Test 22 (miscellaneous modified past questions)

1. The penetration of drug through the blood-ocular barrier is increased by:

a. high lipid solubility of the drugs

b. bolus administration of the drug

c. drugs with high affinity for the plasma proteins

d. ocular inflammation

e. increased sympathetic tone of the blood vessels

answera.T   b.T   c.F   d.T   e.F
The blood-ocular barrier can be penetrated more easily by drugs that are lipid soluble and also in the presence of ocular inflammation.

y
y
2. The following antibiotics inhibit protein synthesis by binding to the ribosomes:

a. rifampicin

b. ciprofloxacin

c. chloramphenicol

d. teicoplanin

e. tetracycline

answera.F   b.F   c.T   d.F   e.T
Tetracycline acts by binding to the 30S subunit of bacterial ribosomes whereas chloramphenicol acts by binding to the 50S subunit of bacterial ribosomes.
Rifampicin acts on the bacterial RNA polymerase.
Ciprofloxacin inhibits the DNA gyrase
Teicoplanin (a glycopeptides similar to vancomycin) acts on the cell wall of Gram positive bacteria by inhibiting peptidoglycan synthesis. 
 
 

3. Chemicals used as preservatives include:

a. povidone-iodine

b. chlorhexidine

c. thimerosal

d. sodium benzoic acid

e. alcohol

answera.F   b.F   c.T   d.T   e.T
Preservatives should not be irritant or toxic to tissues to which they will be applied, must be effective in preventing growth of microbes likely to contaminate them and must have sufficient solubility and stability to remain active.
Commonly used preservative agents include organic acids such as benzoic acid and salts, the parabens, the sorbit acid and salts, phenolic compounds, quaternary ammonium compounds, alcohol, and mercurials such as thimerosal (in concentration of 0.001-0.004%)

y
4. TB (mycobacteria tuberculosis):

a. is a Gram negative bacillus

b. forms spores which are resistant to drying

c. may exist as a commensal in the conjunctiva

d. can only be spread through the pulmonary route

e. grows readily on blood agar

answera.F   b.F   c.F   F   e.F
TB is a non-sporing acid-fast obligate aerobic bacilli.
It does not exist as commensal in human.
It spreads through ingestion and inhalation. Inoculation can also cause infection.
It grows slowly on Lowenstein-Jensen media.
 
 

5. The spinal cord:

a. terminates at the 12th thoracic vertebrae

b. the fibres that transmit pain decussate at the spinal cord 

c. has a proportionately larger grey matter at the thoracic than the cervical 
    segment

d. contains lateral horn that gives rise to preganglionic autonomic nerve fibres

e. contains nucleus proprious which have the cell bodies of secondary 
    neurones subserving touch, pain and temperature.

answera.F   b.T   c.F   d.T   e.T
The spinal cord terminates at opposite the second lumbar vertebra.
The grey matter of the cervical and lumbar cord is larger than that of the thoracic segment. These enlargements correspond to the large nerve roots supplying the limbs.
 

 

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