UGC NTA NET/JRF Exam, Environmental Sciences, June-2021

Total Questions: 41

11. According to the U.S. Department of Agriculture system of classification, the size of silt particles in soil ranges between:

Correct Answer: C. 0.002 to 0.05 mm
Solution:

U.S. Department of Agriculture (USDA) Classification of Soil Particle Size:

TypeDiameter (mm)
Gravel> 2.0
Sand0.05–2
Very Coarse Sand1–2
Coarse Sand0.5–1
Medium Sand0.25–0.5
Fine Sand0.10–0.25
Very Fine Sand0.05–0.10
Silt0.002–0.05
Clay< 0.002

12. Which one among the following has the lowest hydraulic conductivity (m/day)?

Correct Answer: D. Clay
Solution:
Rock TypeHydraulic Conductivity (m/day)
Gravel100–1000
Coarse Sand20–100
Sand Gravel5–100
Fine Sand1–5
Clay0.001–0.01
Fractured or weathered rock0–300
Sandstone0.001–1
ShaleNegligible
LimestoneNegligible

13. At location characterized by latitude ф = 30°, pressure is found to vary by 1.0 mb over a distance of 100 km. If the density of air mass is ~1.25 kg/m³, the geostrophic wind velocity is:

Correct Answer: A. ~11 m/s
Solution:

14. The internal relationship between α, ẞ and γ diversity can be presented as:

×

Correct Answer: E. (*)
Solution:

Alpha diversity describes the species diversity within a community at a small scale or local scale, generally the size of one ecosystem. Beta diversity describes the species diversity between two communities or ecosystems.

Gamma diversity is studied at a very large scale-a biome-where species diversity is compared between many ecosystems. It could range over areas like the entire slope of a mountain, or the entire littoral zone of a sea shore. The internal relationship between α, ẞ and γ diversity can be presented as α × ẞ = γ .

15. The minimum time needed for the formation of one inch of the top soil is:

Correct Answer: С. 100 - 400 years
Solution:

Factors affecting the formation of top soil. When a soil deposits somewhere, it happens as a result of five major factors:
• Climate
• Time
• Topography
• Material
• Activities or organism
All of these factors collectively decide how long will it take for the soil to deposit at a certain location. For example, an area that involves too much human activity will keep eroding. Hence, it will take longer to get deposited.

Time taken for the formation of top 1 inch of soil
• As a result of all of the factors discussed above, the duration for the deposition of top layer of soil cannot be stated clearly.
• However, scientists found out that it takes at least 100 years to deposit top 1 inch of soil.

16. Which zone of a pond/lake ecosystem does not receive light?

Correct Answer: C. Profundal
Solution:The profundal zone is located below the thermocline where the sunlight does not penetrate. Again, the size of this zone depends on the age and water clarity of the pond or lake. The profundal zone typically has lower fish populations because of the lack of oxygen during many parts of the year.

17. "Slash and burn" is a term that is usually associated with the practice of:

Correct Answer: D. Shifting cultivation
Solution:

Slash and burn farming is a form of shifting agriculture where the natural vegetation is cut down and burned as a method of clearing the land for cultivation, and then, when the plot becomes infertile, the farmer moves to a new fresh plat and does the same again. This process is repeated over and over.

18. A species that has profound effect on the еcоlogical processes of an ecosystem and whose removal or loss would result in disturbing the community structure is known as:

Correct Answer: B. Keystone species
Solution:

A keystone species helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether. In any arrangement or community, the "keystone" is considered one of the most vital parts.

In a marine ecosystem, or any type of ecosystem, a keystone species is an organism that helps hold the system together. Without its keystone species, ecosystems would look very different.

19. The flagship species of Kedarnath Wildlife sanctuary is:

Correct Answer: B. Musk Deer
Solution:

This region is the Kedarnath Wildlife Sanctuary which is spread across Chamoli and Rudraprayag districts of Uttarakhand. It is also known as Kedarnath Musk Deer Sanctuary because of the Himalayan Musk deer who form the flagship species of this reserve.

20. The maximum permissible limit of BOD (mg/l) in the treated waste water that can be discharged into garden for watering is:

Correct Answer: B. 30
Solution:

According to standards of Central Pollution Control Board, permissible value of BOD is 30 mg/l and COD is 250 mg/l.