Free NEET Biology practice
Cell: The Unit of Life: MCQs with Solutions
Compare cellular structures by location, membrane organisation, and function rather than memorising isolated names. These original questions focus on distinctions that make closely related options look plausible, especially between prokaryotic cells and eukaryotic organelles.
5 original practice questions — not previous-year paper reproductions. No account required.
By NEET Ninja · Updated
Before you answer
- Prokaryotes lack a membrane-bound nucleus but still possess genetic material and ribosomes. Absence of a nuclear envelope does not mean absence of DNA.
- Ribosomes are non-membranous structures involved in protein synthesis. Their sedimentation coefficients are not arithmetically additive.
- Membrane-bound organelles compartmentalise functions. Match each function to its specific site instead of treating all internal membranes as interchangeable.
Questions and worked answers
Choose an option before reading the answer. For a wrong answer, identify the step or concept that changed the result.
QUESTION 1
Which structure is absent from a typical bacterial cell?
- Plasma membrane
- Ribosomes
- Membrane-bound nucleus
- DNA
Answer: C — Membrane-bound nucleus
Bacteria are prokaryotes and their genetic material is not enclosed by a nuclear envelope. They do have DNA, a plasma membrane, and ribosomes. Selecting DNA would incorrectly equate the absence of a membrane-bound nucleus with the absence of genetic material.
QUESTION 2
Which ribosomes are typically found free in the cytoplasm of a eukaryotic cell?
- 50S
- 60S
- 70S
- 80S
Answer: D — 80S
Eukaryotic cytoplasmic ribosomes are typically 80S, made of 60S and 40S subunits. Prokaryotic ribosomes are 70S. S denotes a sedimentation coefficient influenced by size and shape, so 60S and 40S are not added arithmetically to give 100S.
QUESTION 3
Which organelle modifies, sorts, and packages many proteins received from the endoplasmic reticulum?
- Golgi apparatus
- Nucleolus
- Centrosome
- Peroxisome
Answer: A — Golgi apparatus
The Golgi apparatus receives material from the endoplasmic reticulum and participates in modification, sorting, and packaging for delivery. The nucleolus is associated with ribosome formation, the centrosome with microtubule organisation, and peroxisomes with specialised oxidative reactions.
QUESTION 4
The fluid mosaic model primarily describes which structure?
- The bacterial chromosome
- The plasma membrane
- A ribosomal subunit
- The cellulose cell wall
Answer: B — The plasma membrane
The fluid mosaic model describes a membrane as a lipid bilayer with associated proteins, many of which can move laterally. This explains membrane fluidity and organisation. It is not a model of the cellulose cell wall, which lies outside the plasma membrane in plant cells.
QUESTION 5
Where are the electron-transport-chain complexes of a mitochondrion located?
- Outer mitochondrial membrane
- Inner mitochondrial membrane
- Cytosolic ribosomes
- Nucleoplasm
Answer: B — Inner mitochondrial membrane
The respiratory electron-transport-chain complexes are embedded in the inner mitochondrial membrane. This membrane supports the proton gradient used in ATP synthesis. Many reactions of the citric acid cycle occur in the matrix, but that does not place the membrane-bound electron-transport chain there.
Study source and corrections
Use the matching chapter in NCERT Class XI Biology — Cell: The Unit of Life for the underlying concepts. These questions are written for NEET Ninja, not endorsed or supplied by NCERT or NTA.
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