UGC-NET (NTA) Environmental Sciences, December-2019

Total Questions: 100

1. What is the theoretical maximum fraction of power in the wind that can be extracted by a horizontal axis wind turbine?

Correct Answer: B. ~59%
Solution:

Unfortunately, not all of the power in the wind can be extracted by a wind turbine. This is because some of the kinetic energy is carried downstream of the turbine in order to maintain air flow. This effect imposes a theoretical maximum efficiency of 59% for extracting power from the wind, known as the Betz limit.
The maximum power is generated when downstream of the turbine the wind speed is one-third of the upstream speed u₀ and at the turbine the wind speed is two-third of u₀; i.e.,

2. Given below are two statements, one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): There is a general pattern of increase in biodiversity from equator to poles.
Reason (R) : Due to high level of energy received in tropics, higher is the net primary production, which in turn supports large number of individuals, leading to high biodiversity.
In the light of above two statements, choose the correct options.

Correct Answer: D. (A) is false, but (R) is true.
Solution:

The increase in biological diversity of some groups from the poles toward the equator is one of the most fundamental patterns of life on earth. Currently more than 30 different mechanisms and factors have been proposed and debated to explain the latitudinal gradient in species diversity. Due to high level of energy received in tropics, higher is the net primary production, which in turn supports large number of individuals, leading to high biodiversity. Hence, assertion is false but reason is true.

3. In comparison to its adjoining ecosystems, the biodiversity in the ecotone is:

Correct Answer: B. higher
Solution:

When a project site includes multiple ecosystems, additional consideration must be given to the unique characteristics that occur at the border ("ecotone") of two ecosystems. Ecotones have greater biodiversity than exists in either adjoining ecosystem. Because these edge areas maintain a source of replacements for each adjoining ecosystem, both ecosystems are more resilient to unexpected disturbance. Consequently, the development of designs that create or enhance ecotones is the most commonly available and costeffective avenue to restoration for landscape architects. A typical location for ecotone development is at the cusp between a lawn/ field and woodland border.

4. The ethical view, which argues that any resource of nature is meant for human use/ consumption is termed as:

Correct Answer: B. Utilitarian
Solution:

Economists typically employ Veblen's name in making two kinds of modification to their essentially individualistic and utilitarian model of consumer behaviour. The first, which is more specifically called the Veblen effect, involves recognizing that the price of a commodity is a culturally significant symbol in its own right, and not merely an index of economic worth or utility. The second, which embraces what are called the 'bandwagon' and 'snob' effects, involve recognition of the fact that an individual's consumption of goods is affected by the behaviour of other consumers. Either an individual's demand for goods or services is increased by the fact that others are seen to be consuming them (bandwagon), or decreased by the fact that others are consuming them (snob).

5. Which among the following is the correct sequence of the elements in earth's crust in decreasing order?

Correct Answer: D. Oxygen > Silicon > Aluminium > Iron
Solution:

Given the abundance of oxygen and silicon in the crust, it should not be surprising that the most abundant minerals in the earth's crust are the silicates. Although the Earth's material must have had the same composition as the Sun originally, the present composition of the Sun is quite different. The elemental composition of the human body and life in general is quite different.
These general element abundances are reflected in the composition of igneous rocks.

6. The ability of an ecosystem to recover when the system has been disturbed by any perturbation is known as:

Correct Answer: D. Resilience
Solution:

Discussion of resilience in the literature often involves the related concepts of resistance and robustness. These stability related properties are all concerned with the relationship between an imposed perturbation and a system's response. Resilience has been broadly articulated as a system's ability to recover from disturbance.
As a simple distinction, resilience is concerned with the system's ability to recover its function post-disturbance, while resistance is concerned with the system's ability to maintain its function against a perturbation. In these contexts, resilience (or resistance) denotes the degree to which the quantitative value of any function of interest is recovered to (or maintained at) an initial or reference condition.

7. Match List-I and List-II containing microorganisms and processes associated with them:

List-I (Microorganisms)List-II (Processes)
(a) Bacillus(i) Denitrification
(b) Agrobacterium(ii) Ammonification
(c) Rhizobium(iii) Sulphur into Sulphate
(d) Thiobacillus(iv) N-fixation

Choose the correct answer from the options given below:

(a)(b)(c)(d)
A(i)(iii)(iv)(ii)
B(ii)(iv)(i)(iii)
C(iii)(iv)(ii)(i)
D(ii)(i)(iv)(iii)
Correct Answer: D.
Solution:

(a) Bacillus macerans performs ammonification with the production of ammonia from nitrate
(b) Agrobacterium tumefaciens can grow anaerobically via denitrification.
(c) Rhizobium is the bacteria that live in symbiotic association with the root nodules of the leguminous plants. Fixation of nitrogen cannot be done independently. That is why rhizobium requires a plant host. Rhizobium is a vital source of nitrogen to agricultural soils including those in arid regions. They convert dinitrogen into ammonia. Ammonia, being toxic in nature, is rapidly absorbed into organic compounds.
(d) From all of the SOB, the only group that directly oxidize sulfide to sulfate in abundance of oxygen without accumulating elemental sulfur are the Thiobacilli. The other groups accumulate elemental sulfur, which they may oxidize to sulfate when sulfide is limited or depleted.

8. Which of the following statements in incorrect?

Correct Answer: C. Lowest temperature is found at tropopause.
Solution:

Air is all around us and it extends upwards for many kilometres as the Earth's atmosphere. The atmosphere is commonly described in terms of distinct layers, or regions. The main layers upwards from the Earth's surface are:
Troposphere: Most of the atmosphere is concentrated in this layer, which extends from the surface to an altitude of about 15 km. The temperature decreases rapidly in this region.
Stratosphere: This is a dry layer that lies above the troposphere and extends from 15 km to an altitude of about 50 km. Stratosphere is characterized by an increase in temperature because of the horizontal flow of jet streams. The stratosphere also contains the ozone layer.
Mesosphere: This layer is above the stratosphere in which the temperatures decline with altitude up to 85 km. It is the coldest region of the atmosphere, roughly reaching -85°C.
Thermosphere: This layer lies above the mesosphere. The temperature again rises with the increase in altitude in the thermosphere.
Exposphere: This is the topmost layer of the atmosphere. The density of air is so low here that temperature has no significance. The air in this region is filled with ultraviolet rays and zodiacal lights that are a reflection of the Sun on meteoric dust particles.
Lapse rate: The fall in atmospheric temperature per increase in height. The average lapse rate within the troposphere is about 0.6°C per 100 metres, but the actual lapse rate varies considerably from day to day and from place to place. Lapse rate is some times negative, i.e., temperature increases with height. This is called an inversion Lapse rates determine the vertical stability of the atmosphere

9. Which one among the following is NOT a type of tidal power plant?

Correct Answer: B. Single basin with linked operation
Solution:

Tidal power plants can be broadly classified into the following four categories:
(i) Single-basin single-effect plant
(ii) Single-basin double-effect plant
(iii) Double-basin with linked-basin operation
(iv) Double-basin with paired-basin operation

10. The bioremediation technology which involves the addition of microbial culture is known as:

Correct Answer: B. Bioaugmentation
Solution:

Bioaugmentation is the addition of biocatalysts (generally bacteria, but it also could involve the addition of fungi, genes or enzymes) to degrade target pollutants, either in situ or ex situ. In most commercial applications, bioaugmentation involves the addition of mixed cultures of bacteria that have been derived from natural environments and demonstrated to be capable or rapid biodegradation of problematic contaminants.