Cell Biology – NDA Biology PYQs

Question [NDA 2012-III]
Which of the following groups is present in animal cells?
(a) Mitochondria, Cell membrane, Cell wall, Cytoplasm
(b) Chloroplasts, Cytoplasm, Vacuole, Nucleus
(c) Nucleus, Cell membrane, Mitochondria, Cytoplasm
(d) Vacuole, Cell membrane, Nucleus, Mitochondria

Answer: (c)
Animal cells have no cell wall. So option (a) is wrong — cell wall is in plants, not animals. Chloroplasts are only in plant cells. So option (b) is wrong. Option (c) is correct — nucleus, cell membrane, mitochondria, and cytoplasm are all found in animal cells. Option (d) includes vacuole, which is very small in animal cells and not a defining feature.

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Question [NDA 2013-I] — Osmosis
Consider the statements about osmosis in animal cells:

1. If water concentration outside is too high, the cell shrinks.
2. If water concentration outside is too low, the cell swells and bursts.
3. It is important to maintain a constant water potential inside the animal body.

(a) 1 only
(b) 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

Answer: (b) — 3 only
Statement 1 is wrong. If water concentration is high outside, water enters the cell — the cell swells, not shrinks. Statement 2 is also wrong. If water concentration is low outside, water leaves the cell — the cell shrinks, not swells and bursts. Only Statement 3 is correct. The body must maintain constant water potential. If it does not, cells either burst or shrink, which is dangerous.

Question [NDA 2014-II]
The site of cellular respiration in an animal cell is —
(a) Ribosome
(b) Endoplasmic reticulum
(c) Lysosome
(d) Mitochondria

Answer: (d)
Cellular respiration produces ATP (energy). This happens inside the mitochondria — specifically at the inner membrane. Ribosomes make proteins. ER transports materials. Lysosomes digest waste.

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Question [NDA 2018-II]
Which one of the following groups of cellular organelles contains DNA?
(a) Mitochondria, Golgi bodies, nucleus
(b) Mitochondria, plasma membrane, nucleus
(c) Chloroplast, nucleus, ribosomes
(d) Mitochondria, nucleus, chloroplast

Answer: (d)
Only three organelles contain DNA — mitochondria, nucleus, and chloroplast. Golgi bodies have no DNA. Plasma membrane has no DNA. Ribosomes have no DNA. The correct group is mitochondria + nucleus + chloroplast.

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Question [NDA 2018-III]
One of the additional functions of Smooth Endoplasmic Reticulum (SER) is —
(a) protein synthesis
(b) lipid synthesis
(c) storage of biomolecules
(d) detoxification of toxic substances

Answer: (d)
Smooth ER makes lipids (option b is also a function, but the question asks for the “additional” function). The additional function tested here is detoxification — Smooth ER breaks down harmful toxic substances inside the cell. Protein synthesis is done by ribosomes. Storage is done by vacuoles.

Question [NDA 2019-II]
Which one of the following organelles of a mammalian cell is rich in hydrolytic enzymes?
(a) Mitochondria
(b) Ribosomes
(c) Nucleus
(d) Lysosome

Answer: (d)
Lysosomes are called “suicide bags” because they are full of hydrolytic enzymes. These enzymes break down foreign particles, old organelles, and waste material inside the cell. Mitochondria make energy. Ribosomes make proteins. The nucleus stores DNA.

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Question [NDA 2019-III]
Mitochondria are able to produce their own —
(a) Nucleus
(b) Chloroplasts
(c) Digestive enzymes
(d) Proteins

Answer: (d)
Mitochondria have their own DNA and their own ribosomes. This means they can make their own proteins. They cannot make a nucleus, chloroplasts, or digestive enzymes.

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Question [NDA 2020-I]
In prokaryotic organisms, nuclear region is not surrounded by a membrane. This undefined nuclear region is known as —
(a) Nucleic acid
(b) Nucleolus
(c) Nucleosome
(d) Nucleoid

Answer: (d)
In prokaryotic cells, DNA floats in a region called the nucleoid. There is no membrane around it. Nucleolus is a structure inside the nucleus of eukaryotic cells. Nucleosome is DNA wrapped around histone proteins. Nucleic acid is a general term for DNA or RNA.

Question [NDA 2021-I]
In mitochondria, ATP synthesising chemical reactions take place in the —
(a) Outer membrane
(b) Matrix
(c) DNA of mitochondria
(d) Inner membrane

Answer: (d)
ATP production happens at the inner membrane of the mitochondria. This is where the enzyme complexes for energy production are located. The matrix has other metabolic reactions. The outer membrane is a barrier. DNA of mitochondria stores the genetic information of the mitochondria but is not the site of ATP synthesis.

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Question [NDA 2021-II]
Movement of materials to different parts of cytoplasm and nucleus is generally carried out by —
(a) Ribosomes
(b) Mitochondria
(c) Lysosomes
(d) Endoplasmic reticulum

Answer: (d)
The endoplasmic reticulum works like a road network inside the cell. It carries materials — proteins, lipids — to different parts of the cell and to the nucleus. Ribosomes make proteins. Mitochondria make energy. Lysosomes digest waste.

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Question [NDA 2022-I]
A cell is unable to synthesise lipids. Which of its cell organelles might be defective?
(a) Golgi bodies
(b) Lysosomes
(c) Mitochondria
(d) Smooth endoplasmic reticulum

Answer: (d)
Smooth ER is responsible for making lipids (fats) in the cell. If the cell cannot make lipids, the Smooth ER is not working. Golgi bodies package and dispatch. Lysosomes digest. Mitochondria make energy.

Question [NDA 2024-I]
Which of the following statements regarding animal cell membrane is correct?
(a) Made of phospholipids only
(b) Made of proteins only
(c) Made of phospholipids and proteins only
(d) Made of phospholipids, proteins and cholesterol

Answer: (d)
The cell membrane is a phospholipid bilayer. Protein molecules are embedded in it. Cholesterol is also present. It plays a role in making the membrane fluid and stable. The correct answer is all three together — phospholipids + proteins + cholesterol.

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Question [NDA 2025-I]
Which is the correct base pairing found in a normal DNA molecule?
(a) Adenine pairs with Thymine
(b) Adenine pairs with Guanine
(c) Adenine pairs with Cytosine
(d) Thymine pairs with Guanine

Answer: (a)
DNA base pairing follows a strict rule: A pairs with T, and G pairs with C. Adenine always pairs with Thymine. Guanine always pairs with Cytosine. These pairings are held together by hydrogen bonds.