Question 1

Q1: Which of the following groups contain only biodegradable items? (a) Grass, flowers and leather (b) Grass, wood and plastic (c) Fruit-peels, cake and l...

Accepted Answer

The correct options are (a), (c), and (d) as all items listed in these groups are of natural origin and can be broken down by microorganisms. - (a) Grass, flowers and leather: All are natural products and are biodegradable. - (b) Grass, wood and plastic: Plastic is a non-biodegradable substance. - (...

Question 2

Q2: Which of the following constitute a food-chain? (a) Grass, wheat and mango (b) Grass, goat and human (c) Goat, cow and elephant (d) Grass, fish and go...

Accepted Answer

The correct answer is (b) Grass, goat and human. - A food chain shows a sequence of who eats whom.  - In option (b), grass is the producer, the goat (herbivore) eats the grass, and a human (omnivore) can eat the goat. This represents a valid flow of energy. - Option (a) consists only of producers. -...

Question 3

Q3: Which of the following are environment-friendly practices? (a) Carrying cloth-bags to put purchases in while shopping (b) Switching off unnecessary li...

Accepted Answer

The correct answer is (d) All of the above. - (a) Carrying cloth bags reduces the use of plastic bags, which are non-biodegradable and cause pollution. - (b) Switching off unnecessary lights and fans conserves electricity, which helps reduce the burning of fossil fuels and associated pollution. - (c...

Question 4

Q4: What will happen if we kill all the organisms in one trophic level?

Accepted Answer

If we kill all the organisms in one trophic level, it will cause a serious imbalance in the ecosystem and disrupt the food web. - The organisms in the subsequent (higher) trophic level will be deprived of their food source, leading to their starvation and death. Their population will decline drastic...

Question 5

Q5: Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be...

Accepted Answer

Yes, the impact of removing all the organisms in a trophic level will be different for different trophic levels. - Removing Producers (First Trophic Level): This would have the most catastrophic impact. Producers form the base of the food chain, converting solar energy into food. Their removal would...

Question 6

Q6: What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Accepted Answer

Biological magnification (or biomagnification) is the phenomenon where the concentration of certain harmful, non-biodegradable chemicals, such as pesticides, increases progressively at each successive trophic level in a food chain. These chemicals are not metabolized or excreted by organisms; instea...

Question 7

Q7: What are the problems caused by the non-biodegradable wastes that we generate?

Accepted Answer

The non-biodegradable wastes that we generate cause several environmental problems: 1.  Land and Water Pollution: Since these wastes, like plastics and glass, do not decompose, they persist in the environment for very long periods. They accumulate in landfills, taking up valuable land space, and pol...

Question 8

Q8: If all the waste we generate is biodegradable, will this have no impact on the environment?

Accepted Answer

No, even if all the waste we generate is biodegradable, it would still have an impact on the environment, especially if produced in large quantities. The impacts include: 1.  Air Pollution: The process of decomposition by microorganisms is slow and can release large amounts of foul-smelling and harm...

Question 9

Q9: Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Accepted Answer

Damage to the ozone layer is a major cause for concern because this layer, located in the stratosphere, protects life on Earth by absorbing most of the harmful ultraviolet (UV) radiation from the sun. The depletion of the ozone layer allows more UV radiation to reach the Earth's surface, which can l...

Question 10

Q1: What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Accepted Answer

Trophic levels are the various steps or levels in a food chain at which the transfer of food or energy takes place. An example of a simple food chain is: Grass → Deer → Lion In this food chain, the different trophic levels are: 1.  First Trophic Level: Grass (Producer) - They produce their own food...

Question 11

Q2: What is the role of decomposers in the ecosystem?

Accepted Answer

Decomposers, such as bacteria and fungi, play a crucial role in the ecosystem. Their primary functions are: 1.  Decomposition: They break down the complex organic substances present in dead organisms (plants and animals) and their waste products into simple inorganic substances. 2.  Nutrient Recycli...

Question 12

Q1: Why are some substances biodegradable and some non-biodegradable?

Accepted Answer

The ability of a substance to be broken down by biological processes determines whether it is biodegradable or non-biodegradable. This process is carried out by microorganisms which secrete specific enzymes. - Biodegradable substances: These are substances that can be broken down by the action of mi...

Question 13

Q2: Give any two ways in which biodegradable substances would affect the environment.

Accepted Answer

Two ways in which biodegradable substances can affect the environment are: 1.  Pollution through Decomposition: When biodegradable waste decomposes in large quantities, it can produce foul smells and release harmful gases like methane ($	ext{CH}_4$) and hydrogen sulphide ($	ext{H}_2	ext{S}$), whi...

Question 14

Q3: Give any two ways in which non-biodegradable substances would affect the environment.

Accepted Answer

Two ways in which non-biodegradable substances can affect the environment are: 1.  Land and Water Pollution: Since these substances do not decompose, they persist in the environment for thousands of years. They accumulate in landfills, pollute soil, and can clog drainage systems. When they find thei...

Question 15

Q1: What is ozone and how does it affect any ecosystem?

Accepted Answer

Ozone ($	ext{O}_3$) is a molecule formed by three atoms of oxygen. While it is a deadly poison at ground level, it performs an essential function at higher levels of the atmosphere. In the stratosphere, ozone forms a protective layer that shields the Earth's surface from most of the harmful ultravi...

Question 16

Q2: How can you help in reducing the problem of waste disposal? Give any two methods.

Accepted Answer

We can help reduce the problem of waste disposal in the following two ways: 1.  Segregation of Waste: We can separate our household waste into biodegradable and non-biodegradable categories. Biodegradable waste (like kitchen scraps) can be composted to create manure for plants. Non-biodegradable was...

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