MDCAT Biology — Biological Molecules
Biological Molecules is a core Biology topic in the PMDC MDCAT syllabus, covering 10 subtopics. Below are the subtopics to revise, how often the topic appears in past papers, and real past-paper MCQs to try.
Subtopics (10)
- Biological Importance of Water
- Biological Molecules (Definition and Classification)
- Biomolecules
- Carbohydrates
- Conjugated Molecules
- Lipids
- Nucleic Acids
- Proteins
- Ribonucleic Acid (RNA)
- Structure of DNA
How Biological Molecules is tested
Across the 16 MDCAT past papers on ParhaiKrlo, Biological Molecules accounts for 169 questions. It appears in all 16, about 10.6 questions a paper. The heaviest was MDCAT 2019, with 23 questions, and the most recent is MDCAT 2025, with 12.
| Paper | Questions |
|---|---|
| MDCAT 2025 | 12 |
| MDCAT 2024 | 10 |
| MDCAT 2023 | 10 |
| MDCAT 2022 | 10 |
| MDCAT 2019 | 23 |
| MDCAT 2018 | 20 |
| MDCAT 2017 | 13 |
| MDCAT 2016 | 10 |
| MDCAT 2015 | 11 |
| MDCAT 2014 | 16 |
| MDCAT 2013 | 8 |
| MDCAT 2012 | 5 |
| MDCAT 2011 | 6 |
| MDCAT 2010 | 3 |
| MDCAT 2009 | 6 |
| MDCAT 2008 | 6 |
Biological Molecules MCQs from the MDCAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · MDCAT 2025 · Biological Molecules
The complementary base pairing in DNA is important because it:
- A.Maintains the tertiary structure of enzymes
- B.Provides energy for all cell metabolism
- C.Enables protein to fold properly
- D.Allows DNA to act as a genetic blueprint during replication
Show answer
Answer: D. Allows DNA to act as a genetic blueprint during replication — Complementary base pairing lets DNA serve as an accurate template for replication (genetic blueprint).
- Q2 · MDCAT 2024 · Biological Molecules
Which option is correct about a chlorophyll molecule?
- A.Chemical formula C₅₅H₇₀O₆N₄Mg
- B.Porphyrin ring with nitrogen in centre
- C.Methyl group on second pyrrole ring
- D.Aldehyde group on second pyrrole ring
Show answer
Answer: A. Chemical formula C₅₅H₇₀O₆N₄Mg — The key marks A, the molecular formula of chlorophyll b. Options C and D are each also true of one kind of chlorophyll, so the question is loosely worded.
- Q3 · MDCAT 2023 · Biological Molecules
NAD is an important:
- A.Enzyme
- B.Coenzyme
- C.Hormone
- D.Vitamin
Show answer
Answer: B. Coenzyme — NAD (nicotinamide adenine dinucleotide) is a coenzyme — a non-protein helper molecule that carries electrons during metabolic reactions.