Biodiversity and Conservation Questions Class 12 Biology

ICSE Class 12 Biology

Biodiversity and its Patterns

Very Short Answer Type Questions

Question. Write the level of biodiversity represented by mangrove. Give another example falling in the same level.
Answer : Mangroves represent the ecological diversity. The same level of biodiversity is also shown by rain forests, coral reefs wetlands, estuaries and alpine meadows, etc.

Question. Name the type of biodiversity represented by the following :
(i) 50,000 different strains of rice in India.
(ii) Estuaries and alpine meadows in India.
Answer : (i) Genetic diversity.
(ii) Ecological diversity.

Question. Eichhornia crassipes is an alien hydrophyte introduced in India. Mention the problems posed by this plant. A [Outside Delhi Comptt. 2010]
Answer : When an alien hydrophyte Eichhornia crassipes were introduced unintentionally, they turned invasive and caused decline or extinction of indigenous species. 

Question. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major vertebrate taxa.

Answer : (a) Mammals
(b) Amphibians

Question. Name the type of biodiversity represented by the following :
(i) 1000 varieties of mangoes in India.
(ii) Variations in terms of potency and concentration of reserpine in Rauwolfia vomitoria growing in different regions of Himalayas.
Answer : (i) Genetic diversity.
(ii) Genetic diversity.

Question. The Amazon rain forest is referred to as ‘the lungs of the planet’. Mention any one human activity that causes loss of biodiversity in this region.
Answer : The Amazon rain forest is so huge that it is called the lungs of the planet. Cutting down of forest for cultivation of soya beans and its conversion to grasslands for raising beef cattle caused loss of biodiversity in this region.

Question. Why are mango trees unable to grow in temperate climate? 
Answer : Because temperature affects the basal metabolism/ physiological function of the plant not adapted to low temperature of temperate climate. Mango trees are not able to grow in temperate below 30 degree, thus cannot grow in temperate climate. 

Question. Why is tropical environment able to support greater species diversity ?
Answer : Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and redictable. Such constant environments promote niche specialization and lead to a greater species diversity.

Question. Name the unlabelled areas ‘a’ & ‘b’ of the pie chart representing the biodiversity of plants showing their proportionate number of species of major taxa.

Question. What does the term genetic diversity refer to ? 
What is the significance of large genetic diversity in a population ?
Answer : The genetic diversity refers to the variation of genes within a species. The genetic diversity helps the population to adapt into its environment and to respond to natural selection. It also helps in speciation or evolution of new species.

Question. Name the unlabelled areas ‘a’ & ‘b’ of the pie chart representing biodiversity of vertebrates showing the proportionate number of species of major taxa.

Answer : (i) Fishes
(ii) Amphibians

Question. An exotic variety of prickly pear introduced in Australia turned out to be invasive. How was it brought under control ?
Answer : It was controlled by introducing a cactus – feeding predator (a moth) from its natural habitat. 

Answer : (i) Fungi
(ii) Angiosperms. 

Question. Give an example of a plant which came into India as a contaminant and is a cause of pollen allergy.
Answer : Parthenium / Carrot grass. 

Question. Name the unlabelled area of the pie chart given alongside representing the global biodiversity of invertebrates showing their proportionate number of species of major taxa.

Answer : (i) Insects
(ii) Molluscus.

Short Answer Type Questions – l

Question. Identify the areas labelled i, ii, iii and iv in the pie chart given below representing the biodiversity of plants showing their proportionate number of species of major taxa.

Answer : i – Lichen, ii – Algae, iii – Fungi, iv – Mosses 

Question. Mention the kind of biodiversity of more than a thousand varieties of mangoes in India represent. How is it possible ?
Answer : Genetic diversity/single species show high diversity at genetic level. Single species show high diversity at genetic level over its distributional range/different varieties grow in different geographical areas/climatic conditions/breeding/mutations. 

Question. Plants that inhabit a rain-forest are not found in a wetland. Explain.
Answer : Plants that inhabit rain forest are well adapted to that particular habitat. The climate of rainforest is wet and humid and in this climate, large trees and shrubs are predominantly present. 
The climate of wetlands, on the other hand, is cool and wet.

Question. What is meant by ‘alien species’ invasion ? Name one plant and one animal alien species that are a threat to our Indian native species.
Answer : ‘Alien species’ invasion means introducing those that are, firstly, outside their natural distribution area, and, secondly, threatens biological diversity.
Plants : Lantana camara
Animals : Equus caballus (horse) or, Canis familiaris (dog).

Question. Write what was the percentage of forest cover of India at the beginning and at the end of the twentieth century. How different is it from the one recommended by the National Forest Policy of our country ?
Answer : Beginning of 20th century – 30%
End of 20th century – 19.4%
Recommendations were 33% for the plains and 67% for the hills (thus forest cover shrunk substantially) 

Question. Where would you expect more species diversityin tropics or in polar regions? Give reasons in support of your answer.
Answer : Tropics have more species biodiversity than that of the polar regions. The maximum biodiversity in the tropical regions is due to the following reasons :
(i) Prolonged evolutionary time : The tropics have remained undisturbed in the past and therefore evolved more species diversity.
(ii) High productivity : There is more solar energy available in tropics which contributes directly to more productivity, population sizes and indirectly to greater species diversity. 

Question. Justify with the help of an example where a deliberate attempt by humans has led to the extinction of a particular species.
Answer : The Nile perch introduced into Lake Victoria in East Africa, eventually led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake // Abingdon tortoise in Galapagos islands became, extinct, after goats were introduced due to greater browsing efficiency of goats // Connell’s field experiment showed that the competitively superior barnacle Balanus, excludes smaller barnacle Chathamalus // Over exploitation by man, caused extinction of Stellar’s sea cow / Passenger pigeon.

Question. With the help of one example, explain how does alien species invasion cause biodiversity loss.
Answer : When alien species are introduced, some of them become invasive, compete with the native species and cause extinction of indigenous species. For example :
(i) Partheniun, Lantana and Eichhornia are the exotic species of plants that have invaded India and caused environmental damage. They pose threats to the survival of many of our native species.
(ii) Introduction of African catfish (Clarias gariepinus) for aquaculture purposes is posing a threat to our indigenous catfish Clarias batrachus. 


Write the equation of the curve ‘a’ and explain.
Answer : (i) S = CAZ
Within a region, species richness increases with increasing explored area but only up to a limit.
(ii) Relationship between species richness and area for a wide variety of taxa turns out to be rectangular hyperbola. 

Question. List any two causes of biodiversity loss and explain any one of them. 
Answer : Causes of biodiversity losses :
(i) Habitat loss and fragmentation.
(ii) Over-exploitation.
(iii) Alien species invasions.
(iv) Co-extinctions. 
Co-extinctions : When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct. For example, when a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate. Another example is the case of a co-evolved plant pollinator mutualism where extinction of one invariably leads to the extinction of the other. 

Question. In the biosphere, immense biological diversity exists at all levels of biological organisation. Explain any two levels of biodiversity.
Answer : (i) Genetic diversity : A single species might show high diversity at the genetic level over its distributional range. The genetic variation is shown by the medicinal plant Rauwolfia vomitoria. 
(ii) Species diversity : It is the product of both species richness and evenness i.e. species richness is weighed by species evenness.
E.g., amphibian species are found more in the western ghats as compared to the eastern ghats.

Question. How does over-exploitation of beneficial species affect biodiversity ? Explain with the help of one example. 
Answer : Humans have always depended on nature for food and shelter, but when need turns to ‘greed’, it leads to over-exploitation of natural resources. Many
species extinctions in the last 500 years (Steller’s sea cow, passenger pigeon) were due to overexploitation by human Presently, many marine fish populations around the world are over harvested, endangering the continued existence of some commercially important species.

Question. List the features that make a stable biological community. 
Answer : The features of a stable community are as follows :
(i) Communities should have greater biodiversity for greater stability.
(ii) It should be able to prevent invasion by alien species.
(iii) It should be able to restore itself in a short period of time.
(iv) Variations should be minimal in the community.

Question. Why certain regions have been declared as biodiversity ‘hot spots’ by environmentalists of the world ? Name any two (hotspot) regions of India.
Answer : Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth. Invariably, the number of species waiting to be saved from extinction far exceeds the conservation resources available.
Hence, conservationists have declared certain regions as “hot spots” for maximum protection of these regions which have high levels of species richness and high degree of endemism.
Example, Western Ghats, Sri Lanka and Himalaya.

Question. Giving two reasons explain why there is more species biodiversity in tropical latitudes than in temperate ones.
Answer : (i) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialization and lead to a greater species diversity.
(ii) There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.

Question. Evaluate the effect of loss of biodiversity in a region. Mention any four such effects.
Answer : (i) Decline in plant production/Decline in number of animal species
(ii) Lowered resistance to environmental perturbations such as drought
(iii) Increased variability in certain ecosystem processes such as plant productivity / water use / pest & disease cycles
(iv) Species may become endangered / increased rate of species extinction.

Short Answer Type Questions – ll

Question. Explain, giving three reasons, why tropics show greatest levels of species diversity.
Answer : (i) Tropical latitude have remained relatively undisturbed, have a long evolutionary time for species diversification.
(ii) Less seasonal variations, constant and predictable environmental condition, promote niche specialization for greater species diversity.
(iii) More availability of solar energy, contributes to higher productivity.

Question. The following graph shows the species-area relationship. Answer the following question as directed.
(i) Name the naturalist who studied the kind of relationship shown in the graph. Write the observation made by him.
(ii) Write the situations as discovered by the ecologists when the value of ‘Z’ (slope of the line) lies

a) 0.1 and 0.2
(b) 0.6 and 1.2
What does ‘Z’ stand for ?
(iii) When would the slope of the line ‘b’ become steeper ?
Answer :
(i) Alexander Von Humboldt. Within a region species richness increased with increasing explored area but only up to a limit.
(ii) (a) The slopes of regression lines are similar / unaffected distribution in an area / normal range.
(b) The slope of regression is steeper when we analyse the species area relationship among very large areas like entire continent. Z (slope of the line) regression co-efficient.
(iii) If species richness is more / 0.62 – 1.2.

Question. Since the origin of life on the earth, there were five episodes of mass extinction of species.
(i) How is the ‘Sixth Extinction’, presently in progress, different from the previous episodes ?
(ii) Who is mainly responsible for the ‘Sixth Extinction’ ?
(iii) List any four points that can help to overcome this disaster.
Answer : (i) The rates are faster / accelerated / current species extinction rate are estimated to be 100-1000 times faster than in the pre-human times.
(ii) Human activities.
(iii) (a) Preventing habitat loss and fragmentation
(b) Checking over exploitation
(c) Preventing alien species invasion
(d) Preventing co-extinction
(e) Conservation / Preservation of species. 

Question. Co-extinction and introduction of alien species too are responsible for the loss of biodiversity. Explain, how. 
Answer : Co-extinction : When a species becomes extinct, the plant and animal species associated with it in the obligatory way, also becomes extinct Introduction of alien species : When alien species are introduced, some of them turn invasive (because of not having their predator there), and hence cause decline / extinction of indigenous species

Question. Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with any three examples.
Answer : (i) Nile perch introduced into Lake Victoria in East Africa led to the extinction of Cichlids fish.
(ii) Parthenium/Lantana/Eichhornia are invasive plants and pose a threat to indigenous species.
(iii) Introduction of African catfish (Clarias gariepinus) to aquaculture is a threat to Indian catfishes.

Question. (a) “India has greater ecosystem diversity than 
Norway.” Do you agree with the statement ?
Give reasons in support of your answer.
(b) Write the difference between genetic biodiversity and species biodiversity that exists at all levels of biological organization. 
Answer : (a) Yes
India / tropical region : (i) are less seasonal / more constant / more predictable.
(ii) promote niche specialisation leading to greater bio-diversity.
(iii) Species diversity increases as we move towards equator.
(iv) More number of species exist. Norway / temperate region : (i) more seasonal / less constant / less predictable.
(ii) do not promote niche specialisation leading to low bio-diversity.
(iii) Species diversity decreases as we move away from equator.
(iv) Less number of species exist. (Any one)
(b) (i) Genetic diversity : Diversity / variation within a species over its distributional range/ (same explanation with the help of a correct examples)
(ii) Species diversity : Diversity / variation at a species level (same explained with the help of a correct example).

Question. Taking one example each of habitat loss & fragmentation, explain how are the two responsible for biodiversity loss.
Answer : Habitat loss and fragmentation are two main causes of extinction of plants and animals and therefore loss of biodiversity. One of the important examples of habitat loss is the reduction in area of tropical rain forests. The Amazonian forests commonly called as lungs of planet are cleared for cultivation. This has resulted in extinction of a number of species and thus loss of biodiversity.
Fragmentation of habitat disrupts the interaction amongst species and annihilation of species resulting in the decreased biodiversity. 

Question. Explain the level of biodiversity at genetic, specific and ecological levels with the help of one example for each of the three.
Answer : Genetic level : A single species might show high diversity at genetic level, e.g., Rauwolfia vomitoria/ rice/Mango (any other suitable example) Specific level : Diversity at species level, e.g.
Amphibian species (Any other suitable example) Ecological level : Diversity at ecosystem level,
e.g., Deserts/rain forest/mangroves/ coral reef/ wet lands/estuaries/ alpine meadows/ (Any other suitable example)

Long Answer Type Questions

Question. (i) Taking one example each of habitat loss and fragmentation, explain how are two responsible for biodiversity loss.
(ii) Explain two different ways of biodiversity conservation.
Answer : (i) Habitat loss—Amazon rain forest destroyed for soya beans cultivation for growing grass land, for grazing cattle / colonisation of Pacific islandsextinction of 2000 species of native birds. Fragmentation—By human activity— migratory birds and animals are affected.
(ii) Ex situ, Threatened organism are taken out from the natural habitat and placed in special setting with care and protection. e.g.,
Zoological park / botanical garden / wild safari.
In situ, Threatened organisms are conserved in their natural habitat e.g. National park / Biosphere reserves. 

Question. (i) Indiscriminate human activities such as alien species invasion, fragmentation and habitat loss have accelerated the loss of biodiversity. Justify by taking one example for each.
(ii) State the importance of (a) IUCN Red data list and (b) Hot spots in conservation of biodiversity.
Answer : (i) Alien species invasion :
When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive and decline / extinction of indigenous species Examples:
(a) The introduction of African catfish / Clarias gariepinus (for aquaculture purpose) poses a threat to indigenous catfishes in our rivers.
(b) The Nile perch introduced into lake Victoria in East Africa led to the extinction of more than 200 species of Cichlid fish in the lake.
(c) Carrot grass / Parthenium, Lantana, Water hyacinth / Eichhornia poses a threat to indigenous species.
Fragmentation :
(a) When large habitats are broken into small fragments due to various human activities.
(b) Mammals / birds requiring large territories and certain animals with migratory habits are badly affected.
Habitat Loss : The Amazon rain forest is being cut and cleared for cultivating soyabeans / conversion to grasslands for raising cattle.
(ii) (a) Provides information regarding extinction of species
(b) Regions with very high levels of species richness,
high degree of endemism / species confined to that region and not found anywhere else are identified which need to be conserved in all priority basis.

Conservation of Biodiversity

Very Short Answer Type Questions

Question. Why have Western Ghats in India been declared as biological hot spots ?
Answer : Due to greater species diversity/presence of endemic species. 

Question. State the use of biodiversity in modern agriculture.
Answer : Biodiversity is useful in modern agriculture because it is source of hybrids, GM Crops, biopesticides, biofertilizers, improved variety of plants and also disease resistant plants.

Question. Write the importance of cryopreservation in conservation of biodiversity. 
Answer : Gametes of threatened species / seeds of commercially important strains can be preserved, in viable and fertile condition / for long periods. 

Short Answer Type Questions – l

Question. Differentiate between in-situ and ex-situ pproaches of conservation of biodiversity.
Answer : in-situ ex-situ Protection of endangered species of plants and animals by protecting the natural habitat/ecosysem. Protection of endangered species by removing them from the natural habitat and placing under special care.

Question. List any four techniques where the principle of ex-situ conservation of biodiversity has been employed. 
State how does ex-situ conservation help in protecting biodiversity.
Answer : Cryopreservation, in vitro fertilisation, micropropagation / tissue culture, sperm bank / seed bank / gene bank 

Question. Suggest two practices giving one example of each, that help protect rare or threatened species.
Answer : (i) In situ conservation, biodiversity hotspot / biosphere reserve / national parks / sanctuaries / Ramsar sites / sacred groves
(ii) Ex situ conservation, Zoological parks / botanical garden / wild life safari parks / cryopreservation techniques / Tissue culture / seed bank / pollen banks.

Question. Why are sacred groves highly protected ?
Answer : Sacred groves are highly protected because of religious and cultural traditions, refugees for large number of rare and threatened plants, cologically unique and biodiversity rich regions.

Short Answer Type Questions – ll

Question. Why should biodiversity be conserved ? Explain giving three reasons.
Answer : Narrowly utilitarian : Humans derive direct economic benefits from nature (or explained with example).
Broadly utilitarian : Provides many ecosystem services such as provide oxygen (through photosynthesis), prevents pollution, provides aesthetic pleasure.
Ethical : We share this planet with millions of other organisms and every species has intrinsic value and it is our moral duty to conserve them and pass on the legacy to future generation.

Question. Many plant and animal species are on the verge of their extinction because of loss of forest land by indiscriminate use by the human As biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct ?
Answer : As a biology student, I would suggest the following method that can protect these threatened species from becoming extinct:
Ex situ conservation : The threatened species of plants and animals are taken out of their habitats and are kept in special setting such as zoological parks, botanical gardens and wildlife sanctuaries. In the present scenario, the gametes of endangered species can be preserved by methods like cryopreservation and can be fertilised in vitro followed by propagation through tissue culture methods. Similarly, seeds can be preserved in seed banks. This type of conservation method is an off-site conservation method. 

Question. (i) Why is there a need to conserve biodiversity ?
(ii) Name and explain any two ways that are responsible for the loss of biodiversity.
Answer : (i) (a) To continue to get the products of human consumption.
(b) Plays a major role in many ecosystem services that nature provides and that is invaluable.
(c) Moral duty to pass on biological legacy in good order to future generations.
(ii) (a) Habitat loss and fragmentation : large habitats when broken lead to loss of habitat for animals needing large territories (are badly affected) – population decline.
(b) Over exploitation : leading to extinction of many, especially commercially important species.
(c) Alien species invasion : alien species when introduced may turn invasive causing decline and extinction of indigenous species // explain with an example.
(d) Co-extinction : when one species become extinct, any other organism intimately associated also becomes extinct. 

Question. Narrowly utilitarian arguments are put forth in support of biodiversity conservation. Explain the other two arguments that are put forth in support of the same cause.
Answer : Broadly utilitarian arguments : Biodiversity plays an important role in maintaining sustaining
supply of good & ecological services. The different ecosystem services provided are : purifies air, cycling of nutrients, habitat for wildlife, pollinating crops, aesthetic pleasure.
Ethical reasons : It is our philosophical/spiritual & moral duty to ensure well being of all living beings for utilization of future generations. 

Question. The sacred groves of Aravalli Hills and Ooty botanical garden both aim at biodiversity conservation. How do they differ in their approached ? Explain.
Answer : Sacred groves are the areas of Aravalli Hills where forest patches around places of worship are held in high esteem by tribals. All the trees and wildlife are given protection by tribals. Not a single branch is allowed to be cut from these forests. As a result, many endemic species that are rare or have become extinct elsewhere can be seen to flourish here.
Thus they help to conserve rare and threatened species of plants and animals. Ooty botanical garden conserves threatened and endangered species through ex-situ conservation technologies, involving seed bank, tissue culture facilities etc. 

Question. There are many animals that have become extinct in the wild but continue to be maintained in Zoological parks.
(i) What type of biodiversity conservation is observed in this case ?
(ii) Explain any other two ways that help in this type of conservation.
Answer : (i) It is an example of ex-situ conservation (off–site conservation). In this approach, threatened plants and animals are taken out of their natural habitat and placed into suitable settings and given special care.
(ii) Cryopreservation and tissue culture are two ways that help in ex-situ conservation.
In cryopreservation, gametes of threatened species are preserved in viable and fertile conditions at subzero temperatures, which helps in preserving these cells for longer periods.
In tissue culture, plants are propagated from a small mass of tissue called callus.

Question. Explain the ‘Ex-situ conservation’ of Biodiversity. How is the in-situ conservation different from it ?
Answer : Ex-situ – Threatened animals and plants are taken out from their natural habitat and placed in special settings where they can be protected and given  special care , by keeping the gametes of threatened species preserved in viable and fertile condition for long time 
Zoological parks / botanical gardens / wildlife safari parks / cryopreservation / eggs can be fertilised in vitro / tissue culture method / seed banks (Any correct example explained)  In-situ conservation: Organisms are given protection in their natural habitat in which biodiversity is protected at all levels

Question. ‘In-situ‘ conservation can help endangered / threatened species. Justify the statement.
Answer : Threatened organisms are conserved in their natural habitat / ecosystem, and such regions are legally protected  As hotspots / biosphere reserves / national parks / sanctuaries / sacred groves / ramsar sites

Long Answer Type Questions

Question. (i) Why should we conserve biodiversity ? How can we do it ?
(ii) Explain the importance of biodiversity hot spots and sacred groves. [Delhi Set-I, 2016]
Answer : (i) (a) • Narrowly utilitarian – related examples like derive economic benefits from nature: food (cereals, pulses, fruits) / firewood / fibre / construction materials / industrial products (tannins, lubricants, dyes, resins, perfumes) / product of medicinal importance / drugs. 
• Broadly utilitarian – 20% of total O2 from Amazon forests / pollination / aesthetic pleasures.
• Ethical – millions of species (plants, animals, microbes) share this planet / we need to realise that every species has an intrinsic value / we have a moral duty to care for their well-being and pass on our biological legacy to future generations.
(b) • In situ conservation / biosphere reserves / national parks / sanctuaries / sacred groves.
• Ex situ conservation / zoological parks / botanical gardens / wild life safari parks / cryopreservation / seed banks / tissue culture (eggs in vitro)
(ii) Hot spots : Regions with high level of species richness, high degree of endemism. Sacred groves : Tracts of forest containing tree / wild life were venerated and given total protection / to protect a large number of rare, and threatened plants.

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