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SECTION A
(40)
QUESTION 1 (20)
1.1 Several theories have been postulated to try and explain whether an
HIV virus is a living entity or not. From what you have studied, briefly
discuss whether the HIV virus is a living or non-living entity? Give
reasons to justify your answer.
(5)
1.2 Discuss, why in the early 1860s, scientist erroneously placed bacteria
and fungi under the Kingdom Plantae.
(5)
1.3 Evaluate the use of positive and negative staining techniques in the
identification and classification of bacteria.
(10)
QUESTION 2 (20)
2.1 Distinguish between endotoxins and exotoxins.
(2)
2.2 Briefly discuss how the following factors influence microbial death.
(i) Time of exposure.
(2)
(ii) Environmental factors.
(2)
(iii) Number and type of microorganism present.
(2)
2.3 Briefly discuss the viable plate count method for the enumeration
of bacteria.
(12)
SECTION 8
(60)
QUESTION 3 (20)
3.1 Describe the principle on which the Gram stain is based.
(3)
3.2 Explain why the oil immersion objective lens (marked with black rings)
are immersed in oil during use.
(3)
2