Biodiversity and Conservation
Rajasthan Board · Class 11 · Geography
NCERT Solutions for Biodiversity and Conservation — Rajasthan Board Class 11 Geography.
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EXERCISES
1(i)Conservation of biodiversity is important for:
(a) Animals
(b) Animals and plants
(c) Plants
(d) All organismsShow solution
Biodiversity refers to the variety of all living organisms on Earth — including animals, plants, microorganisms, and fungi. Conservation of biodiversity is important for all organisms because every species plays a role in maintaining ecological balance and the health of ecosystems that support all life forms.
1(ii)Threatened species are those which:
(a) threaten others
(b) Lion and tiger
(c) are abundant in number
(d) are suffering from the danger of extinctionShow solution
Threatened species are those whose population has declined to critically low levels due to habitat destruction, overexploitation, pollution, or other factors, placing them at risk of becoming extinct if the threatening processes continue.
1(iii)National parks and sanctuaries are established for the purpose of:
(a) Recreation
(b) Hunting
(c) Pets
(d) ConservationShow solution
National parks and wildlife sanctuaries are legally protected areas established by the government specifically for the conservation of wildlife, flora, fauna, and their natural habitats. Human activities like hunting and exploitation are strictly restricted within these areas.
1(iv)Biodiversity is richer in:
(a) Tropical Regions
(b) Polar Regions
(c) Temperate Regions
(d) OceansShow solution
Tropical regions receive abundant sunlight and rainfall throughout the year, providing warm and humid conditions that support a very high diversity of plant and animal species. Tropical rainforests, for example, are home to more than half of the world's species despite covering only a small fraction of Earth's surface.
1(v)In which one of the following countries was the 'Earth Summit' held?
(a) the UK
(b) Mexico
(c) Brazil
(d) ChinaShow solution
The Earth Summit (United Nations Conference on Environment and Development — UNCED) was held in Rio de Janeiro, Brazil, in June 1992. It was a landmark international conference where the Convention on Biological Diversity (CBD) was opened for signature, committing nations to conserve biodiversity.
2(i)What is biodiversity?Show solution
Answer:
Biodiversity (short for biological diversity) refers to the variety and variability of all living organisms on Earth — including plants, animals, microorganisms, and fungi — along with the ecosystems they form and the ecological processes they support. It encompasses diversity at three levels: genetic diversity, species diversity, and ecosystem diversity. Biodiversity is essential for maintaining ecological balance and sustaining life on Earth.
2(ii)What are the different levels of biodiversity?Show solution
Answer:
Biodiversity exists at three main levels:
1. Genetic Diversity: Variation in the genetic makeup (genes) within individuals of the same species. It allows species to adapt to changing environments.
2. Species Diversity: The variety of different species present in a given area. It is measured by the number of species (species richness) and their relative abundance.
3. Ecosystem Diversity: The variety of different ecosystems (such as forests, grasslands, wetlands, deserts, and oceans) present in a region, each supporting unique communities of organisms.
2(iii)What do you understand by 'hotspots'?Show solution
Answer:
Biodiversity 'hotspots' are geographic areas that are exceptionally rich in species diversity — particularly endemic species (species found nowhere else on Earth) — but are simultaneously under serious threat from human activities such as deforestation, habitat destruction, and urbanisation. To qualify as a hotspot, a region must contain at least 1,500 species of vascular plants as endemics and must have lost at least 70% of its original habitat. Examples include the Western Ghats of India, the Amazon Basin, and the Mediterranean Basin. Conservation efforts are especially focused on these regions.
2(iv)Discuss briefly the importance of animals to humankind.Show solution
Answer:
Animals are important to humankind in several ways:
1. Food: Animals provide food in the form of meat, milk, eggs, honey, and fish, which are essential components of human diet.
2. Agriculture: Draught animals like bullocks and horses have been used for ploughing fields and transportation for centuries.
3. Medicines: Many medicines and vaccines are derived from animal products (e.g., insulin from pigs, anti-venom from snakes).
4. Ecological Balance: Animals play crucial roles in pollination, seed dispersal, and maintaining food chains and food webs.
5. Economic Value: Animals contribute to industries like leather, wool, silk, and tourism (wildlife tourism).
6. Scientific Research: Animals are used in laboratory research to develop life-saving drugs and treatments.
2(v)What do you understand by 'exotic species'?Show solution
Answer:
Exotic species (also called alien or invasive species) are those species that are not native to a particular region but have been introduced — either intentionally or accidentally — from another part of the world. When exotic species are introduced into a new ecosystem, they may lack natural predators and can multiply rapidly, competing with and displacing native species, thereby threatening local biodiversity. For example, the water hyacinth (Eichhornia crassipes), originally from South America, has become an invasive species in many Indian water bodies, choking aquatic ecosystems.
3(i)What are the roles played by biodiversity in the shaping of nature?Show solution
Answer:
Biodiversity plays the following important roles in shaping nature:
1. Maintenance of Ecological Balance:
Every species in an ecosystem occupies a specific niche and contributes to the functioning of that ecosystem. Biodiversity ensures that energy flows and nutrient cycles (carbon cycle, nitrogen cycle, water cycle) operate efficiently.
2. Productivity of Ecosystems:
Biologically diverse ecosystems are more productive. A variety of plant species ensures better soil fertility, greater biomass production, and more stable food webs.
3. Soil Formation and Protection:
Microorganisms and plants contribute to soil formation through decomposition of organic matter. Plant roots prevent soil erosion, and diverse vegetation maintains soil health.
4. Regulation of Climate:
Forests and other biodiverse ecosystems regulate local and global climate by absorbing carbon dioxide, releasing oxygen, and influencing rainfall patterns through transpiration.
5. Water Purification and Regulation:
Wetlands and forests filter pollutants from water and regulate the water cycle, reducing the risk of floods and droughts.
6. Pollination and Seed Dispersal:
Animals, especially insects (bees, butterflies), birds, and bats, pollinate flowering plants and disperse seeds, enabling plant reproduction and forest regeneration.
7. Resilience to Environmental Change:
Highly biodiverse ecosystems are more resilient — they can better withstand and recover from disturbances such as droughts, floods, diseases, and climate change.
In summary, biodiversity is the foundation upon which all natural processes rest, and its loss can lead to the collapse of entire ecosystems.
3(ii)What are the major factors that are responsible for the loss of biodiversity? What steps are needed to prevent them?Show solution
Answer:
Major Factors Responsible for Loss of Biodiversity:
1. Habitat Destruction and Fragmentation:
Deforestation, urbanisation, agricultural expansion, and mining destroy and fragment natural habitats, leaving species without food, shelter, or breeding grounds. This is the single most important cause of biodiversity loss.
2. Overexploitation:
Overhunting, overfishing, and excessive harvesting of plants and animals for food, medicine, trade, and sport have drastically reduced the populations of many species.
3. Introduction of Exotic/Invasive Species:
Non-native species introduced into new ecosystems can outcompete, prey upon, or bring diseases to native species, leading to their decline or extinction.
4. Pollution:
Air, water, and soil pollution from industrial effluents, pesticides, and plastic waste poison ecosystems and harm or kill many species.
5. Climate Change:
Global warming alters temperature and precipitation patterns, causing habitat shifts, coral bleaching, glacial melting, and sea-level rise — all of which threaten species unable to adapt quickly.
6. Population Growth and Consumerism:
Rapidly growing human populations increase demand for land, water, food, and energy, putting immense pressure on natural ecosystems.
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Steps Needed to Prevent Biodiversity Loss:
1. In-situ Conservation:
Protecting species in their natural habitats through the establishment of national parks, wildlife sanctuaries, biosphere reserves, and marine protected areas.
2. Ex-situ Conservation:
Conserving species outside their natural habitats in zoos, botanical gardens, seed banks, and gene banks to prevent extinction.
3. Legal Protection:
Enacting and enforcing strict laws against poaching, illegal trade in wildlife (CITES), and habitat destruction.
4. International Cooperation:
Global agreements such as the Convention on Biological Diversity (CBD, 1992, Rio Earth Summit) and the Ramsar Convention on Wetlands must be implemented effectively by all nations.
5. Sustainable Use of Resources:
Promoting sustainable agriculture, forestry, and fishing practices that do not deplete natural resources beyond their capacity to regenerate.
6. Awareness and Education:
Raising public awareness about the importance of biodiversity and involving local communities in conservation efforts.
7. Restoration of Degraded Ecosystems:
Undertaking afforestation, wetland restoration, and coral reef rehabilitation programmes to restore lost habitats.
By combining these strategies at local, national, and global levels, the accelerating loss of biodiversity can be significantly reduced and eventually halted.
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