Limiting factors

Question 1

2 principals of LF

Answer 1

1. rate of biochemical process, involving a series of rn, is limited by the slowest rn in the series
2. when biochemical process is affected by several factors, its rate is limited by that factor which is nearest its min. value

Question 2

3 effects of light

Answer 2

1. light intensity
2. light quality
3. compensation point

Question 3

Explain light intensity

Answer 3

• low light intensities, rate increases w increasing light intensity
• v high light intensities may damage chlorophyll and reduce the rate of photosynthesis

Question 4

Explain light quality

Answer 4

-absorption spectra: amt of light absorbed at diff wavelengths

• action spectra: rate of photosynthesis
• > peaks: absorption of light by accessory pigment

Question 5

Define compensation point

Explain

Answer 5

light intensity at which the rate of photosynthesis is equal to the rate of respiration

-> no gaseous exchange

Question 6

7 other effects that affect the rate of photosynthesis

Answer 6

1. CO2 conc.
2. Temp.
3. Water
4. Chlorophyll conc.
5. O2
6. Specific inhibitors
7. Pollutions

Question 7

Explain CO2 conc.

Answer 7

• dark rns

- @normal conditions, LF

Question 8

Explain the effect of water

Answer 8

-close stomata in response to wilting
-> prevent the entry of CO2
=> H2O deficiency reduces crop yield

Question 9

Explain chlorophyll

1. low conc.
2. caused by?

Answer 9

1. leaves become yellow

2. disease, ageing, mineral deficiency, lack of light

Question 10

Explain O2

Answer 10

-high-> inhibit

-competes with CO2 for active site of RuBP carboxylase
=>reduces overall rate of photosynthesis

Question 11

Explain inhibitor

Answer 11

• Herbicides, DCMU

- > short circuits non-cyclic flow of e-