An ecosystem is a community of both living and non-living entities of a particular region, that is in constant interaction with each other, maintaining the ecological balance. The biotic or living entities are constituted by humans, plants, and animals while the abiotic or non-living entities are rock, soil, water, air, and other such related components of that region.
MSBSHSE Class 8 Science Chapter 18 solutions have been meticulously designed by our subject-matter experts keeping in mind the standards set forth by the board. These solutions will help students in understanding the concepts easily. Students should keep MSBSHSE Class 8 solutions of Chapter 18 handy so that they can refer to it whenever they are stuck solving any difficult question.
MSBSHSE Class 8 Science Chapter 18 Objective Questions: Textbook Important Questions and Solutions
MSBSHSE Class 8 Science Chapter 18 Textbook Exercise Questions
Q1. Complete the following by using correct option.
a. Air, water, minerals, soil are…………… factors of an ecosystem.
(physical, organic, inorganic)
b. River, ponds, ocean are …………… ecosystems.
(land, aquatic, synthetic)
c. Man is ……. in an ecosystem.
(producer, consumer, decomposer)
Answer a: Air, water, minerals, soil are physical factors of an ecosystem.
Answer b: River, ponds, ocean are aquatic ecosystems.
Answer c: Man is consumer in an ecosystem.
Q2. Match the following
Q3. Give my information
c. Food web
Answer a: The world around us is made up of living and nonliving factors. Living are called biotic factors while non living are called abiotic factors. There is a continuous interaction between these living and nonliving factors. Living organisms and their habitat, environment are correlated with each other. The structure which is formed due to these reciprocal relationships is called an ecosystem. Biotic and abiotic factors and their interactions form an ecosystem.
Answer b: In some regions on earth, a large area has same climate and abiotic factors. The living organisms in those areas are also similar. So, a specific ecosystem develops in a vast area. Such large ecosystems are called ‘Biomes’. These biomes contain many small ecosystems. Earth itself is a vast ecosytem.Two types of biomes are found on the earth. i. Land biomes ii. Aquatic biomes.
Answer c: There are unique interactions and relationships, which are involved in the transportation of energy. The energy, once produced and captured, is distributed throughout the various living organisms. This transfer of energy is termed as the food web.
Q4. Give scientific reasons
a. Plants in an ecosystem are called consumers.
b. Large dams destroy ecosystems.
c. Rhinos were restored in Dudhwa forest.
Answer a: Plants are called primary consumers in an ecosystem. Typically, they are considered as producers because they don’t depend on other organisms for their food. Plants manufacture their own food by the process of photosynthesis. The photosynthesis is a process through which carbon dioxide and water are converted into oxygen and glucose in plants in the presence of sunlight.
Answer b: Large dams destroy ecosystem because of the following reasons:
- Dams can cause rare flooding and this flooding of large areas of land means that the natural environment is destroyed.
- Relocation is another big concern. People living in villages and towns that are in the valley that could be flooded, must move out. Hence, they lose their farms and businesses.
- The building of large dams can cause serious geological damage, for instance, the building of the Hoover Dam in the USA triggered a number of earthquakes and has depressed the earth’s surface at its location. This is an alarming matter.
- It causes harm to the aquatic organisms living underwater and thus, they destroy the river ecosystem.
Answer c: About 150 years ago, Dudhwa forest was the habitat for single-horned Rhino. But in 20th century this animal became extinct due to unrelenting hunting. On 1st April 1984 this rhino were restored there and were bred in captivity and then released in their habitat. For this, 27 square km grassland and forest where water sources were available were selected and two observatories were established. So, finally, these efforts became successful and Rhinos were restored in Dudhwa forest.
Q5. Answer the following.
a. What are the effects of increased population on ecosystems?
b. How is urbanization responsible for destruction of ecosystems?
c. What are the reasons for war?
d. Explain the interactions among the factors of an ecosystem.
e. Differentiate between evergreen forests and grasslands.
Answer a: Humans are the consumers in an ecosystem. Ecosystems can provide basic needs in normal conditions, but due to increased population, man kept on snatching natural resources on a large scale. Changing lifestyle demands ‘more’ than ‘necessary’. That has increased stress on the ecosystems and has generated vast amount of wastes.
Answer b: Due to continuous process of urbanization, more and more agricultural lands, marshlands, wetlands, forests and grasslands are being destroyed for buildings and other basic facilities around. As a result of this human interference, ecosystems either change or get completely destroyed.
Answer c: Differences and competition over land, water, mineral resources or some economic and political reasons lead to war among human races. Heavy bombing and mine explosions are done in wars. These are not only life-threatening but also change or destroy natural ecosystem.
Answer d: Ecosystems are made up of living things (biotic factors) and non-living things (abiotic factors) that interact with each other. Organisms such as bacteria, worms, birds, plants and snakes are examples of biotic factors. Examples of abiotic factors include water, temperature, pH, salinity and light intensity.
Answer e: Grasslands – Grasslands develop where rainfall is not enough to grow big trees. Vast growth of grass is found in these ecosystems. Longer summer and limited rain develop dwarf plants in these areas. Animals like goat, sheep, giraffe, zebra, elephant, deer, chital, tiger, lion, etc. are found in this ecosystem. Similarly, various birds, insects, microbes are also present.
Evergreen forests – It’s a natural ecosystem where variety of plants, animals and abiotic factors are found.
Q6. Explain the structure of an ecosystem.
Answer: Living organisms need different types of abiotic factors and they have different capacities to adapt with those abiotic factors. Some microbes need oxygen, while others don’t. Some plants need more sunlight, while others grow well in shade. Each and every abiotic factor (air, water, soil, sunlight, temperature, humidity) affects the biotic factors in the ecosystem. The abiotic factors in an ecosystem decide which biotic factors will survive in it and what will be their number. The proportion of abiotic factors in an ecosystem is always changing as biotic factors use or excrete abiotic factors. Every biotic factor affects abiotic factors as well as other biotic factors around it. Every living organism in an ecosystem plays a particular role while living, moving in that ecosystem.
Q7. What are the components of an ecosystem?
Answer: The components of an ecosystem are:
Biotic components are the living things that have a direct or indirect influence on other organisms in an environment. For example, plants, animals, and microorganisms and their waste materials.
Abiotic components of an ecosystem include all chemical and physical elements i.e. non-living components. Abiotic components can vary from region to region, from one ecosystem to another. They mainly take up the role of life supporter. They determine and restrict the population growth, number, and diversity of biotic factors in an ecosystem. Hence, they are called limiting factors.
Q8. Define land biomes and aquatic biomes.
Answer: Land biomes – The biomes which exist only on land are called land biomes. Due to unequal distribution of abiotic factors different types of ecosystems exist. Eg. Grasslands, evergreen forests, deserts, iceland ecosystem, ecosystems in Taiga, tropical rainforests, etc.
Aquatic biomes – 71 % of the earth surface is covered by water and only 29 % has land on it. Therefore, study of aquatic biomes becomes very important. According to the area, aquatic biomes are widespread. Types of aquatic ecosystems are – Freshwater ecosystem, marine ecosystem, creek ecosystem.
Q9. Explain diminishment of ecosystem due to human interference?
Answer: Many human activities have side effects on functions of ecosystems and cause their diminishment. Eg. mining and excessive cutting of trees changes the use of land, so interactions between biotic and abiotic factors are also affected. Different human activities have different effects on ecosystems. There can be transformation of an ecosystem from one to another or extinction of a species.
Q10. Write the functions of an ecosystem?
Answer: The functions of the ecosystem are as follows:
- It regulates the essential ecological processes, supports life systems and renders stability.
- It is also responsible for the cycling of nutrients between biotic and abiotic components.
- It maintains a balance among the various trophic levels in the ecosystem.
- It cycles the minerals through the biosphere.
- The abiotic components help in the synthesis of organic components that involves the exchange of energy.
Q11. How do producers obtain abiotic factors?
Answer: The producers obtain abiotic factors through biotic factors. Producers are those organisms that can prepare their own food such as plants who prepare their own food through photosynthesis. Producers are biotic factors and they are directly dependent on the abiotic factors such as wind, water, temperature, sunlight. For example, plants obtain abiotic factors such as sunlight, water and carbon dioxide and in return liberates oxygen and food.
Q12. From where do the consumers get their food?
Answer: Consumers get their food supply from producers. Producers are plants with the green pigment chlorophyll, and producers can make their own food using sunlight, air and water.
Q13. Discuss the importance of ecosystem.
Answer: The importance of ecosystem are:
- It provides habitat to wild plants and animals.
- It supports different food chains and food webs.
- It regulates essential ecological processes and supports lives.
- Involved in the recycling of nutrients between biotic and abiotic components.
- Maintains the proper flow of energy in an ecosystem including – Water Cycle, Carbon Cycle, Oxygen Cycle, Nitrogen Cycle, Energy Cycle.
Q14. Define freshwater ecosystem and marine ecosystem.
Answer: Freshwater ecosystem – Ponds, lakes and rivers are included in aquatic ecosystems. The transition of energy in these ecosystems is through water currents and rivers. Decomposers are at the bottom of water reservoirs. They decompose dead bodies of plants and animals into abiotic factors.
Marine ecosystem – Marine plants grow in these ecosystems. Shallow water contains small fishes, prawns feeding on algae. The central part of sea has less number of aquatic living organisms. Large fishes are secondary consumers. Ocean has a large amount of nutrients. The bottom of oceans has more decomposers. Dead bodies of plants and animals, waste materials are decomposed by bacteria.
Q15. What makes a good ecosystem?
Answer: A good ecosystem consists of native plants and animal species interacting with each other and the environment. A healthy ecosystem has an energy source and the decomposers that break down dead plants and animal matter, returning essential nutrients to the soil.
Q16. Which is the largest ecosystem in the world?
Answer: The largest ecosystem in the world is the aquatic ecosystem. It comprises the freshwater and marine ecosystem. It constitutes 70% of the surface of the earth.
Q17. Explain the human activities responsible for diminishment of ecosystems.
Answer: The human activities responsible for diminishment of ecosystems are as follows:
Increasing use of resources due to increased population – Humans are the consumers in an ecosystem. Ecosystems can provide basic needs in normal conditions, but due to increased population, man kept on snatching natural resources on large scale. Changing lifestyle demands ‘more’ than ‘necessary’. That has increased stress on the ecosystems and has generated vast amount of wastes.
Urbanization : Due to continuous process of urbanization. More and more agricultural lands, marshlands, wetlands, forests and grasslands are being destroyed for buildings and other basic facilities around. As a result of this human interference, ecosystems either change or get completely destroyed.
Industrialization and traffic : Raw materials required for industrialization are obtained by destroying forests. This result in destruction of forests. To provide the amenities for increased traffic, many times roads and railways are built through forests and wetlands.
Tourism : People visit scenic places mainly for nature watch, entertainment and visit to sacred places. A lot of amenities are created for these tourists. This causes destruction of local ecosystems due to increased stress.
Large Dams : Dams cover vast lands. So the forests or grassland in that area get converted into aquatic ecosystems. Dams also lessen the water current in the lower area. Therefore, the previous ecosystems in that running water get destroyed.
Q18. Which biotic factors get affected due to a dam?
Answer: Soil contains important nutrients, minerals, silt and loam etc. Hence, when the quality and quantity of soil and water gets affected by the dams due to storing of water, controlling flow, digging reservoirs etc, then these abiotic factors are impacted, and the environment also gets impacted.
Q19. Why are microbes said to be Decomposers?
Answer: The organic substances (carbohydrates, proteins and lipids) from dead bodies of plants and animals are converted into inorganic substances (hydrogen, oxygen, calcium, iron, sodium, potassium etc.) by microorganisms. Therefore, microbes are said to be ‘Decomposers’.
Q20. Define food chain.
Answer: A food chain is a chain which shows how organisms are linked to each other through food. A food web shows how two food chains are connected. A single food web consists of many food chains. Every food chain begins with producers and ends with top carnivores.