NEET Practice Questions (MCQs) with Answers & Solutions

The renal vein carries the least amount of urea because it is responsible for transporting blood that has been filtered by the kidneys. During filtration, the kidneys remove waste products like urea from the blood, resulting in lower urea levels in the blood that exits the kidneys through the renal vein.

The assertion (A) that ammonia should be eliminated from the body as rapidly as it is formed is true because ammonia is highly toxic to cells. However, the reason (R) is false because ammonia is actually very soluble in water. Therefore, the correct option is 'If A is true then R is false.'

Both assertion (A) and reason (R) are true and the reason correctly explains the assertion. In the descending limb of the loop of Henle, water is reabsorbed, making the urine hypertonic. In the ascending limb, sodium ions (Na+) are actively transported out, and this limb is impermeable to water, making the urine hypotonic. Therefore, the correct option is 'If both the ‘A’ and ‘R’ are true and ‘R’ is a correct explanation of ‘A’.'

Both are true

The assertion (A) states that the utilization of water and consumption of energy for elimination of waste products are inversely proportional, which is true. The reason (R) states that ammonia is less toxic and can be eliminated with a large amount of water, which is false. Ammonia is actually highly toxic and requires a large amount of water for its elimination, hence (A) is true and (R) is false.

The Widal test is a serological test for enteric fever or undulant fever whereby bacteria causing typhoid fever (Salmonella typhi) are mixed with serum containing specific antibodies obtained from an infected individual. The test identifies the presence of agglutinins in the serum.

Malaria is transmitted by the bite of an infected female Anopheles mosquito. The female mosquitoes require blood to nurture their eggs, making them the vector for the malaria parasite.

Ringworm is a fungal infection caused by dermatophytes such as Trichophyton. It spreads through direct contact with an infected person or contaminated objects. The statement 'It is done by secretion of serotonin chemical' is incorrect as serotonin has no role in causing ringworm.