chapter 3 unit 3 biodiversity

1.                  How many kinds of organisms are present on the earth?        Text Book Page # 31

Ans:         The earth is inhabited by at least 10 million kinds of organisms, but less than one-third of these have been studied and catalogued (put in record) by biologists.

 

2.                  Name the principal groups of organisms.

Ans:    Following are the principal groups of organisms:

•          Prokaryotes

•          Protists

•          Fungi

•          Plants

•          Animals

 

3.                  Define biodiversity.                        (LHR 2014, SWL 2014, FSD 2014, BWP 2015)

Ans:

Definition:

“The measure of the variety of organisms present in different ecosystems is called biodiversity.”

•          It refers to variety within species and among species.

Meaning:

The term ‘Biodiversity’ has been derived from two terms, ‘bio’ — Life

‘diversity’ — variety

 

4.                  What do you mean by flora and fauna? 

Ans:    Flora:

“The diversity of plants in a particular region is called Flora.”

Fauna:

“The diversity of animals in a particular region is called Fauna.”

 

5.                  On what factors the flora and fauna of a region depend?

Ans:    The flora and fauna in a region depend on:

•          Climate

•          Altitude

•          Soils

•          Presence of other species

 

6.                  Stow biodiversity is distributed on earth?

Ans:    Biodiversity is not distributed evenly on Earth,

 

 

Tropics:

It is richest in the tropics.

Temperate Regions:

Temperate regions also have many species.

Polar Regions:

Polar regions have fewer species.

 

7.                  Stow biodiversity has evolved?

Ans:    Biodiversity found on earth today is the result of 4 Billion years of evolution.

 

8.                  What do you know about the origin of life on earth?

Ans: The origin of life is not well known to science, though limited evidence suggests that until 600 million years ago, all life consisted of bacteria and similar unicellular organisms.

 

9.                  Describe the importance of biodiversity.                                    Text  Book  Page # 32

(UtR 2015, 2016, MTN 2015)

Ans:    The biodiversity is important in many ways.

(i)     Food:

Biodiversity provides food for humans.

(ii)   Drugs:

A significant proportion of drugs are derived directly or indirectly from biological sources.

(iii)  Industrial materials:

A wide range of industrial materials, e.g. building materials, fibers, dyes, resins, gums, adhesives, rubber, and oil are derived directly from plants.

(iv)  Maintenance of Ecosystems:

Biodiversity plays an important role in making and maintaining ecosystems.

(v)   Environmental Benefits:

It helps in regulating the chemistry of our atmosphere and water supply.

(vi)  Recycling:

Biodiversity is directly involved in recycling of nutrients and providing fertile soils.

 

10.              How many types of animals and plants are known to biologists?

Ans:    Over 1.5 million types of animals and over 0.5 million types of plants are known to biologists.

 

11.              Why does it become difficult to learn about the characteristics of each species?

Text Book Page # 33

Ans:

•          Living organisms range in complexity from small and simple bacteria to large and complex human beings.

•          Some of them live in sea, others on land. Some walk, others fly. And still others are stationary.

•          

Each has its own way of life, i.e. getting food, avoiding unfavorable environmental conditions, finding a place to live, and reproducing its kind.