HBSE 10th Class Science Important Questions Chapter 15 Our Environment

Haryana State Board HBSE 10th Class Science Important Questions Chapter 15 Our Environment Important Questions and Answers.

Haryana Board 10th Class Science Important Questions Chapter 15 Our Environment

Question 1.
What do you mean by environment? State its main components.
Answer:
Environment:

The air, water and land in or on which people, animals and plants live is called environment.
Biotic components such as plants and animals and abiotic components such as air, water, soil, etc. are the two components of environment.

Question 2.
Discuss the types of waste generated in our house.
Answer:
1. Unwanted or unusable items, remains or leftovers or by-products of household garbage together are termed as waste.
2. Waste is generated in our house on a daily basis.
3. These wastes are mainly in two major forms – solids and liquids.
4. It is easier to handle and manage liquid waste in comparison to solid forms.
5. Vegetables and fruits peels, scales, bones, metal wastes, glasses, plastic and polythene, etc. are all solid wastes.

Further, we can divide waste into biodegradable and non-biodegradabie waste:

1. The waste materials, which are broken down to simpler substances by biological processes, are called biodegradable wastes, while those which cannot be broken down to simpler substances are called non-biodegradable wastes.
2. For example, vegetables and fruits are biodegradable, while glass, plastics and polythene, etc. are non-biodegradable.
3. Non-biodegradable materials are inert. They remain in the environment for a long time and cause harm to our environment.

Question 3.
What do you mean by biodegradable and non-biodegradable waste?
Answer:
Further, we can divide waste into biodegradable and non-biodegradable waste:

Question 4.
What is an ecosystem? Explain.
Answer:
1. The biotic system and the physical environment (i.e. the abiotic components) around it together form an interacting system which is called an ecosystem.

2. Thus, an ecosystem consists of biotic components comprising of living organisms and abiotic components comprising physical factors such as temperature, rainfall, wind, soil and minerals.
Example – Garden ecosystem:

3. A garden consists of different plants, such as grasses, trees; flower bearing plants like rose, jasmine, sunflower, etc. It also consists of animals like frogs, insects and birds.

4. All these living organisms interact with each other and their growth, reproduction and other activities are affected by the abiotic components of ecosystem. Thus, garden is an ecosystem.

5. Deserts, forests, sea, ponds and lakes are other examples of natural ecosystems. Gardens, aquarium and crop-fields are man-made (artificial) ecosystems.

6. Every ecosystem merges with another.

Question 5.
State and explain the components of an ecosystem.
Answer:
Each ecosystem consists of two main components – (A) Biotic component and (B) Abiotic component.
(A) Biotic components:

(i) Producers (Autotrophic): Producers are autotrophic. They possess chlorophyll and prepare food for themselves and other organisms as well through the process of photosynthesis.
→ In the terrestrial ecosystem, green plants are producers while in aquatic ecosystem, algae acts as producers.

(ii) Consumers (Heterotrophic): These type of organisms cannot produce food for themselves. Therefore, these organisms consume other organisms or their products as food. These consumers are also called heterotrophic.

The consumers can further be classified into the following four categories:
(a) Herbivores:

The herbivores are also called the first order consumers.
They obtain their food from green plants.

(b) Carnivores:

The carnivores depend upon herbivores and other carnivores animals to obtain their food.
The carnivores, which consume herbivores, are called second order consumers while the carnivores, which consume other carnivorous animals for their food are called third or higher order consumers.

The third category of consumers is the omnivores animals who consume both plants as well as animals as their food.

(d) Decomposers and transformers:

Decomposers are the last type of consumers.
The decomposers obtain their food by decomposing dead bodies of plants and animals.
The decomposers convert complex organic matter into simple organic constituents and then transform these constituents into inorganic ones and consume them as food.

(B) Abiotic components:

All the non-living factors of an ecosystem are called abiotic components.
Temperature, water, light, wind, pH, mineral elements, topography and habitat, are included in abiotic components.

Question 6.
Explain food chain and trophic levels giving suitable examples.
Answer:
1. No living organism is independent.
2. Each organism has to depend on other for its food requirement. Thus, organisms form a chain in which they depend on other for their food. This is termed as food chain.
3. Each step or level of a food chain forms a trophic level.
4. The producers form the first trophic level, the herbivores form the second and the carnivores form the third level.

An example of food chain has been given below :
Grass → Insects Grasshopper → Rats Snakes Hawks

1. A food chain generally starts with primary producers and ends with carnivores.
2. The autotrophs or the producers are at the first trophic level. They produce energy for themselves.
3. The autotrophs are consumed by herbivores i.e. the primary consumers. The carnivores (the secondary consumers) consume herbivores.
4. This way, the producers are at the first trophic level, the primary consumers (herbivores) at second, small carnivores i.e. secondary consumers at the third level and large carnivores or tertiary consumers at the fourth trophic level.

Question 7.
Explain the flow of energy in an ecosystem. OR Flow of energy in an ecosystem is
Answer:
1. Each step or level of a food chain forms a trophic level.
2. The producers i.e. the green plants form the first trophic level. Only they are capable to capture the energy present in the sunlight and convert it into chemical energy. This chemical energy supports all the activities of all the consumers and hence the living world.
3. The energy then moves up to higher level organisms i.e. herbivores.
4. Carnivores eat herbivores.
5. The energy that the green plants capture from the sun is not received back by the sun. Similarly, the energy which is passed to the herbivores does not come back to the autotrophs.
6. Thus, as energy moves from one trophic level to the other, it is no longer available to the previous the other, it is no longer available to the previous level. Here, we can sum up that the flow of energy in an ecosystem is always unidirectional.

Question 8.
Discuss important conclusions that we derive from the flow of energy in the ecosystem.
Answer:
1. The producers i.e. green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert them into food energy.

2. The primary consumers eat green plants to gain energy. When these consumers eat the greens, some amount of energy is used up in digestion and doing physiological and other physical works, some in growth and reproduction and a majority of energy is lost as heat into the environment.

3. On an average only 10% of the food that these consumers eat is used by their bodies and is available for the next level of consumers.

4. From this it is concluded that the value 10 percent can be taken as the average value for the amount of organic matter present at each step and available for the next level of consumers.

5. As seen, a very less amount of energy is available for the next level of consumers in the food chain. Hence, the chain cannot contain several levels. As a result, there are only 3-4 levels in the food chains. The available energy drops drastically after four trophic levels.

6. The producers form the largest number whereas the top level consumers occur in the smallest number.

Question 9.
Explain food web.
Answer:
1. No living organism is independent. Each organism has to depend on other for its food requirement. Thus, organisms form a chain in which they depend on other for their food. This is termed as food chain.
2. The length and complexity of food chains greatly vary.
3. Generally, each organism of a trophic level is eaten by two or more other kinds of organisms which in turn are eaten by several other organisms.
4. Hence, the relationship among individuals in the food chain is not represented by a straight line but as a series of branching lines which together form the food web.
5. For example, both squirrel and grasshopper that are secondary consumers eat plants (i.e. producers). Squirrel is further eaten by eagle, fox as well as dogs.

Question 10.
Explain the concept of biological magnification or biomagnification.
Answer:
1. Pesticides and other chemicals are sprinkled on crops to protect them from diseases or pests.
2. There is no control over the amount of pesticides used. Hence, gradually, with the passage of time, the amount of these chemicals increase in the soil and water bodies.
3. The pesticides then enter the body of plants through soil or water.
4. Later, when herbivores consume these plants, pesticides enter their bodies too; and when carnivores eat affected herbivores, the pesticides enter the bodies of carnivores too.
5. These pesticides and other harmful chemicals are not degradable. So they get accumulated at each trophic level of a food chain.
6. This phenomenon of progressive accumulation of pesticides at each level in a food chain is called biological magnification.
7. Humans occupy the top level of any food chain. Hence, the maximum concentration of these chemicals get accumulated in human bodies.

Question 11.
How is ozone formed? Where is the ozone layer located? How is it useful to us?
Answer:
Formation of ozone:
1. Ozone layer is located at the higher levels of the atmosphere i.e. in stratosphere.
2. Ozone (O₃) is a type of gas. It is formed by three atoms of oxygen.
3. Ozone is formed by the action of ultraviolet (UV) radiation on oxygen (O₂) molecule.
4. The higher energy of UV radiation convert some oxygen (O₂) molecule into free oxygen (O) atoms.

The free oxygen atom (O) then combines with a molecule of oxygen (O₂) and this is how a molecule of ozone O₃ is formed.
O + O₂ → O₃ (Ozone)

Importance:
The ozone layer absorbs harmful ultraviolet rays coming from the sun and protects us.

Question 12.
Give a brief idea of the depletion of the ozone layer.
Answer:
1. The ozone layer in the stratosphere of the earth protects us from harmful radiations of the sun.
2. Unfortunately, this layer is depleting and this is posing a serious problem for our planet.
3. The amount of ozone in the atmosphere began to drop sharply in the 1980s and since then it has been getting worse.
4. The main cause for the ozone depletion is the addition of chlorine (Cf) in the atmosphere.
5. Appliances like AC and refrigerators contain a compound called Chlorofluorocarbon (CFC). Release of chlorine from CFCs during the use of such appliances is the major cause for ozone layer depletion.
6. In 1987, the United Nations Environment Programme (UNEP) successfully got an agreement done to freeze CFC production at the base year level of 1986.

Question 13.
What is household waste? Why should we reduce it?
Answer:
1. Unwanted or unusable items, remains, left over, or by-products of household garbage together are termed as waste.
2. This waste not only occupies a major amount of land where it is thrown but also spreads disease and epidemics.
Hence, we should reduce the amount of waste we produce so that our future generations may lead a quality life.

Question 14.
Differentiate between biodegradable waste and non-biodegradable waste.
Answer:

Biodegradable	Non-biodegradable waste
The wastes, which can be broken down by biological processes, are called biodegradable wastes.	The wastes, which cannot be broken down by biological processes, are called non-biodegradable waste.
These wastes are converted into biodegradable forms by decomposers.	Decomposers cannot convert this waste into simpler forms.
Kitchen wastes such as vegetable and fruit,peels, scales, bones, etc. are biodegradable.	Plastic, polythene bags, glass, etc. are non – biodegradable.

Question 15.
Differentiate between producers and consumers.
Answer:

Producers	Consumers
These organisms are autotrophic.	These organisms are heterotrophic.
Producers make use of sunlight and produce their own food.	Consumers do not produce their own food but remain dependent on others.
Green plants in terrestrial ecosystem and algae in aquatic ecosystem act as producers.	Herbivores carnivores and omnivores are consumers.
Producers are not divided into trophic levels.	Consumers are divided into various trophy levels.

Question 16.
Why is Improper disposal of waste a curse to environment?
Answer:
1. Disposal of waste means ‘to get rid of waste’. If we do not dispose the waste properly, it can harm human health and safety and also pollute the environment.
2. Improper storage or disposal of waste contaminates surface and groundwater.
3. Birds and animals feed on such wastes. This decreases their longevity.
4. Owing to all these reasons we can say that improper disposal of waste is a curse to environment.

Question 17.
Why are crop fields known as artificial ecosystems?
Answer:
1. Ecosystems which are modified and managed by human beings are called artificial ecosystems.
2. In crop-fields, humans themselves grow plants according to the season, types of soil, demand of the crop, etc.
3. In crop fields, humans prepare the soil for farming. They sow the seeds, irrigate the field, control the pests and put the fertilizers.
4. Since, most of the activities of the crop fields are controlled by humans, crop-fields are called artificial ecosystems

Question 18.
Suggest one word for each of the following statements/ definitions
(a) The physical and biological world where we live in
(b) Each level of food chain where transfer of energy takes place
(c) The physical factors like temperature, rainfall, wind and soil of an ecosystem
(d) Organisms which depend on the producers either directly or indirectly for food
Answer:
(a) Environment
(b) Trophic level
(c) Abiotic factors
(d) Consumers (heterotrophs)

Question 19.
Why decomposers and transformers are necessary in environment?
Answer:
Decomposers and transformers:

Decomposers are the last type of consumers.
The decomposers obtain their food by decomposing dead bodies of plants and animals.
The decomposers convert complex organic matter into simple organic constituents and then transform these constituents into inorganic forms and consume them as food.
Hence, decomposers and transformers are needed in the environment.

Question 20.
Why the food chain has only few trophic levels?
Answer:
1. On an average only 10% of the food that the individuals consume is available for the next trophic level. This value is quite less.
2. Naturally, as the trophic level rises the percentage of available energy reduces drastically and so the trophic level cannot continue to several levels.

Question 21.
The food chain generally starts with primary producers and ends with carnivores. Give reason.
Answer:
1. No living organism is independent.
2. Each organism has to depend on other for its food requirement. Thus, organisms form a chain in which they depend on other for their food. This is termed as food chain.
3. Each step or level of a food chain forms a trophic level.
4. The producers form the first trophic level, the herbivores form the second and the carnivores form the third level.
5. Thus, a food chain generally starts with primary producers and ends with carnivores.

Question 22.
How does bio-magnification affect humans?
Answer:
1. When any harmful chemicals such as DDT, BHC, enter in food chain, the concentration of these chemicals increase at every next trophic level. This phenomenon is called bio-magnification.
2. Humans occupy the top level of any food chain. Hence, there is maximum concentration of harmful chemicals in humans. 3. In other words bio-magnification is highest at the human level. Naturally, higher the percentage of chemicals in body, higher the damage to the body.

Question 23.
Use of pesticides and other chemicals should be controlled. Give reason.
Answer:
1. Pesticides or similar chemicals are used on field crops to protect them from pests.
2. This leads to an increase of these chemicals in the soil or water bodies.
3. From soil or water, they enter in the plants and from there to herbivores, carnivores and omnivores.
4. These chemicals are not degradable and hence they get accumulated progressively at each trophic level.
5. These chemicals cause several disease in organisms in a longer run.
6. Consumption of these chemicals may also affect the future generation.
7. As a result, the use of pesticides and other chemicals should be controlled.

Question 24.
Select the mismatched pair in the following and correct it.
(a) Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain
(b) Ecosystem — Biotic components of environment
(c) Aquarium — A man-made ecosystem
(d) Parasites — Organisms which obtain food from other living organisms
Answer:
Statement (b): An ecosystem consist of biotic components (comprising living organisms) and abiotic components (comprising physical factors like temperature etc.) of environment.

Question 25.
How can the amount of household waste be reduced?
Answer:
1. Buy loose fruits and vegetables instead of buying in plastic bags to reduce plastic waste.
2. Avoid usage of disposable items like pens and razors. Instead, use reusable ones.
3. Instead of disposable diapers, reusable nappies should be used for children.
4. Rather than carrying grocery in plastic bags from supermarket, it is advisable to carry reusable bags to the store.
5. Instead of using use-and-throw batteries, people must insist on using rechargeable batteries.
6. Kitchen waste should be filled in bags or containers before disposing it at a proper designated place.

Question 26.
State two advantages of paper bags over plastic bags during shopping.
Answer:
1. Paper bags can be recycled without polluting environment unlike plastic bags,
2. If paper bags are not recycled and they get littered and deposited in the soil, they do not pollute the soil or other environment unlike non-biodegradable plastic bags.

Question 27.
Why is government stressing upon the use of jute/cloth carrying bags?
Answer:
1. Cloth/jute bags are easily biodegradable. Also, they do not cause environmental pollution.
2. Use of cloth bags would reduce the use of harmful non-biodegradable plastic bags.

Question 28.
Write harmful effects of using plastic bags on the environment. Suggest alternatives to plastic bags.
Answer:
Harmful effects of plastic bags:

If plastic bags get deposited in the soil for long, they make the soil barren.
On burning plastic bags, a lot of toxic gases get released in the atmosphere.

Alternatives to plastic bags: Using jute/cloth bags.

Very Short Answer Type Question:

Question 1.
Define environment.
Answer:
The air, water and land in or on which people, animals and plants live is called environment.

Question 2.
What are biotic components?
Answer:
Living things which form an important component of an ecosystem are called biotic components. For example, animals, plants, fungi and bacteria.

Question 3.
What do you mean by abiotic components?
Answer:
Non-living things that influence the ecosystem are called abiotic components. For example, temperature, wind, humidity, soil, minerals, etc.

Question 4.
What is waste (household)?
Answer:
Unwanted or unusable items remains or left over or by-products of household garbage together are termed as waste.

Question 5.
Define biodegradable waste (or items).
Answer:
The waste (or items) that can be converted into simpler substances without causing harm to the environment is called biodegradable waste. For example, vegetable and fruit peel, newspaper, etc.

Question 6.
Define non-biodegradable waste.
Answer:
Those substances which cannot be converted into simple substances by biological processes are called non-biodegradable waste. For example, plastic, glass, etc.

Question 7.
What is ecosystem?
Answer:
The biotic system and the physical environment around it (i.e. the abiotic components) together form an interacting system called an ecosystem.

Question 8.
Give examples of any two types of ecosystem along with their examples.
Answer:
(i) Terrestrial ecosystem: Forest, grass land and deserts,
(ii) Marine ecosystem: Lake, pond, river, etc.

Question 9.
Give examples of two man-made ecosystem.
Answer:
Garden, aquarium, crop-field, etc. are man-made ecosystems.

Question 10.
What is trophic level?
Answer:
A trophic level is the group of organisms within an ecosystem which occupy the same level in a food chain. For example, herbivores.

Question 11.
Raju’s mother brought an aquarium for him. Raju who is very fond of it later added two carnivorous fishes to it. Do you think Raju did a good job?
Answer:
No. By adding carnivorous fish to the aquarium, Raju is threatening its ecosystem. The carnivores fishes would eat the herbivores and the aquarium ecosystem would soon collapse.

Question 12.
State the role of decomposers.
Answer:
Decomposers are the last type of consumers. They convert complex organic matter into simpler forms.

Question 13.
Why is aquarium known as an artificial ecosystem?
Answer:
Humans build aquarium by putting plants, fishes and other small living organisms. Water, sand, light, etc. are also made available by the humans. Together all these components form a food chain and hence an ecosystem.

Question 14.
Define food chain.
Answer:
Living organisms of an ecosystem depend on each other for their food requirement and form a chain which is known as food chain.

Question 15.
Define food web.
Answer:
The network of interconnected food chains functioning in an ecosystem is called food web.

Question 16.
In a food chain comprising of frogs, insects, birds and grass, which organism is likely to have maximum concentration of harmful non- biodegradable chemicals in its body?
Answer:
In this food chain, birds exist at the top most trophic level. Hence, birds will have maximum concentration of harmful non-biodegradable chemicals in their body.

Question 17.
Why there are only few trophic levels in a food chain?
Answer:
Very less amount of usable energy is available as food to the next trophic level individuals. Hence, there cannot be several trophic levels in a food chain.

Question 18.
Why a food chain is not shown as a branched chain but as a web?
Answer:
In a food chain, generally each organism is eaten by two or more other types of organisms which in turn are eaten by several other organisms. As a result, the chain cannot be represented as a linear chain but as a series of branching lines known as food web.

Question 19.
In a food chain consisting of snake, insect, grass and frog, assign an appropriate trophic level to frog.
Answer:
Grass → Insect → Frog → Snake. Frog occupies 3rd trophic level.

Question 20.
In the food chain given below, which of the organism will have –
(i) Maximum available energy?
(ii) Maximum concentration of pesticides?
Phytoplankton → Zooplankton → Fish → fish eating birds.
Answer:
(i) Phytoplankton
(ii) Fish eating birds

Question 21.
Observe the food chain –
Plant (1000kJ)→ Goat → Lion
(a) If autotrophs occupying the first trophic level are called produces, what are herbivores called as?
(b) How much energy does the lion get in above food chain?
Answer:
(a) Primary consumer, (b) 10 kJ

Question 22.
In the following food chain, grass provides 4000 J energy to the grasshopper. How much energy will be available to snakes and frogs? Grass, Grasshopper, Frogs, Snakes
Answer:
As per 10% law of energy through trophic level. Frogs will get 400 J and snakes 40 J of energy.

Question 23.
Write the appropriate names of the trophic levels Z and X in the figure given below:
Answer:

Question 24.
State the scientific term used for progressive accumulation of harmful chemicals at each trophic level of food chain.
Answer:
Biological magnification

Question 25.
What is biological magnification?
Answer:
When harmful chemicals and pesticides such as DDT, BHC, etc. enter in the food chain, their concentration increases with each trophic level. This phenomenon is called biological magnification.

Question 26.
State a way to prevent accumulation of harmful chemicals in our bodies.
Answer:
One of the ways is to eat vegetarian food. By doing so, chemicals entered in animals in concentrated form will not enter into our bodies.

Question 27.
Why is food chain having two steps most advantageous in terms of energy?
Answer:
As the trophic level increases, the amount of energy available for the consumers decreases. In a two- step food chain maximum energy will be transferred from producers (plants) to primary consumers.

Question 28.
What is ozone?
Answer:
Ozone (O₃) is a gaseous molecule formed by three atoms of oxygen. It is a deadly poisonous gas.

Fill in the blanks:

1. The main components of ecosystem are …………….
Answer: Biotic and ablotic

2. Abiotic components can be divided into ……….. categories.
Answer: Two

3. ………. wastes are easier to handle and manage.
Answer: Liquid

4. The waste materials which are broken down easily are called ………… wastes.
Answer: Biodegradable

5. Biodegradable waste is broken down by ………… process.
Answer: Biological

6. The biotic community together with the physical environment forms an interacting system, which is called, the ……………
Answer: Ecosystem

7. Terrestrial ecosystem : Green plants; Aquatic ecosystem …………….
Answer: Algae

8. …………….. are called first order consumers.
Answer: Herbivores

9. Freshwater ecosystem and marine ecosystem are a part of ……………… ecosystem.
Answer: Aquatic

10. Forest, grasslands and deserts are included in ………….. ecosystems.
Answer: Terrestrial

11. Consumers can be sub-divided into …………. categories.
Answer: Four

12. ……….. converts complex organic matter into simple organic constituents.
Answer:
Decomposers

13. …………. forms the third trophic level of a food chain.
Answer: Carnivores

14. The flow of energy in an ecosystem is in ………. direction(s).
Answer: One

15. One needs to clean an aquarium in regular interval because ……………………..
Answer:
It does not have sufficient number of decomposers to decomposers the waste generated in the aquarium.

16. The green plants capture about energy of sunlight.
Answer: 1%

17. As per the law of energy percent energy is available to a trophic level after producers.
Answer: 10

18. ………………………… out of rat, peacock, wheat grains and snakes will have maximum concentration of harmful chemicals.
Answer: Peacock

19. Ozone layer is located in the ……………….
Answer: Stratosphere

20. The depletion of the ozone layer was first noticed around the year ……………..
Answer: 1980

21. When chlorine reacts with ozone, it removes an atom of ………….. one by one.
Answer: 0

22. The compound that depletes the ozone layer is ………….
Answer: Chlorofluorocarbon (CFC)

True Or False:

1. Producers are autotrophic. — True
2. At the end each ecosystem merges with the other. — True
3. Each ecosystem has mainly three components. — False
4. Scales and bones are biodegradable waste. — True
5. Consumers are heterotrophic. — True
6. Decomposers convert simple organic constituents into organic constituents. — False
7. Lower the trophic level, higher the organisms. — False
8. Biological magnification is highest at decomposors level. — False
9. Carnivores can be called secondary consumers as well as tertiary consumers. — True
10. Herbivores form the first trophic level of a food chain. — False
11. Ozone layers protect us from infrared radiation. — False
12. The main factor responsib’e for the depletion of ozone layer is the addition of Cl^– ions in atmosphere. — True
13. Full form of UNEP is United Nations Ecological Programme. — False
14. The UNEP succeeded in forging an agreement to freeze CFC production at levels. — 1986

Haryana Board 10th Class Science Important Questions Chapter 15 Our Environment

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