Biology

Thyroxine is a hormone produced by the thyroid gland that contains iodine atoms, which are essential for its biological activity. Insulin and adrenaline do not contain iodine.

The calcaneus is the large bone forming the heel of the human foot, making option A the correct answer.

Vitamin B7, also known as biotin, deficiency commonly causes symptoms such as hair loss, skin rashes, and neurological issues. Pellagra is related to niacin (vitamin B3) deficiency, muscle weakness is a general symptom but not specific to B7, and xerophthalmia is due to vitamin A deficiency.

The Peregrine Falcon is known to reach diving speeds of up to approximately 240 miles per hour, making it the fastest bird. This speed is well documented in ornithological studies.

Dmitry Ivanovsky is credited with the discovery of viruses in 1892 when he studied the tobacco mosaic disease and found that the infectious agent could pass through filters that trapped bacteria, indicating a new type of pathogen.

DNA stands for deoxyribonucleic acid and is a type of nucleic acid that carries genetic information in living organisms. Therefore, it is correctly described as a class of nucleic acids.

The skin is composed of three primary layers: the epidermis, dermis, and hypodermis (subcutaneous tissue). These layers together perform protective, sensory, and regulatory functions.

The 'Blink snake' is not a recognized species of snake, whereas the Glass snake, Sea snake, and Tree snake are all types of snakes or legless lizards commonly referred to as snakes. Therefore, 'Blink snake' is not a true snake.

The normal platelet count range is typically 150,000 to 450,000 platelets per microliter (µL) of blood, which corresponds to 1.5 lac to 4.5 lac per microliter. Option B correctly states this range with the appropriate units.

In thrombocytopenia, the blood has too few platelets. The bone marrow typically responds by producing too many platelets in an attempt to compensate for the low platelet count in the blood.