Part 8 — Critical & Complex Questions II (Q176–Q200)
Part 8 — Critical & Complex Questions II (Q176–Q200)
25 MCQs with higher-order thinking — cross-linking Monera, Protista, Fungi, Viruses, Viroids, and Lichens; applications in biotechnology, medicine, and environment.
Q176. Which kingdom contains organisms showing both autotrophic and heterotrophic modes of nutrition in the same individual?
- A. Monera
- B. Protista
- C. Fungi
- D. Plantae
Answer: B
- A: Incorrect — Monera individuals are usually one mode only.
- B: Correct — Euglena (Protista) is mixotrophic.
- C: Incorrect — fungi are heterotrophic only.
- D: Incorrect — plants are autotrophic.
Q177. Which evolutionary evidence suggests cyanobacteria were ancestors of chloroplasts?
- A. Presence of linear DNA
- B. Presence of 70S ribosomes and circular DNA
- C. Absence of pigments
- D. Ability to form endospores
Answer: B
- A: Incorrect.
- B: Correct — chloroplasts have 70S ribosomes, circular DNA like cyanobacteria.
- C: Incorrect — they contain pigments.
- D: Incorrect.
Q178. Which fungal association is most critical in nutrient uptake of forest trees?
- A. Lichens
- B. Mycorrhiza
- C. Endophytes
- D. Saprophytes
Answer: B
- A: Incorrect — lichens colonize surfaces.
- B: Correct — mycorrhiza enhances mineral absorption.
- C: Incorrect.
- D: Incorrect.
Q179. Which viral property is exploited in gene therapy?
- A. Ability to photosynthesize
- B. Ability to integrate into host genome
- C. Ability to produce toxins
- D. Crystallization
Answer: B
- A: Incorrect.
- B: Correct — retroviruses integrate DNA into host genome.
- C: Incorrect.
- D: Incorrect.
Q180. Which organism shows true alternation of generations?
- A. Plasmodium
- B. Diatoms
- C. Rhizopus
- D. Nostoc
Answer: B
- A: Incorrect.
- B: Correct — diatoms alternate generations restoring cell size.
- C: Incorrect.
- D: Incorrect.
Q181. Why are archaebacteria considered primitive but highly adapted?
- A. They lack DNA
- B. Survive in extreme environments due to unique enzymes
- C. Are multicellular
- D. Have chloroplasts
Answer: B
- A: Incorrect.
- B: Correct — archaea enzymes stable in extremes.
- C: Incorrect.
- D: Incorrect.
Q182. Which property makes viruses useful in molecular biology research?
- A. Simplicity and rapid multiplication
- B. Having cell walls
- C. Independent metabolism
- D. Multicellularity
Answer: A
- A: Correct — simple structure, easy to study.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q183. Which disease cycle involves both lytic and lysogenic phases?
- A. Polio
- B. Herpes simplex
- C. Influenza
- D. Rabies
Answer: B
- A: Incorrect.
- B: Correct — herpes alternates lytic/latent (lysogenic) stages.
- C: Incorrect.
- D: Incorrect.
Q184. Which is true about slime moulds?
- A. Multicellular animals
- B. Vegetative phase amoeboid, reproductive phase spore-bearing
- C. Only photosynthetic
- D. Bacteria
Answer: B
- A: Incorrect.
- B: Correct — unique dual nature.
- C: Incorrect.
- D: Incorrect.
Q185. Fungi and cyanobacteria in lichens exhibit:
- A. Parasitism
- B. Commensalism
- C. Mutualism
- D. Amensalism
Answer: C
- A: Incorrect.
- B: Incorrect.
- C: Correct — both partners benefit.
- D: Incorrect.
Q186. Why are viroids considered more primitive than viruses?
- A. They lack nucleic acid
- B. They are naked RNA without protein coat
- C. They are larger and complex
- D. They infect animals only
Answer: B
- A: Incorrect.
- B: Correct.
- C: Incorrect.
- D: Incorrect.
Q187. Which statement explains fungal success as decomposers?
- A. Internal digestion
- B. Ability to secrete extracellular enzymes
- C. Ability to photosynthesize
- D. Nitrogen fixation
Answer: B
- A: Incorrect.
- B: Correct.
- C: Incorrect.
- D: Incorrect.
Q188. Which feature is absent in prokaryotic gene expression?
- A. Operons
- B. RNA splicing
- C. Coupled transcription-translation
- D. Polycistronic mRNA
Answer: B
- A: Incorrect — present.
- B: Correct — no introns, no splicing.
- C: Incorrect — occurs in prokaryotes.
- D: Incorrect.
Q189. Which human disease is caused by protozoan parasite?
- A. Sleeping sickness
- B. Tuberculosis
- C. Cholera
- D. Influenza
Answer: A
- A: Correct — Trypanosoma causes sleeping sickness.
- B: Incorrect — bacterial.
- C: Incorrect — bacterial.
- D: Incorrect — viral.
Q190. A unique feature of bacteriophages is:
- A. Tail fibers for attachment to host
- B. Presence of chloroplast
- C. Ability to fix nitrogen
- D. Photosynthesis
Answer: A
- A: Correct — tail fibers aid in adsorption.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q191. Which type of algae shares similarity with higher plants in pigment composition?
- A. Red algae
- B. Brown algae
- C. Green algae
- D. Cyanobacteria
Answer: C
- A: Incorrect.
- B: Incorrect.
- C: Correct — green algae have chlorophyll a, b like plants.
- D: Incorrect.
Q192. Which property of viruses challenges the traditional definition of life?
- A. They can crystallize
- B. They reproduce only in host
- C. They lack cellular structure
- D. All of these
Answer: D
- A: Correct.
- B: Correct.
- C: Correct.
- D: Correct — all challenge life definition.
Q193. Which bacterial group produces antibiotics naturally?
- A. Streptomyces
- B. Escherichia
- C. Lactobacillus
- D. Salmonella
Answer: A
- A: Correct — Streptomyces.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q194. In lichens, reproduction by soredia ensures:
- A. Fungal reproduction only
- B. Simultaneous propagation of both partners
- C. Only algal reproduction
- D. Sexual recombination
Answer: B
- A: Incorrect.
- B: Correct — soredia carry both fungus + alga.
- C: Incorrect.
- D: Incorrect.
Q195. Which is a distinguishing feature of retroviruses?
- A. dsDNA as genetic material
- B. RNA genome with reverse transcriptase
- C. Lack of nucleic acid
- D. Circular DNA
Answer: B
- A: Incorrect.
- B: Correct.
- C: Incorrect.
- D: Incorrect.
Q196. Which ecological role do diatoms play?
- A. Producers in aquatic ecosystems
- B. Decomposers
- C. Parasites
- D. Symbionts with fungi
Answer: A
- A: Correct — major producers in oceans.
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q197. Which factor makes archaebacteria useful in biotechnology?
- A. Thermostable enzymes
- B. Ability to photosynthesize
- C. Multicellularity
- D. Nucleus with histones
Answer: A
- A: Correct — thermostable DNA polymerases (PCR).
- B: Incorrect.
- C: Incorrect.
- D: Incorrect.
Q198. Which stage of Plasmodium is picked up by mosquito from human blood?
- A. Sporozoite
- B. Gametocyte
- C. Merozoite
- D. Ookinete
Answer: B
- A: Incorrect — sporozoite infects human.
- B: Correct — gametocytes ingested by mosquito.
- C: Incorrect.
- D: Incorrect.
Q199. Which structure in fungi is analogous to seeds in plants for dispersal?
- A. Mycelium
- B. Spores
- C. Hyphae
- D. Fruiting body
Answer: B
- A: Incorrect.
- B: Correct — spores aid in dispersal.
- C: Incorrect.
- D: Incorrect.
Q200. The study of viruses is called:
- A. Mycology
- B. Virology
- C. Bacteriology
- D. Pathology
Answer: B
- A: Incorrect — fungi.
- B: Correct — virology.
- C: Incorrect — bacteria.
- D: Incorrect.