Biological Classification — Class 11 MCQs with Answers

Biological Classification — important questions & MCQs with answers (Class 11 Biology)

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

1. Q1 of 6Easy

   Five-kingdom classification was proposed by:

   AMendelBLinnaeusCDarwinDWhittaker
   Show answerHide answer

   Answer: Whittaker

   Explanation: Whittaker proposed the five-kingdom system in 1969 (Monera, Protista, Fungi, Plantae, Animalia). Linnaeus gave the two-kingdom system; Mendel and Darwin worked on heredity and evolution, not taxonomy.

2. Q2 of 6Easy

   The earliest two-kingdom classification was proposed by:

   AHaeckelBWhittakerCLinnaeusDMargulis
   Show answerHide answer

   Answer: Linnaeus

   Explanation: Linnaeus's two-kingdom system (Plantae and Animalia) predates Haeckel's three-kingdom addition of Protista, Copeland's four-kingdom Monera split, and Whittaker's later five-kingdom scheme.

3. Q3 of 6Medium

   Viruses are considered:

   AAnimalsBFully livingCPlantsDOn the borderline of living and non-living
   Show answerHide answer

   Answer: On the borderline of living and non-living

   Explanation: Viruses sit on the living/non-living border: outside a host they are inert, crystallisable particles with no metabolism, but inside a host cell they hijack machinery to replicate.

4. Q4 of 6Medium

   Fungi cell wall is made of:

   APeptidoglycanBCelluloseCChitinDSilica
   Show answerHide answer

   Answer: Chitin

   Explanation: Fungal cell walls are built of chitin, a nitrogen-containing polysaccharide, unlike the cellulose walls of plants and algae or the peptidoglycan walls of bacteria — the wall material is the giveaway.

5. Q5 of 6Hard

   Assertion: Fungi are placed in a separate kingdom. Reason: They have chitinous cell walls and are heterotrophic.

   AA true, R falseBBoth A and R true; R does not explain ACBoth A and R true; R explains ADA false, R true
   Show answerHide answer

   Answer: Both A and R true; R explains A

   Explanation: Fungi form their own kingdom precisely because chitinous cell walls and obligate heterotrophy set them apart from plants (cellulose walls, autotrophic) and animals (no cell wall) — the reason directly justifies the assertion.

6. Q6 of 6Hard

   Lichens are symbiotic association of:

   AAnimals and fungiBBacteria and plantsCAlgae and FungiDAlgae alone
   Show answerHide answer

   Answer: Algae and Fungi

   Explanation: A lichen is a mutualistic partnership of a fungus (mycobiont) and a photosynthetic alga or cyanobacterium (phycobiont) — the fungus gives shelter and minerals, the alga supplies food, so neither partner alone counts.

Biological Classification notes: key concepts (Class 11 Biology)

Whittaker's five-kingdom system sorts life by cell structure, body organisation, nutrition and phylogeny into Monera, Protista, Fungi, Plantae and Animalia. This chapter details each kingdom's diagnostic features and the acellular oddities — viruses, viroids, prions and lichens — that fall outside the scheme.

Five-kingdom system

Whittaker (1969) used cell type, body organisation, nutrition, reproduction and phylogeny to define Monera, Protista, Fungi, Plantae and Animalia.

Two-kingdom limitation

Linnaeus's Plantae/Animalia split ignored prokaryote–eukaryote and uni-/multicellular differences and lumped green and non-green organisms together.

Monera

Prokaryotes with no true nucleus or membrane-bound organelles — bacteria, cyanobacteria, archaebacteria and mycoplasma. Nutrition autotrophic or heterotrophic.

Archaebacteria

Bacteria of extreme habitats — halophiles, thermoacidophiles and methanogens. A distinctive cell wall lets them survive high salt, heat and acidity.

Bacterial shapes & nutrition

Shapes are coccus, bacillus, vibrio and spirillum. Nutrition spans photo- and chemo-autotrophs to heterotrophs; many fix nitrogen or cause disease.

Protista

Single-celled eukaryotes forming a link to plants, animals and fungi: chrysophytes (diatoms), dinoflagellates, euglenoids, slime moulds and protozoans.

Dinoflagellates

Mostly marine, photosynthetic protists with two flagella and stiff cellulose plates; rapid blooms of red forms produce toxic red tides in the sea.

Euglenoids

Freshwater flagellates with a protein pellicle, not a wall; photosynthetic in light but heterotrophic in the dark — a plant-animal blend, e.g. Euglena.

Fungi

Heterotrophic eukaryotes with chitin walls and a mycelium of hyphae; saprophytic, parasitic or symbiotic. Store glycogen and reproduce by spores.

Classes of fungi

Phycomycetes, Ascomycetes (sac fungi), Basidiomycetes (club fungi, mushrooms) and Deuteromycetes — the 'imperfect fungi' with only an asexual stage known.

Plantae & Animalia

Plantae: multicellular autotrophs with cellulose walls and chloroplasts. Animalia: multicellular heterotrophs without walls, showing holozoic nutrition.

Viruses

Acellular obligate parasites — a nucleic acid (DNA or RNA) in a protein capsid. Plant viruses usually carry RNA; named by Pasteur, crystallised by Stanley.

Viroids

Discovered by Diener; free naked RNA of low molecular weight with no protein coat — the cause of diseases like potato spindle tuber disease.

Lichens & prions

Lichens pair a symbiotic alga (phycobiont) with a fungus (mycobiont) and indicate pollution. Prions are infectious proteins causing BSE (mad-cow disease).