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

Gel filtration (GF) chromatography separates proteins solely on the basis of molecular size.

Separation is achieved using a porous matrix to which the molecules, for steric reasons, have different degrees of access-i.e., smaller molecules have greater access and larger molecules are excluded from the matrix.

Hence, proteins are eluted from the GF column in decreasing order of size. This unit describes the experimental theory behind gel filtration and contains many useful tables listing the properties and characteristics of currently available matrices.

The Most Probable Number (MPN) technique is used to detect the number of microorganisms from foods, especially when the number of microorganisms is less than 10 g or mL of sample. Foods of different quantities (e.g., 100, 10 or 1 g or mL) can be used in the MPN technique.

The geothermal gradient is defined as the increase in temperature with depth in the Earth. In normal continental crust a typical geothermal gradient within the first 3 to 5 kilometers (2 or 3 miles) of Earth's surface is about 25°C/km.

This gradient, however, is not sustained but decreases to no more than about 16°C/km at a depth of 40 km. Mountainbuilding processes have the effect of increasing the geothermal gradient, which results in the metamorphism of crustal rocks.

The Betz limit is the theoretical maximum efficiency for a wind turbine, conjectured by German physicist Albert Betz in 1919. Betz concluded that this value is 59.3%, meaning that at most only 59.3% of the kinetic energy from wind can be used to spin the turbine and generate electricity.

Carbon dioxide (CO₂) forms during coal combustion when one atom of carbon (C) unites with two atoms of oxygen (O) from the air. Because the atomic weight of carbon is 12 and that of oxygen is 16, the atomic weight of carbon dioxide is 44. Based on that ratio, and assuming complete combustion, 1 pound of carbon combines with 2.667 pounds of oxygen to produce 3.667 pounds of carbon dioxide.

Thus, production of Carbon dioxide (CO₂) on combustion of 1 kg of coal = 0.81 x 3.667 = ~3 kg

Chironomus is a genus of nonbiting midges in the subfamily Chironominae of the bloodworm family, Chironomidae, containing several cryptic species that can only be distinguished by experts based on the characteristics of their giant chromosomes.

The larvae of several species inhabit the profundal zone where they can reach relatively high densities. They use a combination of hemoglobin-like proteins and undulatory movements in their burrows to obtain oxygen in poorly oxygenated habitats.

When water moves through the soil, it moves small colloidal-sized particles with it. These particles of clay, iron, humus, and calcium carbonate will be deposited in zones below the surface or in the subsoil.

The zones are called illuvial zones and the process is referred to as illuviation. Illuvial zones are most often referred to as B horizons, and the subscript with the B designates the kind of material translocated (i.e., B, = clay accumulation)

The haemoglobin is the respiratory pigment present in the red blood cells. It binds with the oxygen and transports it to the tissues from the lungs.

The carbon monoxide is a harmful gas that shows higher affinity with the iron-containing heme group of the haemoglobin to form the carboxyhaemoglobin.

Due to this, there is no haemoglobin left to combine with the oxygen. This causes oxygen deficiency in the tissues, called carbon monoxide poisoning.