NCERT Exemplar Class 10 Science Solutions

Chapter 15-Our Environment-Short Answers

Short Answer Type Questions
Q.22. Why is improper disposal of waste a curse to environment?
Answer. Certain substances when burnt in air releases harmful gases. When these substances dumped in river or sea create water pollution. Some sort of waste materials on dumping inside the ground can make the land infertile.
So, if proper method of waste disposal system is not used then it will contaminate the environment.
Q.23. Write the common food chain of a pond ecosystem.
Answer. A common food chain of a pond ecosystem is as follows:
Producers (aquatic plants) → Herbivores (Protozoa) → Carnivore (Small fishes) → Large Carnivores (Large Fishes)
Q.24. What are the advantages of cloth bags over plastic bags during shopping?
Answer.Cloth bags have many advantages over plastic bags, some of them are:
Bags made of clothes can be used again and again by washing or modifying. One can modify these bags in home. Cloth bags are biodegradable and don’t causes pollution.
Q.25. Why are crop fields known as artificial ecosystem?
Answer. Ecosystems which are made by man are known as artificial ecosystem.
In case of crop fields abiotic and biotic components are selected by humans. The essential process such as sowing seeds, then irrigated and further progress is also kept under observation for getting good yield.
Q.26. Differentiate between biodegradable and non-biodegradable substances. Give examples.
Answer. Difference between biodegradable and non-biodegradable substances are:


Q.27. Suggest one word for each of the following statement/definitions.
(a) The physical and biological world where we live in
(b) Each level of food chain where transfer of energy takes place
(c) The physical factors like temperature, rainfall, wind and soil of an ecosystem
(d) Organisms which depend on the producers either directly or indirectly for food
Answer.
(a) Environment
(b) Trophic level
(c) Abiotic factors
(d) Consumers
Q.28. Explain the role of decomposers in the environment.
Answer. The microorganisms, comprising bacteria and fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.
They act as natural cleaning agent by decomposing dead organisms and biodegradable wastes and helps in replenishment of the soil’s nutrients,
Q.29. Select the mis-matched pair in the following and correct it.


Answer. (b)
An ecosystem consists of biotic components (living organisms) as well as abiotic components (soil, air, water etc.) of environment.
Q.30. We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?
Answer. A pond or a lake forms a natural and complete ecosystem. All the food chain presents in these ecosystems are complete. These ecosystems have plenty of producers, consumers and decomposers.
On the other hand an aquarium is an incomplete artificial ecosystem. An aquarium does not have enough population of decomposers to decompose waste material produced by aquatic animals. Due to this reason aquarium needs to be cleaned frequently.