SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions | Assam Eduverse
SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions are prepared to help students understand ecosystem, food chains, and environmental issues for the HSLC examination. These SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions include theory-based questions, diagram-based questions, previous year questions (PYQs), and important MCQs.
The SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions strictly follow the latest SEBA (ASSEB) syllabus for 2026–27. Since students must attempt 45 MCQs in the HSLC Science exam, practising MCQs from SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions is essential.
Topics covered in SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions include ecosystem structure, components of environment, food chains, food webs, trophic levels, 10% law of energy transfer, biological magnification, and ozone layer depletion. Students searching for HSLC Science Chapter 15 Our Environment Important Questions or SEBA Class 10 Science Chapter 15 PYQs will find this resource highly useful.
SEBA Class 10 Science Chapter 15 Our Environment Important Questions with PYQs and MCQs
Table of Contents
A. Previous Year Questions with Answers
Q1. Which of the following is not a biodegradable waste? — [HSLC 2015]
(i) Vegetable waste from the kitchen
(ii) Old and torn clothes
(iii) Plastic packets
(iv) Old newspapers
Answer: (iii) Plastic packets
Q2. Which of the following is a biodegradable waste? — [HSLC 2016]
(i) Polythene bag
(ii) Peeled skin of mango
(iii) torn leather bag
(iv) Plastic bottle
Answer: (ii) Peeled skin of mango
Q3. Ozone, at the higher levels of the atmosphere, prevents ____ — [HSLC 2017]
(i) infra-red radiations
(ii) visible light
(iii) UV radiations
(iv) Both (i) & (ii)
Answer: (iii) UV radiations
Q4. Which of the following groups contain only biodegradable items? — [HSLC 2018]
(i) Grass, flowers and leather
(ii) Grass, wood and plastic
(iii) Fruit-peels, cake and lime-juice
(iv) None of above
Answer: (iii) Fruit-peels, cake and lime-juice
Q5. Which of the following constitute a food chain? — [HSLC 2020]
(i) Grass, Wheat and Mango
(ii) Grass, Goat and Human
(iii) Goat, Cow and Elephant
(iv) Grass, Fish and Goat
Answer: (ii) Grass, Goat and Human
Q6. Which of the following can depleted Ozone layer? — [HSLC 2023]
(i) Chlorofluoro carbon
(ii) Nitrogen
(iii) Hydrogen
(iv) Oxygen
Answer: (i) Chlorofluoro carbon
Q7. Which of the following constitute a food chain? — [HSLC 2023]
(i) Grass, Wheat and Mango
(ii) Grass, Goat and Human
(iii) Goat, Cow and Elephant
(iv) Grass, Fish and Goat
Answer: (ii) Grass, Goat and Human
Q8. The source of the formation of coal and petroleum is [HSLC 2024]
(A) coliform
(B) biomass
(C) greenhouse gas
(D) ocean water
Answer: (B) biomass
Q9. From the energy flow diagram, it is confirmed that the flow of energy is [HSLC 2024]
(A) unidirectional
(B) multidirectional
(C) upward in air
(D) downward in water
Answer: (A) unidirectional
Q10. Which group of the following waste materials can be classified as non-biodegradable? [HSLC 2025]
(a) Plant waste, used tea bags
(b) Polythene bags, plastic toys
(c) Used tea bags, paper straw
(d) Old clothes, broken footwear
Answer: (b) Polythene bags, plastic toys
Q11. Find the correct statement from the following. [HSLC 2025]
(a) Ozone is not considered as poisonous and deadly gas.
(b) Ozone molecule is formed of three atoms of oxygen.
(c) Ozone is the cause of skin cancer.
(d) Oxygen and ozone both are used in respiration.
Answer: (b) Ozone molecule is formed of three atoms of oxygen
B. Extra Questions with Answers
Q.1 Substances that are broken down by biological processes are called —
(i) Non-biodegradable
(ii) Biodegradable
(iii) Synthetic
(iv) Persistent
Answer: (ii) Biodegradable
Q.2 Which of the following is a non-biodegradable substance?
(i) Vegetable peels
(ii) Paper
(iii) Plastic
(iv) Cotton cloth
Answer: (iii) Plastic
Q.3 In an ecosystem, the biotic components include —
(i) Temperature and rainfall
(ii) Soil and minerals
(iii) Plants, animals and microorganisms
(iv) Wind and sunlight
Answer: (iii) Plants, animals and microorganisms
Q.4 Which of the following is an example of a natural ecosystem?
(i) Aquarium
(ii) Crop-field
(iii) Forest
(iv) Garden
Answer: (iii) Forest
Q.5 Organisms that make organic compounds like sugar and starch from inorganic substances using sunlight are called —
(i) Consumers
(ii) Decomposers
(iii) Producers
(iv) Parasites
Answer: (iii) Producers
Q.6 Which of the following organisms are decomposers in an ecosystem?
(i) Frog and fish
(ii) Bacteria and fungi
(iii) Goat and cow
(iv) Grass and trees
Answer: (ii) Bacteria and fungi
Q.7 Assertion (A): The flow of energy in an ecosystem is unidirectional.
Reason (R): Energy captured by autotrophs does not return to the Sun and does not flow back to previous trophic levels.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.8 In a terrestrial ecosystem, green plants capture approximately how much of the sunlight energy that falls on their leaves?
(i) 10%
(ii) 5%
(iii) 1%
(iv) 50%
Answer: (iii) 1%
Q.9 When primary consumers eat green plants, approximately how much of the food eaten is converted into their body and made available for the next trophic level?
(i) 1%
(ii) 10%
(iii) 50%
(iv) 90%
Answer: (ii) 10%
Q.10 Match the following:
Column A
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers
Column B
(i) Bacteria and fungi
(ii) Herbivores
(iii) Green plants
(iv) Small carnivores
Options:
(i) a–(iii), b–(ii), c–(iv), d–(i)
(ii) a–(ii), b–(iii), c–(i), d–(iv)
(iii) a–(iv), b–(i), c–(ii), d–(iii)
(iv) a–(iii), b–(iv), c–(ii), d–(i)
Answer: (i) a–(iii), b–(ii), c–(iv), d–(i)
Q.11 Each step or level of a food chain is called —
(i) Food web
(ii) Trophic level
(iii) Ecosystem
(iv) Community
Answer: (ii) Trophic level
Q.12 Food chains generally consist of only three or four steps because —
(i) There are no carnivores after that
(ii) Producers are very few
(iii) Very little usable energy remains after four trophic levels
(iv) Decomposers stop working
Answer: (iii) Very little usable energy remains after four trophic levels
Q.13 In an ecosystem, the greatest number of individuals are generally found at the —
(i) Tertiary consumer level
(ii) Secondary consumer level
(iii) Primary consumer level
(iv) Producer level
Answer: (iv) Producer level
Q.14 A network of interconnected food chains is called —
(i) Trophic level
(ii) Food web
(iii) Ecosystem
(iv) Biome
Answer: (ii) Food web
Q.15 Assertion (A): Human beings generally accumulate the maximum concentration of non-degradable chemicals in their bodies.
Reason (R): Human beings occupy the top level in most food chains.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.16 The phenomenon in which harmful chemicals accumulate progressively at each trophic level is known as —
(i) Decomposition
(ii) Biological magnification
(iii) Photosynthesis
(iv) Nitrogen fixation
Answer: (ii) Biological magnification
Q.17 Which of the following is mainly responsible for ozone depletion?
(i) Carbon dioxide
(ii) Oxygen
(iii) Chlorofluorocarbons
(iv) Nitrogen
Answer: (iii) Chlorofluorocarbons
Q.18 Ozone protects living organisms on Earth from —
(i) Infra-red radiation
(ii) Visible light
(iii) Ultraviolet radiation
(iv) X-rays
Answer: (iii) Ultraviolet radiation
Q.19 Ozone (O₃) is formed in the upper atmosphere by the action of —
(i) Visible light on O₂
(ii) UV radiation on O₂
(iii) Heat on O₂
(iv) Nitrogen on O₂
Answer: (ii) UV radiation on O₂
Q.20 Which of the following practices helps in reducing waste disposal problems?
(i) Using more disposable items
(ii) Burning plastic waste openly
(iii) Carrying cloth bags while shopping
(iv) Throwing garbage into water bodies
Answer: (iii) Carrying cloth bags while shopping
Q.21 Which of the following materials will persist in the environment for a long time under ambient conditions?
(i) Vegetable peels
(ii) Paper
(iii) Plastics
(iv) Cotton cloth
Answer: (iii) Plastics
Q.22 Which of the following is an abiotic component of an ecosystem?
(i) Frog
(ii) Grass
(iii) Bacteria
(iv) Temperature
Answer: (iv) Temperature
Q.23 Which of the following organisms can make food by photosynthesis?
(i) Herbivores
(ii) Carnivores
(iii) Green plants
(iv) Fungi
Answer: (iii) Green plants
Q.24 Organisms which consume food produced by producers directly are called —
(i) Secondary consumers
(ii) Primary consumers
(iii) Decomposers
(iv) Parasites
Answer: (ii) Primary consumers
Q.25 In a food chain: Grass → Goat → Tiger, the tiger represents —
(i) Producer
(ii) Primary consumer
(iii) Secondary consumer
(iv) Decomposer
Answer: (iii) Secondary consumer
Q.26 Assertion (A): Decomposers are essential for the replenishment of soil.
Reason (R): Decomposers break down complex organic substances into simple inorganic substances.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.27 If decomposers were absent in an ecosystem, then —
(i) Producers would increase rapidly
(ii) Dead organisms and garbage would accumulate
(iii) Consumers would become producers
(iv) Energy flow would increase
Answer: (ii) Dead organisms and garbage would accumulate
Q.28 In a terrestrial ecosystem, approximately how much of the energy available at one trophic level is transferred to the next trophic level?
(i) 1%
(ii) 10%
(iii) 50%
(iv) 90%
Answer: (ii) 10%
Q.29 Which of the following best explains why food chains are short?
(i) Producers are limited
(ii) Carnivores are few
(iii) Energy is lost as heat at each trophic level
(iv) Decomposers consume all organisms
Answer: (iii) Energy is lost as heat at each trophic level
Q.30 Match the following:
Column A
(a) Ozone (O₃)
(b) CFCs
(c) Producers
(d) Biological magnification
Column B
(i) Capture sunlight energy
(ii) Protect from UV radiation
(iii) Increase concentration of harmful chemicals at higher trophic levels
(iv) Responsible for ozone depletion
Options:
(i) a–(ii), b–(iv), c–(i), d–(iii)
(ii) a–(iv), b–(ii), c–(iii), d–(i)
(iii) a–(i), b–(iii), c–(iv), d–(ii)
(iv) a–(iii), b–(i), c–(ii), d–(iv)
Answer: (i) a–(ii), b–(iv), c–(i), d–(iii)
Q.31 Which of the following is a human-made ecosystem?
(i) Forest
(ii) Pond
(iii) Aquarium
(iv) Lake
Answer: (iii) Aquarium
Q.32 If an aquatic animal that feeds on other animals is introduced into a small aquarium, what is most likely to happen?
(i) The ecosystem will remain unaffected
(ii) Other organisms may decrease in number
(iii) Producers will stop photosynthesis
(iv) Decomposers will disappear
Answer: (ii) Other organisms may decrease in number
Q.33 Which of the following is correctly arranged in increasing order of trophic levels?
(i) Herbivores → Producers → Carnivores
(ii) Producers → Herbivores → Carnivores
(iii) Carnivores → Herbivores → Producers
(iv) Producers → Carnivores → Herbivores
Answer: (ii) Producers → Herbivores → Carnivores
Q.34 Which of the following statements is true regarding energy flow in an ecosystem?
(i) Energy flows from consumers to producers
(ii) Energy flows in a cyclic manner
(iii) Energy flow is unidirectional
(iv) Energy increases at higher trophic levels
Answer: (iii) Energy flow is unidirectional
Q.35 Assertion (A): Ozone is a deadly poison at ground level.
Reason (R): Ozone at higher levels of the atmosphere shields the Earth from UV radiation.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (ii) Both A and R are true but R is not the correct explanation of A
Q.36 The decrease in the amount of ozone in the atmosphere has been linked to —
(i) Increase in oxygen concentration
(ii) Use of chlorofluorocarbons
(iii) Increase in nitrogen gas
(iv) Formation of carbon monoxide
Answer: (ii) Use of chlorofluorocarbons
Q.37 Which of the following best describes biological magnification?
(i) Decrease of harmful chemicals at higher trophic levels
(ii) Increase of biodegradable waste in soil
(iii) Progressive accumulation of non-degradable chemicals at each trophic level
(iv) Rapid decomposition of organic matter
Answer: (iii) Progressive accumulation of non-degradable chemicals at each trophic level
Q.38 Which of the following items contributes to non-biodegradable waste?
(i) Fruit peels
(ii) Paper
(iii) Plastic wrappers
(iv) Leftover food
Answer: (iii) Plastic wrappers
Q.39 Match the following:
Column A
(a) Abiotic components
(b) Herbivores
(c) Tertiary consumers
(d) Decomposers
Column B
(i) Temperature and rainfall
(ii) Break down dead remains
(iii) Eat plants
(iv) Large carnivores
Options:
(i) a–(i), b–(iii), c–(iv), d–(ii)
(ii) a–(ii), b–(iv), c–(iii), d–(i)
(iii) a–(iii), b–(i), c–(ii), d–(iv)
(iv) a–(iv), b–(ii), c–(i), d–(iii)
Answer: (i) a–(i), b–(iii), c–(iv), d–(ii)
Q.40 Which of the following statements about waste generation is correct?
(i) All waste generated is biodegradable
(ii) Improvements in lifestyle have increased waste generation
(iii) Disposable items reduce environmental problems
(iv) Non-biodegradable waste decomposes quickly
Answer: (ii) Improvements in lifestyle have increased waste generation
Q.41 Which of the following best describes an ecosystem?
(i) Only living organisms in an area
(ii) Only physical factors of an area
(iii) Living organisms interacting with each other and with non-living components
(iv) Only plants and animals of a region
Answer: (iii) Living organisms interacting with each other and with non-living components
Q.42 In a food chain, autotrophs occupy the —
(i) Second trophic level
(ii) Third trophic level
(iii) First trophic level
(iv) Fourth trophic level
Answer: (iii) First trophic level
Q.43 Which of the following consumers feed directly on producers?
(i) Carnivores
(ii) Herbivores
(iii) Omnivores
(iv) Parasites
Answer: (ii) Herbivores
Q.44 Which of the following statements about energy transfer in an ecosystem is correct?
(i) 50% of energy is transferred to the next trophic level
(ii) 90% of energy is transferred to the next trophic level
(iii) About 10% of energy is transferred to the next trophic level
(iv) No energy is lost between trophic levels
Answer: (iii) About 10% of energy is transferred to the next trophic level
Q.45 If all organisms at one trophic level are removed, what will be the immediate effect?
(i) No change in the ecosystem
(ii) Disturbance in the food chain
(iii) Increase in energy flow
(iv) Decrease in producers only
Answer: (ii) Disturbance in the food chain
Q.46 Which of the following wastes may harm the various members of an ecosystem because it persists for a long time?
(i) Biodegradable waste
(ii) Non-biodegradable waste
(iii) Organic manure
(iv) Compost
Answer: (ii) Non-biodegradable waste
Q.47 Assertion (A): Many pesticides cannot be removed completely by washing food grains and vegetables.
Reason (R): These chemicals are non-degradable and accumulate in the food chain.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.48 The agreement to freeze CFC production at 1986 levels was succeeded by —
(i) WHO
(ii) UNEP
(iii) UNICEF
(iv) FAO
Answer: (ii) UNEP
Q.49 Which of the following practices helps in conserving the environment?
(i) Throwing waste in open areas
(ii) Using more plastic bags
(iii) Switching off unnecessary lights and fans
(iv) Burning garbage openly
Answer: (iii) Switching off unnecessary lights and fans
Q.50 Match the following:
Column A
(a) Producers
(b) Secondary consumers
(c) Ozone layer
(d) CFCs
Column B
(i) Small carnivores
(ii) Protect Earth from UV radiation
(iii) Green plants
(iv) Cause ozone depletion
Options:
(i) a–(iii), b–(i), c–(ii), d–(iv)
(ii) a–(i), b–(iii), c–(iv), d–(ii)
(iii) a–(ii), b–(iv), c–(i), d–(iii)
(iv) a–(iv), b–(ii), c–(iii), d–(i)
Answer: (i) a–(iii), b–(i), c–(ii), d–(iv
SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions for HSLC Exam 2026–27
The SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions provided here are prepared according to the latest SEBA (ASSEB) syllabus 2026–27. These SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions include conceptual MCQs, short answer questions, long answer questions, and diagram-based questions aligned with the HSLC exam pattern.
As per the latest HSLC structure, students must answer 45 MCQs. Therefore, regular practice of SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions ensures strong preparation for MCQ-based and reasoning-type questions.
The SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions cover food chains, food webs, trophic levels, energy flow, biological magnification, and ozone depletion. Continuous revision using SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions improves conceptual clarity and environmental awareness.
These Class 10 Our Environment Important Questions with MCQs are ideal for final revision. Consistent practice of SEBA Class 10 Science Chapter 15 Our Environment Important Extra Questions strengthens exam confidence and scoring performance.
Frequently Asked Questions (FAQ)
1. Why is Chapter 15 Our Environment important for HSLC exam?
This chapter explains ecosystem, food chains, energy flow, and biological magnification frequently asked in HSLC Science exams.
2. How many MCQs are asked in HSLC Science exam?
Students must answer 45 MCQs as per the latest HSLC Science examination pattern.
3. Are MCQs included in Our Environment important questions?
Yes, conceptual and diagram-based MCQs are included according to the updated HSLC exam structure.
4. Are these questions based on SEBA syllabus?
Yes, all questions are prepared strictly according to the latest SEBA (ASSEB) syllabus for 2026–27.
5. Do these include previous year questions?
Yes, previous year questions are included to help students understand HSLC exam trends.
6. Which topics are covered in Chapter 15?
Topics include ecosystem components, food chains, trophic levels, 10% law, biological magnification, and ozone depletion.
7. Can practising these improve exam performance?
Yes, regular revision improves conceptual clarity and MCQ accuracy in the HSLC examination.
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