NEET Test 130

The large space behind the lens contains a thick, gel-like fluid. This is known as vitreous humor or vitreous gel. The chambers in front of the lens are filled with a clear, watery fluid, known as aqueous humor.

The function of these two fluids is to keep the shape of the eyeball intact. It presses against the inside of the eyeball.

The macula is located near the center of the retina at the back of the eyeball, It provides the sharp, detailed, central vision for focusing.

The sclera is the white part of the eye. It forms the supporting wall of the eyeball and is continuous with the clear cornea.

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges: positive and negative. Positively charged substances are repelled from other positively charged substances, but attracted to negatively charged substances; negatively charged substances are repelled from negative and attracted to positive. An object is positively charged if it has a deficiency of electrons, and is otherwise negatively charged or uncharged.

BaF₂ is a AX₂ type salt. In its crystal, Ba²⁺ ions are arranged in ccp arrangement. Since there are two tetrahedral sites for each Ba²⁺ ion and F⁻ ions occupy all the tetrahedral sites, hence one F⁻ is surrounded by four Ba²⁺, i.e., the coordination number of F⁻ is 4.

The nervous system is divided into central and peripheral nervous systems. The PNS is divided into two divisions called somatic neural system and autonomic neural system. The somatic neural system relays impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body.

Calgon is a trading name of a complex salt, sodium hexametaphosphate (NaPO₃)₆.

It is used for softening hard water. Calgon ionizes to give a complex anion: 

(NaPO₃)₆ or Na₂(Na₄P₆O₁₈)? 2Na+ + Na₄P₆O₁₈^2-. 

The addition of Calgon to hard water causes the calcium and magnesium ions of hard water to displace sodium ions from the anion of Calgon

Ca²⁺ + Na₄P₆O₁₈^2-? 2Na+ + CaNa₂ P₆O₁₈^2-.

From hard water anion of calgon goes into solution. This results in the removal of calcium and magnesium ions from hard water in the form of a complex with Calgon. The water is softened and sodium ions are released into the water.

There is a linear relationship between the incident light and CO₂ fixation rates at low light intensities. At higher light intensities, gradually the rate does not show further increase as other factors become limiting. Light saturation occurs at 10 % of the full sunlight. so, except for plants in shade or in dense forests, light is rarely a limiting factor in nature. An increase in incident light beyond a point causes the breakdown of chlorophyll and a decrease in photosynthesis.

Thylakoids can be purified from plant cells using a combination of differential and gradient centrifugation. Disruption of isolated thylakoids, for example by mechanical shearing, releases the lumenal fraction. Peripheral and integral membrane fractions can be extracted from the remaining membrane fraction. Treatment with sodium carbonate (Na₂CO₃) detaches peripheral membrane proteins, whereas treatment with detergents and organic solvents solubilizes integral membrane proteins.