Question 1

The flow of energy in a food chain is:

Accepted Answer

unidirectional (one-way). Energy flows one way — from the Sun to producers to consumers — and is lost as heat at each level.

Question 2

According to the ten-percent law, the energy passed on to the next trophic level is about:

Accepted Answer

10% of the energy at the previous level. Only about 10% of the energy at one level is transferred to the next; the rest is used up or lost as heat.

Question 3

A network of many interconnected food chains in an ecosystem is called a:

Accepted Answer

food web. A food web is formed by the interlinking of several food chains.

Question 4

The conversion of atmospheric nitrogen into compounds usable by plants is called:

Accepted Answer

nitrogen fixation. Nitrogen fixation converts inert N₂ into usable nitrogen compounds, often by bacteria.

Question 5

Bacteria that live in the root nodules of leguminous plants and fix nitrogen are:

Accepted Answer

Rhizobium. Rhizobium bacteria in legume root nodules fix atmospheric nitrogen.

Question 6

Biogeochemical cycles are important because they:

Accepted Answer

recycle essential nutrients so that life can continue. These cycles continuously recycle nutrients (carbon, nitrogen, water) between living things and the environment.

Question 7

Acid rain is caused mainly by the release of ______ into the atmosphere:

Accepted Answer

sulphur dioxide and nitrogen oxides. SO₂ and NOₓ from burning fuels dissolve in rain to form acids, causing acid rain.

Question 8

The excessive use of chemical pesticides and plastics mainly causes:

Accepted Answer

soil pollution. Pesticides and non-degradable plastics accumulate in the soil, causing soil pollution.

Question 9

Which practice would help REDUCE air pollution?

Accepted Answer

Using public transport and clean energy. Public transport and clean (renewable) energy reduce the emission of pollutants.

Question 10

Which of the following is a NON-biodegradable waste?

Accepted Answer

Plastic bag. Plastics are not broken down by microbes and persist in the environment.

Question 11

The "three Rs" recommended for managing waste are:

Accepted Answer

Reduce, Reuse, Recycle. Reduce, Reuse and Recycle help minimise waste and conserve resources.

Question 12

Recycling of materials like paper and metal is beneficial because it:

Accepted Answer

saves natural resources and reduces waste. Recycling conserves resources, saves energy and reduces the amount of waste dumped.

Question 13

The gradual rise in the average temperature of the Earth is called:

Accepted Answer

global warming. Global warming is the increase in Earth's average temperature due to greenhouse gases.

Question 14

The depletion of the ozone layer is caused mainly by:

Accepted Answer

chlorofluorocarbons (CFCs). CFCs released from refrigerants and sprays break down ozone in the stratosphere.

Question 15

Which of the following would help to REDUCE global warming?

Accepted Answer

Planting more trees and using renewable energy. Afforestation absorbs CO₂ and clean energy cuts emissions, both reducing global warming.

Question 16

In a food chain, green plants are called ______ because they make their own food:

Accepted Answer

producers. Green plants are producers (autotrophs) and form the base of every food chain.

Question 17

Animals that eat only plants (herbivores) occupy the level of ______ in a food chain:

Accepted Answer

primary consumers. Herbivores feed directly on producers, so they are primary consumers.

Question 18

Organisms such as bacteria and fungi that break down dead matter are called:

Accepted Answer

decomposers. Decomposers break down dead organisms, returning nutrients to the environment.

Question 19

The continuous circulation of water between the Earth and the atmosphere is called the:

Accepted Answer

water cycle. The water cycle involves evaporation, condensation and precipitation.

Question 20

The process that adds oxygen to the atmosphere in the oxygen cycle is:

Accepted Answer

photosynthesis. Photosynthesis by green plants releases oxygen into the air.

Ecosystem & Environmental Management — Homi Bhabha Exam Biology MCQs with Solutions

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Sample questions with solutions