Question

1.When we breathe in air, nitrogen also goes inside along with oxygen. What is the fate of nitrogen?

(1 Point)

(a) It moves along with oxygen into the cells

(b) It comes out with the CO2 during exhalation

(c) It is absorbed only by the nasal cells

(d) Nitrogen concentration is already more in the cells so it is not at all absorbed.

2.Top-soil contains the following

(1 Point)

(a) Humus and living organisms only

(b) Humus and soil particles only

(c) Humus, living organisms and plants

(d) Humus, living organisms and soil particles.

3.Choose the correct sequences

(1 Point)

(a) CO2 in atmosphere → decomposers → organic carbon in animals → organic carbon in plants

(b) CO2 in atmosphere → organic carbon in plants → organic carbon in animals → inorganic carbon in soil

(c) Inorganic carbonates in water → organic carbon in plants → organic carbon in animals → scavengers

(d) Organic carbon in animals → decomposers → CO2 in atmosphere → organic carbon in plants

4.Major source of mineral in soil is the

(1 Point)

(a) parent rock from which soil is formed

(b) plants

(c) animals

(d) bacteria

5.Total earth’s surface covered by water is

(1 Point)

(a) 75%

(b) 60%

(c) 85%

(d) 50%

6.Biotic component of biosphere is not constituted by

(1 Point)

(a) producers

(b) consumers

(c) decomposer

(d) air

7.An increase in carbon dioxide content in the atmosphere would not cause

(1 Point)

(a) more heat to be retained by the environment

(b) increase in photosynthesis in plants

(c) global warming

(d) abundance of desert plants

8.Oxygen is returned to the atmosphere mainly by

(1 Point)

(a) burning of fossil fuel

(b) respiration

(c) photosynthesis

(d) fungi

9.Low visibility during cold weather is due to

(1 Point)

(a) formation of fossil fuel

(b) unburnt carbon particles or hydrocarbons suspended in air

(c) lack of adequate power supply

(d) none of these

10.Growth of Lichens on barren rocks is followed by the growth of

(1 Point)

(a) moss

(b) ferns

(c) gymnosperms

(d) algae

11.Marked temperature changes in aquatic environment can affect

(1 Point)

(a) breeding of animals

(b) more growth of aquatic plants

(c) process of digestion in animals

(d) availability of nutrients.

12.Soil erosion can be prevented by

(1 Point)

(a) raising forests

(b) deforestation

(c) excessive use of fertilizer

(d) overgrazing by animals

13.What happens when rain falls on soil without vegetational cover?

(1 Point)

(a) Rainwater percolates in soil efficiently

(b) Rainwater causes loss of surface soil

c) Rainwater leads to fertility of the soil

(d) Rainwater does not cause any change in soil

14.Oxygen is harmful for

(1 Point)

(a) ferns

(b) nitrogen-fixing bacteria

(c) chara

(d) mango tree

15.The nitrogen molecules present in air can be converted into nitrates and nitrites by

(1 Point)

(a) a biological process of nitrogen-fixing bacteria present in soil

(b) a biological process of carbon fixing factor present in soil

(c) any of the industries manufacturing nitrogenous compound
plz help​

Answer 1

Answer:

1. (b) It comes out with the CO2 during exhalation
2. (d) Humus, living organisms, and soil particles.
3. (d) Organic carbon in animals → decomposers → CO2 in atmosphere → organic carbon in plants
4. (a) parent rock from which soil is formed
5. (a) 75%
6. (d) air
7. (b) increase in photosynthesis in plants
8. (c) photosynthesis
9. (b) unburnt carbon particles or hydrocarbons suspended in the air
10. (d) algae
11. (a) breeding of animals
12. (a) raising forests
13. (b) Rainwater causes loss of surface soil
14. (b) nitrogen-fixing bacteria
15. (c) any of the industries manufacturing nitrogenous compound