3. Give my information

a. Ecosystem 

Ans: 

(i) An ecosystem is formed of biotic (producers, consumers, etc.) and abiotic (air, soil, water, etc.) factors and their interactions.

(ii) In an ecosystem, the biotic factors affect the abiotic factors as well as other biotic factors. The abiotic factors determine the biotic factors that will survive in an ecosystem.

(iii) Ecosystems are complex, and there is tremendous variation among species in terms of quantity as well as quality.

(iv) A variety of ecosystems are found on earth according to size, place, climate, and types of plants and animals. Each place has a different ecosystem. e.g., a forest, pond, ocean, river, etc.

(v) Each ecosystem looks independent and different; however, they are linked to each other, either directly or indirectly. Thus, these small ecosystems cannot be separated.

b. Biome 

Ans: 

(i) Large ecosystems developed in some regions on Earth with the same climate and biotic and abiotic factors are called “biomes.”

(ii) These biomes contain many small ecosystems.

(iii) There are two types of biomes found on Earth: land biomes and aquatic biomes.

(iv) Land biomes: The biomes that exist only on land are known as land biomes. In these biomes, different types of ecosystems are formed due to the unequal distribution of abiotic factors. e.g., grasslands, evergreen forests, deserts, the Iceland ecosystem, the Taiga ecosystem, etc.

(v) Aquatic biomes: They are widespread, as 71% of the Earth’s surface is covered by water.

(vi) The aquatic biomes include freshwater, marine, and creek ecosystems.

e.g. Ponds, rivers, oceans, lakes, etc.

c. Food web 

Ans: 

(i) An ecosystem is made up of many food chains that are interconnected at various levels, forming an intricate web instead of a linear chain. This kind of intricate network is called a food web.

(ii) In a food web, various organisms are interdependent. Thus, any change in the number of organisms at various levels affects the food web.

4. Give scientific reasons

a. Plants in an ecosystem are called consumers.

Ans: 

(i) An ecosystem consists of biotic and abiotic factors.

(ii) Plants are the biotic factors that can produce their own food using sunlight, carbon dioxide, and water by the process of photosynthesis and are hence called producers.

(iii) In an ecosystem, only producers can produce their own food. The primary consumers derive their nutrition from these producers. Secondary consumers derive nutrition from the primary consumers, and so on.

(iv) Consumers cannot produce their own food and get energy directly or indirectly from the energy trapped in plants.

Thus, plants in an ecosystem are called producers.

b. Large dams destroy ecosystems.

Ans:

(i) Dams are the massive barriers constructed across the rivers and streams to trap and utilise the flow of water for irrigation and the generation of electricity.

(ii) These dams are built by clearing forests or grasslands, thereby converting land ecosystems into aquatic ecosystems.

(iii) The ecosystems get destroyed when submerged under the water due to an overflow of the reservoirs.

(iv) Also, dams reduce the water current in the lower areas thus destroying the local ecosystems. 

c. Rhinos were restored in Dudhwa forest.

Ans:

(i) About 150 years ago, Dudhwa forest was the habitat for one-horned rhinos. The species came very close to extinction due to relentless hunting in the 20th century.

(ii) Rhinos were bred in captivity in 27 km of grassland and forest where water sources were available throughout the year and then released in their natural habitat.

(iii) Two observatories were established. The efforts to restore the one-horned rhino in Dudhwa Forest were successful.

(iv) On April 1, 1984, the population of one-horned rhinos was restored.

5. Answer the following.

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

Ans:

Following are the effects of increased population on ecosystems:

(i) Depletion of natural resources: An increase in population has led to an increase in the demand for natural resources. Ecosystems can fulfill the basic requirements of humans, but a large-scale increase in population and a change in human lifestyle have led to overexploitation of natural resources. This has put a strain on the ecosystems and resulted in a large amount of waste.The burden of waste disposal has also created stress on ecosystems.

(ii) Threat to biodiversity or loss of biodiversity: Due to rapid urbanization, industrialization, etc., more and more forest areas are being cleared. Destruction of agricultural lands, marshlands, wetlands, forests, and grasslands for construction of buildings, roads, dams, etc., has either changed or destroyed ecosystems. The loss of habitat for many organisms has ultimately led to a loss of biodiversity.

(iii) Increase in pollution levels: Population growth has had a negative impact on the quality of the ecosystem. An increase in population has led to the use of fossil fuels, chemical fertilizers, and pesticides, resulting in a rapid increase in waste generation. This has increased the levels of air, water, and soil pollution.

(iv) Global warming: An increased level of CO₂ emissions due to the burning of fossil fuels, deforestation, etc. has caused a rise in the global temperature. It has tremendous impacts on plants, animals, and humans.

b. How is urbanization responsible for destruction of ecosytems ?

Ans: 

(i) Urbanization refers to the movement of people from rural to urban areas.

(ii) Due to urbanization, there has been a rapid increase in the use of agricultural lands, marshlands, wetlands, forests, and grasslands for the construction of buildings, roads, dams, etc.

(iii) Roads and railways are built by destroying forest and wetland ecosystems in order to develop transportation infrastructure.

(iv) Human activities endanger many species of animals and plants. Certain species have become extinct due to human interference, thus disturbing the ecosystem.

As a result of this human interference, ecosystems get destroyed.

c. What are the reasons for war ?

Ans: 

(i) Differences and competition over land, water, mineral resources, or economic and political reasons cause war.

(ii) During wars, heavy bombing and mine explosions occur.

(iii) Wars are not only life-threatening but also permanently change or destroy natural ecosystems.

(iv) The impacts of war on the environment as well as on humans are significant, so we must prevent future wars.

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

Ans: 

(i) An ecosystem consists of biotic and abiotic factors. Both of these factors continuously interact with each other. The biotic and abiotic factors and the interactions between them form an ecosystem.

(ii) Biotic (living) factors include producers, consumers, and decomposers, whereas abiotic (non-living) factors include chemical factors like organic and inorganic substances and physical factors like sunlight, water, etc.

(iii) In an ecosystem, the abiotic factors determine the survival of the biotic factors.

(iv) Producers (plants) are autotrophic; they depend on abiotic factors like sunlight, water, soil, minerals, etc. for photosynthesis. Energy produced during this process enters the ecosystem through the producers.

(v) Primary consumers (herbivores) depend on producers for their food, and secondary consumers depend on the primary consumers. The tertiary consumers depend on the secondary consumers. The primary consumers play a major role in the transfer of energy from plants to other biotic factors in an ecosystem.

(vi) Decomposers breakdown the dead remains of plants and animals and make nutrients available in the ecosystem.

(vii) The sequence of energy transfer from producers to decomposers forms a food chain, and the removal of any of these factors can disrupt the entire food chain.

(viii) Thus, biotic and abiotic factors interact and work together in an ecosystem. They play a major role in the maintenance of the ecosystem.

e. Differentiate between evergreen forests and grasslands.

Ans: