OUR PLANET EARTH ~ENVIRONMENTAL SCIENCE CLASS IX , Chapter 1
ENVIRONMENTAL SCIENCE
CLASS IX – OUR PLANET EARTH
Choose the correct answer:
1. Environment includes:
A. Only living organisms
B. Only non-living things
C. Both living and non-living components
D. Only plants
Answer: C
2. Living components of the environment are called:
A. Abiotic components
B. Biotic components
C. Atmospheric components
D. Lithospheric components
Answer: B
3. Non-living components of the environment are called:
A. Biotic components
B. Ecological components
C. Abiotic components
D. Biospheric components
Answer: C
4. Which of the following is an abiotic component?
A. Tree
B. Human
C. Soil
D. Bacteria
Answer: C
5. Which of the following is a biotic component?
A. Air
B. Water
C. Rock
D. Fungi
Answer: D
6. Producers are organisms that:
A. Eat plants
B. Eat animals
C. Make their own food
D. Decompose dead matter
Answer: C
7. Which among the following is a producer?
A. Lion
B. Deer
C. Green plants
D. Human
Answer: C
8. Organisms that break down dead matter are called:
A. Producers
B. Consumers
C. Decomposers
D. Predators
Answer: C
9. Which of these is a decomposer?
A. Tiger
B. Goat
C. Bacteria
D. Fish
Answer: C
10. Earth supports life because of:
A. Suitable temperature
B. Presence of water
C. Atmosphere
D. All of these
Answer: D
11. The solid outer part of Earth is called:
A. Atmosphere
B. Lithosphere
C. Biosphere
D. Hydrosphere
Answer: B
12. Lithosphere consists of:
A. Water bodies
B. Air
C. Land and rocks
D. Ice sheets
Answer: C
13. All water bodies together form:
A. Lithosphere
B. Biosphere
C. Hydrosphere
D. Cryosphere
Answer: C
14. About how much of Earth's surface is covered by water?
A. 50%
B. 30%
C. 71%
D. 80%
Answer: C
15. The layer of gases surrounding Earth is called:
A. Lithosphere
B. Atmosphere
C. Hydrosphere
D. Cryosphere
Answer: B
16. The atmosphere mainly contains:
A. Nitrogen
B. Hydrogen
C. Helium
D. Carbon monoxide
Answer: A
17. Approximate percentage of oxygen in the atmosphere is:
A. 10%
B. 21%
C. 40%
D. 78%
Answer: B
18. The frozen part of Earth is called:
A. Biosphere
B. Atmosphere
C. Cryosphere
D. Lithosphere
Answer: C
19. Which is part of the cryosphere?
A. River
B. Glacier
C. Forest
D. Desert
Answer: B
ENVIRONMENTAL SCIENCE
CLASS IX – OUR PLANET EARTH
20. The zone where life exists is called:
A. Lithosphere
B. Hydrosphere
C. Biosphere
D. Cryosphere
Answer: C
21. Humans are:
A. Separate from nature
B. Above nature
C. Part of the environment
D. Independent of nature
Answer: C
22. Which human activity damages the environment?
A. Afforestation
B. Recycling
C. Deforestation
D. Conservation
Answer: C
23. Which is NOT an effect of the environment on humans?
A. Flood
B. Drought
C. Cyclone
D. Planting trees
Answer: D
24. Environmental education helps to:
A. Increase pollution
B. Create awareness
C. Destroy forests
D. Reduce biodiversity
Answer: B
25. Plants prepare food by:
A. Respiration
B. Photosynthesis
C. Digestion
D. Transpiration
Answer: B
26. Photosynthesis requires:
A. Sunlight
B. Carbon dioxide
C. Water
D. All of these
Answer: D
27. Photosynthesis releases:
A. Nitrogen
B. Hydrogen
C. Oxygen
D. Helium
Answer: C
28. Breakdown of dead organisms is called:
A. Evolution
B. Adaptation
C. Decomposition
D. Extinction
Answer: C
29. Which organisms mainly carry out decomposition?
A. Birds
B. Fish
C. Fungi and bacteria
D. Mammals
Answer: C
30. Adaptation helps organisms to:
A. Increase pollution
B. Survive in surroundings
C. Stop evolution
D. Cause extinction
Answer: B
31. Gradual changes in organisms over time is called:
A. Adaptation
B. Evolution
C. Decomposition
D. Respiration
Answer: B
32. Permanent disappearance of species is called:
A. Evolution
B. Extinction
C. Adaptation
D. Coexistence
Answer: B
33. Dodo is an example of:
A. Adaptation
B. Evolution
C. Extinct species
D. Producer
Answer: C
34. Living together in the same environment is called:
A. Evolution
B. Coexistence
C. Extinction
D. Adaptation
Answer: B
35. Carbon cycle maintains:
A. Carbon balance
B. Water balance
C. Soil balance
D. Energy balance
Answer: A
36. Plants absorb which gas during photosynthesis?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen
Answer: C
37. Nitrogen cycle is important for formation of:
A. Vitamins
B. Proteins
C. Sugars
D. Fats
Answer: B
38. The first step of water cycle is:
A. Condensation
B. Precipitation
C. Evaporation
D. Collection
Answer: C
39. Formation of clouds occurs during:
A. Evaporation
B. Condensation
C. Collection
D. Transpiration
Answer: B
40. Rainfall occurs during:
A. Evaporation
B. Condensation
C. Precipitation
D. Respiration
Answer: C
41. Interaction among living and non-living components forms:
A. Ecosystem
B. Atmosphere
C. Lithosphere
D. Cryosphere
Answer: A
42. Which sphere connects all Earth's systems?
A. Lithosphere
B. Biosphere
C. Atmosphere
D. Cryosphere
Answer: B
ENVIRONMENTAL SCIENCE
CLASS IX – OUR PLANET EARTH
43. Melting glaciers mainly affect:
A. Atmosphere only
B. Hydrosphere
C. Lithosphere only
D. Biosphere only
Answer: B
44. Which process returns nutrients to the soil?
A. Photosynthesis
B. Evolution
C. Decomposition
D. Respiration
Answer: C
45. Excessive deforestation may cause:
A. Increase biodiversity
B. Soil erosion
C. Increased rainfall always
D. More oxygen production
Answer: B
46. Which of the following is NOT a biotic component?
A. Algae
B. Bacteria
C. Water
D. Fungi
Answer: C
47. Which component provides minerals to plants?
A. Air
B. Soil
C. Sunlight
D. Clouds
Answer: B
48. Consumers depend directly or indirectly on:
A. Rocks
B. Producers
C. Water only
D. Atmosphere only
Answer: B
49. Which of these is a primary consumer?
A. Tiger
B. Lion
C. Deer
D. Eagle
Answer: C
50. Green plants are called producers because they:
A. Absorb oxygen
B. Produce their own food
C. Consume animals
D. Release nitrogen
Answer: B
51. Which sphere includes rivers, lakes and oceans?
A. Atmosphere
B. Biosphere
C. Hydrosphere
D. Lithosphere
Answer: C
52. Which sphere contains mountains and plains?
A. Hydrosphere
B. Lithosphere
C. Cryosphere
D. Atmosphere
Answer: B
53. Ice caps are part of:
A. Biosphere
B. Cryosphere
C. Hydrosphere
D. Atmosphere
Answer: B
54. The biosphere consists of:
A. Only animals
B. Only plants
C. Regions where life exists
D. Only microorganisms
Answer: C
55. Which component protects Earth from harmful radiation?
A. Lithosphere
B. Atmosphere
C. Biosphere
D. Hydrosphere
Answer: B
56. Which activity helps conserve the environment?
A. Deforestation
B. Burning plastics
C. Afforestation
D. Excess mining
Answer: C
57. Excessive industrialization may lead to:
A. Reduced pollution
B. Environmental degradation
C. Increase in forests
D. Increase in biodiversity
Answer: B
58. Human dependence on nature shows:
A. Isolation
B. Interconnection
C. Competition only
D. Independence
Answer: B
59. Photosynthesis occurs mainly in:
A. Roots
B. Stem
C. Leaves
D. Flowers
Answer: C
60. Chlorophyll helps plants to:
A. Absorb sunlight
B. Absorb nitrogen
C. Absorb oxygen
D. Absorb minerals
Answer: A
61. Which process adds oxygen to the atmosphere?
A. Respiration
B. Photosynthesis
C. Decomposition
D. Digestion
Answer: B
62. Organisms suited to desert conditions show:
A. Extinction
B. Adaptation
C. Evolution
D. Coexistence
Answer: B
63. Thick fur in polar bears is an example of:
A. Evolution
B. Adaptation
C. Extinction
D. Decomposition
Answer: B
64. Dinosaurs are examples of:
A. Extinct organisms
B. Producers
C. Consumers
D. Decomposers
Answer: A
65. The process by which organisms gradually change over time is:
A. Digestion
B. Evolution
C. Respiration
D. Excretion
Answer: B
66. Water vapour changes into clouds by:
A. Evaporation
B. Collection
C. Condensation
D. Respiration
Answer: C
67. Nitrogen enters plants mainly through:
A. Leaves
B. Roots
C. Stem
D. Flowers
Answer: B
68. Which cycle helps maintain atmospheric oxygen?
A. Water cycle
B. Oxygen cycle
C. Nitrogen cycle
D. Carbon cycle
Answer: B
69. Which process returns carbon dioxide to the atmosphere?
A. Photosynthesis
B. Respiration
C. Germination
D. Pollination
Answer: B
70. Water falling from clouds is called:
A. Condensation
B. Collection
C. Evaporation
D. Precipitation
Answer: D
ENVIRONMENTAL SCIENCE
CLASS IX – OUR PLANET EARTH
Assertion–Reason Type MCQs
71. Assertion: Plants are producers.
Reason: Plants prepare their own food.
A. Both true and Reason explains Assertion
B. Both true but Reason does not explain Assertion
C. Assertion true, Reason false
D. Assertion false, Reason true
Answer: A
72. Assertion: Humans are a part of the environment.
Reason: Humans are completely independent of nature.
A. Both true
B. Both false
C. Assertion true, Reason false
D. Assertion false, Reason true
Answer: C
73. Assertion: Decomposition improves soil fertility.
Reason: Decomposers recycle nutrients.
A. Both true and Reason explains Assertion
B. Both true but Reason does not explain Assertion
C. Assertion true, Reason false
D. Both false
Answer: A
74. Assertion: The atmosphere contains oxygen.
Reason: Oxygen is needed for respiration.
Answer: A
75. Assertion: Water cycle is important.
Reason: It maintains water balance on Earth.
Answer: A
1. Which of the following interactions is correctly matched?
A. Fish → Atmosphere
B. Plants → Soil minerals
C. Birds → Lithosphere only
D. Humans → Biosphere only
Answer: B
2. Which sphere acts as the meeting point of all Earth's systems?
A. Lithosphere
B. Hydrosphere
C. Biosphere
D. Cryosphere
Answer: C
3. Which statement is incorrect?
A. Producers prepare their own food
B. Decomposers recycle nutrients
C. Consumers produce their own food
D. Plants perform photosynthesis
Answer: C
4. Which of the following is not directly involved in photosynthesis?
A. Carbon dioxide
B. Sunlight
C. Nitrogen gas
D. Water
Answer: C
5. Excessive cutting of trees mainly disturbs:
A. Carbon cycle
B. Water cycle
C. Oxygen cycle
D. All of these
Answer: D
6. If decomposers disappeared from Earth, then:
A. Dead matter would accumulate
B. Nutrient recycling would stop
C. Soil fertility would decrease
D. All of these
Answer: D
7. Which process continuously recycles water in nature?
A. Carbon cycle
B. Water cycle
C. Nitrogen cycle
D. Respiration
Answer: B
8. Thick fur in polar bears mainly helps in:
A. Food preparation
B. Adaptation
C. Extinction
D. Evolution
Answer: B
9. Which pair is wrongly matched?
A. Hydrosphere — Water
B. Cryosphere — Ice sheets
C. Lithosphere — Air
D. Atmosphere — Gases
Answer: C
10. The ultimate source of energy for most ecosystems is:
A. Moon
B. Water
C. Sun
D. Soil
Answer: C
11. Which process removes carbon dioxide from the atmosphere?
A. Respiration
B. Combustion
C. Photosynthesis
D. Decomposition
Answer: C
12. Human beings affect the environment through:
A. Mining
B. Pollution
C. Urbanization
D. All of these
Answer: D
Part B: Match the Following
Column A Column B
1. Lithosphere a. Frozen water
2. Cryosphere b. Land and rocks
3. Hydrosphere c. Living organisms
4. Biosphere d. Water bodies
Answers:
1 → b
2 → a
3 → d
4 → c
Column A Column B
1. Photosynthesis a. Breakdown of dead matter
2. Decomposition b. Gradual change
3. Evolution c. Food preparation
4. Adaptation d. Survival mechanism
Answers:
1 → c
2 → a
3 → b
4 → d
Column A Column B
1. Carbon cycle a. Maintains water balance
2. Oxygen cycle b. Protein formation
3. Nitrogen cycle c. Oxygen balance
4. Water cycle d. Carbon balance
Answers:
1 → d
2 → c
3 → b
4 → a
Part C: Fill in the Blanks
1. Living organisms are called ______ components.
Answer: Biotic
2. Non-living components are called ______ components.
Answer: Abiotic
3. Green plants are called ______ because they make their own food.
Answer: Producers
4. The solid outer layer of Earth is called ______.
Answer: Lithosphere
5. The water present on Earth forms the ______.
Answer: Hydrosphere
6. The frozen part of Earth is called ______.
Answer: Cryosphere
7. Photosynthesis releases ______ gas.
Answer: Oxygen
8. The breakdown of dead organisms is called ______.
Answer: Decomposition
9. Permanent disappearance of species is called ______.
Answer: Extinction
10. Water changes into vapour by ______.
Answer: Evaporation
11. The formation of clouds is called ______.
Answer: Condensation
12. Water falling from clouds is called ______.
Answer: Precipitation
13. Humans are ______ of the environment.
Answer: Part
14. The gas mainly absorbed by plants is ______.
Answer: Carbon dioxide
15. Organisms that break down dead matter are called ______.
Answer: Decomposers
Part D: Assertion–Reason Questions
Choose:
A. Both A and R are true and R explains A
B. Both A and R are true but R does not explain A
C. A is true but R is false
D. A is false but R is true
1. Assertion: Plants are producers.
Reason: Plants prepare food using sunlight.
Answer: A
2. Assertion: Humans are independent of the environment.
Reason: Humans depend on natural resources.
Answer: D
3. Assertion: Decomposers improve soil fertility.
Reason: They recycle nutrients.
Answer: A
4. Assertion: Adaptation helps organisms survive.
Reason: Organisms develop special features.
Answer: A
5. Assertion: Water cycle maintains water balance.
Reason: Water continuously moves through nature.
Answer: A
6. Assertion: Nitrogen is essential for life.
Reason: Nitrogen helps in protein formation.
Answer: A
7. Assertion: Extinction decreases biodiversity.
Reason: Extinct species disappear permanently.
Answer: A
8. Assertion: Atmosphere contains oxygen.
Reason: Oxygen is used for respiration.
Answer: A
9. Assertion: Cryosphere contains oceans.
Reason: Oceans contain water.
Answer: D
10. Assertion: Photosynthesis decreases carbon dioxide.
Reason: Plants absorb carbon dioxide.
Answer: A
CLASS IX – OUR PLANET EARTH
All Possible Short Answer Questions (2 Marks) with Answers
1. What is the environment?
Answer:
Environment is the surroundings in which living organisms exist. It includes both living (biotic) and non-living (abiotic) components.
2. What are biotic components? Give two examples.
Answer:
Biotic components are living organisms present in the environment.
Examples:
Plants
Animals
3. What are abiotic components? Give two examples.
Answer:
Abiotic components are non-living parts of the environment.
Examples:
Air
Water
4. Differentiate between biotic and abiotic components.
Answer:
Answer:
Earth is called a unique planet because it has suitable temperature, water, oxygen and atmospheric conditions that support life.
6. Why do living organisms depend on the environment?
Answer:
Living organisms depend on the environment for food, water, shelter, oxygen and other necessities for survival.
7. What are producers? Give examples.
Answer:
Producers are organisms that prepare their own food by photosynthesis.
Examples:
Green plants
Algae
8. What are consumers? Give examples.
Answer:
Consumers are organisms that depend on other organisms for food.
Examples:
Human beings
Deer
9. What are decomposers?
Answer:
Decomposers are organisms that break down dead plants and animals into simpler substances and recycle nutrients.
Examples: bacteria and fungi.
10. State two functions of decomposers.
Answer:
They break down dead organisms.
They recycle nutrients back into the soil.
11. What is lithosphere?
Answer:
Lithosphere is the solid outer part of Earth consisting of land, rocks and soil.
12. What is hydrosphere?
Answer:
The hydrosphere includes all forms of water on Earth such as rivers, lakes, oceans and groundwater.
13. What is the atmosphere?
Answer:
The atmosphere is the layer of gases surrounding Earth that protects and supports life.
14. What is the cryosphere?
Answer:
Cryosphere is the frozen part of Earth including glaciers, snow and ice caps.
15. What is the biosphere?
Answer:
Biosphere is the zone where life exists on Earth.
16. Mention any two importance of atmosphere.
Answer:
It provides oxygen for respiration.
It protects Earth from harmful radiation.
17. Mention two importance of hydrosphere.
Answer:
Water is essential for life.
It supports aquatic organisms.
18. Mention two importance of lithosphere.
Answer:
Provides land for living organisms.
Supplies minerals and natural resources.
19. Why are humans considered a part of the environment?
Answer:
Humans depend on natural resources like air, water and food, therefore they are part of the environment.
20. Mention two ways humans affect the environment.
Answer:
Deforestation
Pollution
21. Mention two environmental problems caused by humans.
Answer:
Global warming
Air pollution
22. Why is environmental education important?
Answer:
Environmental education creates awareness and helps conserve natural resources.
23. Define photosynthesis.
Answer:
Photosynthesis is the process by which green plants prepare food using sunlight, water and carbon dioxide.
24. Mention two requirements for photosynthesis.
Answer:
Sunlight
Carbon dioxide
25. State two importance of photosynthesis.
Answer:
Produces food.
Releases oxygen.
26. What is decomposition?
Answer:
Decomposition is the breakdown of dead organisms into simpler substances.
27. Why is decomposition important?
Answer:
It recycles nutrients.
It increases soil fertility.
28. What is adaptation? Give one example.
Answer:
Adaptation is a special feature that helps organisms survive.
Example: Thick fur in polar bears.
29. What is evolution?
Answer:
Evolution is the gradual change in living organisms over long periods of time.
30. What is extinction?
Answer:
Extinction is the permanent disappearance of a species from Earth.
31. Give two causes of extinction.
Answer:
Deforestation
Hunting
32. What is coexistence?
Answer:
Coexistence is the process in which different organisms live together in the same environment.
33. What are biogeochemical cycles?
Answer:
Biogeochemical cycles are processes through which nutrients move between living and non-living components.
34. Name four major biogeochemical cycles.
Answer:
Carbon cycle
Oxygen cycle
Nitrogen cycle
Water cycle
35. Why is the carbon cycle important?
Answer:
Carbon cycle maintains carbon balance in the environment.
36. Why is nitrogen important for living organisms?
Answer:
Nitrogen is essential for protein formation and growth.
37. Name the steps of the water cycle.
Answer:
Evaporation
Condensation
Precipitation
Collection
38. What is evaporation?
Answer:
Evaporation is the process by which water changes into water vapour due to heat.
39. What is condensation?
Answer:
Condensation is the conversion of water vapour into liquid droplets.
40. What is precipitation?
Answer:
Precipitation is water falling from clouds as rain, snow or hail.
41. Why are natural cycles important?
Answer:
Natural cycles maintain balance in nature and recycle essential nutrients.
42. How do plants and animals depend on each other?
Answer:
Plants provide food and oxygen while animals provide carbon dioxide for photosynthesis.
CLASS IX – OUR PLANET EARTH
A. Difference-Based Questions
1. Differentiate between producers and consumers.
Producers Consumers
Make their own food Depend on others for food
Example: Green plants Example: Human beings
2. Differentiate between biotic and abiotic components.
Biotic Components Abiotic Components
Living things Non-living things
Example: Plants Example: Water
3. Differentiate between photosynthesis and respiration.
Photosynthesis Respiration
Food is prepared Food is broken down
Oxygen is released Carbon dioxide is released
4. Differentiate between adaptation and evolution.
Adaptation Evolution
Helps survival Causes gradual changes over generations
Short-term survival feature Long-term process
5. Differentiate between lithosphere and hydrosphere.
Lithosphere Hydrosphere
Land and rocks Water bodies
Solid part of Earth Water part of Earth
6. Differentiate between decomposition and extinction.
Decomposition Extinction
Breakdown of dead matter Permanent disappearance of species
B. Give Reasons
7. Why are decomposers called nature's recyclers?
Answer:
They break down dead organisms and return nutrients to the soil for reuse.
8. Why is biosphere called the zone of life?
Answer:
Because all living organisms exist and survive within it.
9. Why is atmosphere important for life?
Answer:
It provides oxygen and protects Earth from harmful radiation.
10. Why are green plants called producers?
Answer:
Because they can prepare their own food through photosynthesis.
11. Why is water important for living organisms?
Answer:
Water is required for biological processes and survival.
12. Why is Earth considered suitable for life?
Answer:
Earth has air, water, suitable temperature and necessary resources.
13. Why does extinction reduce biodiversity?
Answer:
Because the disappearance of species decreases the variety of living organisms.
14. Why are natural cycles necessary?
Answer: Natural cycles maintain ecological balance and recycle nutrients.
15. Why is nitrogen essential for living organisms?
Answer: Nitrogen is required for the formation of proteins.
C. Name the Following
16. Name the process by which plants prepare food.
Answer: Photosynthesis
17. Name the gas released during photosynthesis.
Answer: Oxygen
18. Name the gas absorbed by plants during photosynthesis.
Answer: Carbon dioxide
19. Name the frozen part of Earth.
Answer: Cryosphere
20. Name the solid outer part of Earth.
Answer: Lithosphere
21. Name the zone where life exists.
Answer: Biosphere
22. Name organisms that break down dead matter.
Answer: Decomposers
23. Name one extinct animal.
Answer: Dodo
24. Name one decomposer.
Answer: Fungi
25. Name one producer.
Answer: Green plant
26. What would happen if plants disappeared from Earth?
Answer: Food chains would collapse and oxygen levels would decrease.
27. What would happen if decomposers disappeared?
Answer: Dead organisms would accumulate and nutrients would not be recycled.
28. What would happen if the water cycle stopped?
Answer: Water distribution would be disturbed and life would become difficult.
29. How does deforestation affect the carbon cycle?
Answer: Fewer trees absorb carbon dioxide, increasing its amount in the atmosphere.
30. How do humans disturb environmental balance?
Answer: Humans disturb environmental balance through pollution and deforestation.
31. How do plants and animals depend on each other?
Answer: Plants provide oxygen and food while animals provide carbon dioxide.
32. What happens when glaciers melt excessively?
Answer: Sea levels rise and climate patterns may change.
33. Mention two functions of the atmosphere.
Answer:
1. Provides oxygen
2. Protects from harmful radiation
34. Mention two functions of the hydrosphere.
Answer:
1. Provides water for life
2. Supports aquatic organisms
35. Mention two functions of decomposers.
Answer:
1. Break down dead matter
2. Recycle nutrients
36. Mention two importance of photosynthesis.
Answer:
1. Produces food
2. Releases oxygen
37. Mention two importance of environmental education.
Answer:
1. Creates awareness
2. Promotes conservation
38. Mention two causes of extinction.
Answer:
1. Deforestation
2. Hunting
39. Mention two examples of adaptation.
Answer:
1. Thick fur in polar bears
2. Hump in camels
40. Mention two ways to protect the environment.
Answer:
1. Plant more trees
2. Reduce pollution
CLASS IX ICSE GEOGRAPHY / ENVIRONMENTAL SCIENCE
CHAPTER: OUR PLANET EARTH
DETAILED 5-MARK QUESTIONS AND ANSWERS
1. What is the Environment? Explain its biotic and abiotic components.
Answer: The environment is everything that surrounds us and affects the life of living organisms. It includes both living and non-living components that interact continuously with each other.
The environment is divided into two major components:
1. Biotic Components
Biotic components are the living parts of the environment.
Examples:
Plants
Animals
Human beings
Bacteria
Fungi
Biotic components can be classified into:
Producers – Green plants that prepare their own food.
Consumers – Animals and humans that depend on plants or other animals for food.
Decomposers – Bacteria and fungi that break down dead organisms.
2. Abiotic Components
Abiotic components are the non-living parts of the environment.
Examples:
Air
Water
Soil
Sunlight
Temperature
Minerals
Biotic and abiotic components are interdependent. Plants require sunlight, water and soil, while animals depend on plants and oxygen. Thus, all components work together to support life on Earth.
2. Explain the different spheres of the Earth and their importance.
Answer: The Earth is made up of different spheres that interact with one another and support life.
1. Lithosphere
The lithosphere is the solid outer layer of the Earth consisting of rocks, soil and landforms.
Importance:
Provides land for human settlement.
Supports agriculture.
Supplies minerals and natural resources.
2. Hydrosphere
The hydrosphere includes all water bodies such as oceans, rivers, lakes and groundwater.
Importance:
Provides water for living organisms.
Supports aquatic life.
Regulates climate.
3. Atmosphere
The atmosphere is the layer of gases surrounding the Earth.
Importance:
Provides oxygen for respiration.
Protects Earth from harmful solar radiation.
Helps regulate temperature.
4. Cryosphere
The cryosphere includes glaciers, ice caps and permanently frozen regions.
Importance:
Stores freshwater.
Helps regulate global climate.
5. Biosphere
The biosphere is the zone where life exists.
Importance:
Supports all living organisms.
Connects all Earth's spheres.
All these spheres are interconnected and together make life possible on Earth.
3. Explain the relationship between humans and the environment.
Answer: Humans and the environment are closely related and depend on each other.
Dependence of Humans on Environment
Humans depend on the environment for:
1. Air for breathing.
2. Water for drinking and daily use.
3. Food from plants and animals.
4. Land for settlement and agriculture.
5. Natural resources for industries.
Impact of Humans on Environment
Human activities affect the environment in many ways:
1. Deforestation destroys forests.
2. Industrial activities cause pollution.
3. Mining damages landforms.
4. Excessive use of natural resources leads to depletion.
Importance of Balance
Humans should use resources wisely and conserve nature to maintain environmental balance.
The relationship between humans and the environment is a two-way relationship because humans depend on nature and also influence it.
4. Explain the importance of Environmental Education.
Answer: Environmental education is the process of creating awareness about the environment and teaching people how to protect it.
Importance of Environmental Education
1. Creates Awareness
It helps people understand environmental problems such as pollution and global warming.
2. Encourages Conservation
It promotes the protection of forests, wildlife and natural resources.
3. Promotes Sustainable Development
It teaches people to use resources without harming future generations.
4. Reduces Pollution
People learn methods to reduce air, water and soil pollution.
5. Protects Biodiversity
Environmental education encourages the protection of endangered species and ecosystems.
Environmental education is essential for creating responsible citizens and ensuring a healthy environment.
5. Explain the process of Photosynthesis and its importance.
Answer: Photosynthesis is the process by which green plants prepare food using sunlight, carbon dioxide and water.
Requirements:
1. Sunlight
2. Chlorophyll
3. Water
4. Carbon dioxide
Process:
1. Plants absorb water through their roots.
2. Carbon dioxide enters through the stomata of leaves.
3. Chlorophyll absorbs sunlight.
4. The plant converts water and carbon dioxide into food (glucose).
5. Oxygen is released into the atmosphere.
Importance:
1. Produces food for plants.
2. Forms the base of all food chains.
3. Releases oxygen needed for respiration.
4. Maintains the balance of oxygen and carbon dioxide.
5. Supports life on Earth.
Photosynthesis is one of the most important biological processes because it provides food and oxygen.
6. Explain Decomposition and its importance in nature.
Answer: Decomposition is the process by which dead plants and animals are broken down into simpler substances by microorganisms.
Agents of Decomposition
1. Bacteria
2. Fungi
Process:
When plants and animals die, decomposers act on their remains and convert them into simple nutrients.
Importance:
1. Nutrient Recycling
Decomposers return nutrients to the soil.
2. Improves Soil Fertility
The nutrients released enrich the soil.
3. Prevents Accumulation of Waste
Dead organisms do not accumulate in the environment.
4. Maintains Ecological Balance
Matter is continuously recycled.
5. Supports Plant Growth
Plants absorb recycled nutrients from the soil.
Decomposition is essential for maintaining healthy ecosystems.
7. Explain Adaptation with suitable examples.
Answer: Adaptation refers to special features or behaviours that help organisms survive in their environment.
Importance:
Adaptations increase the chances of survival and reproduction.
Examples:
Camel:
Hump stores fat.
Long legs keep the body away from hot sand.
Wide feet help walking on sand.
Polar Bear:
Thick fur protects against cold.
White fur provides camouflage.
Thick layer of fat provides insulation.
Cactus:
Spines reduce water loss.
Thick stem stores water.
Deep roots absorb moisture.
Adaptations help organisms survive in different environmental conditions.
8. What is Evolution? Explain its significance.
Answer: Evolution is the gradual process by which living organisms change over long periods of time.
Features:
1. Takes place over many generations.
2. Produces variations among organisms.
3. Leads to the formation of new species.
Significance:
1. Explains the diversity of life.
2. Helps organisms adapt to environmental changes.
3. Produces new species.
4. Ensures survival in changing conditions.
5. Helps scientists understand the history of life.
Evolution is a continuous natural process that has shaped all life forms on Earth.
9. What is Extinction? Explain its causes and effects.
Answer: Extinction is the permanent disappearance of a species from Earth.
Causes:
1. Deforestation
2. Habitat destruction
3. Pollution
4. Climate change
5. Overhunting
Effects:
1. Loss of biodiversity.
2. Disturbance of food chains.
3. Ecological imbalance.
4. Loss of valuable genetic resources.
5. Reduction in ecosystem stability.
Examples
Dodo
Dinosaurs
Preventing extinction is important for maintaining biodiversity and ecological balance.
10. Explain the Water Cycle with a diagram and its importance.
Answer: The water cycle is the continuous movement of water between the Earth's surface and the atmosphere.
Steps of Water Cycle:
1. Evaporation
Heat from the Sun changes water into water vapour.
2. Condensation
Water vapour cools and forms clouds.
3. Precipitation
Water falls as rain, snow or hail.
4. Collection
Water collects in rivers, lakes and oceans.
Diagram:
Sun
↓
Evaporation
↓
Condensation
↓
Cloud Formation
↓
Precipitation
↓
Collection
↓
Rivers, Lakes & Oceans
Importance:
1. Maintains water balance.
2. Provides freshwater.
3. Supports agriculture.
4. Regulates climate.
5. Sustains life on Earth.
The water cycle is essential for the continuous supply and distribution of water on Earth.
CLASS IX – OUR PLANET EARTH
Additional 5-Mark Questions with Detailed Answers
11. Explain the interaction between biotic and abiotic components of the environment.
Answer:
The environment consists of biotic (living) and abiotic (non-living) components that interact continuously with each other.
Biotic Components:
Plants
Animals
Human beings
Microorganisms
Abiotic Components:
Air
Water
Soil
Sunlight
Temperature
Interaction:
Plants absorb water and minerals from the soil.
Plants use sunlight and carbon dioxide for photosynthesis.
Animals depend on plants for food and oxygen.
Decomposers break down dead organisms and return nutrients to the soil.
Living organisms depend on suitable temperature and climate for survival.
Biotic and abiotic components are interdependent. Their interaction maintains ecological balance and supports life on Earth.
12. Describe the role of producers, consumers and decomposers in maintaining ecological balance.
Answer:
Producers, consumers and decomposers form the three important groups of living organisms in an ecosystem.
1. Producers
Producers are green plants that prepare their own food through photosynthesis.
Functions:
Produce food.
Release oxygen.
Form the base of food chains.
2. Consumers
Consumers depend on plants and animals for food.
Examples:
Humans
Deer
Lion
Functions:
Transfer energy in food chains.
Help maintain population balance.
3. Decomposers
Examples:
Bacteria
Fungi
Functions:
Break down dead organisms.
Recycle nutrients.
Improve soil fertility.
Together, producers, consumers and decomposers ensure the continuous flow of energy and recycling of nutrients, thereby maintaining ecological balance.
13. Explain why Earth is considered a unique planet capable of supporting life.
Answer:
Earth is the only known planet that supports life because it possesses several favourable conditions.
Reasons:
1. Presence of Water
Water is essential for all living organisms.
2. Suitable Atmosphere
The atmosphere contains oxygen for respiration and carbon dioxide for photosynthesis.
3. Suitable Temperature
Earth is neither too hot nor too cold.
4. Protection from Harmful Radiation
The atmosphere protects Earth from harmful solar radiation.
5. Availability of Natural Resources
Soil, minerals and water support life and human activities.
The combination of water, atmosphere, suitable temperature and resources makes Earth a unique planet capable of supporting life.
14. Describe the Carbon Cycle with a neat diagram.
Answer:
The carbon cycle is the continuous movement of carbon between living organisms and the environment.
Steps:
Plants absorb carbon dioxide from the atmosphere.
Plants convert carbon dioxide into food through photosynthesis.
Animals obtain carbon by feeding on plants.
Respiration releases carbon dioxide back into the atmosphere.
Decomposition of dead organisms returns carbon to the environment.
Burning of fuels also releases carbon dioxide.
Diagram:
Atmospheric CO₂
↓
Photosynthesis
↓
Plants
↓
Animals
↓
Respiration
↓
Atmospheric CO₂
Dead Plants & Animals
↓
Decomposition
↓
Atmospheric CO₂
Importance:
Maintains carbon balance.
Supports photosynthesis.
Regulates climate.
Supports life processes.
The carbon cycle ensures continuous circulation of carbon and maintains ecological balance.
15. Explain the Oxygen Cycle and its importance.
Answer:
The oxygen cycle is the continuous circulation of oxygen between living organisms and the environment.
Process:
Green plants release oxygen during photosynthesis.
Animals and humans inhale oxygen for respiration.
Respiration releases carbon dioxide.
Plants use carbon dioxide during photosynthesis.
Thus oxygen continuously circulates in nature.
Importance:
Maintains oxygen balance in the atmosphere.
Supports respiration in living organisms.
Supports combustion.
Maintains ecological balance.
Essential for life on Earth.
The oxygen cycle ensures a continuous supply of oxygen necessary for life.
16. Describe the Nitrogen Cycle and explain its significance.
Answer:
The nitrogen cycle is the movement of nitrogen through the atmosphere, soil and living organisms.
Steps:
1. Nitrogen Fixation
Nitrogen-fixing bacteria convert atmospheric nitrogen into usable compounds.
2. Nitrification
Ammonia is converted into nitrates.
3. Assimilation
Plants absorb nitrates from the soil.
4. Ammonification
Dead organisms release nitrogen compounds into the soil.
5. Denitrification
Bacteria convert nitrates back into atmospheric nitrogen.
Significance:
Essential for protein formation.
Necessary for plant growth.
Maintains soil fertility.
Supports food production.
Maintains nitrogen balance.
The nitrogen cycle is essential for the growth and survival of living organisms.
17. Explain how the Earth's spheres are interconnected with suitable examples.
Answer:
The Earth consists of the lithosphere, hydrosphere, atmosphere, cryosphere and biosphere. These spheres are closely interconnected.
Examples:
Lithosphere and Biosphere
Plants grow in soil and obtain nutrients from it.
Hydrosphere and Biosphere
Fish and aquatic plants live in water.
Atmosphere and Biosphere
Living organisms depend on atmospheric oxygen.
Hydrosphere and Atmosphere
Water evaporates and forms clouds.
Cryosphere and Hydrosphere
Melting glaciers provide freshwater.
The interaction among Earth's spheres supports life and maintains ecological balance.
18. Discuss the importance of natural processes and cycles in maintaining environmental balance.
Answer:
Natural processes and cycles help maintain stability in ecosystems.
Major Natural Processes:
Photosynthesis
Respiration
Decomposition
Adaptation
Evolution
Major Natural Cycles:
Water Cycle
Carbon Cycle
Oxygen Cycle
Nitrogen Cycle
Importance:
Recycle nutrients.
Maintain ecological balance.
Ensure continuous supply of essential elements.
Support life processes.
Prevent resource depletion.
Natural processes and cycles are essential for the survival of all living organisms.
19. Explain coexistence and coevolution with suitable examples.
Answer:
Coexistence
Coexistence refers to different organisms living together in the same environment without harming one another.
Examples:
Birds nesting in trees.
Fish living with aquatic plants.
Coevolution
Coevolution occurs when two species evolve together and influence each other's development.
Examples:
Flowers and bees.
Certain birds and flowering plants.
Importance:
Promotes biodiversity.
Maintains ecological balance.
Strengthens species interactions.
Coexistence and coevolution help maintain healthy and stable ecosystems.
20. Discuss the major environmental problems caused by human activities and suggest measures to control them.
Answer:
Human activities have created many environmental problems.
Problems:
1. Deforestation
Destruction of forests for agriculture and development.
2. Pollution
Air, water and soil pollution caused by industries and vehicles.
3. Global Warming
Increase in Earth's temperature due to greenhouse gases.
4. Loss of Biodiversity
Many species are becoming endangered.
Control Measures:
Afforestation.
Pollution control.
Use of renewable energy.
Conservation of resources.
Environmental awareness.
Sustainable practices are necessary to reduce environmental problems.
21. Explain the importance of biodiversity and the consequences of its loss.
Answer:
Biodiversity refers to the variety of living organisms on Earth.
Importance:
Maintains ecological balance.
Supports food chains.
Provides food and medicines.
Increases ecosystem stability.
Helps adaptation to environmental changes.
Consequences of Loss:
Ecological imbalance.
Species extinction.
Reduced ecosystem productivity.
Disturbed food chains.
Loss of genetic resources.
Conservation of biodiversity is essential for a healthy environment.
22. Discuss the importance of conservation of natural resources.
Answer:
Natural resources are valuable materials obtained from nature.
Importance of Conservation:
Prevents resource depletion.
Maintains ecological balance.
Protects biodiversity.
Ensures availability for future generations.
Supports sustainable development.
Methods:
Afforestation
Water conservation
Recycling
Controlled use of resources
Conservation is essential for the long-term survival of humans and ecosystems.
23. Explain the role of forests in maintaining ecological balance.
Answer:
Forests play a vital role in maintaining ecological balance.
Functions:
Produce oxygen.
Absorb carbon dioxide.
Prevent soil erosion.
Regulate climate.
Maintain the water cycle.
Provide habitat for wildlife.
Preserve biodiversity.
Forests are called the "lungs of the Earth" because they support life and maintain environmental balance.
24. Describe the importance of water as a natural resource.
Answer:
Water is one of the most important natural resources.
Importance:
Essential for drinking and survival.
Used in agriculture.
Required for industries.
Supports aquatic life.
Maintains ecological balance.
Necessary for biological processes.
Helps regulate climate.
Water is indispensable for life and must be conserved carefully.
25. Explain how adaptation helps organisms survive in different environments with examples.
Answer:
Adaptation refers to special features that help organisms survive in their habitat.
Importance:
Helps organisms obtain food.
Protects from predators.
Helps survive extreme conditions.
Increases chances of reproduction.
Examples:
Camel (Desert)
Hump stores fat.
Wide feet help walk on sand.
Conserves water.
Polar Bear (Polar Region)
Thick fur provides warmth.
White colour provides camouflage.
Cactus (Desert Plant)
Spines reduce water loss.
Thick stem stores water.
Adaptations enable organisms to survive successfully in different environments and ensure the continuation of species.
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