NCERT Class 8 Science — Chapter 4: Reaching the age of adolescence

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The hormone "Thyroxine", which regulates carbohydrate, protein, and fat metabolism, is secreted by:

Official previous-year question

Verified 1 Aug 2026.

Options

APancreas
BAdrenal
CPituitary
DThyroid

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Solution

Correct Option

The correct option is

Thyroid

Explanation

The endocrine system comprises various glands that secrete hormones directly into the bloodstream to regulate physiological processes such as metabolism, growth, and development. Specific glands are responsible for synthesizing distinct hormones with targeted functions.

Detailed Analysis

Thyroid Gland: This gland is located in the neck region and secretes the hormone Thyroxine (tetraiodothyronine). Thyroxine plays a critical role in regulating the basal metabolic rate (BMR) of the body. It controls the metabolism of carbohydrates, proteins, and fats to ensure the optimal balance required for growth and energy production. Iodine is essential for the synthesis of thyroxine.
Pituitary Gland: Often referred to as the "master gland," it secretes hormones like Growth Hormone (GH) and Thyroid Stimulating Hormone (TSH), which regulate other endocrine glands, but it does not directly secrete thyroxine.
Adrenal Gland: Located on top of the kidneys, these glands secrete hormones such as adrenaline (epinephrine) and cortisol, which are involved in the stress response and salt balance, not basal metabolism regulation via thyroxine.
Pancreas: This is a mixed gland that secretes insulin and glucagon, which are primarily responsible for regulating blood glucose levels.

Key Takeaway

Thyroxine is secreted by the thyroid gland and is the primary hormone responsible for regulating the body's metabolism of carbohydrates, proteins, and fats.

Your note

More from Chapter 4: Reaching the age of adolescence

With reference to the role of hormones in the life history of insects and frogs, consider the following statements: 1. The change from larva to adult is called metamorphosis. 2. In frogs, metamorphosis is controlled by the hormone insulin. 3. Thyroxine production requires the presence of iodine in the water. Which of the statements given above is/are correct?

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Consider the following statements regarding the nutritional needs of adolescents: 1. A balanced diet consists exclusively of proteins and vitamins. 2. Iron is essential for adolescents because it builds blood. 3. Chips and packed snacks have high energy but limited nutritional value compared to regular meals. Which of the statements given above is/are correct?

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With reference to HIV/AIDS, consider the following statements: 1. It is caused by a virus. 2. It can be transmitted from an infected mother to an infant through milk. 3. It can be transmitted by sharing syringes used for injecting drugs. 4. It can be transmitted through sexual contact with an infected person. Which of the statements given above are correct?

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Consider the following statements regarding the Pituitary gland: 1. It is located at the base of the brain. 2. It secretes insulin necessary for sugar metabolism. 3. It functions independently and does not influence other endocrine glands. Which of the statements given above is/are correct?

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With reference to the onset of menstruation, consider the following statements: 1. The first menstrual flow which begins at puberty is termed menarche. 2. Menstruation occurs once in about 10 to 15 days. 3. At 45 to 50 years of age, the menstrual cycle stops, which is termed menopause. Which of the statements given above are correct?

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Correct Option

The correct option is

Thyroid

Explanation

Detailed Analysis

Thyroid Gland: This gland is located in the neck region and secretes the hormone Thyroxine (tetraiodothyronine). Thyroxine plays a critical role in regulating the basal metabolic rate (BMR) of the body. It controls the metabolism of carbohydrates, proteins, and fats to ensure the optimal balance required for growth and energy production. Iodine is essential for the synthesis of thyroxine.
Pituitary Gland: Often referred to as the "master gland," it secretes hormones like Growth Hormone (GH) and Thyroid Stimulating Hormone (TSH), which regulate other endocrine glands, but it does not directly secrete thyroxine.
Adrenal Gland: Located on top of the kidneys, these glands secrete hormones such as adrenaline (epinephrine) and cortisol, which are involved in the stress response and salt balance, not basal metabolism regulation via thyroxine.
Pancreas: This is a mixed gland that secretes insulin and glucagon, which are primarily responsible for regulating blood glucose levels.

Key Takeaway

Thyroxine is secreted by the thyroid gland and is the primary hormone responsible for regulating the body's metabolism of carbohydrates, proteins, and fats.