Class 8 Science

Conservation of Plants & Animals

NCERT Solution

Part 1

Fill in the blanks:

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

Answer: (1) Protected Area, (2) Endemic species, (3) in climate

Discuss the effects of deforestation on the following:

(a) Wild animals

Answer: Wild animals lose their natural habitat and have to suffer from shortage of food.

(b) Environment

Answer: Environment undergoes degradation as a result of deforestation.

(c) Villages (Rural areas)

Answer: People in rural areas don't get forest produce which are integral to their life. Deforestation can cause flood or drought which can play havoc with farm productivity.

(d) Cities (Urban areas)

Answer: People in urban areas may not get many products for which raw materials come from forests. Reduction in farm output results in price rise of food items.

(e) Earth

Answer: Earth suffers from environmental damage and global warming.

(f) The next generation

Answer: The next generation may not get many important natural resources. It may not get to see the beauty of many wild animals.

What will happen if:

(a) We go on cutting trees.

Answer: Mindless cutting of trees will result in deforestation. This will result in various kinds of damage to the environment. It will result in global warming, increased cases of floods and droughts. It will also result in many wild animals getting wiped off the earth.

(b) The habitat of an animal is disturbed.

Answer: Wild animals will suffer from shortage of habitat and food. Many wild animals would enter human settlements in search of food. Instances of clash between humans and wild animals will be on rise.

(c) The top layer of soil is exposed.

Answer: Soil will become deficient in humus and important nutrients. In the long run, the soil will become infertile. The whole area would become a desert in due course of time.

Differentiate between the following:

(a) Wildlife sanctuary and biosphere reserve

Answer: A wildlife sanctuary is an area where wild animals are protected from human interference. A wildlife sanctuary is a part of a biosphere reserve. A biosphere reserve encompasses a larger area and is also aimed at facilitating smooth life for people living in or around that area.

(b) Zoo and wildlife sanctuary

Answer: A zoo is an artificial enclosure where wild animals are kept, whereas a wildlife sanctuary is a natural area where wild animals are given protection.

(c) Endangered and extinct species

Answer: Endangered species still exist on the earth but are at risk of getting extinct. Extinct species no longer exist on the earth.

(d) Flora and fauna

Answer: Plants comprise the flora while animals comprise the fauna of a given area.


Crop Production

The science of farming is called agriculture. Farming includes cultivation of plants and rearing of animals for food and other beneficial items.

Microorganisms: Friend or Foe

An organism which cannot be seen by naked eyes is called microorganism or microbe. We need a microscope to see a microbe.

Synthetic Fibres

ibres which are man-made are called synthetic fibres, e.g. nylon, acrylic, etc. A synthetic fibre is made of multiple units of a chemical substance.

Metals Non-metals

Metals are lustrous, sonorous, ductile, and are good conductor of heat and electricity.

Coal & Petroleum

Resources which from nature are called natural resources. Examples: coal, petroleum, air, water, soil, etc.

Combustion & Flame

Combustion is a chemical process in which a substance reacts with oxygen to give off heat. Some substances may also give light along with heat during combustion.

Conservation of Plants and Animals

The part of the earth where all living organisms are present is called biosphere. Biosphere is the narrow zone between hydrosphere, troposphere and atmosphere.

Cell: The Fundamental Unit of Life

The basic structural unit of a living organism is called cell. All living beings are made up of cells.

Reproduction in Animals

The process by which an organism produces its offspring is called reproduction. Reproduction is necessary to continue the lineage of an organism.

Reaching the Age of Adolescence

Adolescence is the period of life when many changes take place in the body, leading to reproductive maturity. Adolescence begins at around 10 years of age and lasts till 18 or 19 years of age.

Force & Pressure

A push or pull on an object is called force. Pressure is the force acting on a unit area on an object.

Friction

When one surface is moving over another surface, a force comes into play and opposes their relative motion. This force is called friction or force of friction.

Sound

Sound is a kind of wave which gives us the sense of hearing. Sound is produced by a vibrating body.

Chemical Effects of Electric Current

When electric current is passed through a conducing solution, some chemical reaction takes place in the solution. This is called chemical effect of electric current.

Natural Phenomena

Transfer of charge from one object to another is called charging. The process of transfer of charge to the earth is called earthing.

Light

When light falls on a shiny surface, most of it bounces back. This phenomenon is called reflection of light.

Solar System

The solar system is made up of the sun, its planets, satellites, asteroids, comets, dwarf planets, etc. All other members of the solar system keep on revolving around the sun.

Pollution

When air is contaminated with unwanted substances and becomes harmful for the living and non-living, this is called air pollution.