Part 7 — Critical & Complex Questions I (Q151–Q175)
Part 7 — Critical & Complex Questions I (Q151–Q175)
25 MCQs with deeper conceptual focus — comparisons across kingdoms, evolutionary perspectives, exceptions, and applied ecology relevant for NEET.
Q151. Which feature best differentiates archaebacteria from eubacteria?
- A. Presence of peptidoglycan
- B. Unique lipid composition in cell membrane
- C. Presence of chlorophyll
- D. Unicellularity
Answer: B
- A: Incorrect — archaebacteria lack peptidoglycan.
- B: Correct — ether-linked lipids unique to archaea.
- C: Incorrect — not universal.
- D: Incorrect — both are unicellular.
Q152. Why are cyanobacteria considered different from eukaryotic algae?
- A. They are prokaryotic without nucleus
- B. They perform photosynthesis
- C. They have chlorophyll-a
- D. They occur in water
Answer: A
- A: Correct — prokaryotic nature is main difference.
- B: Incorrect — both photosynthesize.
- C: Incorrect — both have chlorophyll-a.
- D: Incorrect — both aquatic.
Q153. The absence of histone proteins in DNA is characteristic of:
- A. Archaebacteria
- B. Eukaryotes
- C. Eubacteria
- D. Protista
Answer: C
- A: Incorrect — some archaea have histone-like proteins.
- B: Incorrect — all eukaryotes have histones.
- C: Correct — eubacteria lack histones.
- D: Incorrect — protists are eukaryotic.
Q154. In diatoms, sexual reproduction leads to:
- A. Reduction in cell size
- B. Restoration of normal size
- C. No change in size
- D. Shrinking continuously
Answer: B
- A: Incorrect — asexual reproduction reduces size.
- B: Correct — sexual cycle restores original size.
- C: Incorrect.
- D: Incorrect.
Q155. Which evidence supports fungi being more related to animals than plants?
- A. Presence of chlorophyll
- B. Cell wall composition and glycogen storage
- C. Photosynthesis
- D. Multicellularity
Answer: B
- A: Incorrect.
- B: Correct — fungi store glycogen like animals; cell wall differs from plants.
- C: Incorrect — fungi are non-photosynthetic.
- D: Incorrect — multicellularity is not exclusive.
Q156. Which organism links Monera and Protista in evolution?
- A. Mycoplasma
- B. Blue-green algae
- C. Euglena
- D. Virus
Answer: C
- A: Incorrect.
- B: Incorrect.
- C: Correct — Euglena shows both plant and animal-like features, bridging traits.
- D: Incorrect.
Q157. Virus classification is mainly based on:
- A. Host infected
- B. Type of nucleic acid
- C. Symptoms caused
- D. Mode of transmission
Answer: B
- A: Incorrect — not primary.
- B: Correct — DNA/RNA, ss/ds.
- C: Incorrect.
- D: Incorrect.
Q158. In lichens, which component determines thallus form?
- A. Fungal partner
- B. Algal partner
- C. Both equally
- D. Neither
Answer: A
- A: Correct — fungus decides morphology.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q159. Which of the following can fix nitrogen?
- A. Nostoc (cyanobacterium)
- B. Rhizobium (symbiotic bacteria)
- C. Anabaena (cyanobacterium)
- D. All of these
Answer: D
- A: Correct.
- B: Correct.
- C: Correct.
- D: Correct — all fix nitrogen.
Q160. The unique character of viroids is:
- A. DNA genome
- B. RNA without protein coat
- C. Protein coat with RNA
- D. Both DNA and RNA
Answer: B
- A: Incorrect.
- B: Correct.
- C: Incorrect.
- D: Incorrect.
Q161. Methanogens are important in biogas production because:
- A. They absorb CO₂
- B. Produce methane under anaerobic conditions
- C. Convert methane to CO₂
- D. Use oxygen
Answer: B
- A: Incorrect.
- B: Correct — produce methane in anaerobic digesters.
- C: Incorrect.
- D: Incorrect.
Q162. Which property of fungi makes them ideal decomposers?
- A. Ability to photosynthesize
- B. Secreting extracellular enzymes
- C. Symbiotic association with algae
- D. Ability to fix nitrogen
Answer: B
- A: Incorrect.
- B: Correct — enzymes digest complex organic matter externally.
- C: Incorrect — that is lichens.
- D: Incorrect.
Q163. Which stage in Plasmodium is infective to humans?
- A. Gametocyte
- B. Sporozoite
- C. Merozoite
- D. Ookinete
Answer: B
- A: Incorrect.
- B: Correct — sporozoite transmitted by mosquito bite.
- C: Incorrect.
- D: Incorrect.
Q164. Thermoacidophiles survive due to:
- A. Unique stable enzymes
- B. Photosynthesis
- C. Cellulose walls
- D. Sporulation
Answer: A
- A: Correct — enzymes stable at high heat/acid.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q165. Which kingdom shows maximum nutritional diversity?
- A. Monera
- B. Protista
- C. Fungi
- D. Plantae
Answer: A
- A: Correct — Monera (chemoautotrophs, photoautotrophs, heterotrophs).
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q166. Bacterial conjugation involves:
- A. Transformation
- B. Plasmid transfer via pilus
- C. Transduction
- D. Sporulation
Answer: B
- A: Incorrect.
- B: Correct — conjugation by F-pilus plasmid transfer.
- C: Incorrect — transduction via phages.
- D: Incorrect.
Q167. Which organism is both autotrophic and heterotrophic?
- A. Euglena
- B. Amoeba
- C. Paramecium
- D. Plasmodium
Answer: A
- A: Correct — mixotrophic.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q168. Which evidence supports viral origin from cellular organisms?
- A. Presence of nucleic acids similar to host
- B. Protein coat
- C. Infectivity
- D. Crystallization ability
Answer: A
- A: Correct — viral genomes often similar to host sequences.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q169. Which statement about lichens is false?
- A. They are symbiotic
- B. They can fix nitrogen
- C. They survive in polluted cities
- D. They colonize bare rocks
Answer: C
- A: Correct.
- B: Correct.
- C: False — lichens are absent in polluted air.
- D: Correct.
Q170. Which structure is absent in prokaryotes?
- A. Ribosome
- B. Nucleoid
- C. Mitochondria
- D. Plasma membrane
Answer: C
- A: Incorrect — ribosomes are present.
- B: Incorrect — nucleoid is present.
- C: Correct — mitochondria absent.
- D: Incorrect.
Q171. Endosymbiotic theory is supported by:
- A. 70S ribosomes in mitochondria
- B. Circular DNA in mitochondria
- C. Division by fission in plastids
- D. All of these
Answer: D
- A: Correct.
- B: Correct.
- C: Correct.
- D: Correct.
Q172. Which protist has both plant and animal features?
- A. Euglena
- B. Paramecium
- C. Amoeba
- D. Plasmodium
Answer: A
- A: Correct — autotrophic + heterotrophic.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q173. Which is a distinguishing feature of Mycoplasma?
- A. Lack of cell wall
- B. Presence of chlorophyll
- C. Multicellularity
- D. Nucleus with envelope
Answer: A
- A: Correct — wall-less bacteria.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q174. Which of the following is a dimorphic fungus (yeast-mould)?
- A. Candida albicans
- B. Rhizopus
- C. Puccinia
- D. Agaricus
Answer: A
- A: Correct — Candida shows yeast and mycelial forms.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q175. Which factor makes viruses non-living outside host?
- A. Lack of cellular structure
- B. Lack of metabolism
- C. Inability to reproduce
- D. All of these
Answer: D
- A: Correct.
- B: Correct.
- C: Correct.
- D: Correct — all reasons apply. (more…)