All Free Biology MCQs with Answers

• A. Adrenocorticotropic hormone
• B. Insulin and glucagon
• C. Epinephrine and nor-epinephrine
• D. Aldosterone

Explanation: Based on the explanations provided, the correct answer to the question is option C) Epinephrine and nor-epinephrine.

• A. Nociceptors respond to changes in pressure
• B. Meissner's corpuscles are thermoreceptors
• C. Photoreceptors in the human eye are depolarised during darkness and become hyperpolarised in response to the light stimulus
• D. Receptors do not produce graded potentials.

Explanation: Photoreceptors in the human eye are unique because they are the only type of sensory cells that are relatively depolarised (about -35mV)…

• A. Only rods are present
• B. More rods than cones are found
• C. High density of cones occur, but has no rods
• D. Equal number of rods and cones

Explanation: A small oval, yellowish area of the retina lying exactly opposite to the centre of the cornea is named the macula lutea or yellow spot…

• A. Retinal is the light absorbing portion of visual photo pigments.
• B. In the retina, the rods have the photopigment rhodopsin while cones have three different photopigments.
• C. Retinal is a derivative of vitamin C
• D. Rhodopsin is the purplish red protein present in rods only

Explanation: The retinal pigment is an aldehyde of vitamin A.

• A. Glutamic acid
• B. Acetylcholine
• C. Gamma aminobutyric acid (GABA)
• D. Dopamine

Explanation: Alzheimer's disease is a neurological disease characterized by progressive loss of intellectual ability.

• A. Neurolemma is discontinuous
• B. Myelin sheath is discontinuous
• C. Both neurilemma and myelin sheath are discontinuous.
• D. It is covered by the myelin sheath

Explanation: At the level of the node of Ranvier, the myelin sheath is discontinuous but not the neurilemma lining.

• A. OPTION A
• B. OPTION B
• C. OPTION C
• D. OPTION D

Explanation: Interstitial cells (or Leydig 's cells) are the cells interspersed between the seminiferous tubules of the testis.

• A. Glucagon is secreted by the b-­cells of islets of Langerhans and stimulates glycogenolysis.
• B. Secretion of thymosins is stimulated with aging
• C. In females, FSH first binds with specific receptors on ovarian cell membrane
• D. FSH stimulates the secretion of estrogen and progesterone.

Explanation: Hormone action involves their reception by target cells. Specific proteins called hormone receptors that are located in target tissues…

• A. Cortisone
• B. Cortisol
• C. Corticosterone
• D. 11­deoxycorticosterone

Explanation: Adrenal glands or (suprarenal glands) are two triangular endocrine glands, each of which covers the superior surface of a kidney.

• A. Endocrine glands regulate the neural activity but not vice versa
• B. Neurons regulate endocrine activity, but not vice versa
• C. Endocrine glands regulate neural activity, and nervous system regulates endocrine glands.
• D. Neither hormones control neural activity nor the neurons control endocrine activity

Explanation: The endocrine system links the brain to the organs that control body metabolism, growth and development, and reproduction.

• A. Chemoreceptors
• B. Photoreceptors
• C. Mechanorcceptors
• D. Thermoreceptors

Explanation: Mechanoreceptors are in the skin and on other organs that detect sensations of touch.

• A. Microglia
• B. Oligodendrocytes
• C. Astrocytes
• D. Schwann's cell

Explanation: Some cells are attached with the neurons, along the length of axon that are specialized for the production of myclim sheath; these are…

• A. Na+ into the axon and K+ out of the axon
• B. K+ into the axon and Na+ out of the axon
• C. Na+ and K+ within the axon toward the axon terminal
• D. None of these

Explanation: Due to opening of sodium gates, sodium ions move inward the neuron to cause depolarization.

• A. Glucagon secretion to stop and a decrease in blood glucose
• B. Decrease in calcium secretion from bones into blood.
• C. Insulin secretion to stop and an increase in blood glucose
• D. Insulin secretion to stop and a decrease in blood glucose

Explanation: Beta cells have no relation with calcium regulation.

• A. Hyperthyroidism
• B. Over production of STH
• C. Over production of adrenal cortex
• D. Over production of adrenal medulla

Explanation: aggressive behavior is most closely associated with overproduction of adrenal medulla hormones

• A. Addison's disease
• B. Cushing's disease
• C. Failure to cope stress
• D. Tay-Sach's disease

Explanation: Tay-Sachs disease is a specific disease that is not caused by adrenal cortical abnormality.

• A. Brain
• B. Hypothalamus
• C. Spinal cord
• D. Pituitary gland

Explanation: Reflex actions below the neck are primarily under the control of the "spinal cord".

• A. Digestion of food
• B. Accelerated heart beat
• C. High metabolism
• D. Rapid muscle movement

Explanation: Yes, the parasympathetic nervous system stimulates digestive activities.

• A. Addison's
• B. Alzheimer's
• C. Parkinson's
• D. Cushing's

Explanation: Yes, Addison's disease can be associated with excess secretion of melanocyte-stimulating hormone (MSH).

• A. lodopsin glands
• B. Thyroid gland
• C. Rhodopsin glands
• D. Pituitary glands

Explanation: The pituitary gland is indeed a small, pea-sized gland located at the base of the brain, just below the hypothalamus, to which it is…