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Cell theory; prokaryotic/eukaryotic, plant and animal cells: NEET MCQs with answers

109 questions on this topic of Cell Structure and Function (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.

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easy

1. Which organisms are eukaryotes?

  1. Mycoplasma and PPLO
  2. All of the organisms that lack a nuclear membrane
  3. Protists, plants, animals and fungi
  4. Bacteria and blue-green algae
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Answer: (C) Protists, plants, animals and fungi

All protists, plants, animals and fungi are eukaryotes. Eukaryotic cells have extensive compartmentalisation by membrane-bound organelles and an organised nucleus with a nuclear envelope.

NCERT Class 11

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2. The smallest cells known, about 0.3 μm in length, are:

  1. Bacteria
  2. Mycoplasmas
  3. Human RBCs
  4. Yeast cells
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Answer: (B) Mycoplasmas

Mycoplasmas are the smallest cells (0.3 μm); bacteria are 3–5 μm; human RBCs are about 7.0 μm in diameter.

hard

3. Several ribosomes may attach to a single mRNA and form a chain called a:

  1. Plasmid
  2. Mesosome
  3. Nucleoid
  4. Polysome (polyribosome)
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Answer: (D) Polysome (polyribosome)

Ribosomes of a polysome translate the mRNA into proteins.

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4. A student isolates an unidentified single-celled organism. Biochemical and microscopic examination reveals the following features: (i) 70S ribosomes in the cytoplasm (ii) Peptidoglycan cell wall (iii) Absence of membrane-bound organelles (iv) Extrachromosomal small circular DNA molecules carrying antibiotic resistance markers Which of the following is the most definitive conclusion about this cell?

  1. It is a primitive unicellular eukaryote such as yeast.
  2. It possesses a plasmid and belongs to Kingdom Monera.
  3. It is an obligate intracellular eukaryotic parasite.
  4. It possesses a nucleus without a nucleolus.
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Answer: (B) It possesses a plasmid and belongs to Kingdom Monera.

The presence of a peptidoglycan cell wall, 70S ribosomes, absence of membrane-bound organelles, and circular plasmid conferring antibiotic resistance are hallmark characteristics of prokaryotic cells (Kingdom Monera).

easy

5. Regarding the structure of bacterial flagella, which part represents the longest portion and extends from the cell surface to the exterior?

  1. Basal body
  2. Filament
  3. Hook
  4. Shaft
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Answer: (B) Filament

A bacterial flagellum is composed of three parts: filament, hook, and basal body. The filament is the longest portion that extends from the cell surface to the exterior.

hard

6. Consider the following four statements (A - D) regarding mesosomes in prokaryotes: (A) They are formed by infoldings of the cell wall. (B) They help in cell wall formation and DNA replication. (C) They help in distribution of daughter chromosomes to progeny cells. (D) They decrease the surface area of the plasma membrane and enzymatic content. How many of the above statements are INCORRECT?

  1. One
  2. Four
  3. Three
  4. Two
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Answer: (D) Two

Statements (A) and (D) are incorrect. Mesosomes are formed by extensions of the plasma membrane (not cell wall) into the cell. They increase (not decrease) the surface area of the plasma membrane and enzymatic content. Statements (B) and (C) are correct. Therefore, exactly two statements are incorrect.

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7. In some prokaryotes such as cyanobacteria, there are membranous extensions into the cytoplasm called chromatophores, which contain:

  1. Gas
  2. DNA
  3. Ribosomes
  4. Pigments
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Answer: (D) Pigments

Chromatophores in cyanobacteria contain pigments.

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8. Consider the following statements regarding membranous structures in prokaryotes: Statement I: Chromatophores are pigment-containing membranous extensions present in certain prokaryotes like cyanobacteria. Statement II: Mesosomes can be present in the form of vesicles, tubules, and lamellae. In the light of the above statements, choose the most appropriate answer:

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
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Answer: (A) Both Statement I and Statement II are correct

Both statements are directly from NCERT. Mesosomes exist as vesicles, tubules, and lamellae, while chromatophores are internal membranous structures containing pigments found in cyanobacteria and purple bacteria.

hard

9. Match the organisms/cells in Column I with their typical sizes described in NCERT in Column II: Column I A. Typical eukaryotic cell B. Typical bacterium C. PPLO D. Viruses Column II (i) 0.02 - 0.2 µm (ii) 0.1 µm (iii) 1 - 2 µm (iv) 10 - 20 µm Choose the correct option:

  1. A-(iv), B-(i), C-(ii), D-(iii)
  2. A-(iii), B-(iv), C-(i), D-(ii)
  3. A-(iv), B-(iii), C-(ii), D-(i)
  4. A-(ii), B-(iii), C-(iv), D-(i)
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Answer: (C) A-(iv), B-(iii), C-(ii), D-(i)

According to NCERT Chapter 8 diagrammatic representation of organism sizes: Typical eukaryotic cell = 10 - 20 µm; Typical bacterium = 1 - 2 µm; PPLO = about 0.1 µm; Viruses = 0.02 - 0.2 µm.

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10. Which of the following cellular features is shared by BOTH a prokaryotic bacterium and a photosynthetic eukaryotic plant cell?

  1. Cell wall, plasma membrane, and ribosomes
  2. Double-membrane bound chloroplasts
  3. Endoplasmic reticulum and Golgi apparatus
  4. True membrane-bound nucleus and linear chromosomes
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Answer: (A) Cell wall, plasma membrane, and ribosomes

Both bacteria and plant cells possess a cell wall (though chemically different), a lipid bilayer plasma membrane, and ribosomes (70S in bacteria, 80S/70S in plants). Organelles like chloroplasts, ER, Golgi, and a true nucleus are exclusive to eukaryotes.

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11. Small circular DNA outside the genomic DNA of many bacteria, which confers characteristics such as resistance to antibiotics, is called:

  1. Nucleoid
  2. Plasmid
  3. Mesosome
  4. Episome of eukaryotes
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Answer: (B) Plasmid

Plasmid DNA gives unique phenotypic characters, such as antibiotic resistance, and is used to monitor bacterial transformation with foreign DNA.

easy

12. Which among the following is the smallest living cell known that completely lacks a cell wall?

  1. Bacterium
  2. Mycoplasma
  3. Nostoc
  4. Yeast
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Answer: (B) Mycoplasma

Mycoplasmas are the smallest known living cells, measuring only around 0.3 µm in length, and they lack a cell wall. Bacteria, Nostoc, and Yeast all possess cell walls.

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