Our Environment MCQ: Introduction & Explanation

Ans: a) It increases the need for mining the virgin materials

Explanation: Recycling helps in reducing greenhouse emissions by significantly reducing the consumption of energy. When materials are recycled in order to yield new products, it reduces the need for virgin materials. This reduces greenhouse gas emissions and decreases the need for mining virgin materials. Also, manufacturing products from recycled materials need less energy as compared to the energy required to make products from virgin materials.

Ans: c) They convert organic material into inorganic forms

Explanation: In an ecosystem, the decomposers convert the organic material into inorganic forms that go inside the soil and are again used by the plants. They feed on the waste products of organisms and their dead remains. The producers are the organisms that convert inorganic materials to organic compounds such as starch and sugar with the use of sunlight in the presence of chlorophyll.

Ans: b) Almost little or no usable energy is left after the fourth step of the food chain.

Explanation: When sunlight falls on plants, they trap only 1 percent of the energy from the sun. At each step of the food chain, some energy is lost. Just 10% of the energy flows from one trophic level to the next. Therefore, the loss of energy is so much that after three or four steps, very little energy remains for use. Hence, food chains only have three or four steps.

Ans: a) Ultraviolet radiations (UV)

Explanation: The region of the Earth’s atmosphere known as the stratosphere has an Ozone (O3) layer which is responsible for protecting the Earth from about 99% of the harmful solar Ultraviolet (UV) radiations.

Ans: c) It will kill all the living entities as it will become poisonous.

Explanation: In the lower atmosphere, ozone acts as an air pollutant that causes harmful effects on the respiratory system of plants and animals. However, in the upper atmosphere, this ozone is beneficial as it forms the ozone layer which protects the Earth from the harmful radiations of the sun.

Ans: d) Prevention - Reuse - Recycle - Disposal

Explanation: For effective waste management, the most to least favoured order is prevention, reuses, recycle, and finally disposal.

• The first stage is the prevention of waste wherein less waste is produced by making use of only the most essential things.
• Then comes the stage of reusing the waste material by productively using the material if the material is not disposable after a single-use.
• Then the waste is recycled where it is used in one form or another by separating the toxic substances.
• The last stage involves waste disposal where the waste becomes useless and can't be used further.

Ans: c) They are non-biodegradable

Explanation: Plastic bottles and bags are non-biodegradable products as these can not be further broken down by natural processes. Therefore, they are harmful to the environment and their use shall be avoided.

Ans: b) by splitting the molecular oxygen into free oxygen atoms in the presence of low energy ultraviolet radiations.

Explanation: Ozone absorbs a range of ultraviolet radiations. When a molecule of ozone absorbs low energy ultraviolet radiation, it results in the splitting of the molecule into a free oxygen atom and an ordinary oxygen molecule. This free oxygen usually rejoins the oxygen molecule rapidly to form another ozone molecule.

Ans: d) All of the above

Explanation: Ozone depletion is a great environmental concern as it would increase the amount of UV (Ultraviolet) radiation reaching the surface of the Earth. This is very harmful as it can lead to an increase in the rate of skin cancer, immune system damage, genetic damage, and eye cataracts.

Ans: b) Biological magnification

Explanation: The accumulation of chemical constituents that are toxic such as pesticides, insecticides, herbicides, and DDT in the body of biotic organisms through the food chain is referred to as biological magnification.

Ans: c) Ecology

Explanation: Ecology is a branch of biology that is involved with the study of living organisms and their interaction with the environment around them. It includes the study of relations between living beings and their habitats.

Ans: d) DDT

Explanation: DDT, also known as dichlorodiphenyltrichloroethane, is a type of insecticide used to kill insects. It is absorbed by the plants through the soil which then passes it on to upper levels of the food chain. It is accumulated in human beings due to biological magnification.

Ans: d) Producers

Explanation: Producers, also known as autotrophs, make up the first trophic level of the food chain. This is because these producers absorb the energy from the sun and transfer it to the other trophic levels of a food chain.

Ans: b) Food Chain

Explanation: A food chain is referred to a linear arrangement or network of links in a food web that starts from the producer and ends at the top predator species or decomposers. It shows how the organisms are related to each other through the food they consume. Every level of the food chain is represented through a different trophic level.

Ans: d) This reduces the release of chlorofluorocarbons that react with the ozone molecules.

Explanation: The ozone layer that is present in the stratosphere helps in absorbing the harmful ultraviolet radiations before they reach the surface of the Earth. The main cause of the depletion of the ozone layer is the manufacturing of paraffinized halogen chemicals especially chlorofluorocarbons or CFCs which causes the breakdown of ozone into oxygen. The ozone hole that is formed increases the exposure of ultraviolet rays of Earth that increases the risk of skin cancer and other negative effects that accompany it.

Ans. a) Food Web

Explanation: A food web includes all the food chains that exist in a single ecosystem. It is a network of animals that are interdependent. Each living organism present in an ecosystem is part of many food chains.

Ans. c) Energy Level

Explanation: The trophic level represents the energy levels in a food chain.

Ans. b) Sulphur and Nitrogen

Explanation: Acid rain is caused when nitrogen oxides and Sulphur oxides are emitted in the atmosphere.

Ans. b) Plastic

Explanation: A non-biodegradable substance is a material that cannot be broken down by natural processes. For example, plastic.

Ans. b) Increase in the concentration of non-biodegradable pollutants as these pollutants pass through the food chain.

Explanation: Biomagnification can be understood as the increase in the concentration of toxic substances or non-degradable pollutants in the food chain.

Environment plays a vital role in the existence of life on Earth and for healthy living. Human activities can lead to various environmental disasters such as acidification of oceans, deforestation, disposal of hazardous waste, global warming, acid rain, overpopulation, etc.