mMCQ.

Navigation Menu

Step into mMCQ.

Launch mMCQ. diagnostic

Explore mMCQ.

MDCAT prepFree DiagnosticPricing & SubscribeSign in

Resources

Terms & Conditions

mMCQ.

© 2021 - 2025 mMCQ.All rights reserved.

WhatsApp
  1. Home
  2. MDCAT
  3. Biology
  4. Bioenergetics
MDCAT
Biology
2012

Biology · Bioenergetics

Work through this past-paper style MCQ, then read the full explanation. Practice more biology questions on mMCQ with adaptive practice and topic analytics.

Question

Which one are intermediates in respiration and photosynthesis both?

Options
  • A

    Ribose and heptulose

  • B

    Glyceraldehyde and dihydroxyacetone

  • C

    Glucose and galactose

  • D

    Fructose and ribulose

Explanation

Glyceraldehyde and dihydroxyacetone are intermediates in both glycolysis (respiration) and the Calvin cycle (photosynthesis).

Ribose is a sugar molecule involved in nucleic acids (RNA) and not directly in respiration or photosynthesis. Heptolose is not a commonly recognized sugar molecule in the context of respiration or photosynthesis.

Yes, glyceraldehyde-3- phosphate (G3P) is an intermediate that is common to both respiration (specifically, glycolysis) and photosynthesis (specifically, the Calvin cycle). In glycolysis (a process of cellular respiration), glucose is broken down into two molecules of pyruvate. An early intermediate in glycolysis is glyceraldehyde-3-phosphate (G3P). It's a three-carbon sugar phosphate and plays a central role in the conversion of glucose to pyruvate, producing ATP and NADH in the process. Dihydroxyacetone phosphate (DHAP), on the other hand, is also an intermediate in both glycolysis (respiration) and the Calvin cycle (photosynthesis). In glycolysis, DHAP is an isomer of G3P and can be converted to G3P. In the Calvin cycle, DHAP is an intermediate in the conversion of G3P during the regeneration phase. So, both glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP) are intermediates that are shared between the pathways of cellular respiration and photosynthesis.

Glucose is a central molecule in respiration and is metabolized during glycolysis. It's also involved in photosynthesis indirectly through the Calvin cycle. Galactose is not a common intermediate in either process.

Fructose is not a central intermediate in either respiration or photosynthesis. Ribulose-1,5-bisphosphate (RuBP) is an important intermediate in both processes. It is a key molecule in the Calvin cycle of photosynthesis and is also involved in certain steps of respiration.

Keep practising Biology

Take the free 2 minutes diagnostic to map weak topics, then unlock full Biology, Chemistry, Physics, English, and Logical Reasoning practice for PKR 15,000/month.

Start free diagnosticExplore MDCAT

Tagged under Biology · Bioenergetics · 2012