Our Environment Class 10th Science Gujarat Board Solution

Class 10th Science Gujarat Board Solution

Exercise
Question 1.

Which of the following is an example of biodegradable waste:
A. Vegetables

B. Glass

C. Plastic

D. Metal


Answer:

The wastes that can be degraded by biological processes are called biodegradable wastes. Bio= biological degradable= can be degraded by. Vegetables get broken down and mixed with the soil if they are thrown out as wastes. Thus, they are biodegradable. Glass, plastic or metal remain in same structure and form even after many days of throwing them out. Thus, they are non-biodegradable.


Question 2.

Which of the following is an example of non-biodegradable waste:
A. Fruits

B. vegetables

C. Paper

D. Polythene


Answer:

Polythene cannot be broken down by simple biological processes. Thus, it is a non-biodegradable waste. Fruits, vegetables and paper get easily broken down, and mix with the soil nearby. Thus, they are biodegradable wastes.


Question 3.

Ecosystem is an interacting system made up of:
A. Organisms and their physical surroundings

B. Producers and consumers

C. Producers and their physical surroundings

D. Consumers and their physical surroundings


Answer:

Ecosystem has two components, biotic and abiotic

1. Biotic component consists of living organisms, like human beings, animals, birds, etc. This includes both the producers and the consumers.


2. Abiotic component consists of non-living things, like air, water, soil, etc., which forms the physical surrounding of organisms.


Thus, the ecosystem is an interacting system made up of organisms and their physical surroundings.


Question 4.

The structural and functional unit of the environment is known as:
A. Food chain

B. Food web

C. Ecosystem

D. None of them


Answer:

Ecosystem is the basic part of environment where there is interaction between the biotic and the abiotic components of the environment. It resembles the environment in a miniature form. Therefore, it is the structural and functional unit of environment.

Food chain and food web show the energy flow within an ecosystem. They do not portray the environment as a whole.


Question 5.

First order consumers are:
A. Carnivores

B. Herbivores

C. Decomposers

D. Omnivores


Answer:

Producers are those living organisms which produce energy in the form of food for themselves and other living organisms. Plants are the main producers in the environment.

Consumers are the organisms which cannot produce their own food and depend on other organisms for energy. As herbivores are the animals which eat plants, they depend directly on the producers for their food. Therefore, they are the first order consumers.


Carnivores and omnivores feed on herbivores or other second order consumers for food. Decomposers feed on dated and decaying matter. Thus, they are not the first order consumers.


Question 6.

Omnivorous organisms consume:
A. Only plants

B. Only animals

C. Plants and animals both

D. Microorganisms


Answer:

Omni means 'all' and vores means 'to eat'. Thus, omnivores are those organisms which consume both plants as well as animals.

Only plants are eaten by herbivores and only animals are eaten by carnivores.


Question 7.

Edaphic factors are included in:
A. Abiotic components

B. Biotic components

C. Producers

D. Consumers


Answer:

Edaphic factors are the factors related to soil, such as it’s structure and composition. As soil is a non-living part of the environment, it is included in the abiotic components.

As soil is a non-living entity, it is not included in biotic components, producers and consumers.


Question 8.

How many molecules of ozone can be decomposed by one atom of chlorine?
A. 10,000

B. 1,00,000

C. 1,000,000

D. 1000


Answer:

Addition of chlorine is an important factor in the depletion of ozone layer. Chlorine reacts with ozone and removes one molecule of O at a time, and thus way, one molecule of chlorine reacts with 100,000 molecules of ozone.


Question 9.

The most important compound which accounts for almost 80% for the total depletion of ozone layer is:
A. Chloride ion

B. Sulphur ion

C. Chlorofluorocarbon

D. Magnesium ion


Answer:

Chlorofluorocarbon or CFC are chlorine containing compounds, which account for maximum degradation of the ozone layer. They are used as chemicals in various ways.

E.g. Freon, used in air-conditioners and refrigerators.


The other three options given have ions, and not compounds. So, they cannot be true.


Question 10.

What is an environment?


Answer:

Environment is a system where all organisms, like plants, animals and human beings, interact with their physical surroundings.



Question 11.

Define ecosystem.


Answer:

Ecosystem is a part of environment, where the biotic components are present and interacting with their physical surroundings. It is the structural and functional unit of environment.



Question 12.

Define food chain and food web.


Answer:

As the living organisms depend on each other for their food and energy requirements, they form a chain like arrangement of trophic levels that shows the flow of energy from consumers to producers at different levels. This arrangement is called food chain. A food chain includes organisms from one ecosystem only.

The individual organisms from one ecosystem also depend on organisms from other ecosystems for food and energy interaction. This creates linking of food chains to form a network, called the Food web.



Question 13.

Give examples of solid waste.


Answer:

All the waste materials that are in solid state are called solid waste.

For example: plastic, glass, paper, vegetables, fruits, bones, metal, etc.



Question 14.

What do you mean by biodegradable waste?


Answer:

The waste materials that can be broken down by biological processes, that is they don’t require any help from artificial sources to break down, are called biodegradable wastes.



Question 15.

Give examples of non-biodegradable waste.


Answer:

Examples of non-biodegradable wastes are:

1. Metal wastes


2. Plastic


3. Polythene


4. Glass



Question 16.

How ozone is formed?


Answer:

Ozone layer covers the earth like a blanket, protecting it from the harmful ultraviolet rays of the sun. It is formed in two steps ,

i. Step 1: Photolysis or Photo dissociation.


The oxygen molecule, containing two O atoms, gets broken down or dissociated in the presence of ultraviolet light to give two free O atoms.


ii. Step 2: Fusion of atoms.


The free oxygen atoms, combine with the oxygen molecules to form ozone, containing three atoms of oxygen in one molecule.



Question 17.

Name compounds responsible for depletion of ozone layer.


Answer:

The main factor leading to depletion of ozone layer is addition of chlorine in the atmosphere. This takes place in the form of compounds such as chlorofluorocarbons, which react with the ozone and remove oxygen molecules from it. One such CFC used is Freon, used in refrigerator and air-conditioners.



Question 18.

Describe the types of waste.


Answer:

Wastes are the materials that unwanted or have no use any longer. They can be classified in two ways.

1. Depending on the physical state:


Solid waste- wastes that are solid in state, e.g. paper, glass, etc.


Liquid waste- wastes that are liquid in state.


2. Depending on nature:


Biodegradable wastes- waste that can be degraded by biological processes.


Non-biodegradable waste- wastes that cannot be degraded by biological processes.



Question 19.

Explain the components of an ecosystem.


Answer:

The ecosystem has two components, biotic and abiotic.

•Biotic component- this includes the living organisms like plants, animals, and human beings. The producers and consumers are included in this category.


•Abiotic components – this includes the non-living, physical surroundings of the living organisms, such as air, water , soil, light, temperature, dead and decaying matter, etc. It interacts and supports the biotic components. It is further divide into two parts, (i) climatic factors such as air, water, light, etc.


(ii) Edaphic factors including the structure and composition of soil.



Question 20.

Explain food chain giving suitable example.


Answer:

All living organisms depend on each other for food and energy. The food synthesised by producers, is consumed by the primary consumers, who are in turn consumed by the secondary consumers, and so on. This also shows the flow of energy in an ecosystem. Such an arrangement of different trophic levels, in a linear fashion, indicating the flow of energy is called Food Chain.

Ex :




Question 21.

Explain food web giving suitable example.


Answer:

Food web is an important concept of ecology. It is a graphical representation showing the consumer – resource relationship, interrelationship of different ecosystems and the flow of energy in the environment.

It shows different kinds of feeding pathways, such as herbivory, carnivorous, scavenging, etc. The food web links different food chains, in a mesh like network.



Question 22.

What are the global problems?


Answer:

Global problems are the issues that affect the whole planet at once, and therefore also, the people living on it. They are important and directly affect the mankind. Some of the global problems are:

1. Ozone layer depletion


2. Waste disposal


3. Deforestation


4. Fisheries depletion


5. Ecosystem losses


6. Pollution



Question 23.

How amount of household waste can be reduced?


Answer:

Household waste management can be done by following some very simple, yet good steps. Some of them are:

1. Donate old clothes and shoes instead of throwing them away.


2. Use rechargeable batteries


3. Don’t use disposable pens and razors


4. Don’t buy packed fruits and vegetables


5. Use the back of old notebooks and pages



Question 24.

Explain Food Chain (with figure)


Answer:

All the living organisms require energy in form of food for their survival. For this, they depend on each other. The producers synthesise food in the presence of sunlight and chlorophyll, for themselves as well as for others. First order consumers, which are herbivores, consume the producers to gain energy. They, in turn are consumed by second order consumers, which are carnivorous. Thus, there is a linear arrangement of organisms at different trophic levels, indicating the flow of energy in one ecosystem. This is called a Food Chain.



Question 25.

Explain Food web (with figure)


Answer:

A food web, is a network of more than one food chains, interlinked to each other. It is a graphical representation, showing the flow of energy in the environment and the different kinds of feeding habits, such as herbivory, carnivorous, scavenging, parasitism, etc.

All living organisms are broadly classified into two categories:


•Autotrophs, which synthesise their own food, with the help of energy from sunlight, in the presence of chlorophyll, utilising nutrients and water from soil.



•Heterotrophs, which depend on other organisms, living or dead, for their survival and maintenance of life.


Food web shows consumer-resource relationship, describing the interrelationship of different ecosystems and their roles in the environment.


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