IMO Practice Test — Respiration in Plants
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
Glycolysis is considered the most ancient, universal pathway because it:
Occurs in all organisms and needs no oxygen
Needs sunlight
Occurs only in mitochondria
Requires chlorophyll
Explanation: Glycolysis is common to all cells and works without oxygen, reflecting its early evolution.
Question 2 of 6
A seed respiring fat as its fuel will have an RQ of:
Less than 1 (about 0.7)
Exactly 1
Greater than 2
Infinity
Explanation: Fats need more O₂ to oxidise, so the RQ is below 1.
Question 3 of 6
During vigorous exercise, muscles switch to lactic-acid fermentation chiefly because:
Oxygen supply cannot keep up with demand
There is too much oxygen
Glucose is absent
Mitochondria disappear
Explanation: When O₂ is insufficient, muscles use anaerobic fermentation to keep making some ATP.
Question 4 of 6
Aerobic respiration yields far more ATP than fermentation because in aerobic respiration glucose is:
Completely oxidised to CO₂ and water
Only partly broken down
Not broken down at all
Turned into starch
Explanation: Complete oxidation through the Krebs cycle and ETC releases far more energy than partial breakdown.
Question 5 of 6
Krebs-cycle intermediates can be withdrawn to make amino acids. This shows respiration is:
Amphibolic
Purely catabolic
Purely anabolic
Independent of metabolism
Explanation: Supplying building blocks for synthesis while also breaking food down makes the pathway amphibolic.
Question 6 of 6
An RQ of infinity (or very high) indicates that respiration is:
Anaerobic (no oxygen consumed)
Aerobic with carbohydrate
Aerobic with fat
Not happening
Explanation: If CO₂ is released but no O₂ is used, the RQ is infinite — characteristic of anaerobic respiration.