NCERT Solutions For Class 8 Science Chapter – 7

NCERT Solutions For Class 8 Science Chapter – 7 Conservation of Plants and Animals

Q1. Fill in the blanks.

A place where animals are protected in their natural habitat is called ______.
Species found only in a particular area is known as ______.
Migratory birds fly to faraway places because of ________ changes

Answer:-

A place where animals are protected in their natural habitat is called Sanctuary.
Species found only in a particular area is known as endemic.
Migratory birds fly to faraway places because of climatic changes.

Q2. Differentiate between the following.

Wildlife sanctuary and biosphere reserve
Zoo ad wildlife sanctuary
Endangered and Extinct species
Flora and fauna

Answer:-

Wild sanctuary	Biosphere Reserve
An area within which wild animals are protected from external dangers like hunting	An area constructed for the conservation of biodiversity
Adequate habitat and protection are provided for the wild animals living in a sanctuary.	Several life forms like plants, animals, and micro – organisms conservation are possible in reserve
Eg: Corbett national park	Eg: Nilgiri Biosphere reserve

Zoo	Wildlife sanctuary
Animals are kept in artificially constructed facilities for public exhibition.	An area within which wild animals are protected from external dangers like hunting.
It is an artificial habitat and the animals may oy may not adopt to the new condition	The animals are conserved within their natural habitat itself. So, they won’t have a problem with their surroundings.

Endangered Species	Extinct Species
The species which are n the verge of extinction are called as Endangered species.	The species of animals or plants that no longer exist are called Extinct species.
Eg: Bengal Tiger, Blue Whale, etc.	Eg: Caribbean monk seal, Great Auk , Passenger pigeon.

Flora

Fauna

It is the collective name for the plant life form a particular area.

It is the collective name for the animal life form a particular area

Eg: Spurge and Hogweed from the Nilgiris region

Eg: Langur , Tiger , Tahr the Nigiris region.

Q3. Discuss the effects of deforestation on the following.

Wild animals
Environment
Villages
Earth
The next generation

Answer:-

Effects of deforestation on wild animals: Removal of trees and plant life from a particular area for the constructions of industries agriculture or for other such purposes is termed as Deforestation. Plantlife forms an integral part of the that ecosystem. Destroying the plant life will ultimately threaten the existence of animals in that particular ecosystem and may lead to their extinction.

Effects of deforestation on the environment: In plants, Photosynthesis takes place by the absorption of CO₂from the earth’s atmosphere. The percentage of CO₂ in the atmosphere increases rapidly if the plant life of an ares is destroyed. Increased concentrations of CO₂ result in the trapping of excessive heat radiations within the Earth’s atmosphere contributing a global warming . This results in the rise of the temperature of the Earth and disturbs the water cycle which occurs in nature. Hence, rainfall pattern changes leading to droughts and floods.

Effects of deforestation on villages: The soil particles are held together in a place by the roots of the plants , trees and other vegetation. In the event of water flow or a high – speed wind over the top layer of the soil, the soil particles get removed easily as there are no plants to hold it in place. Thus, soil erosion is increased by deforestation activities. Soil loses fertility and loses humus Hence, a fertile land, fit for agriculture turns into a desert.

Effects of deforestation on cities: The risk of natural calamities like floods and drought in urban areas is increased by deforestation It will also lead to global warming because of increased C0₂levels in the atmosphere. This is a result of continuous pollution from automobiles and industries. The water cycle in the vicinity is also affected.

Effects on deforestation on Earth: Deforestation leads to increased chance and occurrences of desertification, drought and floods. Carbon Dioxide level in the earth’s atmosphere also increases which leads to global warming. The water cycle is disrupted and there is also an increased risk of natural calamities.

Effects of deforestation on the next generation: Our environment is slowly changed by the activities of deforestation, both directly and indirectly . Soil erosion , global warming desertification , drought, green house effect, floods and many other problems are caused only because of deforestation . Ultimately the next generation will be facing the consequences of deforestation.

Q4. What will happen if

We go on cutting trees
The habitat of an animal is disturbed
The top layer of soil is exposed

Answer:-

If we go on cutting the trees : If we go on cutting trees , the animals will lose their natural habitat as an essential part of their ecosystem are destroyed. This reduces the biodiversity of the affected areas. The temperature of the Earth also increases and gives way to global warming. Global warming , in turn , affects the water cycle. Hence, rainfall pattern changes leading to droughts and floods. Risks of soil erosion, global warming , desertification, greenhouse effect increases.

If the habitat of an animal is disturbed

All the basic necessities for an animal , like food , water , shelter and protection is provided by the habitat in which the animal lives – in disturbing the habitat of the animal forces it move to another place in search of food, water, shelter and protection. The animal, in due course, may get killed by other animals.

(c ) If top layer of the soil is removed

Removing the top layer of the soil gradually exposes the lower layers of the soil are hard and rocky in nature and are less fertile . This is because of the reduced quantity of humus. Soil erosion on a continued basis will turn it barren and infertile.

Q5. Answer in brief.

Why should we conserve biodiversity ?
Protected forests are also not completely safe for wild animals. Why ?
Some tribal depend on the jungle. How ?
What are the causes and consequences of deforestation?
What is Red Data Book?
What do you understand by the term migration ?

Answer:-

The number and variety of various life forms such as plants , animals and micro – organisms in the area are called Biodiversity. Both plants and animal have a mutual dependence of one will automatically destroy the other. Hence, biodiversity has to be conserved in order to maintain nature’s balance.

People who live near the forests depend on the resources of the forests in order to fulfill their day – to – day needs. Therefore, it is not safe for animals living in protected forests. The animals would be threatened by the presence of the human population This results in the killing of wild animals and selling their products for huge sums of money.

The forests provide food, fodder and other resources to the tribal people. It is inevitable for them to depend on forests and their resources for everyday needs.

Causes of deforestation:

There are a lot of causes for deforestation . A few of them are listed below.

In order to accommodate the ever – expanding urban population, forests areas are often cleared and converted into lands for various uses.

For agricultural activities like crop cultivation and cattle grazing , forest lands are cleared.

Firewood is a major product from the forests and it is one of the main reasons for cutting the trees on a large scales.

Consequences of deforestation:

There are a lot of fatal consequences caused by deforestation . A few of them are listed below.

Soil erosion
Loss of Biodiversity.
Floods
Droughts
Global warming as a result of climate change
Disruption of the water cycle.

( e ) Red Data Book is basically a sourcebook which has an international list of all plant and animal species which are endangered , that is on the verge of extinction.The International Union for Conservation of Nature and Natural resource (IUCN) maintains the books and adds/ removes the names of the species by conducting a comprehensive survey.

( f ) The movement of an organisms or a group of organisms from its natural habitat to another place on a standard basis at a particular time of each and every year is known as migration . The organisms do so in order to avoid uninhabitable conditions of climate or for the process of breeding.

Q6. In order to to meet the ever – increasing demand in factories and for shelter , trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.

Answer:-

It is not justified to cut trees just to fulfill our needs. Trees are known as ‘the lung of the earth’. They are the habitat of many living organisms including animals. They give us oxygen, and maintain the O₂ – CO₂ balances as well. They firmly bind the soil and hence prevent soil erosion. They also reduce the chances of natural disasters like floods and droughts . They help conserve our rich biodiversity. The cutting of tree causes an increases in the carbon dioxide (CO₂) level, which results in global warming . Moreover , it causes soil erosion, flood, the greenhouse effect, etc Hence tree must be protected.

Q7. How can you contribute to the maintenance of green wealth of your locality ? Make a list of actions to be taken by you.

Answer:-

By taking up of the following actions, I can contribute to the maintenance of green wealth of my locality by:

Planting saplings and tees.
Not throwing the garbage on the streets.
Forbidding others to cut trees.
Making people aware of the significance of a clean and green environment.
Watering the plants regularly and taking proper care of them.
Reusing and recycling paper to save trees, energy and water.

Q8. Explain how deforestation leads to reduced rainfall.

Answer:-

Trees give out a huge amount of water in the form of water vapour during transpiration The reduction of water vapour affects cloud formation and thus, results n less rainfall.

Q9. Find out the national parks in your state. Identify and show their locations on the outline map of india

Answer:-

Periyar National park Kerala in Map

Q10. Why should paper be saved? Prepare a list of ways by which you can save paper.

Answer:-

A large numbers of trees can be saved by saving paper. This will also save water that is used to manufacture paper. Moreover, the harmful chemicals used in paper making will show their least effects on human beings and other organisms.

Some way to save paper are the following: