UGC NTA NET/JRF Exam, Environmental Sciences, September-2022

Total Questions: 100

1. The grain size (USDA) of silt in soil ranges between:

A. 0.2 mm to 0.5 mm
B. 0.5 mm to 0.1 mm
C. 0.1 mm to 0.05 mm
D. 0.05 mm to 0.002 mm

Correct Answer: D. 0.05 mm to 0.002 mm

Solution:

2. What will be BOD for a wastewater sample when 21 ml of sample is diluted to 300 ml in BOD bottle to determine dissolved oxygen.

[Given: Initial DO₁ = 10 mg/l; Five days later DO₅ = 5 mg/l]

A. ~ 5 mg/l
B. ~ 25 mg/l
C. ~ 71.4 mg/l
D. ~ 75 mg/l

Correct Answer: C. ~ 71.4 mg/l

Solution:

Biochemical Oxygen Demand (BOD): It is the total amount of oxygen required to oxidize the biodegradable organic matter present in wastewater through microbial utilization of organics.

BOD = (Initial Dissolve Oxygen - Final Dissolve Oxygen) × Dilution Factor

3. What will be the concentration of 40 ppb SO₂ in µg/m³ unit at 25°C?

A. ~0.04 µg/m³
В. ~1047 µg/m³
С. ~104.7 µg/m³
D. ~10.47 µg/m³

Correct Answer: С. ~104.7 µg/m³

Solution:

4. National Ambient air quality standards typically include following components:

A. Maximum and Minimum pollutant levels, adjustment for co-pollutants
B. Abetment strategies, non-attainment penalties
C. Ambient temperature, size distribution and relative humidity
D. Indicator (Chemical/Chemical class), Averaging time, Pollutant form and level

Correct Answer: D. Indicator (Chemical/Chemical class), Averaging time, Pollutant form and level

Solution:

5. Primary air pollutants differ from secondary air pollutants as they:

A. are present in levels that can be weighed on filter paper.
B. are directly emitted from identified sources.
C. have undergone chemical transformation in air after release from identified sources.
D. are designated as hazardous air pollutants.

Correct Answer: B. are directly emitted from identified sources.

Solution:

Primary pollutants and secondary pollutants can be more dangerous. The first are those that are emitted directly from а source, which can be natural (volcanic eruptions or fires, for example) or of anthropogenic origin (carbon monoxide from vehicles). Secondary pollutants, on the other hand, are not emitted directly.

Its origin lies in the interactions between the primary emissions in the atmosphere. One of the most known secondary pollutants is tropospheric ozone.

6. Continuity equation expresses the law of conservation of:

A. Momentum
B. Mass
C. Entropу
D. Energy

Correct Answer: B. Mass

Solution:

7. Which of the following statements correctly represent the environmental wisdom worldwide?

A. Our success depends on how well we manage the earth's life support systems mostly for our benefits.
B. Our success depends on how well we manage the earth's life support systems for our benefit and for the rest of nature.
C. Our success depends on learning how nature sustains itself and integrating such lessons from nature into the ways we think.
D. Our success depends on using environmentally beneficial forms of economic growth and discourage environmentally harmful forms.

Correct Answer: C. Our success depends on learning how nature sustains itself and integrating such lessons from nature into the ways we think.

Solution:

A comparison of environmental worldviews sheds light on the different value orientations employed in economics and management.

Planetary Management:
• We are separate from the rest of Nature and can manage Nature to meet our increasing needs and wants.
• Because of our ingenuity and technology we will not run out of resources.
• The potential for economic growth is essentially unlimited.
• Our success depends on how well we manage Earth's life-support systems, mostly for our benefit.

Stewardship:
• We have an ethical responsibility to be caring managers or stewards of the earth.
• We will probably not run out of resources, but in any case they should not be wasted.
• We should encourage environmentally beneficial forms of economic growth and discourage environmentally harmful forms.
• Our success depends on how well we manage Earth's life-support systems for our benefit and for the rest of nature.

Environmental Wisdom:
• We are part of and totally dependent on Nature and Nature exists for all species. • Resources are limited, should not be wasted, and are not all for us.
• We should encourage Earth-sustaining forms of economic growth and discourage Earth-degrading forms.
• Our success depends on learning how Nature sustains itself and integrating such lessons from Nature into the ways we think and act.

8. Exposure concentration is ________ .

A. the amount of the chemical that is received by the target.
B. the amount of chemical present in the medium with which an Organism has contact.
C. the amount of the chemical that is excreted by the target.
D. the amount of the chemical that is metabolized by the target

Correct Answer: B. the amount of chemical present in the medium with which an Organism has contact.

Solution:

Humans and other organisms can be exposed to substances in different environmental media - air, water, soil, or food - or they may have direct contact with a sample of the substance. The exposure concentration is the amount of a substance present in the medium with which an organism has contact.

The dose is the amount of the chemical that is received by the target (organ). The exposure concentration may differ from the dose owing to biochemical transformations in living organisms.

Suppose, for example, a substance is present in drinking water. The amount of this substance in the water is the exposure concentration.

For many environmental substances, this amount ranges from less than 1 microgram (µg) to greater than 1 milligram (mg), and is usually reported as milligrams or micrograms of the substance present in 1 liter of water (i.e., in mg L⁻¹ or µg L⁻¹).

9. In ecotoxicology studies, ED-50 is ________ .

A. the dose that affects 50% of the population or observed subjects.
B. the dose that affects 95% of the population or observed subjects.
C. the dose that affects 25% of the population or observed subjects.
D. the dose that do not affect 50% of the total population.

Correct Answer: A. the dose that affects 50% of the population or observed subjects.

Solution:

The ED50 (median effective dose) is the dose of a medication that produces a specific effect in 50% of the population that takes that dose.

This number has common use as what a clinician or patient can expect for a drug effect, but clinicians may use a different dosage for their particular intended effect, depending on the balance of need or benefit of the drug versus the toxicity of the drug.

The toxic dose in 50% of the population is called TD50; the ED50 should hopefully be much less than the TD50, as this would indicate an effective medication at a lower dose.

The ED50 for a particular medication derives from a dose-response curve, in which the ED50 is at the dosage (x-axis) where there is 50% of the desired response (y-axis).

The ED50 should be used as a clinical starting point for practitioners when prescribing medications, as adjustments are made to balance efficacy and toxicity. The E-max would be equivalent to the maximum effect the drug may have.

It is important to remember that as dosages increase, the risk for toxicities will increase, and they may not be directly proportionate.

Each patient requires individualized goals of treatment and should be monitored for such to ensure the lowest effective dose possible, especially for longterm treatment.

10. A hypothesis, that predicts a linear relationship in which rate of ecosystem processes is maximum with greatest number of species, is known as:

A. Rivet-popper hypothesis.
B. Redundancy hypothesis.
C. Diversity-stability hypothesis.
D. Idiosyncratic hypothesis.

Correct Answer: C. Diversity-stability hypothesis.

Solution:

Four hypotheses have been proposed to describe the relationship of biodiversity to ecosystem functioning.

(i) Rivet-Popper hypothesis: According to the rivet-popper hypothesis, species in an ecosystem are something like the rivets on an airplane, with each species playing a small but significant role in the working of the whole.

The loss of each rivet weakens the plane by a small but noticeable amount-until it loses airworthiness and crashes. In this view, progressive loss of species steadily damages ecosystem function.

(ii) Redundancy hypothesis: According to the redundancy hypothesis, most species are superfluous - all that matters is that the biomass of primary producers, consumers, decomposers, etc. is maintained and if it is, only a few species are needed to keep the system in motion.

(iii) Diversity-stability hypothesis: It predicts a linear relationship in which rate of ecosystem processes is maximum with greatest number of species.

(iv) Idiosyncratic hypothesis: This hypothesis acknowledges that there may be no pattern or an intermediate relationship between species diversity and ecosystem function.

According to this hypothesis, the contribution of species to function is. unpredictable, since both the identity and order of deletion will affect function differentially.