Biological Classification – Kingdom-Monera: NEET MCQs with Answers

15 free questions on Biological Classification – Kingdom-Monera for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Kingdom-Monera

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Question 1

Previous-year question
In bacteria, formation of the cell wall is aided by: [NEET 2024 (Sawaimadhopur)]
  1. Mesosomes
  2. Golgi apparatus
  3. Centrosomes
  4. Ribosomes
Show answer
Answer: (A) Mesosomes
Explanation: Mesosomes, infoldings of the bacterial plasma membrane, help in cell wall formation, DNA replication, respiration and secretion. Bacteria lack membrane-bound organelles such as the Golgi apparatus and centrosomes, and ribosomes are sites of protein synthesis.

Question 2

Previous-year question
Pathogenic bacteria become resistant to antibiotics because of changes in their: [Re-NEET 2022]
  1. Cosmids
  2. Plasmids
  3. Nucleus
  4. Nucleoid
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Answer: (B) Plasmids
Explanation: Plasmids are small, circular, extra-chromosomal DNA molecules that confer special phenotypic characters on bacteria, such as resistance to antibiotics. Bacteria have no true nucleus, and cosmids are laboratory cloning vectors, not natural bacterial structures.

Question 3

Previous-year question
Choose the correct statement from the following. [NEET 2022]
  1. Bacteria are exclusively heterotrophic organisms.
  2. Slime moulds are saprophytic organisms classified under Kingdom Monera.
  3. Mycoplasma have DNA, ribosome and cell wall.
  4. Cyanobacteria are a group of autotrophic organisms classified under Kingdom Monera.
Show answer
Answer: (D) Cyanobacteria are a group of autotrophic organisms classified under Kingdom Monera.
Explanation: Cyanobacteria (blue-green algae) are photosynthetic autotrophs placed in Kingdom Monera. Bacteria may be autotrophic (photo- or chemosynthetic) or heterotrophic, slime moulds are saprophytic protists, and Mycoplasma completely lack a cell wall.

Question 4

Previous-year question
Which statement about bacteria is incorrect? [NEET-II 2016]
  1. Cyanobacteria lack flagellated cells.
  2. Mycoplasma is a wall-less microorganism
  3. Bacterial cell wall is made up of peptidoglycan.
  4. Pili and fimbriae are mainly involved in motility of bacterial cells
Show answer
Answer: (D) Pili and fimbriae are mainly involved in motility of bacterial cells
Explanation: Motility in bacteria is due to flagella; pili and fimbriae are surface structures that help in attachment to rocks or host tissues, not movement. Cyanobacteria lack flagella, Mycoplasma has no cell wall, and the bacterial wall is made of peptidoglycan.

Question 5

Previous-year question
Which among the following is NOT a prokaryote? [NEET 2018]
  1. Saccharomyces
  2. Mycobacterium
  3. Oscillatoria
  4. Nostoc
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Answer: (A) Saccharomyces
Explanation: Saccharomyces (yeast) is a unicellular EUKARYOTIC fungus of the class Ascomycetes. Mycobacterium is a bacterium, and Oscillatoria and Nostoc are cyanobacteria — all three are prokaryotes.

Question 6

Previous-year question
Which of the following components provides a sticky character to the bacterial cell? [NEET 2017]
  1. Nuclear membrane
  2. Plasma membrane
  3. Glycocalyx
  4. Cell wall
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Answer: (C) Glycocalyx
Explanation: The glycocalyx is the outermost mucilaginous covering of the bacterial cell. It may be a loose slime layer or a thick capsule and is responsible for the sticky character of the cell as well as for protection and adherence.

Question 7

Previous-year question
Which among the following are the smallest living cells, known without a definite cell wall, pathogenic to plants as well as animals, and able to survive without oxygen? [NEET 2017]
  1. Pseudomonas
  2. Mycoplasma
  3. Nostoc
  4. Bacillus
Show answer
Answer: (B) Mycoplasma
Explanation: Mycoplasmas are the smallest known living cells. They completely lack a cell wall, survive without oxygen and cause diseases in both plants (e.g. little leaf of brinjal) and animals.
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Question 8

Previous-year question
Which of the following are found in extreme saline conditions? [NEET 2017]
  1. Eubacteria
  2. Cyanobacteria
  3. Mycobacteria
  4. Archaebacteria
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Answer: (D) Archaebacteria
Explanation: Archaebacteria include the halophiles of extremely saline habitats, along with the methanogens of marshy areas and thermoacidophiles of hot springs. Their special cell wall structure allows survival in such extreme environments.

Question 9

Previous-year question
Which of the following structures is NOT found in a prokaryotic cell? [AIPMT 2015]
  1. Ribosome
  2. Mesosome
  3. Plasma membrane
  4. Nuclear envelope
Show answer
Answer: (D) Nuclear envelope
Explanation: Prokaryotes possess 70S ribosomes, mesosomes and a plasma membrane, but no nuclear envelope — their genetic material lies naked in the cytoplasm as a nucleoid. Membrane-bound organelles are likewise absent.

Question 10

Previous-year question
The structures that help some bacteria to attach to rocks and/or host tissues are [AIPMT 2015]
  1. fimbriae
  2. mesosomes
  3. holdfast
  4. rhizoids
Show answer
Answer: (A) fimbriae
Explanation: Fimbriae are small bristle-like fibres sprouting out of the bacterial cell that help the bacterium to attach to rocks in streams and to host tissues. Mesosomes are membrane infoldings for respiration and DNA replication.

Question 11

Previous-year question
A true nucleus is absent in [AIPMT 2015]
  1. Mucor
  2. Vaucheria
  3. Volvox
  4. Anabaena
Show answer
Answer: (D) Anabaena
Explanation: Anabaena is a filamentous cyanobacterium and hence a prokaryote lacking a membrane-bound nucleus. Mucor (a fungus), Vaucheria (an alga) and Volvox (a colonial green alga) are all eukaryotes.

Question 12

Previous-year question
Archaebacteria differ from eubacteria in [AIPMT 2014]
  1. cell membrane
  2. mode of nutrition
  3. cell shape
  4. mode of reproduction
Show answer
Answer: (A) cell membrane
Explanation: Archaebacteria possess a distinctive cell membrane made of branched glycerol-ether lipids and a cell wall lacking peptidoglycan, which is why they survive in extreme habitats. Eubacterial membranes are composed of glycerol-ester lipids.

Question 13

Previous-year question
The motile bacteria are able to move by [AIPMT 2014]
  1. fimbriae
  2. flagella
  3. cilia
  4. pili
Show answer
Answer: (B) flagella
Explanation: Bacterial flagella are thin, filamentous extensions of the cell wall composed of flagellin and are the organs of locomotion. Fimbriae and pili are short bristle-like outgrowths used for attachment and for conjugation respectively, not for movement.

Question 14

Previous-year question
Nitrogen-fixing soil organisms belong to [AIPMT 1994]
  1. mosses
  2. bacteria
  3. green algae
  4. soil fungi
Show answer
Answer: (B) bacteria
Explanation: Nitrogen fixation in soil is carried out by bacteria — free-living forms such as Azotobacter and Clostridium, and symbiotic forms such as Rhizobium (in legume root nodules) and Frankia (in Alnus). Mosses, green algae and fungi do not possess nitrogenase.

Question 15

Previous-year question
The temperature tolerance of thermal blue-green algae is due to [AIPMT 1994]
  1. cell wall structure
  2. cell organisation
  3. mitochondrial structure
  4. homopolar bonds in their proteins
Show answer
Answer: (D) homopolar bonds in their proteins
Explanation: Cyanobacteria of hot springs owe their heat tolerance to the compactness of their protein molecules and the strong homopolar (covalent) bonds within them, which prevent denaturation; a gelatinous sheath that withstands long desiccation also helps. Mitochondria are irrelevant here since cyanobacteria, being prokaryotes, possess none.

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