Extra 40 multiple-choice questions (MCQs) with answers on the chapter:13 "Our Environment" for Class 10 CBSE Science:

 

Which of the following is a biotic component of the environment?
(a) Air
(b) Water
(c) Plants
(d) Soil
Ans: (c) Plants

 

Which of the following is an abiotic component of the ecosystem?
(a) Sunlight
(b) Animals
(c) Plants
(d) Microorganisms
Ans: (a) Sunlight

 

Which of the following is a producer in an ecosystem?
(a) Deer
(b) Tiger
(c) Grass
(d) Fungi
Ans: (c) Grass

 

An ecosystem includes:
(a) Only plants
(b) Only animals
(c) Only abiotic components
(d) Both biotic and abiotic components
Ans: (d) Both biotic and abiotic components

 

Decomposers play a vital role in an ecosystem by:
(a) Producing food
(b) Capturing solar energy
(c) Eating herbivores
(d) Breaking down dead organisms
Ans: (d) Breaking down dead organisms

 

Which of the following organisms is a primary consumer?
(a) Tiger
(b) Eagle
(c) Rabbit
(d) Snake
Ans: (c) Rabbit

 

What is the ultimate source of energy in an ecosystem?
(a) Sun
(b) Plants
(c) Animals
(d) Soil
Ans: (a) Sun

 

Which of the following is a non-biodegradable substance?
(a) Plastic
(b) Paper
(c) Cotton
(d) Vegetable peels
Ans: (a) Plastic

 

The biotic components of an ecosystem include:
(a) Air and water
(b) Sunlight and soil
(c) Plants and animals
(d) Rocks and minerals
Ans: (c) Plants and animals

 

Which of the following is an example of a natural ecosystem?
(a) Aquarium
(b) Garden
(c) Zoo
(d) Forest
Ans: (d) Forest

 

A food chain always starts with:
(a) Producers
(b) Herbivores
(c) Carnivores
(d) Decomposers
Ans: (a) Producers

 

Which organism is at the top of the food chain?
(a) Herbivores
(b) Decomposers
(c) Producers
(d) Carnivores
Ans: (d) Carnivores

 

The transfer of energy in a food chain follows the:
(a) Rule of 90%
(b) 10% Law
(c) 50% Law
(d) 25% Rule
Ans: (b) 10% Law

 

In a food chain, which of the following is a secondary consumer?
(a) Grass
(b) Frog
(c) Snake
(d) Eagle
Ans: (b) Frog

 

Which of the following statements is true?
(a) Energy flow in an ecosystem is cyclic.
(b) Energy flow in an ecosystem is unidirectional.
(c) Energy flow in an ecosystem is bidirectional.
(d) Energy can be reused in the same form.
Ans: (b) Energy flow in an ecosystem is unidirectional.

 

The highest amount of energy in a food chain is present in:
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers
Ans: (a) Producers

 

Which of the following is an example of a decomposer?
(a) Cow
(b) Fungi
(c) Snake
(d) Lion
Ans: (b) Fungi

 

The correct sequence in a food chain is:
(a) Plants → Carnivores → Herbivores
(b) Plants → Herbivores → Carnivores
(c) Herbivores → Plants → Carnivores
(d) Carnivores → Plants → Herbivores
Ans: (b) Plants → Herbivores → Carnivores

 

Which type of organisms feed at all trophic levels?
(a) Decomposers
(b) Primary consumers
(c) Secondary consumers
(d) Producers
Ans: (a) Decomposers

 

A food web consists of:
(a) Only one food chain
(b) Interconnected food chains
(c) Only producers and consumers
(d) Only carnivores
Ans: (b) Interconnected food chains

 

Which of the following is a major cause of environmental pollution?
(a) Oxygen
(b) Trees
(c) Plastic waste
(d) Water vapor
Ans: (c) Plastic waste

 

Ozone layer depletion is mainly caused by:
(a) Chlorofluorocarbons (CFCs)
(b) Oxygen
(c) Carbon dioxide
(d) Nitrogen gas
Ans: (a) Chlorofluorocarbons (CFCs)

 

Which gas is responsible for the greenhouse effect?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
Ans: (b) Carbon dioxide

 

The ozone layer is found in the:
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
(d) Exosphere
Ans: (b) Stratosphere

 

The major cause of acid rain is:
(a) Sulphur dioxide and nitrogen oxides
(b) Oxygen
(c) Water vapor
(d) Helium
Ans: (a) Sulphur dioxide and nitrogen oxides

 

The term "biodegradable" refers to substances that:
(a) Do not decompose
(b) Can be broken down by natural processes
(c) Are always toxic
(d) Are made of plastic
Ans: (b) Can be broken down by natural processes

 

Which of the following is a biodegradable substance?
(a) Paper
(b) Plastic
(c) Glass
(d) Aluminium foil
Ans: (a) Paper

 

The major component of smog is:
(a) Smoke and fog
(b) Oxygen and nitrogen
(c) Water vapor
(d) Carbon dioxide
Ans: (a) Smoke and fog

 

Which of the following is an effect of ozone layer depletion?
(a) Increased UV radiation
(b) Decreased global temperature
(c) Reduction in carbon dioxide
(d) None of the above
Ans: (a) Increased UV radiation

 

The 3R’s principle stands for:
(a) Reduce, Reuse, Recycle
(b) Repair, Repaint, Reduce
(c) Refuse, Restore, Recycle
(d) None of the above
Ans: (a) Reduce, Reuse, Recycle

 

Which of the following statements is true about biodegradable substances?
(a) They never decompose.
(b) They break down naturally by microorganisms.
(c) They are harmful to the environment.
(d) They cause air pollution.
Ans: (b) They break down naturally by microorganisms.

 

Which of the following is a man-made ecosystem?
(a) Aquarium
(b) Pond
(c) Desert
(d) Forest
Ans: (a) Aquarium

 

The main source of energy in an ecosystem is:
(a) Wind
(b) Water
(c) Fossil fuels
(d) Sunlight
Ans: (d) Sunlight

 

If a grasshopper eats grass and a frog eats the grasshopper, what is the frog’s trophic level?
(a) Producer
(b) Primary consumer
(c) Secondary consumer
(d) Decomposer
Ans: (c) Secondary consumer

 

Which of the following gases is not responsible for the greenhouse effect?
(a) Carbon dioxide
(b) Methane
(c) Water vapor
(d) Oxygen
Ans: (d) Oxygen

 

The accumulation of harmful substances at each trophic level is known as:
(a) Food chain
(b) Biomagnification
(c) Decomposition
(d) Eutrophication
Ans: (b) Biomagnification

 

Which of the following is an example of a natural pollutant?
(a) Plastic
(b) Volcanic ash
(c) Industrial waste
(d) Chemical fertilizers
Ans: (b) Volcanic ash

 

What is the main cause of soil pollution?
(a) Excessive use of pesticides and fertilizers
(b) Planting more trees
(c) Rainwater
(d) Increase in biodiversity
Ans: (a) Excessive use of pesticides and fertilizers

 

Which of the following activities will reduce environmental pollution?
(a) Cutting trees
(b) Using cloth bags instead of plastic bags
(c) Burning fossil fuels
(d) Increasing industrial waste
Ans: (b) Using cloth bags instead of plastic bags

 

The use of CFCs is being reduced to protect:
(a) Global temperature
(b) The ozone layer
(c) Water bodies
(d) Biodiversity
Ans: (b) The ozone layer