Maharashtra State Board

📘 Standard VIII – Science

Chapter 18: Ecosystems

✏️ 1. Complete the following by using the correct option.

a. Air, water, minerals, soil are __________ factors of an ecosystem.
(physical, organic, inorganic)
Ans: Physical

b. Rivers, ponds, and oceans are __________ ecosystems.
(land, aquatic, synthetic)
Ans: Aquatic

c. Man is a __________ in an ecosystem.
(producer, consumer, decomposer)
Ans: Consumer

🔗 2. Match the following

ProducersEcosystem
a. Cactus4. Desert
b. Aquatic plants3. Aquatic
c. Mangroves2. Creek
d. Pine1. Forest

📚 3. Give My Information

a. Ecosystem

Ans:

  1. An ecosystem is formed by biotic (producers, consumers, decomposers) and abiotic (air, soil, water, sunlight) factors and their interactions.
  2. Biotic factors affect abiotic factors and other biotic factors in the ecosystem.
  3. Abiotic factors determine which organisms can survive in a particular ecosystem.
  4. Different ecosystems are found on Earth depending on size, place, climate, and types of plants and animals (e.g., forest, pond, ocean, river).
  5. Though ecosystems may appear independent, they are interconnected directly or indirectly.

b. Biome

Ans:

  1. Large ecosystems developed in regions with similar climate and similar biotic and abiotic factors are called biomes.
  2. A biome contains many small ecosystems.
  3. There are two main types of biomes:
    • Land biomes
    • Aquatic biomes
  4. Land biomes include grasslands, evergreen forests, deserts, Taiga ecosystem, etc.
  5. Aquatic biomes cover about 71% of the Earth’s surface and include freshwater and marine ecosystems such as ponds, rivers, lakes, and oceans.

c. Food Web

Ans:

  1. An ecosystem consists of many interconnected food chains forming a complex network called a food web.
  2. In a food web, organisms are interdependent.
  3. Any change in the number of organisms at one level affects the entire food web.

🔬 4. Give Scientific Reasons

a. Plants in an ecosystem are called producers.

Ans:

  1. Plants can prepare their own food by photosynthesis using sunlight, carbon dioxide, and water.
  2. Producers are organisms that make their own food.
  3. Consumers depend directly or indirectly on plants for food.
  4. Therefore, plants are called producers in an ecosystem.

b. Large dams destroy ecosystems.

Ans:

  1. Dams are constructed across rivers to store water for irrigation and electricity generation.
  2. Forests and grasslands are cleared to build dams.
  3. Land ecosystems get submerged under water and are destroyed.
  4. Reduced water flow in downstream areas also affects local ecosystems.

c. Rhinos were restored in Dudhwa Forest.

Ans:

  1. About 150 years ago, one-horned rhinos lived in Dudhwa Forest.
  2. Due to excessive hunting, they nearly became extinct.
  3. Rhinos were bred in protected grasslands with adequate water supply.
  4. On April 1, 1984, the population of one-horned rhinos was successfully restored.

📝 5. Answer the Following

a. What are the effects of increased population on ecosystems?

Ans:

  1. Depletion of natural resources: Increased demand leads to overuse of resources.
  2. Loss of biodiversity: Forests and wetlands are destroyed for development.
  3. Increase in pollution: More fossil fuel use and waste generation increase pollution.
  4. Global warming: Increased CO₂ emissions raise global temperatures.

b. How is urbanization responsible for the destruction of ecosystems?

Ans:

  1. Urbanization means the movement of people from rural to urban areas.
  2. Forests, wetlands, and grasslands are cleared for buildings and roads.
  3. Transport infrastructure destroys natural habitats.
  4. Many species become endangered or extinct due to human interference.

c. What are the reasons for war?

Ans:

  1. Competition over land, water, minerals, and political reasons causes war.
  2. Wars involve heavy bombing and explosions.
  3. Natural ecosystems are permanently damaged or destroyed.
  4. Wars negatively affect both the environment and human life.

d. Explain the interactions among the factors of an ecosystem.

Ans:

  1. An ecosystem includes biotic and abiotic factors that interact continuously.
  2. Abiotic factors like sunlight, water, and soil support producers.
  3. Producers prepare food and pass energy to consumers.
  4. Decomposers break down dead plants and animals and recycle nutrients.
  5. The removal of any factor can disturb the food chain and ecosystem balance.

e. Differentiate between Evergreen Forests and Grasslands.

Evergreen ForestsGrasslands
Found in areas with heavy rainfall throughout the year.Found in areas with low to moderate rainfall.
Trees are dense and tall.Mostly grasses with few trees and shrubs.
Leaves are broad and green.Leaves are thin and narrow.
Trees do not shed all leaves at once.Grasslands dry during the dormant season.

🖼 6. Describe the Following Pictures

Ans:

  1. The picture represents a desert ecosystem.
  2. Deserts receive less than 25 cm of rainfall annually.
  3. Animals like camels have adaptations to survive with less water.
  4. Plants such as cactus and desert palm trees are found here.
  5. Many desert animals are nocturnal and live in burrows during the day.
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