthesis

Vulnerable to photorespiration

Question 7

C4 photosynthesis

Answer 7

carbon storage and internal transfer
CO2 turned into a 4-carbon intermediate
Transfer to another cell for photosynthesis
Rubisco physically separated from O2 to avoid
photorespiration

Question 8

CAM photosynthesis

Answer 8

Crassulacean acid metabolism
CO2 captured at night, stored as malic acid
Malic acid used for photosynthesis during day

Question 9

Why don’t all plants use C4 photosynthesis?

Answer 9

Pumping CO2 direct takes about half the energy
More steps = more energy spent
Energy spent (getting CO2 to where it needs to be) vs.
Energy lost (to photorespiration)
More stomata closed (C4) vs. More stomata open (C3)
CAM = stomata closed during the day

Question 10

Nutrients can get to roots via

Answer 10

Diffusion (slow)
Movement of nutrients to the roots surface in response
to a concentration gradient.
Mass flow (fast)
Dissolved nutrients enter the plant as it absorbs water.