NEET Biology: Biology - Human Physiology questions with solutions

Q1. Which of the following substances, if introduced into the bloodstream, would cause coagulation of blood at the site of its introduction?

1. Fibrinogen
2. Prothrombin
3. Heparin
4. Thromboplastin

Answer: Thromboplastin

Thromboplastin (tissue factor) initiates the clotting cascade by activating prothrombin to thrombin, which then converts fibrinogen to fibrin. That local fibrin mesh causes coagulation at the site of introduction.

Q2. Deoxygenated blood

1. Flows to lungs from the left side of the heart.
2. Flows to lungs from the right side of the heart.
3. Flows to right side of the heart from the lungs.
4. Flows to left side of the heart from the.lungs.

Answer: Flows to lungs from the right side of the heart.

Deoxygenated blood is pumped from the right side of the heart into the pulmonary arteries and sent to the lungs. The left side of the heart handles oxygenated blood returning from the lungs.

Q3. is the period between the beginning of sexual maturation and entry into the adult life.

1. Growth
2. Senescence
3. Adolescence
4. None of the above

Answer: Adolescence

Adolescence is the period between the onset of sexual maturation and full entry into adult life. Growth is a general increase in size, and senescence refers to aging and decline.

Q4. Urea synthesis occurs in

1. Kidney
2. Liver
3. Brain
4. Muscles

Answer: Liver

Urea is produced in the urea cycle, which takes place primarily in the liver. The liver converts toxic ammonia from amino acid breakdown into urea for excretion by the kidneys.

Q5. Loop of Henle is connected with

1. Dilution of urine
2. Removal of water
3. counter current multiplier system
4. Remove salt

Answer: counter current multiplier system

The loop of Henle is the key structure that establishes the kidney’s medullary gradient through the countercurrent multiplier mechanism. This gradient is essential for concentrating urine later in the collecting ducts.

Q6. Pancreatic enzyme and bicarbonate secretion is stimulated by

1. Gastrin
2. Cholecystokin
3. Duocrinin
4. Enterogastrone

Answer: Cholecystokin

Cholecystokinin (CCK) is released from the duodenum/jejunum in response to fats and amino acids. It stimulates pancreatic acinar cells to secrete digestive enzymes and, along with secretin, supports bicarbonate-rich pancreatic secretion.

Q7. Blood clot inside a blood vessel is known as

1. Thrombosis
2. Agglutinin
3. clot
4. Thrombus

Answer: Thrombosis

Thrombosis is the process or condition of forming a blood clot within a blood vessel. A thrombus is the clot itself, while agglutinin is an antibody-related term.

Q8. At times ligaments and tendons are overstretched or torn. The phenomenon is

1. Sprain
2. Dislocation
3. Fracture
4. Tension

Answer: Sprain

A sprain is an injury to ligaments, which can be stretched or torn when a joint is forced beyond its normal range. Dislocation involves bones moving out of place, and fracture means a broken bone.

Q9. Lymph transports white blood cells from

1. Spleen
2. Pancreas
3. Lymph nodes
4. liver

Answer: Lymph nodes

Lymph nodes are key lymphatic organs where lymph is filtered and white blood cells, especially lymphocytes, are present and transported. They help move immune cells through the lymphatic system, unlike the spleen, pancreas, or liver in this context.