NCERT Exemplar Class 12 Biology Solutions Chapter 15 Biodiversity and Conservation

Brazil has the richest biodiversity in world because of Amazon rainforest which is full of different types of animals, plants, birds, insects all living together. The climate here is hot and wet which supports the life very well and so many species live there which cannot be found anywhere else. That is why its called the biodiversity hotspot of earth.

Hence, the correct answer is option (a), Brazil.

Keeping animals in zoological parks is not harmful for biodiversity actually it helps to protect them. Zoo gives safe and proper environment with care to the animals so they dont get hunted or their population goes down. But habitat destruction, alien species and overuse of resources are truly main reason for biodiversity loss. So zoo is positive for biodiversity.

Hence, the correct answer is option (c), keeping animals in zoological parks.

Lantana, Parthenium and Eichhornia are invasive alien species which came from other countries and spread in India and they harm the native plants and animals. Cynodon is not alien because it is native grass species of India and not introduced from outside so it is not invasive species. That is the reason why its different from others.

Hence, the correct answer is option (b), Cynodon.

Pitcher plant is found mainly in the rainforests of North-East India. This place has humid and warm climate which supports the pitcher plant to grow and catch insects as food because soil nutrients are less. Other options dont suit pitcher plant habitat because desert and sunderbans are dry or salty. So North east rainforest is perfect for them.

Hence, the correct answer is option (a), the rainforest of North-East India.

Biodiversity hotspots have many species, with lot of endemic ones which means they are only found there. These areas are mostly in tropical parts of world because climate is best for life. Polar areas have harsh weather and very less sunlight, so they can’t support high biodiversity. That is why polar regions are not known for hotspots of life.

Hence, the correct answer is option (d), mostly located in the polar regions.

Dodo lived in Mauritius, Quagga was from Africa, Thylacine was from Australia, and Steller’s sea cow was found in Russia water region. All these animals have now become extinct and they are always asked in exam for match type questions. Remember their locations because they are popular example of extinction by human activities also.

Hence, the correct answer is option (d), A-iii, B-i, C-iv, D-ii.

Nepenthes, Psilotum, Rauwolfia and Aconitum are plants which are collected too much because they have medicinal or commercial uses. This over-collection is the reason they are prone to overexploitation. Some are used in traditional medicines also and so their population is in risk if we don’t do proper conservation of them.

Hence, the correct answer is option (c), all are prone to over-exploitation.

Kaziranga National Park in Assam is famous for the one-horned rhinoceros. This park has protected them from hunting and given safe habitat. Other parks mentioned like Bandipur or Corbett do not have one-horned rhino. Kaziranga is a world heritage site and one of the best rhino conservation areas of the world which is in India.

Hence, the correct answer is option (c), Kaziranga.

Amphibians are very sensitive group because they live both on land and water and their moist skin is affected by pollution, climate change, chemicals, habitat loss etc. That is why they are seen as most vulnerable group now. About 33% amphibians are under threat category which is very serious for biodiversity.

Hence, the correct answer is option (c), Amphibians.

Rauwolfia serpentina, Sandalwood (Santalum album) and Cycas beddonei are all endangered plants of India. These are threatened due to overuse, habitat loss and illegal trade. They are protected under law but still need good conservation. In exam they usually ask about Rauwolfia because of medicinal uses but here all are endangered.

Hence, the correct answer is option (d), all of these.

Lantana, Eichhornia (water hyacinth) and African catfish are not native to India, so they are not indigenous. Also they are not threatened, in fact they are invasive which means they spread too much and cause harm to local biodiversity. So they are neither threatened nor native species of India.

Hence, the correct answer is option (d), all the species are neither threatened nor indigenous species of India.

Passenger pigeon was hunted in huge numbers by humans in North America and could not survive because there was too much exploitation. This led to total extinction of the species which is a classic case of human-caused extinction in wildlife history. Other reasons like food or bird flu were not the cause.

Hence, the correct answer is option (b), overexploitation by humans.

Steller’s sea cow is a marine mammal which is extinct now. It lived near Bering Sea but humans hunted it too much. Parthenium is not endemic, African catfish is threat for native catfish, and Lantana is not carrot grass, it is known as red sage. So the only correct statement here is about extinction of Steller’s sea cow.

Hence, the correct answer is option (c), Steller’s sea cow is an extinct animal.

Coral reefs are called the rainforest of ocean because they have highest biodiversity among marine ecosystems. They support thousands of fish, corals, invertebrates and sea plants. Mangroves, deserts or alpine meadows cannot match this high biodiversity because of limited productivity. Coral reefs are very important but also very threatened worldwide.

Hence, the correct answer is option (c), coral reefs.

Amazon rainforest in South America is called the lungs of the planet because it produces massive oxygen and absorbs carbon dioxide. Its trees and plants do this work on huge scale and maintain earth’s atmosphere. That is why it is so important to protect Amazon rainforest for biodiversity and climate also.

Hence, the correct answer is option (c), Amazon rainforest.

Reserpine is a medicine extracted from Rauwolfia plant which is found in India. It is used for treating high blood pressure and mental disorders in some cases. Rauwolfia is also called sarpagandha in local language and it is an endangered plant due to overharvesting for these drugs.

Hence, the correct answer is option (b), Rauwolfia.

Fungi are the most diverse group among given options. They have so many species which live in soil, dead matter, plants etc. They are very important decomposers in ecosystem. Compared to gymnosperms, algae and bryophytes, the fungi show largest number of known species worldwide.

Hence, the correct answer is option (d), fungi.

Tropics have almost same amount of sunlight and warm temperature the whole year, so they do not have strong seasonal changes like cold or temperate places. This makes tropical climate stable with less variation and is good for stable ecosystems with high biodiversity.

Hence, the correct answer is option (a), tropics.

In 1992 the Earth Summit was held at Rio de Janeiro where countries signed the Convention on Biological Diversity and other climate agreements. This meeting is called historic because it made the world focus on biodiversity protection and sustainable development for the first time in big way.

Hence, the correct answer is option (b), the Earth Summit.

In vitro fertilisation, cryopreservation and tissue culture are all ex-situ conservation techniques because they happen outside the natural habitat. They help to save genetic material or breed plants and animals safely in labs or special facilities. So they are not in-situ conservation methods.

Hence, the correct answer is option (b), all are ex-situ conservation methods.