Question

Distinguish between photorespiration and dark respiration.

Answer 1

Photo respiration:

• It takes place in photosynthetic green cells.
• It takes place only in the presence of light.
• It involves chloroplast, peroxisome and mitochondria.
• It does not involve Glycolysis, Kreb’s Cycle, and ETS.
• Substrate is glycolic acid.
• It is not essential for survival.
• No phosphorylation and yield of ATP.
• NADH₂ is oxidised to NAD⁺ .
• Hydrogen peroxide is produced.
• End products are CO₂ and PGA.

Dark respiration:

• It takes place in all living cells.
• It takes place all the time.
• It involves only mitochondria.
• It involves glycolysis, Kreb’s Cycle and ETS.
• Substrate is carbohydrates, protein or fats.
• Essential for survival.
• Phosphorylation produces ATP energy.
• NAD⁺ is reduced to NADH_2.
• Hydrogen peroxide is not produced.
• End products are CO₂ and water.