Biological Classification

What you'll learn

A friendly tour of Whittaker's five kingdoms - Monera, Protista, Fungi, Plantae and Animalia - plus viruses and lichens, for NEET Biology.

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Biological Classification — solved practice questions

8 NEET Biology questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1easy

   The five-kingdom system of classification was proposed by:

   • ACarolus Linnaeus
   • BR. H. Whittaker
   • CErnst Haeckel
   • DRobert Hooke
   Show answer & solution

   Correct answer: (B) R. H. Whittaker

   R. H. Whittaker (1969) proposed the five-kingdom classification—Monera, Protista, Fungi, Plantae and Animalia—based on cell structure, body organisation, mode of nutrition, reproduction and phylogenetic relationships.

2. Q2easy

   Which of the following is the sole kingdom composed entirely of prokaryotic organisms?

   • AProtista
   • BFungi
   • CMonera
   • DPlantae
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   Correct answer: (C) Monera

   Kingdom Monera includes all bacteria (including archaebacteria and cyanobacteria), which are prokaryotes lacking a true membrane-bound nucleus and organelles; the other four kingdoms are eukaryotic.

3. Q3medium

   Chemosynthetic autotrophic bacteria are important in agriculture because they:

   • AFix atmospheric carbon dioxide using sunlight
   • BOxidise inorganic substances and recycle nutrients like nitrogen, phosphorus and iron
   • CCause decay of dead organic matter only
   • DProduce methane in marshy areas
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   Correct answer: (B) Oxidise inorganic substances and recycle nutrients like nitrogen, phosphorus and iron

   Chemosynthetic autotrophic bacteria oxidise inorganic substances (e.g., ammonia to nitrite, nitrite to nitrate) and use the released energy for ATP production, playing a key role in recycling nutrients such as nitrogen, phosphorus, iron and sulphur.

4. Q4medium

   Which group of organisms possesses a cell wall made of cellulose and silica, and forms diatomaceous earth?

   • ADinoflagellates
   • BDiatoms (Chrysophytes)
   • CEuglenoids
   • DSlime moulds
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   Correct answer: (B) Diatoms (Chrysophytes)

   Diatoms (chrysophytes) have indestructible cell walls of two overlapping silica-embedded shells (frustules); accumulation of these walls over billions of years forms the abrasive material called diatomaceous earth.

5. Q5medium

   The 'red tides' seen in the sea are caused by rapid multiplication of red-pigmented members of which protistan group?

   • ADiatoms
   • BEuglenoids
   • CDinoflagellates
   • DSlime moulds
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   Correct answer: (C) Dinoflagellates

   Dinoflagellates such as red-coloured Gonyaulax can multiply so rapidly that the sea appears red (red tide); toxins released by such blooms may kill fish and other marine animals.

6. Q6medium

   Euglenoids are unusual protists because, although they lack a cell wall, they have:

   • AA silica frustule
   • BA protein-rich flexible layer called pellicle
   • CA chitinous exoskeleton
   • DA cellulose theca
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   Correct answer: (B) A protein-rich flexible layer called pellicle

   Euglenoids (e.g., Euglena) lack a cell wall but have a protein-rich, flexible layer called the pellicle that makes their body flexible; they are also mixotrophic—photosynthetic in light but heterotrophic in its absence.

7. Q7medium

   In which kingdom are the slime moulds (e.g., Physarum) placed in Whittaker's five-kingdom system?

   • AMonera
   • BProtista
   • CFungi
   • DAnimalia
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   Correct answer: (B) Protista

   Slime moulds are saprophytic protists placed in Kingdom Protista; under suitable conditions they form an aggregation called plasmodium, and spores with true walls form during unfavourable conditions.

8. Q8easy

   The mode of nutrition in which fungi absorb soluble organic matter from dead and decaying substrates is called:

   • APhotosynthetic
   • BSaprophytic (heterotrophic by absorption)
   • CChemosynthetic
   • DHolozoic
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   Correct answer: (B) Saprophytic (heterotrophic by absorption)

   Fungi are heterotrophs that obtain nutrition by absorption; those that live on dead organic matter are saprophytes, while those living on living hosts are parasites, and some live in mutualistic associations.

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