EVS_Ch1_Intex

EVS_Ch1_Intex

Approximately how old is the earth?

4.5 billion years

Name the star around which the earth revolves along with other planets of the solar system.

SUN / star

What do you mean by “solar system”?

Planets orbiting central star

Why does the day and night cycle consist of only 24 hours?

Because earth completes one full rotations on its axis in 24 hours

If you were to view earth from space, which colour would earth reflect?

Blue

List the conditions that make earth a unique planet.

(i) Presence of water

(ii) Presence of Air

(iii) Comfortable range of temperature

(iv) Buffering capacity

From where earth gets energy?

Sun

Why oxygen is essential for life?

Oxygen is used in respiration to oxidize food for liberating energy

Name the gases that were found in the primitive atmosphere

Methane, ammonia, carbon dioxide and hydrogen

Which were the earliest organisms that evolved on earth?

Bacteria

How did oxygen come into atmosphere?

Because of photosynthesis

Name the five kingdoms of life

Monera,

Protista,

Fungi,

Plantae

Animalia

Define environment.

Surroundings or condition in which an organism lives and operates.

Name its biotic components.

Biotic- living organism of all kinds including microbes.

List its abiotic components.

Abiotic – light, humidity temperature, atmosphere and substratum

In a sentence, mention why environmental degradation should be prevented.

Because it threatens the survival of living organisms including humans.

State the big bang theory of origin of universe.

According to this theory, universe started with a huge explosion and matter (dust and gases) filled the entire space. The temperature of the universe then, was about hundred billion degrees Celsius

The huge collection of dust and gases then began to spin. As it spun faster and faster, the centre became very hot. It became the Sun.