1. Tick [√] the correct option.
a. Which of the following correctly defines the term ‘ecosystem’?
i. The narrow zone of contact between the lithosphere, the hydrosphere, and the atmosphere.
ii. Complex network of living organisms, their physical surroundings, and the interactions between them.
iii. The process of planting trees in a forest.
iv. An area set aside by the government for the preservation of the natural environment.
Answer: (ii) Complex network of living organisms, their physical surroundings, and the interactions between them. [√]
b. In the following question, two statements are given as Assertion (A) and Reason (R). Read the statements and tick [√] the correct option.
Assertion (A): Equatorial forests are known as evergreen forests.
Reason (R): Due to the lack of a dry season, broad-leaved trees can maintain their green foliage throughout the year.
i. Both A and R are true, and R is the correct explanation of A.
ii. Both A and R are true, but R is not the correct explanation of A.
iii. A is true, but R is false.
iv. A is false, but R is true.
Answer: (i) Both A and R are true, and R is the correct explanation of A. [√]
c. Which of the following are the causes of wildlife depletion?
I. Illegal hunting
II. Deforestation
III. Setting up wildlife sanctuaries
IV. Human migrations
Options:
i. Only I and II
ii. Only III and IV
iii. Only I, II, and IV
iv. All I, II, III and IV
Answer: (iii) Only I, II, and IV [√]
Explanation: Illegal hunting, deforestation, and human migrations that destroy habitats cause wildlife depletion. Setting up wildlife sanctuaries is a step to protect wildlife, not deplete it.
d. What is the most acceptable cause of threat to aquatic animals?
i. Ecological balance
ii. Noise pollution
iii. Mining activities
iv. Discharge of poisonous chemicals and pesticides in water
Answer: (iv) Discharge of poisonous chemicals and pesticides in water [√]
2. Answer the following questions in 10 to 20 words.
a. What is meant by the biosphere?
Answer: The biosphere is the narrow zone where the land (lithosphere), water (hydrosphere), and air (atmosphere) interact, supporting all forms of life.
b. State any two significance of natural vegetation.
Answer: Natural vegetation helps in preventing soil erosion and provides a habitat for wildlife. It also plays a key role in maintaining the oxygen and carbon dioxide balance in the air.
Let Us Exercise
c. What type of vegetation and wildlife is found in temperate deciduous forests?
Answer: These forests have trees like oak, ash, and beech that shed their leaves in autumn. Common wildlife includes deer, foxes, wolves, and animals with thick fur to survive the cold winters.
d. What are endangered species? Give an example.
Answer: Endangered species are animals or plants that are at a very high risk of becoming extinct in the near future. An example is the one-horned rhinoceros found in India.
3. Answer the following questions in 50 to 70 words.
a. State the difference between tropical grasslands and temperate grasslands regarding climate, natural vegetation and wildlife.
Answer: Climate: Tropical grasslands, like the Savannas in Africa, are hot all year round with distinct wet and dry seasons. Temperate grasslands, like the Prairies in North America, have hot summers and very cold winters.
Vegetation: Tropical grasslands have tall, coarse grasses and scattered drought-resistant trees like acacia. Temperate grasslands have shorter, soft, and nutritious grasses with no trees.
Wildlife: Tropical grasslands are home to large herbivores like elephants, zebras, and giraffes, along with predators like lions. Temperate grasslands support animals like bison, wild horses, and burrowing creatures like rabbits.
b. What are the steps taken by the Government of India to conserve natural vegetation?
Answer: The Government of India has taken several important steps to conserve natural vegetation. These include:
1. Protected Areas: Setting up National Parks, Wildlife Sanctuaries, and Biosphere Reserves to protect forests and wildlife.
2. Afforestation Programs: Running campaigns like Van Mahotsav to encourage the planting of trees.
3. Legal Laws: Implementing the Forest Conservation Act to control and prevent the reckless cutting of forests.
c. Discuss any three factors responsible for the loss of forest covers.
Answer: Three major factors responsible for the loss of forests are:
1. Deforestation for Agriculture: Large areas of forests are cleared to create farmland for growing crops and for cattle grazing.
2. Urbanization and Infrastructure: The expansion of cities, the building of roads, dams, and industries requires clearing forest land.
3. Forest Fires: Both natural and man-made fires can destroy vast areas of forest very quickly, leading to significant loss of vegetation and wildlife habitats.
d. ‘The extinction of a single wildlife species in an ecosystem can disrupt the ecological balance.’ Justify the statement.
Answer: Every species is connected in an ecosystem through food chains. For example, if snakes go extinct, the population of rats they eat would explode. The increased number of rats would then eat too many crops, causing food shortages for other animals and humans. This shows how the loss of one species can create a chain reaction, upsetting the entire balance of the ecosystem.
e. Mention any three measures taken to protect wildlife in India.
Answer: Three key measures to protect wildlife in India are:
1. Establishing Protected Areas: Creating National Parks and Wildlife Sanctuaries where hunting and habitat destruction are illegal.
2.Ban on Illegal Hunting: Strict laws like the Wildlife Protection Act make poaching and illegal trade of animal products a punishable crime.
- Conservation Projects: Launching special projects like Project Tiger and Project Elephant to protect and increase the population of specific endangered species.
4. Think Ahead [HOTS]
Deforestation has significantly increased the intensity of the average hottest day of the year in Europe, North America, and Asia. What effect does deforestation have on climate change?
Answer: Deforestation worsens climate change in two main ways. First, trees absorb carbon dioxide (a major greenhouse gas) from the air. Cutting them down means more CO₂ stays in the atmosphere, trapping heat and making the planet warmer. Second, forests help in keeping the local climate cool by releasing moisture and providing shade. Without trees, the land gets hotter and drier, leading to more intense heatwaves.
5. Picture-based Question
a. What could be a man-made cause for the disaster shown in the image given?
Answer: A man-made cause for the forest fire could be a carelessly discarded cigarette or a campfire that was not properly put out by tourists or locals.
b. Suggest any two control measures that can be taken to avoid this disaster.
Answer: Two control measures are:
1.Creating firebreaks (cleared gaps in the forest) to stop the fire from spreading.
2. Running public awareness campaigns to educate people about the dangers of lighting fires in forest areas, especially during dry seasons.
6. Source-based Question
a. ‘The ecosystem is formed of relationships between different organisms that are connected by food chains and food webs’. Explain the statement with an example.
Answer: This statement means that in an ecosystem, every living thing depends on others for food, creating a connected network. For example, in a garden ecosystem, grass is eaten by a grasshopper. The grasshopper is then eaten by a frog, and the frog is eaten by a snake. This is a food chain. If the grass disappears, the grasshopper has no food, which means the frog and then the snake will also be affected. This interconnection is the food web.
b. What are the factors responsible for the imbalance in ecosystem? Mention any two.
Answer: Two factors responsible for the imbalance in an ecosystem are:
1. Deforestation: Cutting down trees destroys the homes and food sources of many animals, disrupting the food web.
2. Pollution: Releasing harmful chemicals into water bodies or air can poison plants and animals, killing them and breaking the links in the food chain.