Measuring the Rate of Photosynthesis

Question 1

Rate of Photosynthesis can be measured using?

Answer 1

• Measuring CO2 Uptake
• Measuring O2 Production
• Measuring Biomass (Indirect)

Question 2

Measuring O2 Uptake

• How can it be measured?
• What does it produce - increase?
• What does the change in PH provide?

Answer 2

• Placing plant in an enclosed space with water/ CO2 interacts with water molecules
• Produces bicarbonate and hydrogen ions - increasing the acidity of the resulting solution
• Provides a measure of CO2 Uptake by a plant

Question 3

Measuring O2 Production
How can it be measured?
- What does it produce?

Answer 3

• Measured by submerging a plant in enclosed space with water attached to a sealed gas syringe/ measured by change in water level
• Oxygen produced will bubble out of solution

Question 4

Measuring Biomass (Indirect)

• How can it be measured?
• Why does plant need to be completely dehydrated before weighing

Answer 4

• Indirectly measured by change in plant’s biomass - requires plant to be completely dehydrated prior to weighing
• Ensure the change in biomass reflects a change in organic matter/ not water content

Question 5

Understanding for factors that effect photosynthesis

Answer 5

• Temperature/ light intensity/ carbon dioxide concentration are possible limiting factors on rate of photosynthesis

Question 6

Enzymes (Factors that effect photosynthesis)

• What is photosynthesis run by
• Any factor that effects enzymes effects the rate of …..

Answer 6

• Run by enzymes (same as respiration)

- Photosynthesis

Question 7

Temperature (Factors that effect photosynthesis)

• What happens to photosynthesis at cold temperatures?
• What does temperature speed upto?
• What happens to enzyme and photosynthesis when temperature gets to hot?

Answer 7

• Photosynthesis is reduced
• Rises until optimum temperature has been reached
• Slows down until the enzyme becomes denatured and photosynthesis stops

Question 8

Amount of carbon dioxide (Factors that effect photosynthesis)

• What happens at low/ medium concentration - what does it make/ what does it control?
• What low levels can CO2 exist at - what does this cause?
• What do high temperatures and other factors limit
• What does increased carbon dioxide increase?

Answer 8

• Combing of CO2 - makes glycerate 3 phosphate - controls the rate of photosynthesis
• 0.03% - changes in CO2 levels can have a big effect
• Limit the rate
• Increase photosynthesis upto a point

Question 9

Limiting Factors

• What is the greatest effect of photosynthesis?
• How many molecules of glucose can be made with .. molecules of CO2/ disregarding?

Answer 9

• whichever factor that is in least supply - light, temp, CO2
• 1 molecule of glucose / 6 molecules of carbon dioxide - no matter how much light there is