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CBSE 12: Biology: Based on Chapter 15 - Biodiversity and Conservation
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CHAPTER 15: BIODIVERSITY AND CONSERVATION
INTRODUCTION
1. There are more than ____ species of ants, ____ species of beetles,
_____ species of fishes and nearly ____ species of orchids on earth.
20,000; 3,00,000; 28,000, 20,000
BIODIVERSITY
2. In our biosphere, immense diversity (or heterogeneity) exists not
only at the species level but al all levels of biological organisation
ranging from ____ within cells to ____.
macromolecules, biomes
3. Biodiversity is the term popularised by sociobiologist ____ ____ to
describe the combined diversity at all levels of biological
organisation.
Edward Wilson
4. Some of the important diversity levels are genetic diversity, species
diversity and ecological diversity.
---
1
5. What do you understand by genetic diversity?
(i) A single species might show high diversity at the genetic level
over its distributional range. (Memorise this sentence)
(ii) The genetic variation shown by the medicinal plant ____
____ growing in different Himalayan ranges might be in
terms of ____ and ____ of the active chemical, ____, that the
plant produces.
Rauwolfia vomitoria, potency, concentration reserpine
6. Give examples of genetic diversity in India.
India has more than ____ genetically different strains of rice and
____ varieties of mangoes.
50,000; 1,000
7. Species diversity is at the ____ level. For example, the Western
Ghats have a greater ____ species diversity than the Eastern Ghats.
amphibian
8. Ecological diversity is at the _____ level. For instance, India, with
its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries
and alpine meadows has a greater ecosystem diversity than a
Scandinavian country like Norway.
ecosystem
HOW MANY SPECIES ARE THERE ON THE EARTH AND
HOW MANY IN INDIA?
9. According to IUCN (2004), the total number of plant and animal
species described so far is slightly more than ____ million. But, we
are not clear on how many species are yet to be discovered and
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described.
1.5
10. For many taxonomic groups, species inventories are more complete
in temperate than in tropical countries. Considering that an
overwhelmingly large proportion of the species waiting to be
discovered are in the tropics, biologists make a statistical
comparison of the temperate-tropical species richness of an
exhaustively studied group of ____ and extrapolate this ratio to
other groups of animals and plants to come up with a gross
estimate of the total number of species on earth.
insects
11. A more conservative and scientifically sound estimate made by
____ ____ places the global species diversity at about _____.
Robert May, 7 million
12. More than ____% of all the species recorded are animals while
plants (including algae, fungi, bryophytes, gymnosperms and
angiosperms) comprise no more than ____% of the total.
70, 22
13. Among animals, ____ are the most species-rich taxonomic group,
making up more than ____% of the total animals
insects, 70
14. The number of ____ species in the world is more than the combined
total of the species of fishes, amphibians, reptiles and mammals.
fungi
3
15. Look in the figure below for biodiversity of major taxa.
16. It is difficult to ascertain the number of species. Conventional
taxonomic methods are not suitable for identifying microbial
species and many species are cannot be ____ under laboratory
conditions.
cultured
17. India has only 2.4% of the world’s land area. But, its share in the
global species diversity is ____%. This makes India one of the 12
mega diversity countries of the world.
8.1
4
18. Nearly ____ species of plants and twice as many of animals have
been recorded in India.
45,000
19. If we accept May’s global estimate, only 22% of the total species
have been recorded so far.
---
PATTERNS OF DIVERSITY
(1) LATITUDINAL GRADIENTS
20. Many groups of animals or plants show a ____ _____ in the
distribution patterns of diversity. In general, species diversity ____
(decreases/increases) as we move from the equator to the poles.
latitudinal gradient, decreases
21. With very few exceptions, the tropics harbour more species than
the temperate or polar areas.
---
22. Colombia, located near the equator, has nearly ____ species of
birds while New York at 410 N has ____ species and Greenland at
710 N has only ____ species of birds. India has more than ____
species of birds.
1400, 105, 56, 1200
23. A forest in a tropical region like Ecuador has up to 10 times as
many species of vascular plants as a forest of equal area in a
temperate region like Midwest of the USA.
---
5
24. The Amazon Rain Forests in South America has the greatest
biodiversity on earth. It is home to more than 40,000 species of
plants, 3,000 species of fishes, 1,300 species of birds, 427 species of
mammals, 427 of amphibians, 378 of reptiles and of more than
_____ species of invertebrates. Scientists believe that in these rain
forests, there may be at least 2 million insect species waiting to be
discovered.
1,25,000
25. Why do tropics have a greater biological diversity?
(i) Speciation is generally a function of time. Unlike the temperate
regions, which have been subjected to frequent glaciations in the
past, tropical latitudes have remained relatively undisturbed for
millions of years. Thus, they had a long evolutionary time for
species diversification.
(ii) Tropical environments, unlike temperate ones, are less seasonal,
relatively more constant and predictable. Such constant
environments promote niche specialisation and lead to greater
species diversity
(iii) There is more solar energy available in the tropics, which
contributes to higher productivity. This contributes, indirectly, to
greater diversity.
SPECIES – AREA RELATIONSHIP
26. Alexander von Humboldt, from Germany, observed that within a
region species richness increased with increasing explored ____,
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but only up to a ____.
area, limit
27. The relationship between species richness and area for a wide
variety of taxa turns out to be a rectangular ____. On a logarithmic
scale, the relationship is a ___ ____described by the equation ____.
hyperbola, straight line
log S = log C + Z log A
Where,
S = Species richness
A = Area
Z = Slope of the line (regression coefficient)
C = Y-intercept (should be log C?)
28. Look at the graph below showing species area relationship.
29. Ecologists have discovered that the value of Z lies in the range of
7
_____ regardless of the taxonomic group or region. However, when
species-area relationships among very large areas like entire
continents are analysed, the slope of the line is steeper – Z values
range from _____.
0.1 – 0.2, 0.6 – 1.2
30. For Frugivorous (fruit-eating birds) and mammals in the tropical
forests of different continents, the slope (Z) is found to be ____.
1.5
THE IMPORTANCE OF SPECIES DIVERSITY
31. What does one understand by the stability of a community?
A stable community
(i) Should not show too much variation in ____ from year to
year.
(ii) It must either be resistant or resilient to occasional ____
(natural or man-made).
(iii) It must also be resistant to invasion by ____ species.
productivity, disturbances, alien
32. ____ ____ long-term ecosystem experiments using outdoor plots
showed that plots with more species showed ____ (less/more) year-
to-year variation in total biomass. He also showed that increased
diversity contributed to ____ (higher/lower) productivity.
David Tilman’s, less, higher
33. TRUE OR FALSE? Rich diversity is not only essential for
ecosystem health but imperative for the very survival of the human
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race on this planet.
True
34. Read the ‘rivet popper hypothesis’ used by Stanford ecologist Paul
Ehrlich.
LOSS OF BIODIVERSITY
35. The colonisation of tropical Pacific Islands by humans is said to
have led to the extinction of more than ____ species of native birds.
2000
36. The IUCN Red List (2004) documents the extinction of ____ species
in the last 500 years. These include ____ vertebrates, ____
invertebrates and ____ plants.
784, 338, 359, 87
37. Name the animal of Mauritius that has become extinct recently.
Dodo
38. Name the animal of Africa that has become extinct recently.
Quagga
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39. Name the animal of Australia that has become extinct recently.
Thylacine
40. Name the animal of Russia that has become extinct recently.
Stellar’s Sea Cow
41. Name the three species of tiger that has become extinct recently.
Bali, Japan, Caspian
42. The last 20 years alone have witnessed the disappearance of ____
species.
27
43. Data shows that extinctions across taxa are not random. Some
groups like ____ appear to be more vulnerable to extinction.
amphibians
44. More than ____ species, worldwide, are facing the threat of
extinction.
15,500
45. Presently, ____% of all bird species, ____% of all mammal species,
____% of all amphibian species, and ____% of all gymnosperms in
the world face the threat of extinction.
12, 23, 32, 31
46. During the long period (> 3 billion years) since the origin and
diversification of life on earth, there were ____ episodes of mass
10
extinction of species.
five
47. The ‘sixth extinction’ presently in progress is different from the
previous episodes in terms of rate. It is 100 – 1000 times faster than
in pre-human times. Human activities are the main culprit for this
extinction. Ecologists warn that if the present trends continue,
nearly ____ of all the species on earth might be wiped out within
the next 100 years.
half
48. What may be the consequences of loss of biodiversity in a region?
(i) Decline in plant production.
(ii) Lowered resistance to environmental perturbations such as
drought.
(iii) Increased variability in certain ecosystem processes such as plant
productivity, water use and pest and disease cycles.
49. There are four main causes of accelerated rates of species
extinctions. These are called ‘____ ____ ____’.
The Evil Quartet
50. There are four main causes of accelerated rates of species
extinctions. What are they?
(i) Habitat loss and fragmentation
(ii) Over exploitation
(iii) Alien species invasions
(iv) Co-extinctions
11
HABITAT LOSS AND FRAGMENTATION
51. TRUE OR FALSE? Habitat loss and fragmentation is the most
important cause driving animals to extinction.
True
52. The most dramatic examples of habitat loss come from ____ ____
forests. Once covering more than ____% of the earth’s land
surface, they now cover no more than ____%.
tropical rain, 14, 6
53. The ____ rain forests are called the ‘lungs of the planet’. These
forests are being cleared for cultivating ____ ____ or for conversion
to ____ for raising beef cattle.
Amazon, soybeans, grasslands
54. Besides total loss, the degradation of many habitats by ____ also
threatens the survival of many species.
pollution
55. When large habitats are broken up into small fragments due to
various human activities, mammals and birds requiring large ____
and certain animals with ____ habits are badly affected leading to a
decline in their population.
territories, migratory
OVER-EXPLOITATION
56. Many species have become extinct in the last five years due to over-
exploitation by humans. Examples are ____ ____ ____ and ____
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____.
Stellar’s sea cow, passenger pigeon
57. Presently many marine fish are over harvested endangering the
continued existence of some commercially important species.
---
ALIEN SPECIES INVASION
58. When alien species are introduced, either unintentionally or
deliberately, for whatever purpose, some of them turn ____ and
cause decline or extinction of indigenous species.
invasive
59. The ____ _____ introduced into Lake Victoria in east Africa led
eventually to the extinction of an ecologically unique assemblage of
more than 200 species of ____ fish in the lake.
Nile perch, cichlid
60. Some invasive weed species of plant that are a threat to our native
species are ____ ____, ____ and ____ _____.
carrot grass (Parthenium), Lantana, water hyacinth (Eicchornia)
61. The recent illegal introduction of the African catfish, ____ _____,
for aquaculture purposes is posing a threat to the indigenous
catfishes in our rivers.
Clarias gariepinus
CO-EXITINCTIONS
62. When a plant becomes extinct, the plant and animal species
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associated with it in an ____ way also become extinct.
obligatory
63. When a host fish species becomes extinct, its unique assemblage of
____ also meets the same fate.
parasites
64. In the case of a co-evolved plant-pollinator ____, where extinction
of one invariably leads to the extinction of the other.
mutualism
BIODIVERSITY CONSERVATION
65. Arguments for conservation of biodiversity can be broadly grouped
into three categories. Name them.
Narrowly utilitarian, broadly utilitarian and ethical
66. Explain the ‘narrowly utilitarian’ concept for conserving
biodiversity.
(i) Humans derive countless direct economic benefits from nature –
food, medicines, industrial products, etc.
(ii) With increasing resources put into ‘bioprospecting’, nations
endowed with rich biodiversity can expect to reap enormous
benefits.
67. What is bioprospecting?
Bioprospecting includes exploring molecular genetic and species-level
diversity for products of economic importance.
68. More than ____% of the drugs currently sold in the market
14
worldwide are derived from plants.
25
69. ____ species of plants contribute to the traditional medicines used
by native people around the world.
25,000
70. Explain the ‘broadly utilitarian’ concept for conserving
biodiversity.
(i) Biodiversity plays a major role in many ecosystem services that
nature provides.
(ii) Such services include provision of oxygen, pollination,
recreation, etc.
(iii) The price for such services is immense and is a reason for
preservation of biodiversity.
71. The Amazon forest is estimated to produce, through
photosynthesis, nearly ____% of the total oxygen in the earth’s
atmosphere.
20
72. Explain the ‘ethical’ concept for conserving biodiversity.
(i) There is an ethical obligation that we owe to plants, animals and
microbe species with whom we share the planet.
(ii) Philosophically or spiritually, we need to realise that every
species has an intrinsic value, even if it is not of any economic
importance to us.
(iii) We have a moral duty of care for their well-being and pass on
15
our biological legacy in good order to future generations.
HOW DO WE CONSERVE BIODIVERSITY?
73. What is ‘in situ’ conservation?When we conserve and protect the whole ecosystem, its biodiversity at
all levels is protected. For example, we save the entire forest to save the
tiger. This approach is called ‘in situ’ (on site) conservation.
74. What is ‘ex situ’ conservation?There are situations where an animal or plant is endangered or
threatened and needs urgent measures to save it from extinction. In
such cases ‘ex situ’ is the desirable approach.
IN SITU CONSERVATION
75. What is the difficulty with in situ conservation?(i) Faced with the conflict between development and conservation,
many nations find it unrealistic and economically not feasible to
conserve all their biological wealth.
(ii) Invariably, the number of species waiting to be saved from
extinction far exceeds the conservation resources available.
76. How has the problem of competition between conservation and
development been resolved?
(i) To solve the problem of competition between conservation and
development, ‘biodiversity hotspots’ have been identified for
maximum protection.
(ii) These areas have very high levels of species richness and high
degree of endemism.
(iii) They are also areas of accelerated habitat loss.
16
77. What is endemism?
Endemism means that species confined to a region are not found
anywhere else.
78. Initially ____ biodiversity hotspots were identified, which has now
expanded to ____.
25, 34
79. Mention three biodiversity hotspots in India that have been
identified.
(i) Western Ghats and Sri Lanka
(ii) Indo – Burma
(iii) Himalayas
80. All the biodiversity hotspots put together cover less than ____% fo
the earth’s land area, the number of species they collectively
harbour is extremely high. Strict protection of these hotspots could
reduce the ongoing mass extinctions by almost ____%.
2, 30
81. In India, ecologically unique and biodiversity-rich regions are
legally protected as ____ ____, ____ ____ and _____.biosphere reserves, national parks, sanctuaries
82. India now has ____ biosphere reserves, ____ national parks and
____ wildlife sanctuaries.
14, 90, 448
17
83. India has a history of religious and cultural traditions that
emphasised the protection of nature. In many cultures, tracts of
forest were set aside and all the trees and wildlife within were
venerated and given total protection. Such sacred groves are found
in ____ and ____ hills in Meghalaya, ____ Hills in Rajasthan, ____
____ regions in Karnataka and Maharashtra and the ____, ____
and ____ areas of Madhya Pradesh.
Khasi, Jaintia, Aravalli, Western Ghats, Sarguja, Chanda, Bastar
84. In _____, the sacred groves are the last refuges for a large number
of rare and threatened plants.
Meghalaya
EX SITU CONSERVATION
85. In the ex situ conservation approach, threatened animals and
plants are taken out from their natural habitats and placed in
special settings where they can be protected and given special care.
____ parks, ____ gardens and wildlife ____ parks serve this
purpose. Zoological, botanical, safari
86. TRUE OR FALSE? There are many animals that have become
extinct in the wild but continue to be maintained in zoological
parks.
True
87. In recent years, ex situ conservation has advanced beyond keeping
threatened species in enclosures. Now, ____ of threatened species
18
can be preserved in viable and fertile conditions for long periods
using ____ techniques. Eggs can be fertilised ____ ____ and plants
can be propagated using ____ ____ methods. Seeds of different
genetic strains of commercially important plants can be kept for
long periods in ____ ____.
gametes, cryopreservation, in vitro, tissue culture, seed banks
88. Mention some international efforts in biodiversity conservation.
The Convention on Biological Diversity (‘The ____ Summit’) held
in Rio de Janeiro in ____ called upon all nations to take
appropriate measures for the conservation of ____ and ____
utilisation of its benefits.
Earth, 1992, biodiversity, sustainable
89. In a follow up to the Earth Summit, at the World Summit on
Sustainable Development held in ____ in ____, South Africa, 190
countries pledged their commitment to achieve, by ____, a
significant reduction in the current rate of ____ loss at global,
regional and local levels.
2002, Johannesburg, 2010, biodiversity
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