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.

51.

Regarding the hypothalamus:

A. it has neural connections with the anterior pituitary gland
B. it integrates the vomiting reflex
C. the anterior hypothalamus responds to cold
D. it controls circadian rhythms via the supraoptic nuclei
E. it has osmoreceptors in the anterior hypothalamus to stimulate thirst and vasopressin release
Answer» C. the anterior hypothalamus responds to cold
Discussion
52.

GABA:

A. decreases Cl- conductance
B. is broken down by glutamate decarboxylase (GA????)
C. there are five receptor subtypes
D. benzodiazepines bind to the subunit of the GABA receptor
E. is involved in 20% of CNS synapses
Answer» F.
Discussion
53.

Regarding acetylcholine:

A. it is oxidised to choline and acetate by acetylcholinesterase
B. nicotinic receptors are blocked by atropine
C. it is the main excitatory transmitter in the spinal cord
D. it is secreted by the adrenal medulla
E. tetanus blocks its release at the NMJ
Answer» F.
Discussion
54.

Regarding isometric ventricular reaction:

A. it occurs late in diastole
B. ventricular filling occurs
C. intraventricular pressure remains constant during this phase
D. it ends when the AV valve close
E. it ends when the AV valve open
Answer» F.
Discussion
55.

Transmitters all are true EXCEPT:

A. angiotensin II is a neurotransmitter of the polypeptidillars
B. glutamate is an inhibitory amino acid
C. glucagons is found in hypothalamus and retina
D. vasopressin is found in posterior pituitary, medulla, spinal cord
E. serotonin is an amine
Answer» C. glucagons is found in hypothalamus and retina
Discussion
56.

Local vasoconstriction results from:

A. increased potassium concentration
B. increased magnesium concentration
C. increased sodium concentration
D. decrease in pH
E. increased calcium concentration
Answer» F.
Discussion
57.

Glomeruli:

A. minimally filters protein, so plasma protein concentration is not altered
B. are supplied by an extensive anastomotic arterial network
C. lie distal to the juxtaglomerular apparatus
D. each receive approximately 20-25% of resting cardiac output
E. do not filter appreciable albumin since membrane pores are too small
Answer» D. each receive approximately 20-25% of resting cardiac output
Discussion
58.

Regarding sound and hearing:

A. high pitched sounds are detected at the apex of the cochlear
B. Harr cells are bathed in endolymph
C. defected by hair cells found within the tectorium membrane
D. 95% of afferent neurones outer ??? cells
E. supplied by retinal vessels
Answer» F.
Discussion
59.

Lymph flow is:

A. an average 500ml/hr into the circulation
B. proportional to interstitial fluid pressure
C. increased with decreased interstitial fluid protein
D. decreased with contraction of muscles
E. decreased with elevated capillary pressure
Answer» C. increased with decreased interstitial fluid protein
Discussion
60.

Regarding neurotrophins:

A. NGF and BDNF share the same receptor
B. the structure of the subunit of NGF resembles that of insulin
C. CNTF is necessary for the growth and maintenance of sympathetic neurons
D. disruption of GDNF by gene knockout causes a marked loss of cutaneous mechanoreceptors
E. none of the above are true
Answer» C. CNTF is necessary for the growth and maintenance of sympathetic neurons
Discussion
61.

Hyperaldosteronism:

A. causes low plasmic Na+ and high H+
B. retains acid H+ ions and can cause acidosis
C. doesn t cause oedema due to the escape phenomenon
D. may cause hypocalcaemic nephropathy
E. may be caused by high sodium intake
Answer» D. may cause hypocalcaemic nephropathy
Discussion
62.

Ionic:

A. movement across an impermeable membrane occurs due to an osmotic gradient
B. equilibrium potential can be determined using the Nernst equation
C. movement across the capillary wall is not affected by the Donnan effect
D. valency determines osmotic effect in an ideal solution
E. forms of weak acids cross cell membranes easily
Answer» C. movement across the capillary wall is not affected by the Donnan effect
Discussion
63.

More on muscles; which is TRUE?

A. skeletal muscle cells act as syncytram, though intercellular communications
B. some skeletal muscles are not subject to voluntary control
C. smooth muscle contains regularly discharging pacemaker
D. a variant of smooth muscle is found in the eye, which resembles skeletal muscle
E. cardiac muscle does not contain regular striation
Answer» E. cardiac muscle does not contain regular striation
Discussion
64.

More on muscles; which is FALSE?

A. T tubules are extensions of extracellular space
B. cystems of SR are in contact with T-tubules
C. myosin molecules combine to form thick filaments while actin, tropomyosin, and the troponins the t ..
D. an individual muscle cell is a myofibril, containing myofilaments
E. the sarcolemnia transmits action potentials
Answer» E. the sarcolemnia transmits action potentials
Discussion
65.

In regard to plasma volume:

A. it contributes to 10% of body weight
B. can easily be measured by radioisotope chromium
C. if the plasma volume is known, the blood volume can be calculated by multiplying100-HCT/100
D. measured by injecting Evans blue
E. the average plasma volume is 500ml
Answer» E. the average plasma volume is 500ml
Discussion
66.

Regarding HDL:

A. HDL transports ingested cholesterol from the intestine
B. HDL transports triglycerides from peripheral tissues
C. HDL receptors on macrophages are called scavenger receptors
D. elevated HDL levels are associated with increased risk of atherosclerosis
E. none of the above are correct
Answer» D. elevated HDL levels are associated with increased risk of atherosclerosis
Discussion
67.

Regarding neurotransmitters, which of the following is INCORRECT?

A. glutamate is excitatory
B. GABA is inhibitory at presynaptic neurons
C. glycine is excitatory at postsynaptic neurons
D. GHB (gamma hydroxybutyrate) is inhibitory
E. aspartate is excitatory
Answer» D. GHB (gamma hydroxybutyrate) is inhibitory
Discussion
68.

Neurotransmitters:

A. atropine blocks effect of acetylcholine at ???? receptor
B. reaction between active acetate and choline is catalysed by acetylcholinesterase
C. nicotinic cholinergic receptors are serpentine receptors
D. the rate limiting step in synthesis of NOVA is ?????(concussion) of tyrosine to dopa
E. MAOA is found in nerve endings and platelets
Answer» E. MAOA is found in nerve endings and platelets
Discussion
69.

Regarding mitochondria, which of the following is TRUE?

A. 99% of mitochondrial proteins are products of mitochondrial DNA
B. the outer membrane of the mitochondria is folded to form cristae
C. the space between the outer and inner mitochondrial space is called matrix space
D. it is the sperm which contributes to the formation of mitochondria in the zygote
E. the synthesis of ATP in the mitochondria is triggered by diffusion of H+ from matrix to intracristal space
Answer» F.
Discussion
70.

Ubiquitin is:

A. an essential amino acid
B. a polypeptide that tags proteins for degradation
C. a cell membrane glycoprotein
D. a precursor or uric acid
E. none of the above
Answer» C. a cell membrane glycoprotein
Discussion
71.

Which of the following enzymes are missing in the zona glomerulosa?

A. 17 hydroxylase
B. 11 hydroxylase
C. 21 hydroxylase
D. cholesterol desmolase
E. 3 hydroxysteroid
Answer» B. 11 hydroxylase
Discussion
72.

Creatinine:

A. is synthesised in the liver from methionine, glycine and anganine
B. is converted directly to creatine
C. has variable excretion from day to day
D. creatinuria occurs normally in the elderly and in pregnant women
E. all of the above
Answer» E. all of the above
Discussion
73.

Regarding mitochondria:

A. genome inheritance is strictly maternal
B. the citric acid cycle occurs at the outer membrane
C. the space between the two membranes is called the matrix
D. the mutation rate for mitochondrial DNA is less than for nuclear DNA
E. involutions of the outer membrane are called cristae
Answer» B. the citric acid cycle occurs at the outer membrane
Discussion
74.

What percentage of body weight is plasma?

A. 2%
B. 5%
C. 8%
D. 15%
E. 20%
Answer» C. 8%
Discussion
75.

Regarding cellular components:

A. peroxisomes are larger than lysosomes
B. pH of lysosomes is higher than the rest of the cytoplasm
C. microfilaments are hollow
D. myosin 1 molecules are characteristically found in muscle cells
E. microfilaments are made up of actin
Answer» F.
Discussion
76.

For neurotransmitters, which is TRUE?

A. acetylcholine is synthesised by true cholinesterase
B. atropine blocks muscarinic cholinergic receptors
C. catecholamines are formed from VMA (vanillylmandelic acid)
D. adrenaline has a higher affinity for rather than adrenergic receptors
E. dopamine is formed by COMT from tryptophan
Answer» C. catecholamines are formed from VMA (vanillylmandelic acid)
Discussion
77.

For the genome, which is TRUE?

A. the human genome encodes 3 X 109 genes
B. adenine binds to cytosine and guanine to thymine
C. uracil replaces thymine in RNA
D. 3% of DNA are introns
E. haploid DNA in germ cells is single stranded
Answer» D. 3% of DNA are introns
Discussion
78.

For mitochondria, which is TRUE?

A. NADH-DH, 5DH, bc, cox synthesise ATP
B. the matrix is between the inner and outer mitochondrial DNA
C. mitochondrial DNA is not transmitted paternally
D. 99% of mitochondrial proteins are encoded by mitochondrial DNA
E. ATP synthetase is powered by an electron gradient
Answer» D. 99% of mitochondrial proteins are encoded by mitochondrial DNA
Discussion
79.

In muscle construction, which is TRUE?

A. only contraction is energy requiring, not relaxing
B. sequestering of Ca2+ causes separation of actin-myosin bands and muscle relaxation
C. ATPase clefts are on the tips of the myosin beads
D. ryanodine receptors are voltage gated Ca2+ chains
E. Troponin T inhibits the interaction of actin and myosin
Answer» C. ATPase clefts are on the tips of the myosin beads
Discussion
80.

The golgi apparatus, which is TRUE?

A. is found only in secretory cells
B. vesicles containing newly synthesised proteins bind to trans side of the apparatus
C. constitutive pathway of cell secretion is responsible for further processing and storage of proteins
D. is responsible for glycorylation of proteins
E. none of the above
Answer» F.
Discussion
81.

Bone:

A. osteoblasts are multinucleate
B. osteoclasts attach to bone via integins
C. compact bone makes up 60% of a long bone
D. osteoblasts secrete large quantities of type IV collagen and other bone matrix proteins
E. oestrogens inhibit osteoblasts and stimulate osteoclasts
Answer» C. compact bone makes up 60% of a long bone
Discussion
82.

Which of the following is NOT a purine?

A. adenine
B. cytosine
C. guanine
D. hypoxanthine
E. xanthine
Answer» C. guanine
Discussion
83.

Regarding plasma protein, all of the following are correct EXCEPT:

A. albumin, globulin and fibrinogen constitute the major plasma proteins in the plasma
B. the fibrinogen polymerises into long fibrin threads during blood coagulation
C. the principal function of albumin is to provide colloid osmotic pressure in the plasma
D. the majority of plasma proteins are formed in the lymphoid tissue
E. rapid loss of plasma proteins may occur during severe burns
Answer» E. rapid loss of plasma proteins may occur during severe burns
Discussion
84.

Creatinine appears in the urine in significant amounts in all of the following EXCEPT:

A. normal men
B. thyrotoxicosis
C. post-partum
D. poorly controlled diabetes mellitus
E. children
Answer» B. thyrotoxicosis
Discussion
85.

Regarding free fatty acids, which statement is INCORRECT?

A. circulate in plasma bound to globulin
B. they are the major source of energy for cardiac muscle
C. combine with glycerol to form the triglyceride of neutral fat
D. contain an even number of carbon atoms
E. require linkage to carnitine in order to cross mitochondrial membranes prior to oxidation
Answer» B. they are the major source of energy for cardiac muscle
Discussion
86.

How many ATP molecules are produced from one glucose molecule metabolised aerobically via the Embden-Meyerhof pathway and citric acid cycle?

A. 32
B. 34
C. 36
D. 38
E. 40
Answer» E. 40
Discussion
87.

Regarding cholesterol, which statement is INCORRECT?

A. dietary cholesterol is absorbed in the intestine and incorporated into chylomicrons formed in the mucosa
B. about 20% is in the plasma, with the remainder intracellular
C. negatively feeds back on its synthetic pathway
D. most hepatic synthesised cholesterol is incorporated into VLDL
E. thyroid hormones decrease the plasma cholesterol level
Answer» C. negatively feeds back on its synthetic pathway
Discussion
88.

Which amino acid is NOT ketogenic (ie CAN T be converted into acetoacetate)?

A. leucine
B. isoleucine
C. phenylalanine
D. tyrosine
E. proline
Answer» F.
Discussion
89.

Basal metabolic rate is GREATER in all of the following circumstances EXCEPT:

A. children compared with adults
B. Caucasians compared with Chinese and Indians
C. females compared with males
D. anxiety compared with depression
E. feeding compared with starvation
Answer» D. anxiety compared with depression
Discussion
90.

Which lipoprotein contains the GREATEST proportion of triglyceride?

A. VLDL
B. IDL
C. chylomicrons
D. LDL
E. HDL
Answer» D. LDL
Discussion
91.

Regarding endothelins, which statement is INCORRECT?

A. they can cause dose-dependent vasoconstriction in most vascular beds
B. they activate phospholipase C
C. they are structurally similar to vasoactive intestinal contractor
D. they have negative inotropic effect
E. there are low concentrations present in blood
Answer» E. there are low concentrations present in blood
Discussion
92.

Which lipoprotein contains the GREATEST proportion of cholesterol and cholesterol esters?

A. VLDL
B. IDL
C. chylomicrons
D. LDL
E. HDL
Answer» E. HDL
Discussion
93.

Regarding parathyroid hormone, which is NOT true?

A. it decreases plasma phosphate
B. it is secreted by chief cells of he parathyroid glands
C. it is cleared by Kupffer cells of the liver
D. its secretion is regulated by the level of bound Ca++ in plasma
E. it increases bone reabsorption
Answer» E. it increases bone reabsorption
Discussion
94.

Which lipoprotein contains the GREATEST proportion of protein?

A. VLDL
B. IDL
C. chylomicrons
D. LDL
E. HDL
Answer» F.
Discussion
95.

What is the basal metabolic rate of an average sized man per day?

A. 1000 Kcal
B. 2000 Kcal
C. 3000 Kcal
D. 4000 Kcal
E. 5000 Kcal
Answer» C. 3000 Kcal
Discussion
96.

What is the most important factor affecting metabolic rate?

A. muscular exertion
B. recent ingestion of food
C. high or low environmental temperature
D. height, weight and surface area
E. sex
Answer» B. recent ingestion of food
Discussion
97.

Which of the following are NON ESSENTIAL amino acids?

A. valine
B. leucine
C. isoleucine
D. cysteine
E. methionine
Answer» E. methionine
Discussion
98.

Factors that predisposes to atherosclerosis includes all of the following EXCEPT:

A. diabetes
B. hypothyroidism
C. smoking
D. male sex
E. female sex hormone
Answer» F.
Discussion
99.

Lipoproteins:

A. chylomicrons are themselves very large lipoproteins composed of cholesterol, phospholipids, triglycerides and proteins
B. VLDL contains a higher concentration of triglycerides and a moderate concentration of cholesterol and proteins
C. HDL contains a very higher concentration of cholesterol and a moderate concentration of phospholipids and triglycerides
D. the majority of the lipoproteins are synthesised in the liver
E. the primary function of the lipoproteins are to transport lipids in the blood from liver to adipose tissue
Answer» D. the majority of the lipoproteins are synthesised in the liver
Discussion
100.

Regarding body surface area, which of the following statements is TRUE?

A. is calculated using weight/height
B. is calculated using 0.007184 X weight + 0.425 X weight + 0.725
C. it does not affect the basal metabolic rate
D. it does not affect the general metabolic rate
E. it has an effect on the specific dynamic action of foodstuffs
Answer» C. it does not affect the basal metabolic rate
Discussion