Download CBSE MCQs for Class 10 Science: Chapter 13 Our Environment
Review structured MCQ sets for Class 10 Science Chapter 13 Our Environment. Built according to official CBSE guidelines, these downloadable questions support daily revision and core concept reinforcement.
Chapter-wise Objective Questions: Chapter 13 Our Environment
Navigate directly to the 50 objective questions for Chapter 13 Our Environment using the digital viewer below. Each practice set includes verified answer keys, allowing students to instantly cross-check their work and identify areas requiring further revision.
Class 10 Biology students can practise 40 more Our Environment MCQs here, each with the correct answer, an explanation and a Teacher's Note. The questions include assertion-reason items on trophic levels, the 10 per cent energy law and biomagnification.
Multiple Choice Questions
(a) food web
(b) ecological pyramid
(c) ecosystem
(d) food chain
Show Answer & Explanation
Answer: (a) food web
Explanation:
1. A network of interlinked food chains is a food web.
2. One organism feeding on several kinds of organisms of a lower level links many chains together, which forms a food web.
Teacher's Note:
1. A food chain is a single line, while a food web is many chains joined.
2. A food web makes an ecosystem more stable.
(a) primary consumers
(b) secondary consumers
(c) producers
(d) tertiary consumers
Show Answer & Explanation
Answer: (c) producers
Explanation:
1. Green plants make their own food, so they are producers.
2. Green plants prepare food by photosynthesis and form the first trophic level as producers.
Teacher's Note:
1. Producers are also called autotrophs.
2. All other organisms depend on them.
(a) heat energy
(b) light energy
(c) chemical energy
(d) mechanical energy
Show Answer & Explanation
Answer: (c) chemical energy
Explanation:
1. The energy passed on is chemical energy stored in food.
2. Plants store solar energy as chemical energy in food; this is the energy that passes to the next level.
Teacher's Note:
1. Energy is transferred as food.
2. The rest is lost mainly as heat.
(a) Grass since it grows in the contaminated soil
(b) Goat since it eats the grass
(c) Tiger since it feeds on the goat which feeds on the grass
(d) Vulture since it eats the tiger, which in turn eats the goat, which eats the grass
Show Answer & Explanation
Answer: (d) Vulture since it eats the tiger, which in turn eats the goat, which eats the grass
Explanation:
1. The vulture is at the top, so it has the most pesticide.
2. Pesticide concentration increases at each level, and the vulture occupies the highest level here.
Teacher's Note:
1. This is biomagnification.
2. The top consumer gets the highest dose.
(a) decomposers
(b) producers
(c) herbivores
(d) carnivores
Show Answer & Explanation
Answer: (b) producers
Explanation:
1. Organisms that make food from inorganic compounds using sunlight are producers.
2. Green plants and algae make carbohydrates from CO2 and water using sunlight, so they are producers.
Teacher's Note:
1. Producers capture solar energy.
2. Decomposers and carnivores cannot do this.
Assertion (A): In an ecosystem, the function of producers is to convert organic compounds into inorganic compounds.
Reason (R): Green plants, the producers, transduce solar energy.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (d) A is false, but R is true.
Explanation:
1. Producers convert inorganic to organic compounds, so the assertion is false.
2. Producers make organic compounds from inorganic ones. The reason is true: plants change solar energy into chemical energy.
Teacher's Note:
1. Reverse the process in the assertion.
2. A false A with a true R is option (d).
(a) ocean
(b) pond
(c) underground caves
(d) forest
Show Answer & Explanation
Answer: (d) forest
Explanation:
1. A forest is on land, so it is terrestrial.
2. Oceans and ponds are aquatic; caves are not an ecosystem type; forest is a land ecosystem.
Teacher's Note:
1. Terrestrial means on land.
2. Aquatic means in water.
(a) All plants and bacteria are producers.
(b) All green plants and certain bacteria are producers.
(c) Only some species of green plants and all bacteria are producers.
(d) Only green plants are producers.
Show Answer & Explanation
Answer: (b) All green plants and certain bacteria are producers.
Explanation:
1. All green plants and certain bacteria are producers.
2. Only organisms that can photosynthesise or use chemical energy are producers; not all bacteria or plants are.
Teacher's Note:
1. Look for the careful wording.
2. Non-green plants are not producers.
(i) Primary consumers transfer 10% of energy to the next trophic level in the food chain.
(ii) The population at a lower trophic level is greater than the population at a higher trophic level.
(iii) Producers depend entirely on sunlight to make food.
(iv) Decomposers work at a double pace to convert complex molecules into simpler forms in case of an epidemic.
(a) Only (ii)
(b) Only (iv)
(c) (i) and (iii)
(d) All of these
Show Answer & Explanation
Answer: (b) Only (iv)
Explanation:
1. Decomposers do not double their pace in an epidemic.
2. Statements (i) to (iii) are correct, while (iv) is wrong, so only (iv) is the error.
Teacher's Note:
1. Check each point.
2. Do not accept unusual claims.
(a) harmful chemicals get washed into water bodies and enter the aquatic food chains.
(b) fishes can also produce these chemicals in their bodies.
(c) fishes increase in number rapidly.
(d) fishes have special enzymes in their body to digest these pesticides.
Show Answer & Explanation
Answer: (a) harmful chemicals get washed into water bodies and enter the aquatic food chains.
Explanation:
1. Harmful chemicals wash into water and enter the aquatic food chain.
2. Pesticides from fields wash into water bodies and accumulate in fish diet and increase up the chain.
Teacher's Note:
1. Biomagnification affects aquatic chains too.
2. Fish eaters get high doses.
(a) presence of active molecules of carbon
(b) presence of high energy UV rays
(c) presence of activated oxides of carbon
(d) presence of longer wavelength radiations
Show Answer & Explanation
Answer: (b) presence of high energy UV rays
Explanation:
1. High energy UV rays split O2 and make ozone formation possible.
2. UV rays break O2 into atoms, which combine with O2 to form O3.
Teacher's Note:
1. Ozone needs UV.
2. Remember O2 + O → O3.
Assertion (A): Energy available at each trophic level gets diminished progressively.
Reason (R): Little usable energy remains after four trophic levels.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. Energy diminishes at every level and little remains after four levels, so both are true.
2. Both statements are true, but the reason says why food chains are short rather than directly explaining the fall at each step.
Teacher's Note:
1. This key was corrected: the reason is true, not false.
2. Check each statement on its own.
Assertion (A): Plastics are non-biodegradable.
Reason (R): Enzymes cannot degrade plastics.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (a) Both A and R are true, and R is the correct explanation of A.
Explanation:
1. Microbial enzymes cannot degrade plastics, so plastics are non-biodegradable.
2. Both statements are true and the reason gives the explanation.
Teacher's Note:
1. Enzymes are specific.
2. Plastics lack matching enzymes.
(a) Troposphere
(b) Stratosphere
(c) Biosphere
(d) Ionosphere
Show Answer & Explanation
Answer: (b) Stratosphere
Explanation:
1. The ozone layer lies in the stratosphere.
2. The stratosphere holds a layer rich in ozone.
Teacher's Note:
1. Do not confuse stratosphere with troposphere.
2. Ozone high up is protective.
(a) Grass, flowers, lime-juice, and leather.
(b) Grass, wood, leather, and plastic.
(c) Cake, wood, flowers, and grass.
(d) Fruit-peels, cake, leather, and lime-juice.
Show Answer & Explanation
Answer: (b) Grass, wood, leather, and plastic.
Explanation:
1. Plastic is non-biodegradable.
2. Grass, wood and leather are biodegradable, but plastic is not.
Teacher's Note:
1. Find the one non-degradable item.
2. The group with plastic is correct.
(a) composting
(b) sewage treatment
(c) recycling
(d) incineration
Show Answer & Explanation
Answer: (d) incineration
Explanation:
1. Burning at high temperature to ash is incineration.
2. Composting, sewage treatment and recycling are different methods.
Teacher's Note:
1. Incinerators handle hospital waste.
2. Ash is left behind.
Assertion (A): Producers are present at the first trophic level.
Reason (R): Consumers or heterotrophs fix energy and make it available for autotrophs.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (c) A is true, but R is false.
Explanation:
1. Producers are at the first level, but heterotrophs do not supply energy to autotrophs.
2. The assertion is true, but the reason is false; autotrophs fix energy for consumers.
Teacher's Note:
1. Reverse the reason.
2. Producers feed the consumers.
(a) producer
(b) primary consumer
(c) secondary consumer
(d) decomposer
Show Answer & Explanation
Answer: (c) secondary consumer
Explanation:
1. Among the options, secondary consumers are the highest level.
2. Concentration rises with trophic level.
Teacher's Note:
1. Look for the highest consumer.
2. Producers have the least.
(1) Paper cups
(2) Glass bowls
(3) Fruit peels
(4) Rubber slippers
She then covers the pit with soil. Which item will decompose first?
(a) Glass bowls
(b) Fruit peels
(c) Paper cups
(d) Rubber slippers
Show Answer & Explanation
Answer: (b) Fruit peels
Explanation:
1. Fruit peels are biodegradable and decompose first.
2. Paper takes longer; glass and rubber are non-biodegradable.
Teacher's Note:
1. Organic matter decays quickly.
2. Glass and rubber last long.
Assertion (A): Ozone shields the surface of the Earth from ultraviolet radiations from the Sun.
Reason (R): Ozone at the higher levels of the atmosphere is a product of UV radiations acting on oxygen molecule.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. Both statements are true, but R does not explain A.
2. Ozone shields UV, and ozone forms from O2 by UV; the reason describes formation, not shielding.
Teacher's Note:
1. Two true facts are not always cause and effect.
2. Check the link.
Assertion (A): Man-made materials such as glass persist in the environment for a very long time.
Reason (R): Bacteria and other saprophytes break down the organic matter in our environment.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. Glass persists; saprophytes break down organic matter.
2. Both are true, but the reason does not explain the assertion.
Teacher's Note:
1. Glass is not organic.
2. Saprophytes cannot act on it.
(I) All plants
(II) Only green plants
(III) Blue green algae
(IV) Herbivores
(a) Only (I)
(b) Only (II)
(c) Both (II) and (III)
(d) Both (II) and (IV)
Show Answer & Explanation
Answer: (c) Both (II) and (III)
Explanation:
1. Only green plants and blue green algae make food from inorganic substances.
2. Statements II and III are correct.
Teacher's Note:
1. Herbivores cannot make food.
2. Producers do photosynthesis.
Assertion (A): Ozone is formed in upper atmosphere by O2 in presence of UV radiations.
Reason (R): Ozone depletion will lead to UV rays reaching earth which may cause skin cancer.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. UV forms ozone and depletion causes cancer, but the reason does not explain formation.
2. Both are true; the reason is a separate fact.
Teacher's Note:
1. Two true facts need not be linked.
2. Check the explanation.
(a) more energy
(b) less energy
(c) same energy
(d) any of these.
Show Answer & Explanation
Answer: (a) more energy
Explanation:
1. Shorter food chains pass on more energy.
2. Less energy is lost in fewer steps.
Teacher's Note:
1. 10% rule.
2. Fewer steps, more energy.
(a) primary consumer
(b) secondary consumer
(c) tertiary consumer
(d) decomposer.
Show Answer & Explanation
Answer: (b) secondary consumer
Explanation:
1. Fish that eat zooplankton are secondary consumers.
2. Zooplankton are primary consumers.
Teacher's Note:
1. Count levels.
2. Phytoplankton are producers.
Assertion (A): Ozone depletion can be reduced by limiting the use of air conditioners and refrigerators.
Reason (R): Air conditioner and refrigerators release chlorofluorocarbons in the atmosphere that destroy ozone.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (a) Both A and R are true, and R is the correct explanation of A.
Explanation:
1. CFCs from air conditioners and refrigerators destroy ozone.
2. Both statements are true and the reason explains the assertion.
Teacher's Note:
1. CFCs are the culprit.
2. Less use reduces damage.
Assertion (A): A food chain comprises of producers and consumers.
Reason (R): Consumers can be herbivores, carnivores and omnivores.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. A food chain has producers and consumers; consumers can be of three types.
2. Both statements are true but R does not explain A.
Teacher's Note:
1. Two separate facts.
2. Consumers are of many types.
Assertion (A): Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain.
Reason (R): Harmful chemicals are sprayed on the crops to protect them from diseases and pests.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (b) Both A and R are true, but R is not the correct explanation of A.
Explanation:
1. Harmful chemicals are highest at the top, and sprays are used on crops.
2. Both are true but R does not explain A.
Teacher's Note:
1. Biomagnification explains A.
2. Spraying is the source.
Assertion (A): Flow of energy in a food chain is unidirectional.
Reason (R): Energy captured by autotrophs does not revert back to the solar input and it passes to the herbivores.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (a) Both A and R are true, and R is the correct explanation of A.
Explanation:
1. Energy captured by autotrophs does not return, so the flow is unidirectional.
2. Both statements are true and the reason explains the assertion.
Teacher's Note:
1. One way flow.
2. No return.
Column-I: (P) Saprotrophs, (Q) Parasites, (R) Autotrophs, (S) Herbivores
Column-II: (i) Organisms obtaining food from green plants, (ii) Organisms obtaining food from host, (iii) Organisms obtaining food from dead plants and animals, (iv) Organisms which prepare their own food
(a) P-(i), Q-(iii), R-(ii), S-(iv)
(b) P-(ii), Q-(iv), R-(i), S-(iii)
(c) P-(iv), Q-(i), R-(iii), S-(ii)
(d) P-(iii), Q-(ii), R-(iv), S-(i)
Show Answer & Explanation
Answer: (d) P-(iii), Q-(ii), R-(iv), S-(i)
Explanation:
1. Saprotrophs feed on dead matter, parasites on hosts, autotrophs make food, herbivores eat green plants.
2. P-iii, Q-ii, R-iv, S-i.
Teacher's Note:
1. Learn the modes of nutrition.
2. Match by feeding.
(a) pyramid of Biomass.
(b) nutrient cycle.
(c) food chain.
(d) food web.
Show Answer & Explanation
Answer: (c) food chain.
Explanation:
1. The sequence in which organic matter passes is a food chain.
2. Food web is a network; pyramids show quantity.
Teacher's Note:
1. Chain means sequence.
2. Web means many chains.
(a) 50 percent.
(b) 90 percent.
(c) 99 percent.
(d) 70 percent.
Show Answer & Explanation
Answer: (b) 90 percent.
Explanation:
1. About 90% of energy is lost.
2. Only 10% passes to the next level.
Teacher's Note:
1. 10% law.
2. Heat and respiration take the rest.
(a) No, it has producers, consumers but there is absence of decomposers.
(b) Yes, it only has producers and consumers.
(c) No, dogs will not get their favorite food.
(d) Yes, it has all the levels required for transfer of energy from one trophic level two another.
Show Answer & Explanation
Answer: (a) No, it has producers, consumers but there is absence of decomposers.
Explanation:
1. Without decomposers the ecosystem cannot sustain.
2. Decomposers recycle nutrients.
Teacher's Note:
1. Producers, consumers and decomposers are needed.
2. All three.
(a) Are not readily degraded and they dissolve in fat.
(b) Are not readily degraded and they dissolve in water.
(c) Are readily degraded and do not dissolve in water.
(d) Are readily degraded and do not dissolve in fat.
Show Answer & Explanation
Answer: (a) Are not readily degraded and they dissolve in fat.
Explanation:
1. Biomagnifying chemicals resist degradation and dissolve in fat.
2. They stay in body fat.
Teacher's Note:
1. Persistent and fat soluble.
2. Not water soluble.
(a) Ozone layer
(b) Lithosphere
(c) Water layer
(d) Atmosphere
Show Answer & Explanation
Answer: (a) Ozone layer
Explanation:
1. The ozone layer shields from UV.
2. Lithosphere and water layer do not.
Teacher's Note:
1. Ozone is the shield.
2. Learn it.
(a) Herbivores
(b) Carnivores
(c) Parasite
(d) All of these
Show Answer & Explanation
Answer: (d) All of these
Explanation:
1. Herbivores, carnivores and parasites are all consumers.
2. All depend on others for food.
Teacher's Note:
1. Consumers eat others.
2. Heterotrophs.
(a) Multidirectional
(b) Bidirectional
(c) Unidirectional
(d) None of these
Show Answer & Explanation
Answer: (c) Unidirectional
Explanation:
1. Energy captured by autotrophs does not return, so the flow is unidirectional.
2. Not bidirectional.
Teacher's Note:
1. One way.
2. Learn it.
Assertion (A): Each step or level of the food chain forms a trophic level. Generally there are four trophic level in a food chain.
Reason (R): Very less energy remains after fourth trophic level.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Show Answer & Explanation
Answer: (a) Both A and R are true, and R is the correct explanation of A.
Explanation:
1. Four trophic levels are common and little energy remains after them.
2. Both true and R explains A.
Teacher's Note:
1. Energy limits levels.
2. 3 to 4 levels.
(a) sedimentation
(b) burning
(c) Scrubers
(d) none of these
Show Answer & Explanation
Answer: (b) burning
Explanation:
1. Incineration is disposal by burning.
2. Sedimentation is different.
Teacher's Note:
1. Burn to ash.
2. Hospital waste.
(a) First
(b) Second
(c) Third
(d) Fourth
Show Answer & Explanation
Answer: (b) Second
Explanation:
1. Primary consumers form the second trophic level.
2. Producers form the first.
Teacher's Note:
1. Second level.
2. Herbivores.
Free study material for Science
Multiple Choice Questions (MCQs) for Class 10 Science Chapter 13 Our Environment
Download Multiple Choice Questions: Chapter 13 Our Environment (Class 10 Science)
Review structured objective questions for Class 10 Science Chapter 13 Our Environment. Built according to official CBSE guidelines, these MCQ sets support daily revision and core concept reinforcement.
Concept Clarification for Chapter 13 Our Environment
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FAQs
You can get most exhaustive CBSE Class 10 Biology Our Environment MCQs Set 10 for free on StudiesToday.com. These MCQs for Class 10 Science are updated for the 2026-27 academic session as per CBSE examination standards.
Yes, our CBSE Class 10 Biology Our Environment MCQs Set 10 include the latest type of questions, such as Assertion-Reasoning and Case-based MCQs. 50% of the CBSE paper is now competency-based.
By solving our CBSE Class 10 Biology Our Environment MCQs Set 10, Class 10 students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Science.
Yes, Science MCQs for Class 10 have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused CBSE exams.
Yes, you can also access online interactive tests for CBSE Class 10 Biology Our Environment MCQs Set 10 on StudiesToday.com as they provide instant answers and score to help you track your progress in Science.