NIOS Class 12 Environmental Science Chapter 1
INTEXT QUESTIONS 1.1
1. Approximately how old is the Earth?
Ans: 4.5 billion years
2. Name the star around which the Earth revolves, along with other planets of the solar system.
Ans: Sun
3. What do you mean by “solar system”?
Ans: A solar system consists of a star in the middle with several planets orbiting around it.
4. Why does the day and night cycle consist of only 24 hours?
Ans: Because Earth completes one full rotation on its axis in 24 hours.
5. If you were to view Earth from space, which colour would Earth reflect?
Ans: From space, the Earth looks like a beautiful, bright, bluish planet because of its blue oceans.
INTEXT QUESTIONS 1.2
1. List the conditions that make Earth a unique planet.
Ans:
- (i) Presence of water
- (ii) Presence of Air
- (iii) Comfortable range of temperature
- (iv) Buffering capacity
2. From where does Earth get energy?
Ans: Sun
3. Why is oxygen essential for life?
Ans: Oxygen is necessary to oxidize food to liberate the energy required for various activities in living
organisms.
INTEXT QUESTIONS 1.3
1. Name the gases that were found in the primitive atmosphere.
Ans: Methane, ammonia, carbon dioxide and hydrogen
2. Which were the earliest organisms that evolved on Earth?
Ans: Bacteria
3. How did oxygen come into atmosphere?
Ans: The chlorophyll-containing bacteria used carbon dioxide and water and released oxygen through photosynthesis, which started accumulating in the atmosphere. Continued photosynthesis by such bacteria progressively accumulated oxygen in the atmosphere.
4. Name the five kingdoms of life
Ans: Monera, Protista, Fungi, Plantae and Animalia
INTEXT QUESTIONS 1.4
1. Define environment.
Ans: The environment may be defined as the surroundings or conditions in which an organism lives or operates. The environment broadly includes living and nonliving components.
2. Name its biotic components.
Ans: Living organisms, including plants, animals, microorganisms (bacteria, fungi, protozoa), and human beings.
3. List its abiotic components.
Ans: Light, climate (humidity and temperature), atmospheric gases, water, substrata (soil, river/sea bed).
4. In a sentence, mention why environmental degradation should be prevented.
Ans: Because it threatens the survival of living organisms, including humans.
TERMINAL EXERCISE
1. Trace the origin of the Earth.
Ans: The Earth broke off about 4.5 billion years ago with an explosion. It was a burning hot white mass of gas and dust. Over a long period of time, dust and gas gradually condensed to form solid rock. The crust of the Earth was formed from the cooling and hardening of the molten matter and hot gases. With the cooling of the Earth, the crust hardened and formed the land. Cooling of the Earth also condensed water vapour into liquid water, filling the depressions to form seas.
2. Describe briefly the solar system to which the Earth belongs.
Ans: A solar system consists of a star in the middle with several planets orbiting around it. The Earth is a part of its solar system. It is one of the eight planets of the solar system that has the sun (a star) at the
center and the eight planets moving around it. Until recently solar system was believed to have nine planets. However, based on the latest scientific assessment, Pluto is no longer regarded as a planet of the solar system.
3. State the Big Bang theory of origin of universe.
Ans: According to the Big Bang theory, the universe started with a huge explosion and matter (dust and gases) filled the entire space. The temperature of the universe then was about a hundred billion degrees Celsius. Scientists believe that the Big Bang occurred about 15 to 20 billion years ago. 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. From the edges of this ball of dust and gas, big blobs or chunks of dust broke off and formed eight ball-shaped planets. This formed our solar system.
4. Why is Earth able to sustain life while no other planet is known to have life?
Ans: In our solar system, Earth is the only planet which is known to sustain life. Only Earth has air and water to support life. Moreover, there is water, atmosphere, ideal temperature, and the buffering capacity of Earth that also helps.
5. Name the five kingdoms of living organisms.
Ans: Monera, Prototictista, Fungi, Plantae and Animalia.
6. Define environment. List the various components of the environment.
Ans: The environment may be defined as the surroundings or conditions in which an organism lives or operates. The environment broadly includes living and nonliving components.
- Biotic components: Living organisms, including plants, animals, microorganisms (bacteria, fungi, protozoa), and human beings.
- Abiotic components: Light, climate (humidity and temperature), atmospheric gases, water, substrata (soil, river/sea bed).
Additional Study Materials
- NIOS Class 12 Environmental Science Syllabus
- NIOS Class 12 Environmental Science Sample Question Paper
