NCERT Solutions for Class 11 Biology Chapter 2

Biological Classification Class 11

Chapter 2 Biological Classification Exercise Solutions

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Exercise : Solutions of Questions on Page Number : 28

Q1 :  

Discuss how classification systems have undergone several changes over a period of time?


Answer :

The classification systems have undergone several changes with time. The first attempt of classification was made by Aristotle. He classified plants as herbs, shrubs, and trees. Animals, on the other hand, were classified on the basis of presence or absence of red blood cells. This system of classification failed to classify all the known organisms.

Therefore, Linnaeus gave a two kingdom system of classification. It consists of kingdom Plantae and kingdom Animalia. However, this system did not differentiate between unicellular and multicellular organisms and between eukaryotes and prokaryotes. Therefore, there were large numbers of organisms that could not be classified under the two kingdoms.

To solve these problems, a five kingdom system of classification was proposed by R.H Whittaker in 1969. On the basis of characteristics, such as cell structure, mode of nutrition, presence of cell wall, etc., five kingdoms, Monera, Protista, Fungi, Plantae, and Animalia were formed.

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Q2 :  

State two economically important uses of:

(a) Heterotrophic bacteria

(b) Archaebacteria


Answer :

(a) Heterotrophic bacteria

(1) They act as decomposers and help in the formation of humus.

(2) They help in the production of curd from milk.

(3) Many antibiotics are obtained from some species of bacteria.

(4) Many soil bacteria help in fixation of atmospheric nitrogen.

(b) Archaebacteria

(1) Methane gas is produced from the dung of ruminants by the methanogens.

(2) Methanogens are also involved in the formation of biogas and sewage treatment.

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Q3 :  

What is the nature of cell-walls in diatoms?


Answer :

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Q4 :  

Find out what do the terms 'algal bloom' and 'red-tides' signify.


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Q5 :  

How are viroids different from viruses?


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Q6 :  

Describe briefly the four major groups of Protozoa.


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Q7 :  

Plants are autotrophic. Can you think of some plants that are partially heterotrophic?


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Q8 :  

What do the terms phycobiont and mycobiont signify?


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Q9 :  

Give a comparative account of the classes of Kingdom Fungi under the following:

(i) Mode of nutrition

(ii) Mode of reproduction


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Q10 :  

What are the characteristic features of Euglenoids?


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Q11 :  

Give a brief account of viruses with respect to their structure and nature of genetic material. Also name four common viral diseases.


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Q12 :  

Organise a discussion in your class on the topic- Are viruses living or non-living?


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<< Previous Chapter 1 : The Living World Next Chapter 3 : Plant Kingdom >>

Biology : CBSE NCERT Exercise Solutions for Class 11th for Biological Classification will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.

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