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Question

Three environmental problems of the Sunderbans are-

  • imbalance in the numbers of prey and predators
  • destruction of mangrove plants due to urbanisation
  • rising sea level

Analyse the probable effects of the three problems. Mention the location and the name of one endangered species of a biodiversity hotspot distributed in and outside the geographical area of India. [3+2=5]

OR

Describe the nitrogen cycle with the help of a word diagram. Analyse any two problems which may arise if the nitrogen cycle is disturbed. [3+2=5]

WBBSE Class X Life Science 05 (a) Nitrogen 05 (d) Biodiversity and Its Conservation 5 2023

Answer

The probable effects of the three environmental problems of the Sundarbans:

  • Imbalance in the numbers of prey and predators: This can lead to the extinction of prey species, as they will be hunted to extinction by predators. It can also lead to the overpopulation of predator species, which can then prey on other species in the ecosystem.
  • Destruction of mangrove plants due to urbanisation: This can lead to the loss of habitat for many species that depend on mangroves for food and shelter. It can also lead to the erosion of coastlines, as mangroves help to protect them from the forces of the ocean.
  • Rising sea level: This can inundate low-lying areas of the Sundarbans, displacing people and wildlife. It can also lead to the salinization of freshwater sources, making them unusable for drinking and irrigation.

One endangered species of a biodiversity hotspot distributed in and outside the geographical area of India is the Royal Bengal tiger. It is found in the Sundarbans, as well as in other parts of India, Bangladesh, and Nepal. The Royal Bengal tiger is listed as endangered on the IUCN Red List, and its population is declining due to habitat loss, poaching, and conflict with humans.

Here is a table summarizing the probable effects of the three environmental problems of the Sundarbans:

Problem Probable effect
Imbalance in the numbers of prey and predators Extinction of prey species, overpopulation of predator species
Destruction of mangrove plants due to urbanisation Loss of habitat for many species, erosion of coastlines
Rising sea level Inundation of low-lying areas, salinization of freshwater sources

Or

Nitrogen cycle

  1. Nitrogen fixation: Nitrogen gas is converted into ammonia by bacteria.
  2. Ammonification: Ammonia is converted into nitrites and then nitrates by bacteria.
  3. Nitrification: Nitrates are converted into nitrogen gas by bacteria.
  4. Denitrification: Nitrates are converted back into nitrogen gas by bacteria.

Two problems that may arise if the nitrogen cycle is disturbed are:

  1. Decreased crop yields: Nitrogen is an essential nutrient for plants and plays a critical role in their growth. If the nitrogen cycle is disrupted, plants may not receive adequate nitrogen, leading to poor growth and reduced agricultural productivity, which can cause food shortages.
  2. Increased pollution: Disruption in the nitrogen cycle can cause excess nitrogen compounds to accumulate in the environment, leading to issues like water pollution and the formation of smog and acid rain. These pollutants harm human health, aquatic life, and ecosystems.

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