Melatonin is known to: 1. Regulate diurnal rhythms such as sleep-wake cycle. 2. Influence body temperature. 3. Affect metabolism and pigmentation. 4. It has no influence on the menstrual cycle. Select the correct answer using the code below:

The correct option is 1, 2 and 3 only. Explanation Melatonin is a hormone secreted by the pineal gland, a small endocrine gland located on the dorsal side of the forebrain. It plays a critical role in the regulation of the 24-hour (diurnal) rhythm of the body. Statement-wise Analysis - Statement 1 is Correct: Melatonin is the primary hormone responsible for regulating the body's internal clock. It maintains the normal rhythms of the sleep-wake cycle (circadian rhythm). - Statement 2 is Correct: Along with the sleep-wake cycle, melatonin helps regulate body temperature, typically lowering it during sleep to facilitate rest. - Statement 3 is Correct: Melatonin influences metabolism and pigmentation. In many vertebrates, it affects skin coloration (pigmentation), and in mammals, it plays a role in metabolic processes. - Statement 4 is Incorrect: Melatonin does influence the menstrual cycle. Additionally, it plays a role in the body's defense capability (immunity). Key Takeaway Melatonin, secreted by the pineal gland, regulates the diurnal rhythm (sleep-wake cycle), body temperature, metabolism, pigmentation, the menstrual cycle, and defense capabilities.

NCERT Class 11 Science — Chapter 9: Chemical Coordination and Integration

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Melatonin is known to:

Regulate diurnal rhythms such as sleep-wake cycle.
Influence body temperature.
Affect metabolism and pigmentation.
It has no influence on the menstrual cycle.

Select the correct answer using the code below:

Official previous-year question

Verified 1 Aug 2026.

Options

A1, 2, 3 and 4
B1, 2 and 3 only
C2, 3 and 4 only
D1 and 4 only

Did you get this right?

Solution

The correct option is 1, 2 and 3 only.

Explanation

Melatonin is a hormone secreted by the pineal gland, a small endocrine gland located on the dorsal side of the forebrain. It plays a critical role in the regulation of the 24-hour (diurnal) rhythm of the body.

Statement-wise Analysis

Statement 1 is Correct: Melatonin is the primary hormone responsible for regulating the body's internal clock. It maintains the normal rhythms of the sleep-wake cycle (circadian rhythm).
Statement 2 is Correct: Along with the sleep-wake cycle, melatonin helps regulate body temperature, typically lowering it during sleep to facilitate rest.
Statement 3 is Correct: Melatonin influences metabolism and pigmentation. In many vertebrates, it affects skin coloration (pigmentation), and in mammals, it plays a role in metabolic processes.
Statement 4 is Incorrect: Melatonin does influence the menstrual cycle. Additionally, it plays a role in the body's defense capability (immunity).

Key Takeaway

Melatonin, secreted by the pineal gland, regulates the diurnal rhythm (sleep-wake cycle), body temperature, metabolism, pigmentation, the menstrual cycle, and defense capabilities.

Your note

More from Chapter 9: Chemical Coordination and Integration

Consider the following statements about the thyroid gland: 1. It consists of a single lobe located on the trachea. 2. Follicular cells synthesize thyroxine (T4) and triiodothyronine (T3). 3. Iodine is essential for the normal rate of hormone synthesis. Which of the statements given above are correct?

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Which of the following are associated with deficiency of thyroid hormones? 1. Cretinism occurs when deficiency happens in old age. 2. Goitre formation due to iodine deficiency. 3. It ensures perfectly regular menstrual cycles. Select the correct answer using the code below:

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Regarding exophthalmic goitre (Graves' disease), which of the following is/are correct? 1. It is a form of hyperthyroidism. 2. It involves sinking of the eyeballs. 3. It is characterised by an increased basal metabolic rate. Select the correct answer using the code below:

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Assertion (A): Thyrocalcitonin (TCT) helps regulate blood calcium levels. Reason (R): Parathyroid hormone (PTH) acts on bones to stimulate bone resorption.

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With reference to parathyroid hormone (PTH), consider the following statements: 1. Its secretion is regulated by circulating sodium levels. 2. It increases bone resorption and renal reabsorption of calcium. 3. It increases calcium absorption from the digested food. Which of the statements given above are correct?

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The correct option is 1, 2 and 3 only.

Explanation

Statement-wise Analysis

Statement 1 is Correct: Melatonin is the primary hormone responsible for regulating the body's internal clock. It maintains the normal rhythms of the sleep-wake cycle (circadian rhythm).
Statement 2 is Correct: Along with the sleep-wake cycle, melatonin helps regulate body temperature, typically lowering it during sleep to facilitate rest.
Statement 3 is Correct: Melatonin influences metabolism and pigmentation. In many vertebrates, it affects skin coloration (pigmentation), and in mammals, it plays a role in metabolic processes.
Statement 4 is Incorrect: Melatonin does influence the menstrual cycle. Additionally, it plays a role in the body's defense capability (immunity).

Key Takeaway

Melatonin, secreted by the pineal gland, regulates the diurnal rhythm (sleep-wake cycle), body temperature, metabolism, pigmentation, the menstrual cycle, and defense capabilities.