3.5.2.3 Factors affecting rate of photosynthesis

Question 1

List 5 factors affecting rate of photosynthesis (and which stage)

Answer 1

1. wavelength of light (LDR)
2. volume of water (LDR)
3. temperature (RUBISCO in LIR)
4. Light intensity (LDR)
5. Concentration of CO2 (LIR - carbon fixation)

Question 2

Light intensity

Answer 2

1. As light intensity increases, rate of photosynthesis increases
   - light intensity is the limiting factor
2. After light saturation point, as light intensity increases, rate of photosynthesis remains constant
   - light intensity is not limiting
   - CO2 concentration and / temperature are most likely the limiting factors

Question 3

What is net CO2?

Answer 3

The difference between CO2 uptake and CO2 production

- ie the difference between the rate of photosynthesis and the rate of respiration

Question 4

What is rate?

Answer 4

Amount / volume / concentration of X (oxygen) produced in a TIME period

Question 5

Link of temperature to agriculture

Answer 5

• use industrial heat lamps
• grow plants indoors - greenhouses
• creates optimal temperature for enzymes (rubisco)
• to maximise yield thus profit

Question 6

Temperature

Answer 6

1. As temperature increases, rate of photosynthesis increases
   - increase in successful collisions
   - * increased number of E.S complexes
   - RuBP combined with CO2 by rubisco
2. Decrease - as temperature increases, rate of photosynthesis decreases
   - enzyme denatured
   - Tertiary structure of active site changed
   - because hydrogen bonds broken
   - * active site no longer complementary to the substrate
   - less / no E.S. complexes

Question 7

Link of light intensity to agriculture

Answer 7

• artificial lights

- increase day length artificially