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MCQ practice · SSC Biology Board questions · Chapter 4: Bioenergetics

Dhaka Board 2021

Which is an external factor of the photosynthesis process?

Think it through first, then pick an option.

  1. a Oxygen
  2. b Carbohydrate
  3. c Potassium
  4. d Enzyme
Answer and explanation

Correct answer: a Oxygen

Oxygen is an external factor; a higher concentration lowers the rate and a lower one raises it.

Why the other options are wrong

  • b Carbohydrate: The amount of carbohydrate is an internal factor; piling up in the leaf slows the rate.
  • c Potassium: Potassium is an internal factor; its shortage lowers the rate.
  • d Enzyme: Enzyme is an internal factor, since it belongs inside the cell; the question asks for an external one.