Lipids

Lipids MDCAT MCQs with answers

31 past paper MCQs on Lipids, 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.Butyric acid is a ______ carbon fatty acid. (MDCAT 2022)

  1. 4
  2. 6
  3. 12
  4. 3
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Correct answer: (a) 4

Butyric acid, the acid of rancid butter, has four carbons.

2.When glycerol reacts with a fatty acid, which type of chemical bond is formed? (MDCAT 2024)

  1. ester bond
  2. ether bond
  3. hydrogen bond
  4. ionic bond
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Correct answer: (a) ester bond

The acid and the alcohol condense to an ester, with water as the other product.

3.The hydrophilic end of a phospholipid molecule is polar because of the presence of: (MDCAT 2024)

  1. glycerol
  2. an amine group
  3. a fatty acid
  4. a phosphate group
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Correct answer: (d) a phosphate group

The charged phosphate head is what faces the water.

4.Fats are considered as a very efficient source of energy because they: (KMU MDCAT 2025)

  1. Produce ATP directly and without requiring respiration
  2. Enter into glycolysis without any modification
  3. Are highly oxidized compounds
  4. Generate multiple acetyl groups that produce more ATP
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Correct answer: (d) Generate multiple acetyl groups that produce more ATP

A fatty acid chain is cut into many acetyl groups, and each one takes a turn of the Krebs cycle.

5.Which of the following biological molecule releases highest energy from its one gram? (SIBA MDCAT 2025)

  1. Carbohydrates
  2. Lipids
  3. Protein
  4. Water
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Correct answer: (b) Lipids

A gram of fat gives about $38\,\mathrm{kJ}$, roughly twice what a gram of carbohydrate or protein gives.

6.The most abundant lipids in living things are: (SIBA MDCAT 2025)

  1. Terpenes
  2. Waxes
  3. Steroids
  4. Acylglycerols
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Correct answer: (d) Acylglycerols

The acylglycerols, the fats and oils, are much the commonest lipids.

7.Which of the following hormones in the body of animal is lipid-based in nature? (SZABMU MDCAT 2025)

  1. Insulin
  2. FSH
  3. Oxytocin
  4. Aldosterone
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Correct answer: (d) Aldosterone

Aldosterone is a steroid, built on the cholesterol skeleton; the other three are proteins or peptides.

8.Which of the following is common between aldosterone, sex hormone and cortisone ? (SZABMU MDCAT 2025)

  1. They are peptides
  2. They are Phospholipids
  3. They are steroids
  4. They are glycoproteins
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Correct answer: (c) They are steroids

All three are built on the cholesterol ring system, so all three are steroids.

9.Arachidonic acid, which is the precursor molecule for prostaglandins is: (SZABMU MDCAT 2025)

  1. A saturated fatty acid with 18 carbons
  2. An unsaturated fatty acid with 18 carbons
  3. A tri-unsaturated fatty acid with 20 carbons
  4. A tetra-unsaturated fatty acid with 20 carbons
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Correct answer: (d) A tetra-unsaturated fatty acid with 20 carbons

Arachidonic acid has twenty carbons and four double bonds.

10.When glycerol reacts with fatty acid, which type of chemical bond will form? (UHS MDCAT 2024)

  1. Ester Bond
  2. Ether Linkage
  3. Hydrogen Bond
  4. Ionic Bond
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Correct answer: (a) Ester Bond

A fatty acid and an alcohol group condense into an ester linkage, with water lost.

11.The hydrophilic end of phospholplid molecule is polar because of the presence of (UHS MDCAT 2024)

  1. Glycerol
  2. Amine group
  3. Fatty Acid
  4. Phosphate group
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Correct answer: (d) Phosphate group

The phosphate group carries a charge, which is what makes that end water loving.

12.What is the ester of fatty acids and long chain alcohol called? (KMU MDCAT 2024)

  1. Acylglycerol
  2. Glycerol
  3. Phospholipid
  4. Wax
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Correct answer: (d) Wax

A wax is the ester of a long chain fatty acid with a long chain alcohol.

13.Lipids, which do not contain fatty acid are: (KMU MDCAT 2024)

  1. Neutral lipids
  2. Phosphatidic acids
  3. Steroids
  4. Waxes
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Correct answer: (c) Steroids

Steroids are built on a four ring skeleton and carry no fatty acid at all.

14.Three hydrophobic fatty acid tails and a glycerol molecule join to form a: (SZABMU MDCAT 2023)

  1. Monoglyceride
  2. Diglyceride
  3. Triglyceride
  4. Phospholipid
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Correct answer: (c) Triglyceride

Glycerol esterified with three fatty acids is a triglyceride.

15.Which hormone is chemically a steroid? (NUMS MDCAT 2023)

  1. ADH
  2. Thyroxin
  3. Cortisone
  4. Insulin
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Correct answer: (c) Cortisone

Cortisone is built on the cholesterol ring system, so it is a steroid.

16.C-H bonds in lipids are important: (NUMS MDCAT 2023)

  1. As insulating material
  2. Providing more energy
  3. As exoskeleton
  4. As cuticle of leaves
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Correct answer: (b) Providing more energy

Fats are rich in carbon hydrogen bonds, so a gram of fat yields about twice the energy of a gram of sugar.

17.How many fatty acid molecules does an acylglycerol contain at minimum? (PMC MDCAT 2022)

  1. 1
  2. 2
  3. 3
  4. 4
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Correct answer: (a) 1

A monoacylglycerol carries a single fatty acid on the glycerol.

18.The palmitic acid melts at _____ (PMC MDCAT 2022)

  1. 8 C
  2. 72 C
  3. 63.1 C
  4. 7 C
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Correct answer: (c) 63.1 C

Palmitic acid is saturated and solid at room temperature, melting at about $63^{\circ}\mathrm{C}$.

19.Cholesterol is not present in ________ (PMC MDCAT 2022)

  1. milk
  2. egg white
  3. egg yolk
  4. fish
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Correct answer: (b) egg white

Egg white is protein and water; the cholesterol of an egg is all in the yolk.

20.Which is a steroid hormone? (NUMS MDCAT 2022)

  1. Cortisone
  2. Adrenaline
  3. Insulin
  4. Thyroxin
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Correct answer: (a) Cortisone

Cortisone is built on the cholesterol ring system, so it is a steroid.

21.Cholesterol is: (PMC Practice 2021)

  1. Animal sterol
  2. C27H46O
  3. 5 methyl groups
  4. All of these
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Correct answer: (d) All of these

Cholesterol is the animal sterol $\mathrm{C_{27}H_{46}O}$, built on the four ring steroid skeleton.

22.Nitrogenous bases such as choline and serine are a significant part of which of the following? (PMC Practice 2021)

  1. Sphingolipids
  2. Phospholipids
  3. Phosphodiester
  4. None of these
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Correct answer: (b) Phospholipids

A phospholipid carries a phosphate esterified to a base such as choline or serine.

23.Saponification number describes _____. (PMC Practice 2021)

  1. Unsaturation in fat
  2. Average molecular weight of fatty acid
  3. Acetyl number
  4. Acid number
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Correct answer: (b) Average molecular weight of fatty acid

The saponification number is the alkali needed to hydrolyse a gram of fat, so it measures the mean chain length.

24.Lipids store double the amount of energy as compared to carbohydrates because of: (PMC MDCAT 2020)

  1. High proportion of oxygen
  2. High C-O ratio
  3. Low proportion of Carbon
  4. High proportion of C-H
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Correct answer: (d) High proportion of C-H

A fat is rich in carbon hydrogen bonds and poor in oxygen, so more energy is released when it is oxidized.

25.Which of the following is an unsaturated fatty acid? (PMC MDCAT 2020)

  1. Oleic acid
  2. Palmitic acid
  3. Butyric acid
  4. Acetic acid
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Correct answer: (a) Oleic acid

Oleic acid has one double bond in its chain; the others are saturated.

26.Lipids contain double amount of energy as compared to the same amount of carbohydrates due to the presence of: (UHS MDCAT 2019)

  1. Higher proportion of C-H
  2. Higher proportion of C-O
  3. Higher proportion of Oxygen
  4. Low proportion of C-H bonds
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Correct answer: (a) Higher proportion of C-H

A fat is rich in carbon hydrogen bonds and poor in oxygen, so its oxidation yields more energy.

27.Which of the following is Unsaturated “Fatty Acid”? (UHS MDCAT 2018)

  1. Stearic Acid
  2. Palmitic Acid
  3. Butyric Acid
  4. Oleic Acid
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Correct answer: (d) Oleic Acid

Oleic acid has a double bond in its chain; the other three are saturated.

28.Which lipid is hydrophilic and soluble? (UHS MDCAT 2018)

  1. Triglycerides
  2. Phospholipids
  3. Waxes
  4. Terpenoids
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Correct answer: (b) Phospholipids

A phospholipid has a charged phosphate head that dissolves in water and two tails that do not.

29.Among the following, which acid is an unsaturated acid: (UHS MDCAT 2017)

  1. Butyric Acid
  2. Oleic Acid
  3. Palmitic Acid
  4. Both Oleic Acid and Palmitic Acid
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Correct answer: (b) Oleic Acid

Oleic acid has a double bond in its chain; butyric and palmitic acids are saturated.

30.Waxes are formed by combination of fatty acids with: (UHS MDCAT 2016)

  1. Alcohol
  2. Glycerol
  3. Serine
  4. Cysteine
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Correct answer: (a) Alcohol

A wax is the ester of a fatty acid with a long chain alcohol.

31.Which one of the following is an example of unsaturated fatty acid? (UHS MDCAT 2015)

  1. Butyric Acid
  2. Oleic Acid
  3. Palmitic Acid
  4. Acetic Acid
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Correct answer: (b) Oleic Acid

Oleic acid has a double bond in its chain; the others are saturated.

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