Earth and Life On It

This concept mainly deals with the life on Earth and various landforms on Earth.
After reading the concept, students will be able to:

• Explain what is the distance between Earth and Sun.
• Understand the difference between rotation and revolution.
• Explain Earth atmosphere composition and what gases are present in this atmospheric layer.
• Know about different types of landforms on the earth.
• Summarise what is the difference between a mountain and a plateau.
• Know what is a valley and what is a lake.

Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Life on Earth provided in PDF format.

The Earth is the third planet from the Sun in the solar system. It is a huge planet whose surface is mostly covered with water. It belongs to the category of terrestrial planets.

 

Measurement of the Earth:

• Scientists believe that the Earth is not a perfect sphere; rather it resembles an oblate sphere.
• The Earth's total surface area is 509,7000,000 sq. km, out of which 361,300,000 sq. km is covered with water. The surface covered with water makes up 71% of the total surface area of this planet.
• The diameter of the Earth is 12,742 km. If compared to the size of the Sun, then the diameter of the Earth is 109 times smaller than that of the Sun.

 

Distance of the Earth from the Sun:

Motions of the Earth:

The Earth shows two types of motions—Rotation and Revolution.

1. Rotation:
• It denotes the circular movement of the Earth on its axis.
• The Earth takes 24 hours to complete one rotation on its axis. It leads to the occurrence of day and night.
2. Revolution:
• It signifies the circular movement of the Earth around the Sun in a fixed elliptical path called the orbit.
• The Earth takes 365 days, 6 hours and 9 minutes to complete one revolution around the Sun. This duration is considered a year.
• These extra 6 hours yearly combine to add one extra day every fourth year, which is called a leap year and has 366 days.

 

Atmosphere on the Earth:

• The Earth is surrounded by an envelope of a mixture of gases.
• The gases in the air, along with their percentage, are as follows—
• Nitrogen: 71%
• Oxygen: 21%
• Carbon dioxide: 0.03%
• Apart from these, some inert gases, water vapour, dust, smoke, germs, etc. are present in air.
• The presence of life-supporting gases like carbon dioxide and oxygen allows the existence of life on the Earth.
• Plants use carbon dioxide during photosynthesis.
• Other living organisms use oxygen for breathing. Oxygen is also necessary for essential processes like combustion.

Landforms on the Earth:

• The Earth has a variety of landforms due to the significant variation in temperature and climatic conditions across the globe.
• The landmass is divided into different continents, as shown in the image below—

 

• India is a part of Asia, the largest continent on Earth.
• Australia is the smallest continent in the world.
• The continent of Africa is occupied by 54 countries, the highest among all other continents.
• South America is known for its natural wonders. The longest mountain range—the Andes, the highest waterfall—Angel Falls and the driest place— Atacama Desert are located on this continent.

 

The different landforms found on the Earth are discussed below—

1. Mountains and Hills:

2.Plateaus:

3.Valleys:

4.Plains:

5.Deserts:

6.Basins:

7.Oceans and Seas:

• • A large area covered with saltwater is called an ocean. A sea is a part of an ocean which remains fully or partially enclosed by land.
  • 71 % of the Earth is covered with oceans and seas.
  • 70% of the biotic components found on the Earth are aquatic. It means that aquatic plants release 70% of the oxygen found in the atmosphere.
  • Oceans have an average depth of 12,100 feet.
  • Example: The Pacific Ocean is the world’s largest ocean, whereas the Arctic Ocean is the smallest.

 

8.Lakes:

9.Rivers:

Life on the Earth:

• Due to the availability of life-supporting factors, our planet is home to many animal and plant species, including humans.
• The present species found on the Earth have evolved gradually over a long period in which the environmental factors have played a vital role.
• The easiest evolution one would be able to relate is that of humans from the early men to the present Homo sapiens.

 

 New Words

 

Did You Know?

• The Earth rotates around an imaginary line that runs through the north and south poles.
• Imaginary horizontal and vertical lines are running through the surface of the Earth, which are called latitudes and longitudes.

 

• The Equator is a latitude that divides the Earth into two hemispheres—Northern and Southern Hemispheres.
• The heat of the Sun is maximum at the places falling on the Equator.
• The longitude named Prime Meridian divides the Earth vertically into Eastern and Western Hemispheres.