Biological Classification - Exercise

Subject: Biology
Class: 11
Topic: Biological Classification

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Section A: Multiple Choice Questions (MCQs)

1. The main criterion for the five kingdom classification was NOT: a) Cell structure b) Mode of nutrition c) Phylogenetic relationships d) Geographical location

2. Which kingdom includes all prokaryotic organisms? a) Monera b) Protista c) Fungi d) Animalia

3. 'Diatomaceous earth' is formed by the cell wall deposits of: a) Dinoflagellates b) Chrysophytes c) Euglenoids d) Slime moulds

4. Red tides are caused by: a) Amoeba b) Gonyaulax c) Euglena d) Plasmodium

5. The cell wall of fungi is composed of: a) Cellulose b) Chitin c) Pectin d) Silica

6. Which group of fungi is commonly known as 'imperfect fungi'? a) Phycomycetes b) Ascomycetes c) Basidiomycetes d) Deuteromycetes

7. Viruses contain: a) Only DNA b) Only RNA c) Either DNA or RNA d) Both DNA and RNA

8. Who discovered viroids? a) Dmitri Ivanowsky b) M.W. Beijerinck c) W.M. Stanley d) T.O. Diener

9. Lichens are symbiotic associations between: a) Algae and Bacteria b) Algae and Fungi c) Fungi and Roots d) Bacteria and Viruses

10. Prions consist of: a) Genetic material only b) Abnormally folded proteins c) Protein-rich layer d) RNA only

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Section B: NCERT Textbook Exercises (Questions & Answers)

1. Discuss how classification systems have undergone several changes over a period of time? Answer: Classification systems have evolved from simple morphological systems (Aristotle) to the Two Kingdom system (Linnaeus) and eventually to the Five Kingdom system (Whittaker). Changes occur as we include more scientific criteria like cell structure, mode of nutrition, body organization, reproduction, and phylogenetic relationships.

2. State two economically important uses of: (a) heterotrophic bacteria (b) archaebacteria Answer: (a) Heterotrophic bacteria: Used in making curd from milk and production of antibiotics. (b) Archaebacteria: Methanogens are used to produce biogas (methane) from dung; some are studied for their survival in extreme environments.

3. What is the nature of cell-walls in diatoms? Answer: Diatom cell walls form two thin overlapping shells that fit together like a soap box. They are embedded with silica, making them indestructible and leading to the formation of 'diatomaceous earth'.

4. Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify. Answer:

• Algal bloom: Rapid growth of algae (like cyanobacteria) in polluted water bodies, often turning the water green.
• Red tides: Rapid multiplication of red dinoflagellates (e.g., Gonyaulax) that makes the sea appear red.

5. How are viroids different from viruses? Answer: Viroids are smaller than viruses and consist only of free RNA without a protein coat. Viruses have genetic material (DNA or RNA) enclosed in a protein coat called a capsid.

6. Describe briefly the four major groups of Protozoa. Answer:

• Amoeboid: Move using pseudopodia (e.g., Amoeba).
• Flagellated: Have flagella (e.g., Trypanosoma).
• Ciliated: Have thousands of cilia (e.g., Paramoecium).
• Sporozoans: Have an infectious spore-like stage (e.g., Plasmodium).

7. Plants are autotrophic. Can you think of some plants that are partially heterotrophic? Answer: Yes, insectivorous plants like Bladderwort and Venus flytrap capture insects for nutrients, and parasitic plants like Cuscuta derive nutrition from other plants.

8. What do the terms phycobiont and mycobiont signify? Answer: In lichens, the algal component is called the phycobiont (autotrophic, prepares food), and the fungal component is called the mycobiont (heterotrophic, provides shelter and absorbs nutrients).

9. Give a comparative account of the classes of Kingdom Fungi under (i) nutrition (ii) reproduction. Answer:

• Phycomycetes: Saprophytic/parasitic; asexual (zoospores/aplanospores), sexual (zygospores).
• Ascomycetes: Saprophytic/decomposers; asexual (conidia), sexual (ascospores).
• Basidiomycetes: Parasitic (rusts/smuts); vegetative (fragmentation), sexual (basidiospores).
• Deuteromycetes: Saprophytic/decomposers; asexual (conidia), sexual stage unknown.

10. What are the characteristic features of Euglenoids? Answer: They lack a cell wall but have a protein-rich pellicle. They have two flagella and are mixotrophic (photosynthetic in light, heterotrophic in dark).

11. Give a brief account of viruses with respect to their structure and nature of genetic material. Also name four common viral diseases. Answer: Viruses are non-cellular with a protein coat (capsid) surrounding genetic material (either DNA or RNA). Diseases: Mumps, smallpox, herpes, influenza, AIDS.

12. Are viruses living or non-living? Answer: Viruses are considered on the borderline. They are non-living because they lack a cellular structure and are inert outside a host. However, they are living because they can replicate inside a host cell using its machinery.

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Answer Key for MCQs

1. d 2. a 3. b 4. b 5. b 6. d 7. c 8. d 9. b 10. b