[Mission 2023] STATIC QUIZ, 26 January 2023 – Environment

Solution: b)

The solid portion of the earth on which we live is called the Lithosphere.

The gaseous layers that surround the earth, is the Atmosphere, where oxygen, nitrogen, carbon dioxide and other gases are found.

Water covers a very big area of the earth’s surface and this area is called the Hydrosphere. The Hydrosphere comprises water in all its forms, that is, ice, water and water vapour.

The Biosphere is the narrow zone where we find land, water and air together, which contains all forms of life.

Solution: d)

The nitrogen cycle contains several stages:

1. Nitrification
2. Assimilation
3. Ammonification
4. Denitrification

Nitrification – Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea.

Assimilation – Nitrogen compounds in various forms, such as nitrate, nitrite, ammonia, and ammonium are taken up from soils by plants which are then used in the formation of plant and animal proteins.

Ammonification – When plants and animals die, or when animals emit wastes, the nitrogen in the organic matter re-enters the soil where it is broken down by other microorganisms, known as decomposers. This decomposition produces ammonia which is then available for other biological processes.

Denitrification – Nitrogen makes its way back into the atmosphere through a process called denitrification, in which nitrate (NO3-) is converted back to gaseous nitrogen (N2).

Solution: b)

Ecological succession, the process by which the structure of a biological community evolves over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.

The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community.

Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.

Increased niche development is the characteristic feature of Ecological succession.

Solution: c)

Everything that surrounds or affects an organism during its life time is collectively known as its environment which comprises both living (biotic) and non-living (abiotic) components. The environment is not static. Both biotic and abiotic factors are in a flux and keep changing continuously.

Solution: a)

Introduction of new species into the ecosystem often cause disruption in stability of ecosystem. For ex: Presence of alien species like lantana in tropical deciduous forest has resulted in frequent forest fires.