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CBSE · Class 11 · Social Science

Biodiversity and Conservation

Standard difficulty · 20 questions · 40 marks · Time: 36 minutes

Name: Date: Score: ____ / 40

Write full answers in Sections B and C. Answers are on the last page — try every question first!

Section A — Choose the correct answer8 × 1 = 8 marks
1.
The best estimate of the number of species on the earth is about:
  1. 1 billion
  2. 100 thousand
  3. 2 thousand
  4. 10 million
2.
What is meant by “ecosystem diversity”?
  1. the variety of ecosystem types and habitats
  2. species introduced from outside a habitat
  3. tropical countries holding much of the world’s species
  4. areas very rich in species and most vulnerable
3.
What are rare species?
  1. in danger of extinction
  2. species with a rising population
  3. species introduced from outside
  4. very small populations in limited areas
4.
Which of these is a cause of the loss of biodiversity?
  1. declaring biosphere reserves
  2. setting up national parks
  3. deforestation
  4. protecting habitats
5.
Which of these countries is one of the twelve mega diversity centres?
  1. Mongolia
  2. Finland
  3. Libya
  4. Mexico
6.
About 99 per cent of all species that ever lived are extinct. Suppose 1,300 species of a group ever lived. How many would survive today?
  1. 13 species
  2. 14 species
  3. 1,287 species
  4. 130 species
7.
About 85 per cent of Madagascar’s plants and animals are found nowhere else. Out of 820 species, about how many would be found only there?
  1. 782 species
  2. 123 species
  3. 697 species
  4. 820 species
8.
The tropics cover about one-fourth of the world’s area but hold about three-fourths of its people. Suppose a world of 52 crore people: how many crore live in the tropics?
  1. 52 crore
  2. 39 crore
  3. 13 crore
  4. 41 crore
Section B — Short answer8 × 2 = 16 marks
9.
What is biodiversity?
10.
What is meant by each? (a) hotspots (b) agro-biodiversity
11.
Why is each step taken to conserve biodiversity? (a) regulating trade in wild plants and animals (b) protecting habitats
12.
Name the kind of species: (a) in danger of extinction (b) introduced from outside the habitat
13.
About 99 per cent of all species that ever lived are extinct. If 66,000 species of a group ever lived, how many survive and how many are extinct?
14.
Tropical rain forests hold about 50 per cent of the earth’s species. Suppose a survey lists 4,200 species: about how many would live in tropical rain forests, and why is their destruction disastrous?
15.
About 85 per cent of Madagascar’s plants and animals are found nowhere else. Of 3,940 species there, how many are found only there and how many also elsewhere?
16.
How does each cause the loss of biodiversity? (a) natural calamities (b) poaching
Section C — Longer answers4 × 4 = 16 marks
17.
Explain the ecological role of biodiversity.
18.
Match each with its meaning: (a) hotspots (b) agro-biodiversity (c) species diversity. Choose from: the diversity of crops; the variety of species in an area; areas very rich in species and most vulnerable.
19.
A region has 3,800 species, of which 85 per cent are endemic and 25 per cent are threatened. (a) How many are endemic? (b) How many are threatened? (c) Name the three IUCN categories of threatened species. (d) Suggest two ways to protect them.
20.
Explain how each causes the loss of biodiversity: (a) deforestation in the tropics (b) poaching
AmbifulWorksheets
Practice that never repeats
CBSE · Class 11 · Social Science

Answer key

Biodiversity and Conservation · AW-11SS-GBC-2026-V1 · For parents — fold back or tear off before handing the sheet to your child.

QAnswerWorking
1(d) 10 million—
2(a) the variety of ecosystem types and habitats—
3(d) very small populations in limited areas—
4(c) deforestation—
5(d) Mexico—
6(a) 13 species1% of 1,300
7(c) 697 species85% of 820
8(b) 39 crore52 × 3 ÷ 4
9The number and variety of plants, animals and micro-organisms in a region, their genes and the ecosystems they form.—
10(a) areas very rich in species and most vulnerable (b) the diversity of crops—
11(a) reduces over-exploitation (b) safeguards places where species feed, breed and rest—
12(a) endangered (b) exotic—
13660 survive; 65,340 are extinct1% and 99% of 66,000
142,100; destroying them wipes out habitats of half of all species.50% of 4,200
153,349 only there; 591 also elsewhere85% and 15% of 3,940
16(a) floods, fires and droughts damage flora and fauna (b) animals are killed for horns, tusks and hides—
17Species capture and store energy, produce and decompose matter, cycle water and nutrients, fix gases and regulate climate; diverse ecosystems are more stable and productive.—
18(a) areas very rich in species and most vulnerable (b) the diversity of crops (c) the variety of species in an area—
19(a) 3,230 (b) 950 (c) endangered, vulnerable and rare (d) protecting habitats and regulating wildlife trade (also involving local people).85% and 25% of 3,800
20(a) destroys habitats holding half the earth’s species (b) animals are killed for horns, tusks and hides—