Class 11 Biology

Class 11 Biology WBCHSE Chemical Coordination Questions And Answers

Question 1. Why are the hormones considered as chemical messengers?

Answer: Hormones are considered as chemical messengers because—

• Hormones are peptides or steroidal substances, secreted in very small quantities, from the endocrine glands.
• They are carried by blood to more than one target cell.
• They act as messengers i.e., transmit information and affect different physiological and metabolic processes of the target cells.

Question 2. Justify the same hormone being named vasopressin as well as ADH.

Answer: The ADH hormone has two names due to its different physiological functions. They are as follows—

It helps to constrict the muscles of the blood vessels, mainly that of blood capillaries and arteries.

So, it increases the blood pressure. Hence, it has been rightly named vasopressin (vaso: blood vessel; pressin: pressure).

It increases water reabsorption in the DCT as well as the collecting duct, thereby releasing less amount of concentrated urine. This phenomenon is known as antidiuresis. Thus, it has been rightly named an Antidiuretic hormone (ADH).

Question 3. Write down the characteristics of the neurohypophysis. or Name the hormone secreted by this region.

Answer: There are no endocrine cells present in the pars nervosa region of the neurohypophysis. The axons of the neurosecretory cells present in the adenohypophysis remain scattered over the neurohypophysis region.

Two neurohormones are secreted by the neurohypophysis region—ADH or antidiuretic hormone and oxytocin.

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Question 4. What is the full form of HIOMT? or Which gland shows the presence of HIOMT?or Name one hormone secreted by this gland.

Answer: The full form of HIOMT is hydoxy-indolO-methyl transferase. It is a type of enzyme.

The pineal gland shows the presence of HIOMT.

Melatonin is secreted by the pineal gland.

Question 5. Mention the roles of the emergency hormone.

Class 11 Biology WBCHSE

Answer: The roles of the emergency hormone (adrenaline) are as follows—

• Pupillary dilation (varies the size of the pupil), piloerection, sweating, etc.
• Increase in rate of heartbeat, strength of heart contraction, rate of breathing, etc.
• Stimulates glycogenolysis and breaks down glycogen into glucose, thereby increasing its level in the blood.

Question 6. Which part of the body secretes aldosterone? Or why is it considered a mineralocorticoid? Mention the functions of aldosterone.
Answer:

Aldosterone is synthesized and secreted by the adrenal cortex.

It is considered a mineralocorticoid because it helps in the metabolism of the mineral salts within the body.

The functions of aldosterone are—

It regulates Na+ and water reabsorption in – the renal tubule.

It stimulates the removal of K+ and phosphate ions. Through this mechanism, it maintains electrolyte balance, volume of body fluids, osmotic pressure, and blood pressure.

Question 7. Name the endocrine regions of the pancreas. What percentage of the pancreas of a healthy human being, comprises the endocrine region?

Answer: Islets of Langerhans constitute the endocrine region of the pancreas.

About 1-2% of the pancreas of a healthy human being, comprises the endocrine region.

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Question 8. Which hormone is known as the ‘hyperglycemia hormone’? Why?  Mention its source.

Answer: Glucagon hormone is known as the ’hyperglycemia hormone’, because it stimulates the process of glycogenolysis within the hepatocytes. It helps to break down glycogen into glucose, thereby increasing its concentration in the blood.

Glucagon is synthesized and secreted by a-cells of the islets of Langerhans of the pancreas.

Question 9. What are the primary symptoms of the disease, diabetes mellitus?

Answer: The primary symptoms of diabetes mellitus are—

• Increase in the concentration of glucose in the blood of the patient, i.e, hyperglycemia.
• Glucosuria, i.e., release of glucose through urine.
• Release of excess ketone bodies through the urine, i.e., ketonuria, in case of hyperglycemia, that extends for a long period.

Question 10. Which cells secrete testosterone? Why is it known as ‘androgen’?

Answer:

• Interstitial cells or Leydig cells secrete testosterone.
• Testosterone is a sex steroid hormone, that carries out the following functions—
• It regulates the appearance of secondary sexual characteristics.
• It stimulates the production of sperm (spermatogenesis).
• It controls the male libido (desire for sexual activity). For carrying out these functions, it is known as an ‘androgen’ (Greek word ‘andro’, meaning masculine). Androgens are the male sex hormones.

Question 11. Which hormone synthesises the placenta, in pregnant women? From where is it synthesized and secreted?

Answer: Progesterone is the hormone responsible for the synthesis of the placenta, in pregnant women. It is synthesized and secreted by the corpus luteum present in the ovaries of women. Some amount of progesterone is also secreted by the adrenal cortex (zona reticularis).

Question 12. Which hormone is known as ‘calorigenic hormone’? Why?
Answer: Triiodothyronine (T₃) and tetraiodothyronine (T₄), secreted by thyroid follicles of the thyroid gland, are known as calorigenic hormones. They stimulate the oxidation of carbohydrates thereby releasing large amounts of energy. They increase BMR. Hence, they are known as ‘calorigenic hormones’.

Class 11 Biology WBCHSE Chemical Coordination Very Short Answer Type Questions

Question 1. Name the gland that requires iodine to produce most of its hormones.

Answer: Thyroid gland.

Question 2. Define hormone.

Answer: Hormones are biochemical substances synthesised and secreted by endocrine glands, which are transported by circulator)7 system to their target organs where they regulate various physiological processes.

Question 3. Name the two hormones secreted by the posterior pituitary.

Answer: ADH and oxytocin.

Question 4. What stimulates the release of epinephrine?

Answer: Stress, intense emotions like anger, fear, etc., stimulate the release of epinephrine.

Question 5. What is a mixed gland?

Answer: A mixed gland is a gland which has both endocrine and exocrine functions.

Question 6. Where are the adrenal glands located?

Answer: The adrenal glands are located at tire apex of the kidneys.

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Question 7. What are the hormones secreted by the adrenal medulla?

Answer: Epinephrine and norepinephrine.

Question 8. What are tropic hormones?

Answer: Hormones that control the secretion of hormones from other glands are called tropic hormones.

Question 9. Mention one important function of the pineal gland.

Answer: An important function of pineal gland is to secrete melatonin. Melanin regulates body’s circadian rhythm.

Question 10. What is neurohypophysis?

Answer: Neurohypophysis is the posterior pituitary gland. It principally consists of the pars nervosa (neural lobe of hypophysis) and the infundibulum (stalk-like structure that connects the pituitary gland to the hypothalamus).

Question 11. Name one steroid hormone in human and mention its source.

Answer: Aldosterone is a steroid hormone. Its source is the adrenal cortex.

Question 12. Which hormone is called stress hormone?

Answer: Cortisol.

Question 13. Write the full names of TSH and ADH.

Answer: TSH—Thyroid stimulating hormone, ADHAntidiuretic hormone.

Question 14. Which type of cell is stimulated by calcitonin?

Answer: Osteoblast cells

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Question 15. Where are chromaffin cells located?

Answer: Adrenal medulla. terms italicised.

Question 16. Name that hormone that aids in sodium conservation and potassium excretion.

Answer: Aldosterone.

Question 17. Define the term erythropoiesis. Also name the hormone that stimulates it.

Answer: Erythropoiesis is the process of formation of RBC. The hormone erythropoietin, secreted by juxtaglomerular cells of the kidney, stimulate the process.

Question 18. Name the cells that produce testosterone.

Answer: Leydigcell.

Question 19. What is second messenger?
Answer: Diffusible small signalling molecules, synthesisedin the target cells by those hormones or enzymes which are unable to enter the cells to bring about the biochemical changes, are known as second messengers.

Question 20. There are many endocrine glands in human body. Name the gland, which is absent in male and the one absent in female.
Answer: The two endocrine glands, ovary and testis are absent in male and female respectively.

Question 21. Which of the two adrenocortical layers, zona glomerulosa and zona reticularis, lies outside enveloping the other?
Answer: Zona glomerulosa lies outer to zona reticularis.

Question 22. Name the only hormone secreted by pars intermedia of pituitary gland.
Answer: Melanocyte stimulating hormone (MSH).

Question 23. A patient was complaining of constant thirst, excessive passing of urine and low blood pressure. When the doctor checked the patient’s blood glucose and blood insulin level, the levels were normal or slightly low. The doctor diagnosed the condition as diabetes insipidus. To confirm his diagnosis, he decides to measure the concentration of a specific hormone in the patient’s blood. Which hormone does the doctor intend to measure?
Answer: ADH.

Chemical Coordination Multiple-Choice Questions

Question 1. A decrease in blood pressure/volume will not cause the release of—

1. Atrial Natriuretic Factor
2. Aldosterone
3. ADH
4. Renin

Answer: 1. Atrial Natriuretic Factor

Question 2. A hypothalamic hormone, needed in

1. The anterior pituitary gland stimulates the secretion of LH and FSH
2. The posterior pituitary gland stimulates the secretion of oxytocin and FSH
3. The posterior pituitary gland stimulates the secretion of LH and relaxin
4. The anterior pituitary gland stimulates the secretion of LH and oxytocin

Answer: 1. Anterior pituitary gland stimulates the secretion of LH and FSH

Question 3. Hypersecretion of Growth Hormone in adults does not cause further increase in height because—

1. Epiphyseal plates close after adolescence
2. Bones lose their sensitivity to Growth Hormone in adults
3. Muscle fibers do not grow in size after birth
4. Growth Hormone becomes inactive in adults

Answer: 1. Epiphyseal plates close after adolescence

Question 4. Changes in GnRH pulse frequency in females are controlled by circulating levels of—

1. Oestrogen and inhibin
2. Progesterone only
3. Progesterone and inhibin
4. Oestrogen and progesterone

Answer: 4. Oestrogen and progesterone

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Question 5. Identify the correct statement on ‘inhibin’—

1. Is produced by granulosa cells in the ovary and inhibits the secretion of FSH
2. Is produced by granulosa cells in
3. Is produced by nurse cells in the testes and inhibits the secretion of LH
4. Inhibits the secretion of LH, FSH, and prolactin

Answer: 1. Is produced by granulosa cells in the ovary and inhibits the secretion of FSH

Question 6. Select the incorrect statement—

1. LH and FSH trigger ovulation in the ovary
2. LH and FSH decrease gradually during the follicular phase
3. LH triggers the secretion of androgens from the Leydig cells
4. FSH stimulates the Sertoli cells which help in spermiogenesis.

Answer: 2. LH and FSH decrease gradually during the follicular phase

Question 7. The amino acid, tryptophan is the precursor for the synthesis of—

1. Thyroxine and triiodothyronine
2. Oestrogen and progesterone
3. Cortisol and cortisone
4. Melatonin and serotonin

Answer: 4. Melatonin and serotonin

Question 8. Which of the following pairs of hormones are not antagonistic (having opposite effects) to each other?

1. Insulin—Glucagon
2. Aldosterone—Atrial natriuretic factor
3. Relaxin—Inhibin
4. Parathormone—Calcitonin

Answer: 3. Relaxin—Inhibin

Question 9. Which hormones stimulate the production of pancreatic juice and bicarbonate?

1. Angiotensin and epinephrine
2. Gastrin and insulin
3. Cholecystokinin and secretin
4. Insulin and glucagon

Answer: 3. Cholecystokinin and secretin

Question 10. Name a peptide hormone that acts mainly on hepatocytes, and adipocytes and enhances cellular glucose uptake and utilisation.

1. Insulin
2. Glucagon
3. Secretin
4. Gastrin

Answer: 1. Insulin

Question 11. The posterior pituitary gland is not a ‘true’ endocrine gland because—

1. It is provided with a duct
2. It only stores and releases hormones
3. It is under the regulation of the hypothalamus
4. It secretes enzymes

Answer: 2. It only stores and releases hormones

Question 12. several hormones like hCG, hPL, estrogen and progesterone are produced by—

1. Ovary
2. Placenta
3. Fallopian tube
4. Pituitary

Answer: 2. Placenta

Question 13. Graves’ disease is caused due to—

1. Hyposecretion of the thyroid gland
2. Hypersecretion of the thyroid gland
3. Hyposecretion of the adrenal gland
4. Hypersecretion of the adrenal gland

Answer: 2. Hypersecretion of thyroid gland

Question 14. Which of the following events is not associated with ovulation in human females?

1. LH surge
2. Decrease in estradiol
3. Full development of Graafian follicle
4. Release of secondary oocyte

Answer: 2. Decrease in estradiol

Question 15. Which one of the following hormones is not involved in sugar metabolism?

1. Glucagon
2. Cortisone
3. Aldosterone
4. Insulin

Answer: 3. Aldosterone

Question 16. Which one of the following hormones though synthesised elsewhere, is stored and released by the master gland?

1. Melanocyte stimulating hormone
2. Antidiuretic hormone
3. Luteinizing hormone
4. Prolactin

Answer: 4. Prolactin

Question 17. Injury localized to the hypothalamus would most likely disrupt—

1. Short term ’Memory’
2. Coordination during locomotion
3. Executive function, such as decision-making
4. Regulation of body temperature

Answer: 2. Coordination during locomotion

Question 18. Identify the hormone with its correct matching of source and function—

1. Oxytocin—Posterior pituitary, growth and maintenance of mammary glands
2. Melatonin—The pineal gland, regulates the normal rhythm of the sleep-wake cycle
3. Progesterone—Corpus luteum, stimulation of growth and activities of female secondary sex organs
4. Atrial natriuretic factor—Ventricular wall, increases the blood pressure

Answer: 2. Melatonin—The pineal gland, regulates the normal rhythm of the sleep-wake cycle

Question 19. Fight or flight reactions cause activation of—

1. The parathyroid glands, leading to an increased metabolic rate
2. The kidney, leading to suppression of the renin-angiotensin-aldosterone pathway
3. The adrenal medulla, leading to increased secretion of epinephrine and norepinephrine
4. The pancreas, leading to a reduction in the blood sugar levels

Answer: 3. The adrenal medulla, leading to increased secretion of epinephrine and norepinephrine

Question 20. Which of the following hormones is a derivative of fatty acid?

1. Gastrin
2. Thyroxine
3. Oestrogen
4. Prostaglandins

Answer: 4. Prostaglandins

Question 21. Which of the following pituitary hormones is secreted without the involvement of a Releasing Hormone (RH)?

1. Thyroid Stimulating Hormone (TSH)
2. Follicle Stimulating Hormone (FSH)
3. Oxytocin
4. Prolactin

Answer: 3. Oxytocin

Question 22. The diurnal rhythms are regulated by—

1. Adrenaline
2. Melatonin
3. Serotonin
4. Vasopressin

Answer: 2. Melatonin

Question 23. Match the hormones secreted by various endocrine structures and choose the correct option:

1. 1-5,2-1,3-4,4-2,5-3
2. 1-5,2-4,3-1,4-2,5-3
3. 1-3,2-1,3-4,4-2,5-5
4. 1-3,2-1,3-4,4-5,5-2

Answer: 4. 1-3,2-1,3-4,4-5,5-2

Question 24. Which of the following statements is wrong?

1. Sella turcica is a bony cavity where the pituitary gland is located
2. The parathyroid hormone decreases the Ca2+ levels in the blood
3. Thymosins play a major role in T-cell differentiation
4. The middle layer of the adrenal cortex is the zona fasciculata
5. Insulin stimulates Glycogenesis

Answer: 2. Parathyroid hormone decreases the Ca2+ levels in blood

Question 25. An endocrine gland in humans, which plays an important role in the regulation of the rhythm of the body is-

1. Adrenal gland
2. Pineal gland
3. Thymus
4. Thyroid gland

Answer: 2. Pineal gland

Question 26. Insulin causes rapid movement of glucose from the blood to hepatocytes and adipocytes resulting in—

1. Hyperglycemia
2. Hypoglycemia
3. Diabetes
4. None of these

Answer: 2. Hypoglycemia

Question 27. Identify the hormones, A, B, and C that are labeled in the given flowchart—

1. 1-GnRH 2-ICSH 3-FSH
2. 1-GH 2-FSH 3-LH
3. 1-GnRH 2-PRL 3-ICSH
4. 1-GnRH 2-FSH 3-LH

Answer: 4. 1-GnRH 2-FSH 3-LH

Question 28. Which one of the following hormones also produces anti-inflammatory reactions in man and suppresses the immune response in addition to its primary functions?

1. Cortisol
2. Thymosin
3. Thyrocalcitonin
4. Erythropoietin

Answer: 1. Cortisol

Question 29. Match the following columns:

1. 1-3,2-1,3-4,4-2
2. 1-1,2-3,3-2,4-4
3. 1-1,2-3,3-4,4-2
4. 1-3,2-1,3-2,4-4

Answer: 3. 1-1,2-3,3-4,4-2

Question 30. The Hormone Responsible For Fight And fight-and-fight response is

1. Adtenaline
2. Thyrocine
3. ADH
4. Oxytocin

Answer: 1. Adtenaline

Question 31. Name The Hormome that has no role in menstruation

1. LH
2. FSH
3. GH
4. TSH

Answer: 3. GH

Question 32. Select the answer which correctly matches the endocrine gland with the hormone it secretes and its function/deficiency symptom.

Answer: 3.

Question 33. Which of the following statements is correct in relation to the endocrine system?

1. The adenohypophysis is under direct neural regulation of the hypothalamus.
2. Organs in the body gastrointestinal tract, heart, kidney, and liver do not produce any hormones.
3. Non-nutrient chemicals produced by the body in trace amounts that act as intercellular messenger are known as hormones.
4. Releasing and inhibitory hormones are produced by the pituitary gland.

Answer: 3. Non-nutrient chemicals produced by the body in trace amount that act as intercellular messenger are known as hormones.

Question 34. Removal or absence of thymus in early life shall bring about—

1. Lack of lymphocytes
2. Lack of antibodies
3. Lack of lymph nodes
4. Both 1 and 2

Answer: 4. Both 1 and 2

Question 35. Gland responsible for calcium metabolism is—

1. Thymus
2. Thyroid
3. Parathyroid
4. Adrenal

Answer: 3. Parathyroid

Question 36. The Leydig cells secrete—

1. Oestrogen
2. Testosterone
3. Progesterone
4. Corticosterone

Answer: 2. Testosterone