All Free Biology MCQs with Answers

• A. Glucagon
• B. Cortisol
• C. Insulin
• D. Epinephrine

Explanation: Insulin decreases blood glucose by promoting glucose uptake and glycogen formation.

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

Explanation: The pituitary controls many other endocrine glands and is called the "master gland".

• A. Progesterone
• B. Prolactin
• C. Oxytocin
• D. Relaxin

Explanation: Oxytocin stimulates strong uterine contractions during labor and aids milk ejection.

• A. Somatotrophic Hormone
• B. Aldosterone Hormone
• C. Gonadotrophic Hormone
• D. Thyroxine Hormone

Explanation: Aldosterone is a steroid hormone. Its main role is to regulate salt and water in the body, thus having an effect on blood pressure.Growth hormone (GH), also called somatotropin or human growth hormone, is a peptide hormone secreted by the anterior lobe of the pituitary gland. It stimulates the growth of essentially all tissues of the body, including bone.Gonadotropins: Luteinizing and Follicle Stimulating Hormones. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are called gonadotropins because they stimulate the gonads - in males, the testes, and in females, the ovaries.Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.

• A. Phosphate
• B. Calcium
• C. Iodine
• D. Sodium

Explanation: Iodine is essential to maintain a healthy thyroid. Iodine is the critical 'ingredient' for the production of thyroid hormones.

• A. Aldosterone: Atrial Natriuretic Factor
• B. Relaxin: Inhibin
• C. Parathormone: Calcitonin
• D. Insulin: Glucagon

Explanation: Relaxin hormone is secreted by ovary and placenta during pregnancy, which relaxes ligaments in pelvis and softens and widens cervix during childbirth. Inhibin secreted by granulosa cells in the ovaries inhibits secretion of FSH by anterior pituitary. Thus, relaxin and inhibin have different functions and are not antagonistic.

• A. The sympathetic nervous system is activated releasing epinephrine and norepinephrine from the adrenal medulla
• B. Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.
• C. Hypothalamus activates the parasympathetic division of brain
• D. Sympathetic nervous system is activated releasing epinephrine and norepinephrine from the adrenal cortex.

Explanation: Hormones epinephrine and norepinephrine are secreted from the adrenal medulla. They are emergency hormones released in conditions of stress, emergency, etc. Epinephrine and norepinephrine are also released by adrenergic nerve fibres of the sympathetic nervous system, where they act as neurotransmitters.

• A. Biogenic amines only
• B. Proteins, steroids and biogenic amines
• C. Proteins only
• D. Steroids only

Explanation: Hormones are chemical messengers produced by the ductless glands (sometimes by neurons) and transported in the circulation to target cells. They regulate metabolic processes. Chemically, hormones are of different natures like biogenic amines (like thyroxine, adrenaline, etc), proteinaceous or polypeptides (like hypothalamic hormones, etc.), and steroids (like sex hormones and adrenocorticoids).

• A. Cortisone
• B. Cortisol
• C. Corticosterone
• D. Deoxycorticosterone

Explanation: Adrenal glands or (suprarenal glands) are two triangular endocrine glands, each of which covers the superior surface of a kidney. Each gland has two parts, the medulla and cortex. The medulla forms the grey core of the gland; it consists mainly of chromaffin tissue and is stimulated by the sympathetic nervous system to produce adrenaline and noradrenaline. The cortex is a yellowish tissue surrounding the medulla. It is stimulated by pituitary hormones (principally ACTH) to produce three kinds of corticosteroid hormones, which affect carbohydrate metabolism (e.g., cortisol), electrolyte metabolism (e.g., aldosterone), and the sex glands (oestrogens and androgens). Thus injury to adrenal cortex is not likely to affect the secretion of adrenaline.

• A. Adrenaline
• B. Glucagon
• C. Gastrin
• D. Thyroxine

Explanation: The correct answer is Adrenaline. This hormone is crucial during stressful situations, such as feeling the tremors of an earthquake, as it prepares the body for rapid physical action, which is essential for survival. Adrenaline enhances heart rate, increases blood flow to muscles, and facilitates quicker responses, which would enable a resident to climb down stairs rapidly.In contrast, Glucagon, Gastrin, and Thyroxine do not have immediate effects on the physical responses associated with stress. Glucagon is primarily involved in blood sugar regulation, Gastrin aids in digestion, and Thyroxine controls metabolic rate, making them irrelevant to the scenario described in the question.