84. Which among these organisms is NOT a prokaryote?
[NEET UG, 2018]
(A) Nostoc
(B) Mycobacterium
(C) Saccharomyces
(D) Oscillatoria
Answer: (C) Saccharomyces
Explanation: Saccharomyces is a yeast and therefore a eukaryotic fungus with a membrane-bound nucleus. Nostoc and Oscillatoria are cyanobacteria, whereas Mycobacterium is a bacterium. All three are prokaryotes.
83. Which assertion is wrong?
[NEET UG, 2018]
(A) Sporozoans use pseudopodia for obtaining food and moving
(B) Mushrooms are basidiomycetes
(C) Cell walls are common in Plantae and Fungi
(D) Monerans lack mitochondria
Answer: (A) Sporozoans use pseudopodia for obtaining food and moving
Explanation: Sporozoans such as Plasmodium generally lack locomotory organelles in the stages described by traditional classification. Pseudopodia characterise amoeboid protozoans. Mushrooms are basidiomycetes, and monerans are prokaryotes lacking mitochondria.
82. Which fungus produces spores externally on basidia following meiosis?
[NEET UG, 2018]
(A) Agaricus
(B) Alternaria
(C) Neurospora
(D) Saccharomyces
Answer: (A) Agaricus
Explanation: Agaricus is a basidiomycete; basidiospores form externally upon basidia after meiosis. By contrast, Neurospora and Saccharomyces produce sexual spores within asci. Alternaria was traditionally classified among imperfect fungi.
81. A characteristic distinguishing ciliate protozoans is:
[NEET UG, 2018]
(A) Pseudopodia for capturing prey
(B) Possession of contractile vacuoles only
(C) Flagella as the chief locomotory structure
(D) Two different nuclear types
Answer: (D) Two different nuclear types
Explanation: Ciliates often possess both a macronucleus for everyday functions and micronuclei involved in sexual reproduction. Other protists may have contractile vacuoles, but this nuclear dimorphism is characteristic of ciliates.
80. Which microorganisms are often termed the chief producers in oceans?
[NEET UG, 2018]
(A) Cyanobacteria
(B) Diatoms
(C) Dinoflagellates
(D) Euglenoids
Answer: (B) Diatoms
Explanation: Diatoms are photosynthetic chrysophytes widely present in marine plankton. Their abundant primary production supports ocean food webs. They possess siliceous cell coverings known as frustules that can accumulate as diatomaceous earth.
79. Which groups can thrive in extremely saline conditions?
[NEET UG, 07 May 2017]
(A) Archaebacteria
(B) Eubacteria
(C) Cyanobacteria
(D) Mycobacteria
Answer: (A) Archaebacteria
Explanation: Halophilic archaea possess distinctive molecular adaptations to concentrated salt solutions. Their protein and membrane systems allow growth where most familiar organisms cannot survive, illustrating physiological diversity within Archaea.
78. Who suggested a five-kingdom classification of living organisms?
[SSC CGL Tier I, 08 August 2017]
(A) Ernst Mayr
(B) R. H. Whittaker
(C) Martinus Beijerinck
(D) Dmitri Ivanovsky
Answer: (B) R. H. Whittaker
Explanation: Whittaker proposed five kingdoms in 1969, separating prokaryotes, unicellular eukaryotes, fungi, plants and animals. This replaced some shortcomings of earlier two- and three-kingdom schemes.
77. Which criteria did Whittaker use in creating the five-kingdom system?
[RPSC Second Grade Science, 01 July 2017]
(A) Mode of nutrition only
(B) Mode of reproduction only
(C) Cellular structure only
(D) All of these criteria
Answer: (D) All of these criteria
Explanation: Whittaker combined nutrition, cellular organisation, reproduction and other evidence in his classification. Using a single trait would mix organisms with fundamentally different cell types or nutritional strategies.
76. How do viroids differ structurally from typical viruses?
[NEET UG, 2017]
(A) DNA plus protein
(B) Naked DNA
(C) RNA plus a protein coat
(D) RNA without a protein coat
Answer: (D) RNA without a protein coat
Explanation: A viroid is a minute infectious RNA molecule lacking the protein capsid found in viruses. Viroids cause certain plant diseases and rely entirely on host-cell mechanisms for multiplication.
75. Which statement is not correct for kingdom Monera?
[NEET UG Gujarati Paper, 2017]
(A) Its members existed very early in Earth’s history
(B) Its cellular organisation is prokaryotic
(C) Autotrophic and heterotrophic modes both occur
(D) Cell division occurs by typical mitosis
Answer: (D) Cell division occurs by typical mitosis
Explanation: Monerans do not have membrane-enclosed nuclei or a mitotic spindle. Most multiply by binary fission rather than eukaryotic mitosis. The kingdom includes autotrophic cyanobacteria and many heterotrophic bacteria.
