Question

1 g of dry green algae absorbs 4.7 10-3 mole of co2 per hour by photosynthesis. If the fixed carbon atoms were all stored after photosynthesis as starch, (c6 h10 o2)n ,how long would it take for the algae to double their own weight assuming photosynthesis takes place at a constant rate?

Answer 1

Answer:

The time taken for the algae to double their own weight is 11.19 hours

Explanation:

Rate of absorption of CO₂ = 4.7 × 10^-3 moles per hour

Since one mole of CO₂ has one mole of Carbon and 1 mole of starch has 6 moles of Carbon

Therefore starch formed = 4.7 × 10^-3/6 moles per hour

                                         = 7.83 × 10^-4 moles per hour

Molecular weight of starch (C₆H₁₀O₂) = 114.14 g/mol

Therefore, amount of starch formed in one hour = 114.14 × 7.83 × 10^-4 = 0.0893 gm

∴ In 1 hour, starch formed = 0.0893 gm

∴ for 1 gm to be formed the time required = 1/0.0893 hour = 11.19 hour