All Free Biology MCQs with Answers

• A. Stimulates the pituitary gland to release GH
• B. Stimulates the liver to convert glycogen to glucose
• C. Stimulates the liver to store glucose
• D. Decreases sugar level in blood

Explanation: When the pituitary gland releases human growth hormone (GH), it primarily stimulates the liver to convert glycogen to glucose. This process, called glycogenolysis, provides a quick source of energy to meet the body's demands, especially during times of stress or exercise. This increased availability of glucose in the bloodstream helps to maintain blood sugar levels and provide energy for various physiological processes.

• A. It promotes glycogenolysis
• B. It inhibits gluconeogenesis
• C. It's under secretion causes glycosuria
• D. It's under secretion causes hypoglycemia

Explanation: Glucagon promotes glycogenolysis in liver cells, its primary target with respect to raising circulating glucose levels. This effect appears to be mediated through stimulation of adenylyl cyclase, production of intracellular cAMP, and activation of phosphorylase-a.

• A. A
• B. B
• C. C
• D. D

Explanation: Row D is mismatched.Vasopressin, also known as antidiuretic hormone (ADH), released from posterior pituitary regulates water balance by increasing water reabsorption in the kidneys and constricting blood vessels to regulate blood pressure. It's produced in the hypothalamus and released by the pituitary gland in response to changes in blood osmolarity or volume. Imbalances in vasopressin can lead to conditions like SIADH or diabetes insipidus.

• A. A
• B. B
• C. C
• D. D

Explanation: When we drink a sugar drink, pancreas release insulin to facilitate glucose uptake by cells for energy production and storage. Simultaneously, the liver converts glycogen to glucose via glycogenolysis, releasing glucose into the bloodstream to maintain blood sugar levels. This coordinated response ensures that excess glucose from the sugar drink is efficiently utilized by cells or stored for later use, helping to regulate blood glucose levels.

• A. Adrenaline
• B. Parathormone
• C. Insulin
• D. Aldosterone

Explanation: The steroids that are made almost exclusively in the adrenal glands are cortisol, 11-deoxycortisol, aldosterone, corticosterone, and 11-deoxycorti-costerone. Most other steroid hormones, including the estrogens, are made by the adrenal glands and the gonads

• A. Is released by sympathetic fibers
• B. Is released by parasympathetic fibers
• C. Decrease the heart rate
• D. Decrease blood pressure
• E. Released by sympathetic fibers and decreases blood pressure

Explanation: Norepinephrine, also known as noradrenaline, is a neurotransmitter and hormone released by sympathetic fibers of the autonomic nervous system. Its effects on the body include increasing heart rate, constricting blood vessels, and raising blood pressure.

• A. Estradiol
• B. Aldosterone
• C. Testosterone
• D. Prostaglandins
• E. Oestrogen

Explanation: Prostaglandins are lipid compounds derived from fatty acids that have various physiological functions in the body. They act as local hormones, influencing processes such as inflammation, pain perception, blood flow, and the regulation of blood pressure. Prostaglandins play a key role in the menstrual cycle, mediating uterine contractions, and are involved in the healing process by promoting inflammation. They are produced in response to injury or infection and have diverse effects depending on their specific types and the tissues in which they act.

• A. Option A: Thyroid gland - Insulin - Regulates blood sugar levels
• B. Option B: Adrenal gland - Estrogen - Regulates female reproductive system
• C. Option C: Testis - Testosterone - Develops male characteristics
• D. Option D: Pancreas - Thyroxine - Regulates metabolism

Explanation: Testis are produced by testosterone. The testes are the male reproductive glands that produce sperm for fertilization and the hormone testosterone. Testosterone is a crucial hormone that drives male sexual development, responsible for features like a deepened voice, muscle and body hair growth, and the development of male reproductive organs. It also supports adult male characteristics such as maintaining bone density, muscle mass, and libido.

• A. Anterior lobe of the pituitary
• B. Middle lobe of pituitary
• C. Posterior lobe of the pituitary
• D. Endostyle

Explanation: Option B is correct.The middle lobe of the pituitary secretes a hormone named melanocyte-stimulating hormone. It stimulates the synthesis of the black pigment melanin in the skin, and also causes dispersal of melanin granules in the pigment cells, thereby darkening the colour in certain animals (fish, amphibians). In man, it has no such role. The anterior lobe of the pituitary secretes FSH, LH, TSH, ACTH, and STH. The posterior lobe of the pituitary secretes oxytocin and vasopressin.

• A. Growth of body
• B. Body metabolism
• C. Glucose breakdown
• D. Heat production

Explanation: STH stands for Somatotropin, also known as Growth Hormone (GH), which is produced by the anterior pituitary gland. It stimulates growth of the body by promoting cell division, increasing cell size, and encouraging the development of bone and muscle tissue.