MCQ practice · SSC Biology Board questions · Chapter 4: Bioenergetics
Which of the following is an internal factor of respiration?
Think it through first, then pick an option.
- a Inorganic salts
- b Water
- c Carbon dioxide
- d Oxygen
Answer and explanation
Correct answer: a Inorganic salts
Inorganic salts are an internal factor: salts must be present in the cell.
Why the other options are wrong
- b Water: Water is in the list of external factors (water inside the cell is internal, but that is not what this option says).
- c Carbon dioxide: Carbon dioxide comes from the air, so it is external; the question asks for an internal factor.
- d Oxygen: Oxygen is taken from the air, so it is external; the question asks for an internal factor.
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