NCERT Class 11-Biology: Chapter –2 Biological Classification Part 2

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Question 11:

Viruses are non-cellular organisms but replicate themselves once they infect the host cell. To which of the following kingdom do viruses belong to?

a. Monera

b. Protista

c. Fungi

d. None of the above

Answer: (d)

Question 12:

Members of phycomycetes are found in

i. Aquatic habitats

ii. On decaying wood

iii. Moist and damp places

iv. As obligate parasites on plants

Choose from the following options

a. None of the above

b. i and iv

c. ii and iii

d. All of the above

Answer: (d)

Very Short Answer Type Questions

Question 1:

What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?


Many species of cyanobacteria can carry out nitrogen fixation in soil. Hence, they are used in agricultural fields for crop improvement.

Question 2:

Suppose you accidentally find an old preserved permanent slide without a label. In your effort to identify it, you place the slide under microscope and observe the following features:-

a. Unicellular

b. Well defined nucleus

c. Biflagellate–one flagellum lying longitudinally and the other transversely.

What would you identify it as? Can you name the kingdom it belongs to?


All unicellular eukaryotes belong to the kingdom Protista. Hence, this organism belongs to Protista.

Question 3:

How is the five–kingdom classification advantageous over the two kingdom classification?


In two – kingdom classification many unrelated organisms were kept under the same kingdom. This anomaly has been removed after the introduction of five-kingdom classification. For example, the bacteria were kept under plant kingdom previously but many bacteria are heterotrophic. Now, a separate kingdom has been made for bacteria.

Question 4:

Polluted water bodies have usually very high abundance of plants like Nostoc and Oscillatoria. Give reasons.


These organisms get plenty of nutrients in polluted water. Hence, they often bloom in such conditions and are found in abundance in polluted water.

Question 5:

Are chemosynthetic bacteria-autotrophic or heterotrophic?


Chemosynthetic bacteria are autotrophic because they can synthesize their own food. During chemosynthesis it uses chemicals as source of energy.

Question 6:

The common name of pea is simpler than its botanical (scientific) name Pisum satirum. Why then is the simpler common name not used instead of the complex scientific/ botanical name in biology?


The common name ‘pea’ is an English word and this can have different names in different languages. It is easier to remember a standard scientific name as compared to so many names. Hence, instead of using simple common names; it is preferred to use scientific names which may appear complicated but universally accepted.

Question 7:

A virus is considered as a living organism and an obligate parasite when inside a host cell. But virus is not classified along with bacteria or fungi. What are the characters of virus that are similar to non-living objects?


Characters of virus that are similar to non-living objects;

(a) They have inert crystalline structure outside the living cell.

(b) They do not have any cell organelles.