Class X Biology - Chapter: Life Processes - Topic: Photosynthesis Rate Numerical Problems

Problem 1: Rate of Oxygen Release

A hydrilla plant releases 10 bubbles of oxygen in 5 minutes when kept under optimal conditions. If the experiment is repeated with the same plant but under conditions of higher light intensity, and it releases 15 bubbles in 5 minutes, what is the percentage increase in the rate of photosynthesis?

Solution:

Rate of photosynthesis is directly proportional to the rate of oxygen release.

• Initial rate: 10 bubbles / 5 minutes = 2 bubbles/minute
• New rate: 15 bubbles / 5 minutes = 3 bubbles/minute

Increase in rate = New rate - Initial rate = 3 - 2 = 1 bubble/minute

Percentage increase = (Increase in rate / Initial rate) * 100 Percentage increase = (1 bubble/minute / 2 bubbles/minute) * 100 = 50%

Therefore, there is a 50% increase in the rate of photosynthesis.

Problem 2: Carbon Dioxide Uptake (Conceptual)

If a plant absorbs 6 molecules of carbon dioxide to produce one molecule of glucose during photosynthesis, how many molecules of carbon dioxide would be required to produce 5 molecules of glucose?

Solution:

The balanced equation for photosynthesis is: 6CO2 + 6H2O → C6H12O6 + 6O2

This shows that 6 molecules of CO2 are required to produce 1 molecule of glucose.

To produce 5 molecules of glucose: Required CO2 = 5 molecules of glucose * (6 molecules CO2 / 1 molecule glucose) Required CO2 = 30 molecules of CO2

Therefore, 30 molecules of carbon dioxide would be required to produce 5 molecules of glucose.