When cells are exposed to sunlight, radiant energy can damage the DNA. For example, ultraviolet irradiation causes covalent bond formation between adjacent thymines on the same strand of DNA. Ultraviolet light is absorbed by a double bond in thymine and cytosine bases in DNA. This added energy opens up the bond and allows it to react with a neighboring base.

Correct Option: D

When cells are exposed to sunlight, radiant energy can damage the DNA. For example, ultraviolet irradiation causes covalent bond formation between adjacent thymines on the same strand of DNA. Ultraviolet light is absorbed by a double bond in thymine and cytosine bases in DNA. This added energy opens up the bond and allows it to react with a neighboring base.

Nitrosomonas is a genus comprising rod shaped chemoautotrophic bacteria. This rare bacteria oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in treatment of industrial and sewage waste and in the process of bioremediation.

Correct Option: D

Nitrosomonas is a genus comprising rod shaped chemoautotrophic bacteria. This rare bacteria oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in treatment of industrial and sewage waste and in the process of bioremediation.

AIDS virus destroys the T-cells inside of the immune system. T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity.

Correct Option: A

AIDS virus destroys the T-cells inside of the immune system. T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity.

Quenching is a process in which absorbed light energy is dissipated as heat and does not take part in photo-chemistry. The phenomenon involves quenching of chlorophyll a (Chla) fluorescence, which is induced under steady-state illumination.

Correct Option: A

Quenching is a process in which absorbed light energy is dissipated as heat and does not take part in photo-chemistry. The phenomenon involves quenching of chlorophyll a (Chla) fluorescence, which is induced under steady-state illumination.

Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is a protein with a bilin chromophore. It detects mainly red and far-red region of the visible spectrum and regulates germination of seeds.

Correct Option: C

Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is a protein with a bilin chromophore. It detects mainly red and far-red region of the visible spectrum and regulates germination of seeds.