Our Environment

NCERT Exemplar Problems

Short Answer Questions

Question 22: Why is improper disposal of waste a curse to environment?

Answer: Improper disposal of waste can be a curse to the environment because it leads to many problems. Let us take example of non-segregation of waste into biodegradable and non-biodegradable. If waste is not properly segregated, it can hamper the process of decomposition. If waste is disposed off near a residential area and is not covered properly, it can create a problem of stench in the surrounding. This can also cause many epidemics.




Question 23: Write the common food chain of a pond ecosystem.

Answer: Example of a food chain in the pond ecosystem:

Algae → Small Fish/shrimp → Medium Fish → Large fish/crane/duck

Question 24: What are the advantages of cloth bags over plastic bags during shopping?

Answer: Cloth bags are biodegradable, while plastic bags are non-biodegradable. So, cloth bags are environment-friendly but plastic bags are not. In most of the cases, a cloth bag is more durable than a plastic bag. Cloth bags also teach us about importance of recycling of materials.

Question 25: Why are crop fields known as artificial ecosystems?

Answer: In a crop field, plants do not grow naturally rather most of the plants are grown by humans. An ecosystem is nevertheless present in a crop field, but it is an artificial ecosystem as a major component of the ecosystem comes into origin because of human intervention.




Question 26: Differentiate between biodegradable and non-biodegradable substances. Cite examples.

Answer:

BiodegradableNon-biodegradable
They are decomposed by microbes.They cannot be decomposed.
They are environment friendly.They are not environment friendly.
Examples: fruit peels, jute bags, stale food Examples: plastic bags, glass, aluminium cans.

Question 27: Suggest one word for each of the following statements/ 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) Ecosystem, (b) Trophic Level, (c) Abiotic factors, (d) Consumers




Question 28: Explain the role of decomposers in the environment?

Answer: Decomposers decompose dead remains of plants and animals. By doing so, they serve two purposes, which are as follows.

  1. They reduce the burden on the environment by clearing dead remains.
  2. They channelize the raw materials back to the environment.

Question 29: Select the mis-matched pair in the following and correct it.

  1. Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain
  2. Ecosystem — Biotic components of environment
  3. Aquarium — A man-made ecosystem
  4. Parasites — Organisms which obtain food from other living organisms

    Answer: (b) Ecosystem: The system of interdependency among living beings and non-living things; in a given habitat.

Question 30: We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?

Answer: A pond or a lake has its own natural system of cleaning the waste materials to maintain its ecosystem. Due to this, ponds are lakes normally do not need to be cleaned. An aquarium is a man-made ecosystem which has a very small space. The abiotic components are not supplied naturally to the aquarium. So, an aquarium needs frequent cleaning so that the living beings in it can survive.






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