Our Environment Part 4: MCQs (Q76–Q100)
🌍 Our Environment – MCQs (Class 10 Science, NCERT)
🔹 Part 4: Questions 76–100
Q76. Which of the following is a biodegradable substance?
A) Polythene bag
B) Banana peel
C) Glass bottle
D) Aluminium can
Correct Answer: B) Banana peel
Explanation:
- ✅ B) Biodegradable → decomposes by microbes.
- A, C, D → Non-biodegradable, persist for years.
Q77. Which one of the following is the correct sequence of food chain in a grassland ecosystem?
A) Grass → Lion → Deer
B) Grass → Deer → Lion
C) Lion → Grass → Deer
D) Deer → Grass → Lion
Correct Answer: B) Grass → Deer → Lion
Explanation:
- ✅ B) Producer → Herbivore → Carnivore.
Q78. Which activity contributes directly to acid rain?
A) Burning fossil fuels
B) Deforestation
C) Ozone depletion
D) Use of plastic
Correct Answer: A) Burning fossil fuels
Explanation:
- ✅ A) Fossil fuels release SO₂ & NO₂ → acids in rainwater.
Q79. Which chemical is mainly responsible for ozone depletion?
A) SO₂
B) CFCs
C) CO₂
D) O₃
Correct Answer: B) CFCs
Explanation:
- ✅ B) Chlorofluorocarbons release chlorine radicals that destroy ozone.
Q80. The accumulation of harmful chemicals in higher trophic levels is called:
A) Biomagnification
B) Eutrophication
C) Decomposition
D) Pollution
Correct Answer: A) Biomagnification
Explanation:
- ✅ A) DDT & pesticides accumulate and magnify at higher levels.
Q81. Which of the following gases is NOT a greenhouse gas?
A) CO₂
B) CH₄
C) N₂
D) O₃
Correct Answer: C) N₂
Explanation:
- ✅ C) Nitrogen is inert, does not trap heat.
Q82. Which organisms are known as autotrophs in ecosystems?
A) Lions
B) Humans
C) Green plants
D) Fungi
Correct Answer: C) Green plants
Explanation:
- ✅ C) Autotrophs prepare food by photosynthesis.
Q83. Which of the following is the best way to manage biodegradable waste?
A) Landfilling
B) Composting
C) Burning
D) Plastic coating
Correct Answer: B) Composting
Explanation:
- ✅ B) Converts organic waste → manure, eco-friendly.
Q84. Which group of organisms forms the decomposers in an ecosystem?
A) Bacteria and fungi
B) Plants and trees
C) Fish and frogs
D) Snakes and lizards
Correct Answer: A) Bacteria and fungi
Explanation:
- ✅ A) Decomposers recycle nutrients into soil.
Q85. Which of the following represents an aquatic food chain?
A) Grass → Rabbit → Fox
B) Algae → Small fish → Big fish
C) Plant → Cow → Human
D) Grass → Goat → Man
Correct Answer: B) Algae → Small fish → Big fish
Explanation:
- ✅ B) Aquatic ecosystems start with algae (producers).
Q86. Which is an example of a primary consumer?
A) Frog
B) Grasshopper
C) Snake
D) Eagle
Correct Answer: B) Grasshopper
Explanation:
- ✅ B) Herbivore feeding on plants.
Q87. Which is NOT a non-biodegradable substance?
A) Cow dung
B) Plastics
C) Glass
D) Polythene
Correct Answer: A) Cow dung
Explanation:
- ✅ A) Cow dung decomposes naturally → biodegradable.
Q88. The ozone layer prevents entry of:
A) UV rays
B) X-rays
C) IR rays
D) Visible light
Correct Answer: A) UV rays
Explanation:
- ✅ A) Protects life by absorbing ultraviolet radiation.
Q89. Which of these causes eutrophication in water bodies?
A) Excess fertilizers
B) Plastic waste
C) Oil spills
D) Heavy metals
Correct Answer: A) Excess fertilizers
Explanation:
- ✅ A) Nutrient enrichment → algal bloom → oxygen depletion.
Q90. Which of the following is a natural ecosystem?
A) Crop field
B) Pond
C) Aquarium
D) Garden
Correct Answer: B) Pond
Explanation:
- ✅ B) Self-sustained natural ecosystem.
Q91. Which pyramid is always upright?
A) Pyramid of biomass
B) Pyramid of numbers
C) Pyramid of energy
D) All of these
Correct Answer: C) Pyramid of energy
Explanation:
- ✅ C) Energy decreases at each trophic level → upright.
Q92. The organisms feeding on dead remains of animals are called:
A) Decomposers
B) Scavengers
C) Herbivores
D) Omnivores
Correct Answer: B) Scavengers
Explanation:
- ✅ B) Scavengers like vultures feed on carcasses.
Q93. Which is the major cause of loss of biodiversity?
A) Soil erosion
B) Deforestation
C) Rainfall
D) Photosynthesis
Correct Answer: B) Deforestation
Explanation:
- ✅ B) Cutting forests destroys habitats and species.
Q94. Which of the following is NOT a fossil fuel?
A) Coal
B) Petroleum
C) Natural gas
D) Biogas
Correct Answer: D) Biogas
Explanation:
- ✅ D) Biogas is renewable, made from organic waste.
Q95. Which waste disposal method is most eco-friendly?
A) Burning
B) Dumping
C) Composting
D) Landfilling
Correct Answer: C) Composting
Explanation:
- ✅ C) Produces manure, reduces pollution.
Q96. Which of the following contributes to global warming?
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Hydrogen
Correct Answer: C) Carbon dioxide
Explanation:
- ✅ C) Major greenhouse gas responsible for global warming.
Q97. Which factor is NOT part of an ecosystem?
A) Plants
B) Animals
C) Rocks
D) Mobile phones
Correct Answer: D) Mobile phones
Explanation:
- ✅ D) Not natural, man-made objects are not ecosystem components.
Q98. Which one is a secondary consumer in this chain: Grass → Grasshopper → Frog → Snake → Hawk?
A) Grasshopper
B) Frog
C) Snake
D) Hawk
Correct Answer: B) Frog
Explanation:
- ✅ B) Grasshopper = primary consumer, Frog = secondary consumer.
Q99. Which one is an artificial ecosystem?
A) Ocean
B) Aquarium
C) Desert
D) River
Correct Answer: B) Aquarium
Explanation:
- ✅ B) Aquarium is man-made, maintained by humans.
Q100. Which of the following is NOT a step of the 3Rs principle?
A) Reduce
B) Reuse
C) Recycle
D) Repair
Correct Answer: D) Repair
Explanation:
- ✅ D) 3Rs = Reduce, Reuse, Recycle (Repair is not included).
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