Class 10th Our Environment Important Questions

🌱 OUR ENVIRONMENT — Important Questions & Answers

VERY SHORT / SHORT ANSWER TYPE

1. How does making of Kulhads affect our environment? (CBSE 2013)

Making kulhads requires clay, which is obtained by digging the soil. Excessive removal of fertile topsoil can cause soil erosion and loss of soil fertility. Also, large-scale production requires fuel for heating the kulhads.

1. कुल्हड़ बनाने से हमारे पर्यावरण पर क्या प्रभाव पड़ता है? (CBSE 2013)

उत्तर:
कुल्हड़ बनाने के लिए मिट्टी (Clay) की आवश्यकता होती है। इसके लिए जमीन की ऊपरी उपजाऊ मिट्टी को खोदा जाता है। इससे मृदा अपरदन (Soil Erosion) होता है और मिट्टी की उर्वरता कम हो सकती है।

इसके अलावा, कुल्हड़ों को पकाने के लिए ईंधन की आवश्यकता होती है, जिससे प्रदूषण बढ़ सकता है।

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2. State two differences between a consumer and producer.

Producer	Consumer
Make their own food.	Cannot make their own food.
Usually green plants and algae.	Depend directly or indirectly on producers.

2. उत्पादक (Producer) और उपभोक्ता (Consumer) में दो अंतर बताइए।

उत्पादक (Producer)	उपभोक्ता (Consumer)
1. ये अपना भोजन स्वयं बनाते हैं।	1. ये अपना भोजन स्वयं नहीं बना सकते।
2. उदाहरण: हरे पौधे और शैवाल (Algae)।	2. ये भोजन के लिए उत्पादकों पर प्रत्यक्ष या अप्रत्यक्ष रूप से निर्भर रहते हैं।

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3. Draw the line diagram showing flow of energy in an ecosystem.

Sun → Producers → Primary consumers → Secondary consumers → Tertiary consumers

Example:

Sun → Grass → Grasshopper → Frog → Snake → Hawk

👉 Energy flow is unidirectional, i.e. it moves in one direction only.

3. पारिस्थितिक तंत्र में ऊर्जा के प्रवाह को दर्शाने वाला रेखा-चित्र बनाइए।

उत्तर:

☀️ सूर्य
   ↓
🌱 उत्पादक (हरे पौधे)
   ↓
🦗 प्राथमिक उपभोक्ता
   ↓
🐸 द्वितीयक उपभोक्ता
   ↓
🐍 तृतीयक उपभोक्ता

उदाहरण:

☀️ सूर्य → 🌿 घास → 🦗 टिड्डा → 🐸 मेंढक → 🐍 साँप → 🦅 बाज

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4. Define a food web. State its significance.

A food web is a network of interconnected food chains in an ecosystem.

Significance:

• Shows different feeding relationships.

• Provides alternative food sources to organisms.

• Makes an ecosystem more stable because organisms can have more than one food source.

4. खाद्य जाल (Food Web) क्या है? इसका महत्व बताइए।

उत्तर:
खाद्य जाल (Food Web) किसी पारिस्थितिक तंत्र में एक-दूसरे से जुड़ी हुई कई खाद्य श्रृंखलाओं का जाल होता है।

महत्व:

1. यह जीवों के बीच भोजन संबंध को दर्शाता है।

2. इसमें किसी जीव के लिए भोजन के कई विकल्प हो सकते हैं।

3. इससे पारिस्थितिक तंत्र अधिक स्थिर और संतुलित रहता है।

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5. What are phytoplanktons?

Phytoplanktons are microscopic, plant-like organisms that float in water and prepare their own food by photosynthesis.

Examples: diatoms and green algae.

They act as producers in aquatic ecosystems.

5. फाइटोप्लवक (Phytoplanktons) क्या होते हैं?

उत्तर:
फाइटोप्लवक पानी में पाए जाने वाले बहुत छोटे पौधे जैसे जीव होते हैं। ये पानी में तैरते रहते हैं और प्रकाश संश्लेषण (Photosynthesis) द्वारा अपना भोजन स्वयं बनाते हैं।

उदाहरण:

• डायटम (Diatoms)

• हरे शैवाल (Green Algae)

🌿 फाइटोप्लवक = पानी में पाए जाने वाले सूक्ष्म पौधे जैसे जीव, जो अपना भोजन स्वयं बनाते हैं।

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6. Name two natural ecosystems.

1. Forest ecosystem

2. Pond ecosystem

Other examples: lake, river, desert, ocean, grassland.

6. दो प्राकृतिक पारिस्थितिक तंत्रों (Natural Ecosystems) के नाम बताइए।

उत्तर:
प्राकृतिक पारिस्थितिक तंत्र के दो उदाहरण हैं:

1. 🌳 वन पारिस्थितिक तंत्र (Forest Ecosystem)

2. 🐟 तालाब पारिस्थितिक तंत्र (Pond Ecosystem)

अन्य उदाहरण:
झील (Lake), नदी (River), रेगिस्तान (Desert), समुद्र (Ocean), घास का मैदान (Grassland) आदि।

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7. What is an ecosystem? List its two main components.

An ecosystem is a functional unit in which living organisms interact with one another and with their physical environment.

Two main components:

1. Biotic components – living organisms such as plants, animals and microorganisms.

2. Abiotic components – non-living factors such as air, water, soil, temperature and sunlight.

7. पारिस्थितिक तंत्र (Ecosystem) क्या है? इसके दो मुख्य घटक बताइए।

उत्तर:
पारिस्थितिक तंत्र वह तंत्र है जिसमें जीवित जीव एक-दूसरे के साथ तथा अपने आसपास के निर्जीव वातावरण के साथ परस्पर क्रिया करते हैं।

इसके दो मुख्य घटक हैं:

घटक	अर्थ और उदाहरण
1. जैविक घटक (Biotic Components)	सभी जीवित चीजें, जैसे पौधे, जानवर और सूक्ष्मजीव।
2. अजैविक घटक (Abiotic Components)	सभी निर्जीव चीजें, जैसे वायु, जल, मिट्टी, तापमान और सूर्य का प्रकाश।

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8. We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain.

A pond or lake is generally a natural ecosystem. It contains producers, consumers and decomposers that maintain natural cycles.

An aquarium is an artificial ecosystem. It has limited organisms and often lack of decomposers and natural nutrient cycles.

Therefore, an aquarium needs regular cleaning and maintenance.

8. हम तालाब या झील को साफ नहीं करते, लेकिन एक्वेरियम को नियमित रूप से साफ करना पड़ता है। समझाइए।

उत्तर:
तालाब और झील प्राकृतिक पारिस्थितिक तंत्र (Natural Ecosystem) हैं। इनमें उत्पादक, उपभोक्ता और अपघटक पाए जाते हैं, जो प्राकृतिक रूप से कचरे को तोड़ने और पोषक तत्वों का चक्र बनाए रखने में मदद करते हैं।

वहीं, एक्वेरियम कृत्रिम पारिस्थितिक तंत्र (Artificial Ecosystem) है। इसमें प्राकृतिक रूप से होने वाली सभी प्रक्रियाएँ पूरी तरह नहीं हो पाती हैं और अपघटकों की संख्या भी सीमित हो सकती है।

इसलिए एक्वेरियम में गंदगी और अपशिष्ट जमा हो जाते हैं, जिसके कारण उसे नियमित रूप से साफ और व्यवस्थित करना पड़ता है।

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9. In the following food chain, 20 J of energy was available to the hawks. How much energy would have been present in plants?

Plants → Rats → Snakes → Hawks

According to the 10% law, only 10% energy is transferred to the next trophic level.

Hawks = 20 J

Snakes = 200 J
Rats = 2,000 J
Plants = 20,000 J

Answer: 20,000 J

10. निम्न खाद्य श्रृंखला में बाज (Hawks) को 20 J ऊर्जा उपलब्ध है। पौधों में कितनी ऊर्जा उपस्थित होगी?

खाद्य श्रृंखला:
🌱 पौधे → 🐀 चूहे → 🐍 साँप → 🦅 बाज

10% नियम (10% Law):
एक पोषण स्तर की केवल 10% ऊर्जा अगले पोषण स्तर तक पहुँचती है।

दिया है:
बाज को ऊर्जा = 20 J

अब पीछे की ओर चलते हैं:

• बाज = 20 J
• साँप = 20 × 10 = 200 J
• चूहे = 200 × 10 = 2,000 J
• पौधे = 2,000 × 10 = 20,000 J

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SHORT ANSWER TYPE QUESTIONS

1. Why are green plants called producers?

Green plants are called producers because they prepare their own food from carbon dioxide and water using sunlight and chlorophyll through photosynthesis.

They also provide food and energy to other organisms.

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2. Name two materials which can be recycled.

Two recyclable materials are:

1. Paper

2. Glass

Other examples: metals, cardboard and some plastics.

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3. What will happen if we kill all the organisms of a trophic level?

Removing all organisms from a trophic level will disturb the food chain and ecosystem.

It may:

• Cause an increase in organisms at the lower trophic level.

• Cause starvation and decline of organisms at the higher trophic level.

• Disturb the balance of the ecosystem.

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4. Why is only 10% energy transferred to the next trophic level?

A large amount of energy is used by organisms for respiration, movement, growth and other life processes. Some energy is also lost as heat.

Therefore, only about 10% of the energy at one trophic level is transferred to the next trophic level.

Important: This is called the 10% law of energy transfer.

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5. Which bag will you prefer for shopping and why?

(a) Jute bag ✅

I would prefer a jute bag because:

• It is biodegradable.

• It can be reused.

• It causes less environmental pollution.

• It is made from a natural fibre.

Polythene is generally non-biodegradable and causes pollution.

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6. Why is the ozone layer important for the existence of life on Earth?

The ozone layer protects living organisms from harmful ultraviolet (UV) radiation coming from the Sun.

Excessive UV radiation can cause:

• Skin damage and cancer.

• Eye damage.

• Harm to plants and other organisms.

Therefore, the ozone layer acts as a protective shield around Earth.

11. पृथ्वी पर जीवन के अस्तित्व के लिए ओजोन परत (Ozone Layer) क्यों महत्वपूर्ण है?

उत्तर:
ओजोन परत सूर्य से आने वाली हानिकारक पराबैंगनी (UV) किरणों को रोकती है। ये किरणें जीव-जंतुओं और पौधों के लिए हानिकारक हो सकती हैं।

अधिक UV किरणों के कारण:

1. त्वचा को नुकसान हो सकता है और त्वचा कैंसर का खतरा बढ़ सकता है।

2. आँखों को नुकसान पहुँच सकता है।

3. पौधों और अन्य जीवों को हानि हो सकती है।

इसलिए, ओजोन परत पृथ्वी के चारों ओर एक सुरक्षात्मक ढाल (Protective Shield) की तरह काम करती है।

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7. What is the role of decomposers in an ecosystem?

Decomposers such as bacteria and fungi break down dead plants, animals and organic waste into simpler substances.

Their importance:

• Recycle nutrients back into the soil.

• Maintain nutrient cycles.

• Help clean the environment.

• Make nutrients available to producers.

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8. Draw an energy pyramid showing different trophic levels.

              Tertiary Consumers
                    /\
                   /  \
                  /____\
            Secondary Consumers
                /        \
               /__________\
             Primary Consumers
            /              \
           /________________\
                 Producers
        /________________________\

Example:

Grass → Grasshopper → Frog → Snake → Hawk

Energy decreases as we move upward.

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9. Differentiate between biodegradable and non-biodegradable waste.

Biodegradable waste	Non-biodegradable waste
Can be decomposed naturally by microorganisms.	Cannot be easily decomposed by microorganisms.
Does not remain in the environment for a very long time.	May remain for a very long time.
Examples: vegetable peels, paper, leaves.	Examples: plastic, glass, synthetic fibres.

12. जैव-अपघटनीय और अजैव-अपघटनीय कचरे में अंतर बताइए।

जैव-अपघटनीय कचरा (Biodegradable Waste)	अजैव-अपघटनीय कचरा (Non-biodegradable Waste)
1. इसे सूक्ष्मजीवों द्वारा प्राकृतिक रूप से आसानी से विघटित किया जा सकता है।	1. इसे सूक्ष्मजीवों द्वारा आसानी से विघटित नहीं किया जा सकता।
2. यह पर्यावरण में बहुत लंबे समय तक नहीं रहता।	2. यह पर्यावरण में बहुत लंबे समय तक रह सकता है।
3. उदाहरण: सब्जियों के छिलके, कागज, पत्तियाँ।	3. उदाहरण: प्लास्टिक, काँच, कृत्रिम रेशे।

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10. How is an ozone molecule formed in the atmosphere?

Under the action of UV radiation, oxygen molecules split into oxygen atoms:

O₂ → O + O

The oxygen atom then combines with an oxygen molecule:

O + O₂ → O₃

Thus, ozone (O₃) is formed.

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11. Define consumers. What are their further divisions?

Consumers are organisms that cannot prepare their own food and depend directly or indirectly on producers for food.

They are mainly divided into:

1. Primary consumers – herbivores
   Example: deer, rabbit, grasshopper

2. Secondary consumers – eat primary consumers
   Example: frog, small fish

3. Tertiary consumers – eat secondary consumers
   Example: snake, eagle

Note: Consumers are also broadly called heterotrophs.

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12. Why is a natural ecosystem more stable than an artificial ecosystem?

A natural ecosystem contains a greater variety of organisms and has natural food chains, food webs, nutrient cycles and decomposers.

It can regulate itself naturally.

Artificial ecosystems require human maintenance, so they are comparatively less stable.

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13. Why are some materials not decomposed by the action of microorganisms?

Some materials have chemical structures that microorganisms cannot easily break down.

Therefore, they remain in the environment for a long time.

Examples: plastics, synthetic fibres and some chemicals.

Such materials are called non-biodegradable materials.

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14. What is a food web? Explain with an example.

A food web is a network of interconnected food chains in an ecosystem.

Example:

             Hawk
            /    \
         Snake   Eagle
          ↑       ↑
       Frog ← Grasshopper
          ↑       ↑
          └── Grass ──┘

In an actual ecosystem, one organism may have several food sources and may be eaten by several organisms. Therefore, several food chains become interconnected to form a food web.

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15. Give any two ways in which non-biodegradable wastes affect the environment.

1. They accumulate in the environment and cause pollution.

2. They can enter food chains and undergo biomagnification, causing harmful effects on organisms.

They may also contaminate soil and water.

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16. How are the components of an ecosystem dependent on each other?

The biotic and abiotic components of an ecosystem are interconnected.

For example:

Sunlight → Plants → Herbivores → Carnivores → Decomposers → Nutrients → Plants

• Plants need sunlight, water, CO₂ and minerals.

• Animals depend on plants or other animals for food.

• Decomposers return nutrients to the environment.

Thus, all components are interdependent.

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LONG ANSWER TYPE QUESTIONS

1. What are different methods for disposal of garbage?

Garbage can be disposed of by several methods:

1. Segregation

Waste should be separated into:

• Biodegradable waste

• Non-biodegradable/recyclable waste

2. Composting

Biodegradable waste such as vegetable peels and leaves can be converted into compost/manure.

3. Recycling

Materials such as paper, glass and metals can be processed and reused.

4. Reuse

Items should be reused whenever possible to reduce waste.

5. Sanitary landfill

Waste that cannot be reused or recycled can be disposed of in properly designed landfills.

6. Incineration

Certain wastes can be destroyed by controlled burning in specially designed facilities.

Best approach:
Refuse → Reduce → Reuse → Recycle → Recover → Dispose safely

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2. What is a food chain? Give its characteristics. Explain how energy flows through different trophic levels.

Definition

A food chain is a sequence of organisms in which one organism is eaten by another, transferring food and energy from one trophic level to the next.

Example:

Grass → Grasshopper → Frog → Snake → Hawk

Characteristics of a food chain

1. It begins with producers.

2. It contains different trophic levels.

3. Each organism depends on another for food.

4. Energy flows in one direction.

5. Energy decreases at successive trophic levels.

6. Generally, a food chain has only a few trophic levels because very little energy reaches higher levels.

Energy flow

Sun
 ↓
Producers
 ↓
Primary Consumers
 ↓
Secondary Consumers
 ↓
Tertiary Consumers

According to the 10% law, only approximately 10% of the energy at one trophic level is transferred to the next level.

For example:

Plants = 10,000 J

↓ 10%

Herbivores = 1,000 J

↓ 10%

Primary carnivores = 100 J

↓ 10%

Top carnivores = 10 J

Therefore, energy decreases at each successive trophic level.

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3. Explain how harmful chemicals enter our body.

Some harmful chemicals, especially non-biodegradable chemicals, enter ecosystems through industrial waste, pesticides and other pollutants.

They may enter the food chain:

Pesticides → Plants → Herbivores → Carnivores → Humans

These chemicals are not easily broken down by microorganisms. As they pass through successive trophic levels, their concentration may increase. This process is called biomagnification.

Example:

Water/Soil
     ↓
   Plants
     ↓
 Herbivores
     ↓
 Carnivores
     ↓
   Humans

Humans are often at a higher trophic level, so harmful chemicals can accumulate in greater concentration in their bodies.

Key term for exam: BIOMAGNIFICATION = increase in concentration of harmful, non-biodegradable chemicals at successive trophic levels.

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⭐ EXAM REVISION: MUST-REMEMBER POINTS

Topic	Key Point
Producers	Make their own food
Consumers	Depend on other organisms
Decomposers	Recycle nutrients
Food chain	Transfer of food and energy
Food web	Interconnected food chains
Energy flow	Unidirectional
10% law	Only about 10% energy passes to next trophic level
Phytoplankton	Aquatic producers
Ozone	O₃
Ozone function	Protects from harmful UV rays
Biodegradable	Decomposed by microorganisms
Non-biodegradable	Not easily decomposed
Biomagnification	Increase of harmful chemical concentration along trophic levels
Ecosystem	Biotic + Abiotic components
Natural ecosystem	More self-sustaining/stable
Artificial ecosystem	Requires human maintenance

2. What will happen if all the phytoplanktons are eliminated from a pond?

Phytoplanktons are producers and form the first trophic level in a pond ecosystem.

If they disappear:

• Zooplanktons will lose their food.

• Small fish will be affected.

• Other organisms will also be affected.

• The food chain will be disrupted.

• Ultimately, the pond ecosystem may collapse.