Biological Molecules

Biological Molecules MDCAT MCQs with answers

10 past paper MCQs on Biological Molecules, from the Biological Molecules unit of MDCAT Biology. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.Hydrolysis is the reverse of which process? (MDCAT 2022)

  1. condensation
  2. oxidation
  3. reduction
  4. hydrogenation
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Correct answer: (a) condensation

Condensation joins two molecules and removes water; hydrolysis adds water back and splits them.

2.Name the biomolecule essential for information storage and transmission within cells. (SIBA MDCAT 2025)

  1. Carbohydrates
  2. Lipids
  3. Nucleic acids.
  4. Proteins
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Correct answer: (c) Nucleic acids.

DNA holds the information and RNA carries it, so the nucleic acids are the information molecules.

3.Hydrolysis process is a reverse of -------------------- process. (UHS MDCAT 2023)

  1. Photolysis
  2. Condensation
  3. Deduction
  4. Convection
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Correct answer: (b) Condensation

Condensation joins two units with the loss of water; hydrolysis splits them by adding it back.

4.Which bond is the potential source of chemical energy for cellular activities? (SZABMU MDCAT 2023)

  1. C=O
  2. C-H
  3. C-R
  4. C-N
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Correct answer: (b) C-H

The carbon hydrogen bond is where the energy of a food molecule is stored.

5.Most abundant organic compound in mammalian cells are: (NUMS MDCAT 2023)

  1. Water
  2. Lipids
  3. Carbohydrates
  4. Proteins
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Correct answer: (d) Proteins

Proteins are the most abundant organic molecules of an animal cell; water is not organic.

6.Energy is by the breakdown of complex molecules into simpler ones, such reactions are called catabolic reactions (UHS MDCAT 2023)

  1. Released
  2. Consumed
  3. Produced
  4. Destroyed
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Correct answer: (a) Released

Catabolism breaks large molecules down and releases the energy held in their bonds.

7.Which of the following is the most abundant organic molecule in the human body? (PMC MDCAT 2022)

  1. Enzymes
  2. Lipids
  3. Water
  4. Proteins
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Correct answer: (d) Proteins

Proteins are the most abundant organic molecules of the body; water is not organic.

8.All organic biomolecules contain: (PMC MDCAT 2022)

  1. Iron and oxygen
  2. Carbon and hydrogen
  3. Carbon and nitrogen
  4. Carbon and Sulphur
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Correct answer: (b) Carbon and hydrogen

Every organic molecule is built on a skeleton of carbon carrying hydrogen.

9.Hydrolysis is the breakdown of polymer into its monomers by the addition of: (NUMS MDCAT 2022)

  1. Hydroxyl group
  2. Hydrogen
  3. Water
  4. Nitrogen
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Correct answer: (c) Water

Hydrolysis is the splitting of a polymer by the addition of water.

10.What type of atom is the carbon atom? (PMC Practice 2021)

  1. Divalent
  2. Monovalent
  3. Trivalent
  4. Tetravalent
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Correct answer: (d) Tetravalent

Carbon has four outer electrons and makes four bonds.

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