APPG 2013; 061-080

61. All the following similarities are TRUE regarding DNA and RNA, EXCEPT `- 

A. Both have adenine, guanine, cytosine 

B. Pentose sugar is ribose 

C. Main function involves protein biosynthesis 

D. The bonding is in 3'-5' direction 

Ans B 

The chemical structure of RNA is very similar to that of DNA, but differ in three main ways: 

• Unlike double-stranded DNA, RNA is a single-stranded molecule in many of its biological roles and has a much shorter chain of nucleotides. However, RNA can, by complementary base pairing, form intrastrand double helixes, as in tRNA. 

• While DNA contains deoxyribose, RNA contains ribose (in deoxyribose there is no hydroxyl group attached to the pentose ring in the 2' position). These hydroxyl groups make RNA less stable than DNA because it is more prone to hydrolysis. 

• The complementary base to adenine is not thymine, as it is in DNA, but rather uracil, which is an unmethylated form of thymine 

62. One of the following has energy-rich bonds 

A. Glucose 

B. Long chain fatty acids 

C. Gamma globulins 

D. Guanosine triphosphate (GTP) 

Ans D 

63. Coenzyme A contains the Vitamin 

A. Biotin 

B. Niacin 

C. Pyridoxine 

D. Pantothenic acid 

Pantothenic acid is found throughout living cells in the form of coenzyme A (CoA) 

64. Blood levels of which of the following amino acids serve as an index of the increased risk of cardiovascular disease ? 

A. Cysteine 

B. Methionine 

C. Homoserine 

D. Homocysteine 

Ans D 

65. Profuse watery diarrhoea in Cholera is due to following action of its toxin 

A. Phosphorylation of inhibitory G protein (Gi) 

B. ADP ribosylation of stimulatory G protein (Gs) 

C. ADP ribosylation of inhibitory G protein (Gi) 

D. Phosphorylation of stimulatory G protein (Gs) 

Ans B 

CTA1 is then free to bind with a human partner protein called ADP-ribosylation factor 6 (Arf6); binding to Arf6 drives a change in the shape of CTA1 which exposes its active site and enables its catalytic activity.[5] The CTA1 fragment catalyses ADP-ribosylation of the Gas proteins using NAD. The ADP-ribosylation causes the Gas subunit to lose its catalytic activity in hydrolyzing GTP to GDP + Pi so it remains activated longer than normal. Increased Gas activation leads to increased adenylate cyclase activity, which increases the intracellular concentration of cAMP to more than 100-fold over normal and over-activates cytosolic PKA. 

66. Anti-platelet effect of Aspirin is due to inhibition of synthesis of 

A. PGE2 

B. PGI2 

C. TXA2 

D. PGF2 

Ans C 

TXA2 is generated from prostaglandin H2 by thromboxane-A synthase. Aspirin irreversibly inhibits platelet cyclooxygenase 1 preventing the formation of prostaglandin H2, and therefore thromboxane A2. 

67. Which of the following 5-HT agonists is anti anxiety drug ? 

A. Buspirone 

B. Cisapride 

C. Renzapride 

D. Rizatriptan 

Ans A 

Buspirone functions as a serotonin 5-HT1A receptor partial agonist 

It is this action that is thought to mediate its anxiolytic and antidepressant effects. Additionally, it functions as a presynaptic dopamine agonist D2,D3, dopamine antagonist D4,as well as a partial a1 receptor agonist 

68. Which of the following statements is NOT correct about Sulfonylureas ? 

A. Orally effective 

B. Used in insulin dependent Diabetes Mellitus (Type-1) 

C. Causes insulin secretion 

D. Long term use down regulates sulfonylurea receptors 

Ans B 

69. A novel nicotinic agonist approved recently for use in smoking cessation is 

A. rimonabant 

B. varenicline 

C. nefopam 

D. pimozide 

Ans B 

Varenicline is a prescription medication used to treat smoking addiction. Varenicline is a nicotinic receptor partial agonist - it stimulates nicotine receptors more weakly than nicotine itself does. In this respect it is similar to cytisine and different from the nicotinic antagonist, bupropion, and nicotine replacement therapies (NRTs) like nicotine patches and nicotine gum. As a partial agonist it both reduces cravings for and decreases the pleasurable effects of cigarettes and other tobacco products. Through these mechanisms it can assist some patients to quit smoking. 

70. Which of the following effects is NOT produced by Cholinomimetics ? 

A. Miosis 

B. Bronchospasm 

C. Urinary retention 

D. Spasm of accommodation 

Ans C


71. An organism that does NOT grow at normal atmospheric tension but requires traces of oxygen in metabolism is known as 

A. microaerophilic 

B. capnophilic 

C. facultative anaerobe 

D. aerotolerant anaerobe 

Ans A 

A microaerophile is a microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere (~20% concentration). Many microphiles are also capnophiles, as they require an elevated concentration of carbon dioxide. In the laboratory they can be easily cultivated in a candle jar. A candle jar is a container into which a lit candle is introduced before sealing the container's airtight lid. The candle's flame burns until extinguished by oxygen deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar. 

Examples include: 

Borrelia burgdorferi, a species of spirochaete bacteria that causes Lyme disease in humans. 

Helicobacter pylori, a species of proteobacteria that has been linked to peptic ulcers and some types of gastritis. Some do not consider it a true obligate microaerophile.[1] 

Campylobacter has been described as microaerophilic.[2] 

Streptococcus intermedius has also been described as microaerophilic. 

Streptococcus pyogenes, a well known microaerophile that causes streptococcal pharyngitis. 

72. Intracellular survival of M.tuberculosis is due to 

A. Interference with oxidative burst 

B. Prevention of fusion of phagosome with lysosome 

C. Inhibition of degranulation 

D. Resistance to lysosomal enzymes 

Ans B 

Intracellular parasites (e.g., Mycobacterium tuberculosis, Toxoplasma gondii, and some Chlamydiae) may promote their survival within the host by acting from within phagosomes to prevent phagolysosome formation, thus avoiding exposure to the lysosomal hydrolases 

73. Enterotest is done for the diagnosis of 

A. Intestinal amoebiasis 

B. Trypanosomiasis 

C. Giardiasis 

D. Leishmaniasis 

Ans C 

It is well recognised that stool examination is an unsatis- factory method of searching for Giardia lamblia. The parasite lives primarily in the duodenum and jejunum and is therefore more readily found in duodenojejunal aspirate'. The parasite is excreted in intermittent 'showers' and it is therefore likely that an isolated stool specimen could be negative despite a heavy Giardia lamblia infes- tation. The Enterotest is a simple and safe way of sampling duodenojejunal contents. We have compared this method with examination of stools and the aspirate from the Crosby capsule, obtained at jejunal biopsy. 

74. All are vapour phase disinfectants, EXCEPT 

A. Ethylene oxide 

B. Thiomersal 

C. Formaldehyde gas 

D. Betapropiolactone (BPL) 

Ans B 

Vapor-phase Disinfectants 

Propiolactone is used for vaccines, tissue grafts, surgical instruments, and enzymes, as a sterilant of blood plasma, water, milk, and nutrient broth, and as a vapor-phase disinfectant in enclosed spaces. Acute (short-term) inhalation exposure to beta-propiolactone causes severe irritation of the eyes, nose, throat, and respiratory tract in humans. 

Alkylating agents such as formaldehyde, ethylene oxide, and propylene oxide are broad-spectrum biocides active against bacteria, viruses, and fungi, including spores. 

Ethylene and propylene oxides are highly reactive gaseous fumigants used for sterilizing animal feed, human food, surgical equipment that cannot be autoclaved (eg, endoscopes, gloves, syringes, catheters, tubing, implantable devices), laboratory equipment, etc. Both are noncorrosive. However, ethylene oxide has better penetrability than propylene oxide and, therefore, is more commonly used. For this application, ethylene oxide is mixed with chlorofluorocarbons or carbon dioxide and sold in gas cylinders. 

Other gaseous disinfectants (eg, formaldehyde, sulfur dioxide, methylbromide) have been used infrequently because of their toxic or corrosive properties. 

Thiomersal (INN), commonly known in the US as thimerosal, is an organomercury compound. This compound is a well established antiseptic and antifungal agent.

75. Mice are used for isolation of all of the following EXCEPT 

A.Rabies virus 

B.Arbovirus 

C.Coxsackie virus 

D.Echo viruses 

Ans D 

Coxsackie A - some will grow in Rhadomyosarcoma (Rd) cell lines. Otherwise will require innoculation into newborn mice 

Virus isolation - intracerebral inoculation of laboratory mice is the method of choice. Rabies virus will propagate in a variety of cell cultures including human diploid cells but have not replaced the mouse system 

Arboviruses 

1. Virus isolation - the arbovirus is usually present in the blood during the acute febrile phase of the illness. To reduce the effect of serum inhibitors, isolation attempts should be made not only with undiluted serum, but dilutions of 1:5 or 1:10 or higher. Virus isolation is not usually attempted from tissue biopsies with the exception of brain tissue from patients with encephalitis. 3 systems are available for virus isolation;- 

a. intracerebral inoculation of newborn mice 

b. tissue culture eg. LLC-MK2, Vero, artrhopod cell lines 

intrathoracic inoculation of arthropods 

76. Warthin Finkedly cells are seen in 

A. Warthin Tumor 

B. Wolman disease 

C. Whooping cough 

D.Measles 

Ans D 

A Warthin–Finkeldey cell is a type of giant multinucleate cell found in various organs in infections with measles 

77. Philadelphia chromosome is the first tumor specific chromosomal change discovered by 

A Nowell and Hungerford 

B Watson and Crick 

C Alfred Knudsen 

D Maurice Wilkins 

Ans A 

The discovery of the Philadelphia chromosome as a hallmark of chronic myelogenous leukemia in 1960 by Peter Nowell provided evidence for a genetic link to cancer. 

In 1960, Peter C. Nowell then a junior faculty member at the University of Pennsylvania School of Medicine, together with a graduate student, David Hungerford, described an unusual small chromosome present in leukocytes from patients with chronic myelogenous leukemia (CML 

78. Parathyroid hormone — related protein (PTHrP) is a polypeptide normally produced by 

A. parafollicular cells of thyroid - 

B. chief cells of parathyroid 

C. pituicytes 

D. squamous epithelial cells of he skin 

Ans D 

Parathyroid hormone-related protein (or PTHrP) is a protein member of the parathyroid hormone family. It is occasionally secreted by cancer cells (breast cancer, certain types of lung cancer including squamous cell carcinoma). However, it also has normal functions. 

Human keratinocytesin primaryculturewerethefirstnormalcellsshowntosecrete PTHrP (5). Immunohistochemical studies have localized PTHrPfromthebasallayerthroughthegranulosalayerofthe epidermis, in skin appendages, and in fetal rat skin as early as 14 days of gestation (4, 6). PTHrP gene expression is regulated in cultured keratinocytes by serum, by 1,25- dihydroxyvitamin D, and by an as-yet-unidentified dermal fibroblast-derivedfactor(7,8).The classicalPTH/PTHrP receptorispresentondermalfibroblasts(9),butthereisalso evidenceforspecificPTHrPreceptorsonkeratinocytes(10). Thus,PTHrPisproducedinskin;itsproductionisregulated, and its effects in skin may be mediated by autocrine or paracrinepathways,orboth. 

79. TRUE statement about metastases of malignant tumors of brain is 

A. drop metastases can occur in the spinal cord 

B. lymph node metastases in patients who have had brain surgery 

C. metastases through man made shunts 

D. All of the above 

Ans D 

intradural metastases 

Metastasis to the dura may arise from a variety of primary malignancies, most commonly breast cancer, lung cancer, and melanoma. Tumors of the central nervous system (glioblastoma multiforme and posterior fossa ependymomas) may produce "drop metastases." These metastatic lesions usually appear as small, round, multifocal lesions that enhance and stud the surface of the cord. Lymphomatous metastases, on the other hand, tend to produce a more diffuse pial enhancement, as may breast and prostate metastases. In a patient with metastatic disease, these radiographic appearances generally indicate extramedullary-intradural disease. It should be noted, however, that multiple cerebral spinal fluid analyses are far more sensitive than imaging studies in the determination of this process. 

80. Which of the following structures in the lung is likely to be affected the most in a patient who smoked a pack and half of cigarettes per day for 30 years and developed centrilobular emphysema ? 

A .Alveolar sac 

B . Terminal bronchiole 

C . Alveolar duct 

D . Respiratory bronchiole 

Ans D 

there are two major types of emphysema: centrilobular (centriacinar) and panlobular (panacinar). The former involves primarily the upper lobes while the latter involves all lung fields, particularly the bases. 

Centrilobular emphysema occurs with loss of the respiratory bronchioles in the proximal portion of the acinus, with sparing of distal alveoli. This pattern is most typical for smokers. 

Panacinar emphysema occurs with loss of all portions of the acinus from the respiratory bronchiole to the alveoli. This pattern is typical for alpha-1-antitrypsin deficiency.