Explore topic-wise MCQs in Biology.

This section includes 697 Mcqs, each offering curated multiple-choice questions to sharpen your Biology knowledge and support exam preparation. Choose a topic below to get started.

601.

All of the following factors inhibit renin secretion EXCEPT:

A. prostaglandins
B. angiotensin II
C. vasopressin
D. increased afferent arteriolar pressure
E. increased Na+ and Cl- reabsorption across the macular densa
Answer» B. angiotensin II
Discussion
602.

With regard to pain pathways, all the following are true EXCEPT:

A. peripheral afferents are transmitted along A (delta) and C fibres
B. an intact cerebral cortex is necessary for pain sensation
C. the synaptic transmitter released by primary afferent fibres subserving pain is substance P
D. afferent fibres subserving pain sensation from viscera reach the CNS by both sympathetic and parasympathetic pathways
E. the sensory organs for pain are marked nerve endings
Answer» C. the synaptic transmitter released by primary afferent fibres subserving pain is substance P
Discussion
603.

Regarding calcium metabolism:

A. the adult human body contains 15% of its body mass as calcium
B. calcium is passively absorbed from the intestinal brush border
C. oestrogen inhibits osteoclasts
D. TNF inhibits osteoclasts
E. corticosteroids stimulate osteoblasts
Answer» D. TNF inhibits osteoclasts
Discussion
604.

Regarding the role of vitamin D in calcium metabolism, which of the following is INCORRECT?

A. it increases renal tubular calcium and phosphate reabsorption
B. it causes an increase in synthesis of calcium-binding protein
C. it increases bone resorption
D. it decreases bone formation
E. it increases intestinal calcium and phosphate absorption
Answer» E. it increases intestinal calcium and phosphate absorption
Discussion
605.

With regard to chemoreceptors, all of the following are true EXCEPT:

A. the medullary chemoreceptors respond to a change in blood pCO2
B. the medullary chemoreceptors respond to blood (H+)
C. the predominant peripheral chemoreceptors are located in the carotid and aortic bodies
D. the peripheral chemoreceptors respond to pO2
E. the peripheral chemoreceptors respond to blood (H+)
Answer» C. the predominant peripheral chemoreceptors are located in the carotid and aortic bodies
Discussion
606.

Which of the following nerve fibre types has the LARGEST diameter?

A. C
B. A-alpha
C. B
D. A-gamma
E. A-beta
Answer» C. B
Discussion
607.

Which of the following nerve fibre types is MOST sensitive to pressure?

A. A-beta
B. A-gamma
C. A-delta
D. B
E. C
Answer» B. A-gamma
Discussion
608.

Which of the following nerve fibre types represents the efferent limb of the muscle spindle reflex arc?

A. A-alpha
B. A-beta
C. A-gamma
D. A-delta
E. B
Answer» D. A-delta
Discussion
609.

In a resting adult, the kidneys receive how much of the cardiac output?

A. 15%
B. 20%
C. 25%
D. 30%
E. 35%
Answer» D. 30%
Discussion
610.

Which of the following nerve fibre types has the fastest conduction velocity?

A. B
B. A-delta
C. A-beta
D. A-gamma
E. C
Answer» D. A-gamma
Discussion
611.

Regarding nerve action potential, which is TRUE?

A. normal resting membrane potential is -40mV
B. initial rapid depolarisation is due to rapid influx of Ca2+ via fast channels
C. during depolarisation, Na+ permeality is greater than K+ permeality
D. hyperpolarisation is due to continuous opening of Na+ channels
E. plateau is formed by slow Ca2+ channels
Answer» D. hyperpolarisation is due to continuous opening of Na+ channels
Discussion
612.

Regarding blood pressure, which is TRUE?

A. M.A.P. = pulse pressure / 2 + diastolic pressure
B. elastance increases progressively with age
C. increase in arterial blood pressure causes a subsequent increase in stroke volume
D. increased sympathetic stimulation may sometimes lead to decreased cardiac output
E. pulse pressure increases with age because of decreased arterial elastance
Answer» C. increase in arterial blood pressure causes a subsequent increase in stroke volume
Discussion
613.

In visceral smooth muscle:

A. Ca2+ for contraction is released from sarcoplasmic reticulum
B. membrane potential has a resting value of -90mV
C. the excitation contraction coupling time is rapid (<10ms)
D. muscle contracts when stretched in absence of innervation
E. binding of acetylcholine to nicotine receptors increases Ca2+ influx
Answer» E. binding of acetylcholine to nicotine receptors increases Ca2+ influx
Discussion
614.

Regarding the kidney:

A. glucose is reabsorbed mainly in distal tubule
B. normal GFR is 125ml/hour
C. glomeruli filter 180L fluid per day
D. Na+ is actively transported out of think loop of Henle
E. ethanol promotes vasopressin secretion
Answer» D. Na+ is actively transported out of think loop of Henle
Discussion
615.

Concerning the respiratory exchange ration (R)

A. it falls during exercise
B. it falls in metabolic acidosis
C. the stomach has a positive R during secretion of acid
D. it rises after ingestion of alkali
E. at steady state, it equals the respiratory quotient
Answer» F.
Discussion
616.

Glucose reabsorption occurs in the:

A. proximal tubule
B. loop of Henle
C. distal tubule
D. cortical collecting system
E. medullary collecting system
Answer» B. loop of Henle
Discussion
617.

With regard to gastric acid secretion, all the following are true EXCEPT:

A. acetylcholine stimulates secretion
B. both G protein and direct calcium channels are involved
C. an H+ - K+ antiport transports H+ into the gastric lumen
D. parietal cells have high levels of carbonic anhydrase
E. acid secretion is maintained at constant levels by local feedback mechanisms
Answer» F.
Discussion
618.

The following physiological events that occur in the body are listed in random sequence:a. decreased CSF pHb. increased PaCO2c. increased CSF PCO2d. stimulation of medullary chemoreceptorse. increased PACO2What is the usual sequence?

A. a, b, c, d, e
B. d, a, c, b, e,
C. c, d, e, b, a,
D. e, b, c, a, d,
E. e, c, b, d, a
Answer» E. e, c, b, d, a
Discussion
619.

Regarding fat metabolism, all are true EXCEPT:

A. brown fat is characterised by a H+ short circuit protein in the mitochondria
B. heparin is a cofactor for lipoprotein lipase
C. ketone bodies accumulate in diabetic ketoacidosis due to reduced removal from the circulation
D. the essential fatty acids are used to produce autocoids
E. there is no major pathway for converting fat to carbohydrate
Answer» E. there is no major pathway for converting fat to carbohydrate
Discussion
620.

The following are true of chylomicrons EXCEPT:

A. they are large lipoprotein complexes
B. they are part of the exogenous lipid transport system
C. they enter the circulation via the lymphatic ducts
D. they are cleared from the circulation by lipoprotein lipase on the surface of hepatocytes
E. chylomicron remnants are bound to LDL R and endocytosed
Answer» E. chylomicron remnants are bound to LDL R and endocytosed
Discussion
621.

Respiratory peripheral chemoreceptors:

A. carotid bodies respond to PO2, PCO2, and pH
B. peripheral chemoreceptor response to arterial PCO2 is more important than central chemoreceptor response
C. aortic bodies are located within the aortic valve ring
D. drop in PO2 < 100mmHg causes increase in firing rate
E. carotid bodies respond to venous PO2
Answer» E. carotid bodies respond to venous PO2
Discussion
622.

Central respiratory chemoreceptors:

A. are located in the medulla near exit of cranial nerve X, XI
B. respond directly to changes in external PCO2
C. respond directly to changes in arterial PO2
D. are located on dorsal surface of medulla
E. respond to pH of CSF
Answer» F.
Discussion
623.

Regarding the nerve fibre action potential, which statement is INCORRECT?

A. does not involve calcium ions
B. after-depolarisation commences when repolarisation is 70% complete
C. total number of ions involved is minute compared to the total number present
D. spike potential peaks at sodium equilibrium potential
E. firing level (threshold) is at about -55mV
Answer» E. firing level (threshold) is at about -55mV
Discussion
624.

Regarding tubular function:

A. 90% of the water is absorbed by the proximal convoluted tubule
B. renal threshold for glucose is 300mg/dl
C. the main mechanism of the Na reabsorption from the tubular fluid to proximal convoluted tubule is via Na/K/ATP a pump
D. the main mechanism of Na absorption in the ascending loop of Henle is via cotransport of Na/K/2Cl:
E. collecting duct
Answer» E. collecting duct
Discussion
625.

Regarding membrane potential:

A. it is only found in nervous tissue
B. Na+/K+ pump does not contribute to the membrane potential
C. its magnitude does not change from tissue to tissue
D. the membrane potential is negative inside in relation to the outside
E. it is mainly caused by leaking Na+/K+ channels
Answer» E. it is mainly caused by leaking Na+/K+ channels
Discussion
626.

Regarding the resting membrane potential in peripheral nerves:

A. membrane permeability of potassium ions via K+ leak channels produces the resting potential
B. a decrease in extracellular Ca2+ decreases excitability
C. decreasing external Na+ concentration lowers the resting membrane potential
D. changing the external Na+ concentration has no effect on the action potential
E. decreasing the external K+ concentration increases the resting membrane potential
Answer» B. a decrease in extracellular Ca2+ decreases excitability
Discussion
627.

With respect to blood volume:

A. the greater proportion is present in the arterial system
B. the pulmonary vessels contain 50%
C. the systemic capillaries and arterioles contain 7%
D. the heart contains 20%
E. the aorta contains 20%
Answer» D. the heart contains 20%
Discussion
628.

Which of the following does not decrease smooth muscle membrane potential?

A. acetylcholine
B. stretch
C. cold
D. noradrenaline
E. parasympathetic stimulation
Answer» E. parasympathetic stimulation
Discussion
629.

Smooth muscles differ from skeletal muscle by:

A. not having actin/myosin
B. not having striated appearance
C. not using ATP for contraction
D. not using Ca2+ for contraction
E. not having sarcoplasmic reticulum
Answer» C. not using ATP for contraction
Discussion
630.

Regarding tubular reabsorption in kidney:

A. glucose and amino acids passively reabsorbed
B. Cl- mainly actively reabsorbed
C. only passive reabsorption occurs in proximal tubule
D. urea is not passively reabsorbed
E. Na+ actively reabsorbed in most parts of tubule
Answer» F.
Discussion
631.

Regarding basic physiological measures all of the following are true EXCEPT

A. Osmolarity is the number of osmoles / litre of solution
B. PH is the log to base 10 of the reciprocal of hydrogen ion concentration
C. Carbon has a molecular mass of 12 dalton
D. Osmolarity is measured by freezing point depression
E. One equivalent of sodium is 23 g/l
Answer» E. One equivalent of sodium is 23 g/l
Discussion
632.

Regarding insulin, which statement is INCORRECT?

A. it consists of two polypeptide chains linked by two disulphide bridges
B. the majority of exogenous insulin is metabolised by the liver
C. it is not the only molecule responsible for insulin-like activity in the blood
D. it increases intracellular potassium concentration
E. exercise increases the affinity of its receptors for insulin
Answer» C. it is not the only molecule responsible for insulin-like activity in the blood
Discussion
633.

All of the following are true regarding chylomicrons EXCEPT:

A. they contain triglycerides, cholesterol and phospholipids
B. they are formed in the intestinal mucosa
C. they are cleared from the circulation by lipoprotein lipase
D. they are transported to the liver by the portal circulation
E. large numbers after a meal give the plasma a milky appearance
Answer» E. large numbers after a meal give the plasma a milky appearance
Discussion
634.

Regarding the comparison of ECF with CSF all of the following are true EXCEPT

A. CSF has less protein
B. CSF has lower osmolality
C. CSF has lower pH
D. CSF has more bicarbonate
E. CSF has lower specific gravity
Answer» C. CSF has lower pH
Discussion
635.

Regarding the action of insulin on adipose tissue, which of the following is INCORRECT?

A. it induces lipoprotein lipase which actively hydrolyses triglyceride from circulating lipoproteins
B. it reduces circulating free fatty acids
C. it promotes triglyceride storage in adipocytes
D. it directly inhibits intracellular lipase
E. its effects appear to involve phosphorylation of lipases
Answer» F.
Discussion
636.

The functions of tropomyosin in skeletal muscle include:

A. releasing Ca2+ after an action potential
B. sliding on actin to produce shortening
C. binding to myosin during contraction
D. acting as a relaxing protein at rest by covering up the sites where myosin binds to actin
E. generating ATP which passes to the contractile mechanism
Answer» E. generating ATP which passes to the contractile mechanism
Discussion
637.

Which respiratory volume is INCORRECT?

A. tidal volume is the normal breathing volume
B. vital capacity is the volume from maximal inspiration followed by maximal expiration
C. residual volume is the volume remaining in lungs after maximal expiration
D. functional residual capacity is the volume after normal inspiration
E. total lung capacity is the vital capacity plus residual volume
Answer» E. total lung capacity is the vital capacity plus residual volume
Discussion
638.

Thyroxine (T4):

A. secretion is regulated by positive feedback at the hypothalamus
B. is transported principally by albumin in the blood
C. causes increased LDLD in plasma
D. is physiologically more active than T3
E. increases receptors in the cardiovascular system
Answer» F.
Discussion
639.

At which site does tubular fluid osmolality exceed that of plasma by the greatest amount?

A. proximal tubule
B. thin limb of loop of Henle
C. thick limb of loop of Henle
D. distal tubule
E. collecting duct
Answer» C. thick limb of loop of Henle
Discussion
640.

Regarding exercise, which statement is INCORRECT?

A. the energy cost of breathing is up to 10% of total energy expenditure
B. total pulmonary ventilation increases by up to 20 fold
C. total oxygen consumption increases by up to 20 fold
D. total carbon dioxide production increases by up to 40 fold
E. P5O increases
Answer» B. total pulmonary ventilation increases by up to 20 fold
Discussion
641.

Regarding the action of insulin on the liver, which of the following is INCORRECT?

A. it increases gluconeogenesis
B. it decreases glycogenolysis
C. it increases synthesis of triglyceride and VLDL
D. it decreases cyclic AMP
E. it increases phosphate uptake
Answer» B. it decreases glycogenolysis
Discussion
642.

ECF volume can be estimated using:

A. inulin
B. D2O
C. Evan s blue
D. radioactive chromium
E. iron isotopes
Answer» B. D2O
Discussion
643.

In exercise:

A. oxygen consumption is about 6L/min in a moderately fit subject
B. the respiratory exchange ratio rises to 0.8
C. diffusing capacity increases 3-fold
D. the change in cardiac output is only about a sixth of the increase in ventilation
E. the oxygen dissociation curve moves to the left
Answer» D. the change in cardiac output is only about a sixth of the increase in ventilation
Discussion
644.

Regarding cell membrane, which of the following is FALSE?

A. the diameter of the cell membrane is about 7.5nm
B. 50% of the cell membrane is made up of proteins
C. the main lipids of the cell membrane are phospholipids
D. the hydrophilic ends of the lipid molecules are faced towards the interior of the cell membrane
E. the proteins in the cell membrane function as carriers, ion channels, enzymes and receptors
Answer» E. the proteins in the cell membrane function as carriers, ion channels, enzymes and receptors
Discussion
645.

Which of the following does NOT stimulate insulin secretion?

A. acetoacetate
B. glucagon
C. hypokalaemia
D. acetylcholine
E. theophylline
Answer» D. acetylcholine
Discussion
646.

Action potentials in skeletal muscle:

A. travel along muscle fibres at varying rates
B. have larger retratory periods compared to nerves
C. causes uptake of Ca++ into sacroplasmic reticulum
D. results in sustained contraction of muscle fibres
E. the haploid human genome is made up of 3 X 106 base pairs
Answer» C. causes uptake of Ca++ into sacroplasmic reticulum
Discussion
647.

Where does glucose reabsorption occur?

A. proximal convoluted tubule
B. thin descending limb of loop of Henle
C. thick ascending limb of loop of Henle
D. distal convoluted tubule
E. collecting duct
Answer» B. thin descending limb of loop of Henle
Discussion
648.

Regarding skeletal muscle, which is FALSE?

A. metabolic rate of muscle may increase 100 times in maximal activity
B. muscle cells can be excited chemically, mechanically and electrically, to produce action potentials in the cell membrane
C. actin is a myosin-binding protein which is a molecular motor, converting ATP energy to monomers
D. mitochondria are packed in between myofibrils
E. T tubules occur over the junction of I and A bands
Answer» D. mitochondria are packed in between myofibrils
Discussion
649.

Regarding the action of insulin in skeletal muscle, which of the following is INCORRECT?

A. it decreases protein catabolism
B. it induces glucogen synthase
C. it decreases ketone uptake
D. it increases amino acid uptake
E. it decreases the release of gluconeogenic amino acids
Answer» D. it increases amino acid uptake
Discussion
650.

Regarding the proximal tubule, the following statements are true EXCEPT:

A. sodium is co-transported out of the tubule with glucose
B. sodium is actively transported into the intercellular spaces by Na-K-ATPase
C. the cells are characterised by a brush border and tight junctions
D. vasopressin increases the permeability to water by causing the rapid insertion of water channels into the luminal membrane
E. water moves passively out of the tubule along osmotic gradients
Answer» E. water moves passively out of the tubule along osmotic gradients
Discussion