Free Chemical Coordination and Hormones MCQs with Answers

1. Which organ produces insulin in the human body?

• A. Liver
• B. Pancreas
• C. Thyroid gland
• D. Adrenal gland

Explanation: Insulin is produced by the beta cells of the islets of Langerhans in the pancreas, and it lowers blood glucose. The alpha cells of the same islets produce glucagon, which raises it.

2. Insulin lowers the concentration of glucose in the blood by

• A. converting glycogen in the liver into glucose
• B. increasing the uptake of glucose by cells and its storage as glycogen in the liver and muscle
• C. increasing the excretion of glucose in the urine
• D. stopping the digestion of carbohydrate in the gut

Explanation: Insulin from the beta cells of the islets of Langerhans makes cell membranes more permeable to glucose and stimulates the enzymes that build glycogen, so glucose leaves the blood. Glucagon from the alpha cells does the opposite, breaking glycogen down when blood glucose falls, and the two hormones form a negative feedback pair. Glucose in the urine is a symptom of untreated diabetes, not the way the hormone works.

3. A person whose diet lacks iodine may develop a goitre because

• A. iodine is needed to make insulin
• B. iodine destroys the thyroid gland directly
• C. the thyroid cannot make enough thyroxine and enlarges under continued stimulation by the pituitary
• D. excess iodine accumulates in the neck

Explanation: Thyroxine contains iodine, so a shortage means output falls, and the low blood level removes the negative feedback on the pituitary, which keeps releasing thyroid stimulating hormone until the gland swells visibly. This is why iodised salt is used to prevent goitre in areas where the soil is deficient. Insulin is made in the pancreas and contains no iodine at all.

4. Which of the following is NOT an effect of adrenaline?

• A. Increased heart rate
• B. Conversion of glycogen to glucose in the liver
• C. Dilation of the bronchioles
• D. Increased peristalsis and secretion in the gut

Explanation: Adrenaline prepares the body for fight or flight, so it diverts blood and resources to the heart, muscles and lungs and slows digestion rather than speeding it up. Raising heart rate, releasing glucose for respiration and widening the airways all fit that pattern, which is the quickest way to answer this kind of question. It is secreted by the adrenal medulla and acts within seconds.

5. The master endocrine gland is the

• A. Thyroid
• B. Adrenal
• C. Pituitary
• D. Pancreas

Explanation: The pituitary gland is called the master gland because its hormones regulate other endocrine glands.

6. Insulin is produced by

• A. Alpha cells
• B. Beta cells
• C. Delta cells
• D. Acinar cells

Explanation: Beta cells of the pancreatic islets produce insulin in response to high blood glucose.

7. Thyroid hormones regulate

• A. Only growth
• B. Basal metabolic rate
• C. Only blood pressure
• D. Only digestion

Explanation: T3 and T4 regulate basal metabolic rate (BMR), growth, development, and body temperature.

8. Cortisol is produced by

• A. Adrenal medulla
• B. Adrenal cortex
• C. Anterior pituitary
• D. Thyroid

Explanation: Cortisol (a glucocorticoid) is produced by the adrenal cortex, especially in response to stress.

9. The posterior pituitary releases

• A. GH and TSH
• B. ADH and oxytocin
• C. ACTH and FSH
• D. Prolactin and LH

Explanation: The posterior pituitary stores and releases ADH and oxytocin, which are produced in the hypothalamus.

10. Goiter is caused by

• A. Excess iodine
• B. Iodine deficiency
• C. Excess calcium
• D. Vitamin D deficiency

Explanation: Iodine deficiency causes goiter (enlarged thyroid) as the gland tries to compensate for insufficient T3/T4 production.