An unknown microbial specimen measures 18 millimetres under a total magnification of 400 x , when examined under the microscope. What is the actual size of the unknown specimen? \( \begin{array}{ll}\text { (A) } 45 \text { micrometres. Total magnification }=400 x \\ \text { (B) } 4.5 \text { micrometres. } \quad \frac{18}{400 x}=0.045 \mathrm{~mm} \\ \text { (C) } 0.45 \text { micrometres. } \\ \text { (D) } 0.045 \text { micrometres. } & \text { micrometers }=0.045 \times 1000=45 \text { micrometers }\end{array} \)

(B) (i) Explain THREE precaution steps during decontamination of biohazard wastes in bag using an autoclave. (ii) Describe TWO materials that will remain undamaged after autoclaving.

(A) State ONE example of selective media that can be used to isolate [3 marks] EACH of the following microorganisms. (i) Gram positive bacteria. (ii) Staphylococci spp. (iii) Gram negative bacteria.

Glycerol a) Name the: (i) Process \( X \) (ii) Enzyme \( Y \) (iii) Molecule Z

34 (A) (i) Explain ONE purpose of air monitoring. (ii) Describe TWO factors that will affect air quality.

(B) State TWO ways in which flagellum helps a microorganism survive in an open environment. (2 ma All rights reserved. No part of this publication may be reproduced, stored in a retrieval sys transmitted in any form or by any means, electronic, mechanical, photocopying, reco otherwise, without the prior written permission of the Institute of Technical Education, Singapo Institute of Technical Education has made every effort to trace copyright holders, but if inadvertently overlooked any, we will be pleased to make the necessary arrangements a