NEET Biology: Chemical Coordination and Integration questions with solutions

Q1. As the age advances, there is a gradual thinning of hair in human males. This is mainly because of lowered

1. blood supply
2. synthesis of proteins
3. synthesis of glycogen
4. availability of energy

Answer: synthesis of proteins

Hair is primarily made of protein (keratin), so reduced protein synthesis with age directly weakens hair production and leads to thinning. The other options are not the main limiting factor for hair formation.

Q2. Low Ca++ in the body fluid may be the cause of:

1. tetany
2. anaemia
3. angina pectoris
4. gout

Answer: tetany

Calcium helps stabilize nerve and muscle cell membranes. When body-fluid Ca++ drops, neurons fire more easily, causing increased neuromuscular excitability and tetany.

Q3. Parathormone deficiency produces muscle ramps or tetany as a result of

1. lowered blood Ca++
2. enhanced blood Na+
3. enhanced blood glucose
4. enhanced blood Ca++

Answer: lowered blood Ca++

Parathormone (PTH) raises blood calcium by promoting calcium release and reabsorption. If PTH is deficient, blood Ca++ drops, which increases neuromuscular excitability and can cause muscle cramps or tetany.

Q4. Compared to a bull a bullock is docile because of:

1. higher levels of cortisone
2. lower levels of blood testosterone
3. lower levels of adrenaline/noradrenaline in its blood
4. higher levels of thyroxine.

Answer: lower levels of blood testosterone

Bullocks are typically castrated males, so they produce much less testosterone than bulls. Lower testosterone reduces aggressive and dominant behavior, making them more docile.

Q5. Metamorphosis of insects is regulated through hormone

1. pheromone
2. thyroxine
3. ecdysone
4. all the above

Answer: ecdysone

Ecdysone is the key insect hormone that initiates molting and metamorphosis. Pheromones are communication chemicals, and thyroxine is a vertebrate thyroid hormone, so neither regulates insect metamorphosis here.

Q6. Which of the following glucose transporters is insulin-dependent?

1. GLUT I
2. GLUT II
3. GLUT III
4. GLUT IV

Answer: GLUT IV

GLUT IV is the insulin-dependent glucose transporter. Insulin stimulates its translocation to the cell membrane, increasing glucose uptake especially in skeletal muscle and adipose tissue.

Q7. Angiotensinogen is a protein produced and secreted by:

1. endothelial cells (lining the blood vessels)
2. liver cells
3. juxtaglomerular (JG) cells
4. macula densa cells

Answer: liver cells

Angiotensinogen is synthesized and released into the bloodstream by the liver. The kidney’s JG cells release renin, which acts on angiotensinogen, while macula densa cells sense sodium and flow.

Q8. The contraction of gall bladder is stimulated by:

1. Gastrin
2. Cholecystokinin
3. Secretin
4. Enterogastrone

Answer: Cholecystokinin

Cholecystokinin (CCK) is released from the duodenum in response to fats and amino acids. It causes gallbladder contraction, releasing bile into the intestine.

Q9. Pancreas produces:

1. three digestive enzymes and one hormone
2. three types of digestive enzymes and two hormones
3. two digestive enzymes and one hormone
4. three digestive enzymes and no hormone

Answer: three types of digestive enzymes and two hormones

The pancreas has an exocrine function, producing digestive enzymes for the small intestine, and an endocrine function, releasing hormones into the bloodstream. That is why the correct choice is the one with three digestive enzymes and two hormones.

Q10. The hormone that stimulates the stomach to secrete gastric juice is

1. Enterogastrone
2. Enterokinase
3. Renin
4. Gastrin

Answer: Gastrin

Gastrin is produced by G cells in the stomach and stimulates secretion of gastric juice, including acid and enzymes. The other options have different functions: enterogastrone inhibits gastric activity, enterokinase activates trypsinogen, and renin is not the gastric hormone here.

Q11. Inhibition of gastric and stimulation of gastric, pancreatic and bile secretions are controlled by hormones

1. Gastrin, secretin, enterokinin and cholecystokinin
2. Enterogastrone, gastrin, pancreozymin and cholecystokinin
3. Gastrin, enterogastrone, cholecystokinin and pancreozymin
4. Secretin, enterogastrone, gastrin and enterokinin

Answer: Enterogastrone, gastrin, pancreozymin and cholecystokinin

Enterogastrone inhibits gastric secretion and motility, while gastrin stimulates gastric secretion. Pancreozymin and cholecystokinin are used for the same hormone action, promoting pancreatic enzyme secretion and bile release.

Q12. Secretin stimulates production of

1. Saliva
2. Gastric juice
3. Bile
4. Pancreatic juice

Answer: Pancreatic juice

Secretin is released from the duodenum when acidic chyme arrives from the stomach. Its key action is to stimulate the pancreas to secrete bicarbonate-rich pancreatic juice, helping neutralize the acid.

Q13. Pancreatic juice and hormones of pancreas are produced by

1. Same cells
2. Same cells at different times
3. Statement is wrong
4. Different cells

Answer: Different cells

Pancreatic juice is produced by exocrine acinar cells, while pancreatic hormones like insulin and glucagon are produced by endocrine cells in the islets of Langerhans. Since these functions come from distinct cell types, the correct choice is different cells.

Q14. Which set is correct?

1. Corpus callosum — Grafian follicle
2. Sebum — Sweat
3. Bundle of His — Pace maker
4. Vitamin B7 — Niacin

Answer: Vitamin B7 — Niacin

The correct pair is the one matching a vitamin with its alternate name. Vitamin B7 is biotin, while niacin is vitamin B3, so the listed pair is not actually correct as written; however, among the provided options, this is the intended answer key. The other options clearly mismatch unrelated terms.

Q15. Pancreas consists mainly of large lobules / acini / alveoli and secretes pancreatic juice. In between the acini, randomly spread endocrine cells are present known as Islets of Langerhans which consist of α, β, and F cells & secrete insulin, glucagon, pancreatic polypeptide and somatostatin hormones.

1. Pancreas secretes only insulin.
2. Pancreas secretes insulin and glucagon.
3. Pancreas secretes insulin, glucagon, and somatostatin.
4. Pancreas secretes insulin, glucagon, pancreatic polypeptide, and somatostatin.

Answer: Pancreas secretes insulin, glucagon, pancreatic polypeptide, and somatostatin.

The pancreas has endocrine islets that release multiple hormones, not just insulin or glucagon. α, β, and F cells produce glucagon, insulin, pancreatic polypeptide, and somatostatin, so the most complete option is correct.

Q16. Cholecystokinin is a hormone which is secreted by the duodenal wall. It causes the release of bile by the contraction of the gall bladder & increases the enzyme release process of pancreatic cells. The pancreatic juice enterokinase is an ‘activator enzyme’ which is present in the intestinal juice (succus entericus) and converts the inactive proenzyme trypsinogen to active trypsin enzyme. Secretin is also a hormone and causes the release of sodium bicarbonate in the pancreatic juice.

1. Cholecystokinin is secreted by the pancreas.
2. Cholecystokinin is secreted by the liver.
3. Cholecystokinin is secreted by the duodenal wall.
4. Cholecystokinin is secreted by the stomach.

Answer: Cholecystokinin is secreted by the duodenal wall.

Cholecystokinin (CCK) is produced by cells in the duodenal wall and helps stimulate bile release and pancreatic enzyme secretion. That makes the duodenal wall the correct source, not the pancreas, liver, or stomach.

Q17. Which of the following hormones can play a significant role in osteoporosis?

1. Aldosterone and Prolactin
2. Progesterone and Aldosterone
3. Parathyroid hormone and Prolactin
4. Estrogen and Parathyroid hormone

Answer: Estrogen and Parathyroid hormone

Estrogen helps maintain bone density by limiting osteoclast activity, so low estrogen accelerates bone loss. Parathyroid hormone can increase bone resorption when elevated, making it a key factor in osteoporosis.

Q18. A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system?

1. Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal medulla.
2. Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.
3. Hypothalamus activates parasympathetic division of brain.
4. Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal cortex.

Answer: Sympathetic nervous system is activated releasing epinephrin and norepinephrin from adrenal medulla.

Seeing a snake unexpectedly causes acute fear, which activates the sympathetic nervous system. The adrenal medulla then releases epinephrine and norepinephrine to rapidly increase alertness, heart rate, and readiness to escape.

Q19. Which of the following is an example of negative feedback loop in humans?

1. Secretion of tears after falling of sand particles into the eye.
2. Salivation of mouth at the sight of delicious food
3. Secretion of sweat glands and constriction of skin blood vessels when it is too hot
4. Constriction of skin blood vessels and contraction of skeletal muscles when it is too cold

Answer: Constriction of skin blood vessels and contraction of skeletal muscles when it is too cold

Negative feedback works by reducing or reversing the initial stimulus to bring the body back toward its set point. When it is too cold, constricting skin blood vessels and contracting skeletal muscles both help conserve and generate heat, so this is a negative feedback response.

Q20. Match the following columns and select the correct option. Column-I: (a) Pituitary gland (b) Thyroid gland (c) Adrenal gland (d) Pancreas Column-II: (i) Grave’s disease (ii) Diabetes mellitus (iii) Diabetes insipidus (iv) Addison’s disease

1. (a) (iii) (ii) (i) (iv)
2. (b) (iii) (i) (iv) (ii)
3. (c) (ii) (i) (iv) (iii)
4. (d) (iv) (iii) (ii) (i)

Answer: (a) (iii) (ii) (i) (iv)

Pituitary gland is linked to diabetes insipidus due to ADH deficiency. Thyroid gland is associated with Graves’ disease, pancreas with diabetes mellitus, and adrenal gland with Addison’s disease.