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

The regression coefficient is a statistical measure of the average functional relationship between two or more variables. In regression analysis, one variable is considered as dependent and the other(s) as an independent.

Thus, it measures the degree of dependence of one variable on the other(s). The geometric mean between the two regression coefficients is equal to the coefficient of correlation.

Properties of regression line and correlation coefficient:

Noise exposure can cause two kinds of health effects. These effects are non-auditory effects and auditory effects. Non-auditory effects include stress, related physiological and behavioural effects, and safety concerns.

Auditory effects include hearing impairment resulting from excessive noise exposure. Hearing loss leading to the inability to understand speech in everyday situations can have a severe social effect. It can also affect cognitive performance and decrease attention to tasks.

Isokinetic sampling techniques were developed to prevent skewed particulate concentration measurements due to inertial effects of particles as they enter a sampling nozzle. Basically, the idea is to sample at the same velocity as the gas stream so that the streamlines in the vicinity of the nozzle are straight. Attempts to avoid distorting the size distribution are made through isokinetic sampling, in which

• The sampler inlet velocity is matched with
• The free-stream air velocity, and the sampling probe is aligned parallel to air streamlines.

Walkley-Black Method quantifies the amount of oxidizable organic matter in which OM is oxidized with a known amount of chromate in the presence of sulphuric acid.

The remaining chromate is determined spectrophotometrically at 600 nm wavelength. The calculation of organic carbon is based on organic matter containing 58% carbon.
Equipment required:
• 500-mL Erlenmeyer flasks.
• 10-mL pipette.
• 10- and 20-mL dispensers.
• 50-mL burette.
• Analytical balance.
• Magnetic stirrer.
• Incandescent lamp.
Reagents:
• H₃PO₄, 85%.
• H₂SO₄ concentrated (96%).
• NaF, solid.
• Standard 0.167 M K₂ Cr₂,O₇,: Dissolve 49.04 g of dried (105°C) K₂Cr₂O₇, in water and dilute to 1 L.
• 0.5 M Fe²⁺ solution: Dissolve 196.1 g of Fe(NH₄)₂ (SO₄) • 6H₂O in 800 mL of water containing 20 mL of concentrated H₂SO₄ and dilute to 1 L.The Fe²⁺ in this solution oxidizes slowly on exposure to air so it must be standardized against the dichromate daily.

• Ferroin indicator: Slowly dissolve 3.71 g of o-phenanthroline and 1.74 g of FeSO₄ H₂O in 250 mL of water.

In the respiratory tract, Inertial Impaction is the primary mechanism of deposition for particles >5 µm in diameter and is an important deposition mechanism for particles as small as 2 µm, depending on flow rate.

In the respiratory tract, deposition by Gravitational Sedimentation is most effective for particles in the size range of ~1-8 µm, with larger particles depositing mainly by inertial impaction and smaller particles depositing by Brownian diffusion.

The third main mechanism of deposition in the lung is that of Brownian Diffusion that results from the random motions of the particles caused by their collisions with gas molecules.

Vermicomposting technology using earthworms as versatile natural bioreactors for effective recycling of organic wastes to the soil is an environmentally acceptable means of converting wastes into nutritious composts for crop production.

The chief objective is to compost organic wastes not for the disposal of solid organic wastes but also to produce superior quality manure to feed our "nutrient/ organic matter hungry" soils.

Large volume of organic matter generated from agricultural activities, dairy farms and animal shelters usually dumped in corners emanating foul smell, can be utilized by properly composting it into a value-added end product.

Briefly, when the earthworm consumes organic wastes, the substrate passes through earthworm's gut and gets digested in the intestine of earthworm with the aid of beneficial microbes.

Waste Incineration is an alternative method of waste disposal to landfill. Waste incinerators use the process of combustion to convert the waste materials into carbon dioxide and water. Incineration residues usually consist of small quantities of HCI, S, and other volatile compounds and ash.

However, it is obvious that not all household waste materials are combustible. Reduction of waste volume by 75-95% is achieved with incineration.

Therefore, it should be considered as a means of reducing the amount of waste to be disposed of by landfill rather than a method of ultimate disposal on its own.

Waste Incinerators dispose of the ash by sending it to landfills, which is both costly and takes up physical space.

Eurythermal Organisms are those which can tolerate a wide range of temperatures. Eg: Cow, Human, Monkey, Goats, Sheep.

Stenothermal Organisms are those which can tolerate a narrow range of temperatures. These organisms can be classified into two main groups. Thermophilic: Species which are only able to survive at high temperatures. Eg: Few reptiles, Coral reefs, Fishes. Cryophilic: Stenotherms which can only survive in regions with low temperatures. Eg: Arctic crustaceans, Salmons, Seals.

Cyclomorphosis: The occurrence of seasonal changes in the phenotype of an organism through successive generations.

It occurs in small aquatic invertebrates that reproduce by parthenogenesis and give rise to several generations annually, such as rotifers and cladoceran crustaceans.

Cyclomorphic species of Daphnia, for example, undergo changes in the shape of the head during the year; it is rounded from about midsummer to spring, and thereafter becomes helmet-shaped, reverting to the rounded shape at midsummer.

Also, summer generations tend to be smaller and more transparent than at other times.

Circalunar Rhythm: A biorhythm that corresponds with the lunar cycle (approximately 29.5 days). The reproductive cycles of many organisms, especially marine organisms, are linked to changing levels of moonlight and the tidal cycle, both of which are governed by the phases of the moon.