54. Which grouping correctly singles out an organism that differs taxonomically from the others?
[AIPMT Mains, 2012]
(A) UAA, UAG, UGA as stop codons, excluding UAG
(B) Kangaroo, koala, wombat as marsupials, excluding wombat
(C) Plasmodium, Cuscuta, Trypanosoma as protozoan parasites, excluding Cuscuta
(D) Typhoid, pneumonia, diphtheria as bacterial diseases, excluding diphtheria
Answer: (C) Plasmodium, Cuscuta, Trypanosoma as protozoan parasites, excluding Cuscuta
Explanation: Cuscuta is a parasitic flowering plant, whereas Plasmodium and Trypanosoma are unicellular parasitic protists. UAG is a stop codon and wombats are marsupials, so the proposed exceptions in those groups fail.
53. Which kingdom displays the widest variety of nutritional strategies?
[AIPMT Prelims, 2012]
(A) Plantae
(B) Fungi
(C) Animalia
(D) Monera
Answer: (D) Monera
Explanation: Bacteria possess remarkable metabolic diversity: photosynthesis, chemosynthesis, fermentation, saprotrophy and parasitism all occur. This breadth surpasses the predominantly photosynthetic plants and chiefly heterotrophic fungi and animals.
52. Useful microorganisms responsible for curd making and many antibiotics are largely classified as:
[AIPMT Prelims, 2012]
(A) Heterotrophic bacteria
(B) Cyanobacteria
(C) Archaebacteria
(D) Chemosynthetic autotrophs
Answer: (A) Heterotrophic bacteria
Explanation: Lactobacillus uses organic substrates to ferment milk into curd, while Streptomyces produces numerous antibiotics. Both are heterotrophic bacteria. They differ from cyanobacteria and chemoautotrophs that make food using light or inorganic chemical energy.
51. Which taxonomic assignment is correct?
[AIPMT Prelims, 2012]
(A) Nostoc and Anabaena are protists
(B) Paramecium and Penicillium belong to the same kingdom
(C) Lichen consists of algae and protozoa
(D) Bread-making yeast is a fungus
Answer: (D) Bread-making yeast is a fungus
Explanation: Saccharomyces yeast is a fungus used for fermentation. Nostoc and Anabaena are cyanobacteria, Paramecium is a protist, Penicillium a fungus, and lichens involve a fungus together with a photosynthetic partner.
50. Which organism lacks a nuclear membrane?
[AIPMT Prelims, 2012]
(A) Nostoc
(B) Penicillium
(C) Agaricus
(D) Volvox
Answer: (A) Nostoc
Explanation: Nostoc is a cyanobacterium with prokaryotic cellular architecture. Its DNA is not enclosed by a nuclear envelope. The two fungi and the green alga listed are eukaryotic and possess nuclei.
49. What is another traditional name for cyanobacteria?
[AIPMT Prelims, 2012]
(A) Blue-green algae
(B) Protists
(C) Golden algae
(D) Slime moulds
Answer: (A) Blue-green algae
Explanation: Cyanobacteria were historically called blue-green algae because many are photosynthetic and contain blue phycocyanin pigments. Unlike true eukaryotic algae, however, they are bacteria lacking a membrane-bound nucleus.
48. Who is credited with introducing binomial nomenclature?
[TNPSC Group I Preliminary Examination, 2011]
(A) Charles Darwin
(B) Gregor Mendel
(C) Ernst Mayr
(D) Carolus Linnaeus
Answer: (D) Carolus Linnaeus
Explanation: Carolus Linnaeus established a consistent system of naming species with a genus followed by a specific epithet. The practice improves communication across languages and remains foundational despite continuing taxonomic revisions.
47. Microsporum belongs to the same kingdom as which organism?
[AIPMT Mains, 2011]
(A) Rhizopus
(B) Ascaris
(C) Taenia
(D) Wuchereria
Answer: (A) Rhizopus
Explanation: Microsporum causes fungal ringworm infections, and Rhizopus is another member of kingdom Fungi. Ascaris and Wuchereria are nematodes, while Taenia is a flatworm, all belonging to Animalia.
46. Methanogenic microorganisms occur abundantly in which environment?
[AIPMT Prelims, 2011]
(A) Hot sulphur springs
(B) Dry sulphur rock
(C) Cattle yards
(D) Well-aerated freshwater
Answer: (C) Cattle yards
Explanation: The rumen of cattle and decomposing dung provide anaerobic conditions that support methanogens. These archaea release methane and are important in the production of biogas from livestock waste.
45. Which association is incorrectly matched?
[AIPMT Prelims, 2011]
(A) Cassia-imbricate aestivation
(B) Root pressure-guttation
(C) Puccinia-smut disease
(D) Root-exarch xylem
Answer: (C) Puccinia-smut disease
Explanation: Puccinia species cause rust diseases, particularly wheat stem rust. Smuts are caused by other fungi such as Ustilago. The remaining pairings describe recognised botanical structures and physiological phenomena.
