Written Questions

This document provides answers to written questions on various topics including NATA, infection control, biological safety cabinet, bacterial reproduction, differences between viruses, bacteria, and molds, and more. It also includes a cleaning schedule for a deli.

Running head: WRITTEN QUESTIONS 1
Written Questions
Student’s name
Course
Institution
Date

Running head: WRITTEN QUESTIONS 2
Contents
Question One: What is NATA and when might you need a certified laboratory testing?..2
Question Two: What are some of the principles of infection control you have to consider
when working in a microbiology laboratory?...................................................................................... 2
Question Three: What is biological safety cabinet for?....................................................................2
Question Four: Describe how bacteria reproduce and draw the bacterial growth curve
describing the difference phases and why they occur (including a diagram and
description of each phase)........................................................................................................................... 3
Question Five: If you have a sandwich that has 3 S.aureus cells present and it was left in
ideal growth conditions for 4 hours – How many generations would be present? How
many cells would be now in the sandwich?.......................................................................................... 3
Question Six: Briefly explain the difference between the reproduction of viruses,
bacteria and mould......................................................................................................................................... 3
Question Seven: Describe the difference between pili and flagella and the different roles
they play for an organism............................................................................................................................. 4
Question Eight: How does the concentration of solutes in a solution affect the movement
of water across a semi permeable membrane of cells in that solution?....................................4
Question Nine: Classification in Microbiology is based on a number of processes and
principles. One species is likely to differ from another in a number of ways. Briefly
explain some differences that might occur from the following criteria: Morphology,
Biochemistry and Nutritional requirements........................................................................................ 5
Question Ten: Identify the main differences between animal, plant and bacterial cells....5
Question Eleven: Draw and explain the following components of a cell. (cytoplasm,
vacuole, mitochondria, nucleus)................................................................................................................ 6
Question Twelve: Explain the process of disinfection and sterilisation. Use at least two
examples of each in their practical use in production......................................................................6
Question Thirteen: Explain the different ways quality assurance of media is carried out
both when it is prepared and when it is used...................................................................................... 6
Question Fourteen: Identify at least 4 factors a microbiologist needs to consider when
selecting a sampling plan for testing products and explain why.................................................7
Question Fifteen: You own a small deli that has food displayed in a refrigerated cabinet.
You slice meats on a slicer and prepare other ingredients by slicing on a chopping
board. You use tongs to select the food for the customer and place it in containers for
take away services. In this exercise you are to complete the following cleaning schedule
for the deli including:..................................................................................................................................... 7
Question Sixteen: What are the possible consequences of not following a strict cleaning
regime?................................................................................................................................................................. 8
Question Seventeen: Briefly describe the legal responsibilities in maintaining a food
production area clean and sanitised? Hint:
http://www.comlaw.gov.au/Details/F2012C00774........................................................................8
_____..................................................................................................................................................................... 8
Question Eighteen: How should media be labelled and stored after preparation?..............8

Running head: WRITTEN QUESTIONS 3
Question Nineteen: Look up food standards code for microbiology found at:
http://www.comlaw.gov.au/Details/ F2012C00862.......................................................................9

Running head: WRITTEN QUESTIONS 4
Written Questions
Question One: What is NATA and when might you need a certified
laboratory testing?
___ The National Association of Testing Authorities is a not-for-profit company that
accredits services to inspection agents and bodies. NATA is involved in accrediting and
certifying the facilities to carry out definite types of testing, inspection and connected
activities. A NATA accreditation reveals that a facility is following the protocol in the right
way and it maintains the correct standards. A certified laboratory testing is essential to
maintain the quality of producing accurate or dependable results.
Question Two: What are some of the principles of infection control you have
to consider when working in a microbiology laboratory?
______Infection control deals with prevention of healthcare related infections. It is practiced
within a healthcare facility or a laboratory. In a microbiological laboratory, the staff members
should be educated on following hygienic clinical practices. The equipment should be
thoroughly cleaned, sterilized and stored.
 The sterile supplies should be separately stored and maintained
 The disinfection policy should be efficiently maintained
 The single use objects should be disposed with care
 The laboratory staff should be educated on hygienic laboratory practices
Question Three: What is biological safety cabinet for?
_______A biological safety cabinet is an enclosed workspace in a laboratory that prevents
contamination. It is adequately ventilated and illuminated aiding safe work with pathogens
and other harmful microbes. The safety cabinet protects the worker as well as the

Running head: WRITTEN QUESTIONS 5
surroundings from the microbes they are working with. The air that leaves the cabin is
purified with HEPA filters, thereby eliminating the pathogens and other microbes.
Question Four: Describe how bacteria reproduce and draw the bacterial
growth curve describing the difference phases and why they occur (including
a diagram and description of each phase).
Bacteria reproduce by three means: Vegetative, Asexual and sexual means. The
vegetative method includes process such as budding, fragmentation and binary
fission methods. The asexual reproduction is carried out by endospore formation.
The sexual reproduction is carried out by genetic recombination by the process of
transformation, transduction or conjugation.
The most common type of bacterial growth happens by asexual means where
the single celled bacterium divides into two progeny cells. In a batch culture, the
gowth of the bacteria is clasiified into four phases:
(i) Lag phase: The adaption process occurs to the growth conditions
(ii) Log phase: The phase of cell doubling or growth
(iii) Stationary phase: Where the growth limits
(iv) Death phase: Where the cells die
Question Five: If you have a sandwich that has 3 S.aureus cells present and it
was left in ideal growth conditions for 4 hours – How many generations
would be present? How many cells would be now in the sandwich?
Question Six: Briefly explain the difference between the reproduction of
viruses, bacteria and mould.
____Most bacteria reproduce by asexual means, by a method known as binary fission.
Viruses reproduce in a host cell where the virus injects into a host cells. Within the host cells,
the genetic material of the virus takes over the activities of the host cell. Virus reproduces

Running head: WRITTEN QUESTIONS 6
inside of the host cell, the host cell fills and later splits open and viruses leave the host cell
and attack new cells for further reproduction. Molds reproduce by means of cyst formation.
The mould cell forms a macrocyst by undergoing meiosis. Within the macrocyst the spores
are formed and released.
Question Seven: Describe the difference between pili and flagella and the
different roles they play for an organism.
Flagella are long appendages that have a whip-like look and originate from the cell
membrane. They are made up of a protein named flagellin. Flagella are lesser in number
when compared to pili. Flagella are mostly used for motility.
Pili are short appendages that are thick and resemble hair. They originate from the surface of
the cell. Pili are responsible for motility and it plays a vital role in conjugation. When bacteria
reproduce through conjugation, the transfer of genetic material takes place through pili.
Question Eight: How does the concentration of solutes in a solution affect the
movement of water across a semi permeable membrane of cells in that
solution?
_________When the concentration of solute molecules differ, there are different
concentrations of free water molecules on both the side of the membrane. The side with lower
concentration of solute has higher water concentration and vice versa. The movement of
water is always from a lower solute concentration to a higher solute concentration across a
semi-permeable membrane. This theory is termed osmosis.

Running head: WRITTEN QUESTIONS 7
Question Nine: Classification in Microbiology is based on a number of
processes and principles. One species is likely to differ from another in a
number of ways. Briefly explain some differences that might occur from the
following criteria: Morphology, Biochemistry and Nutritional requirements.
____In terms of morphology, the species are classified based on the shape, presence or
absence of spores and capsules, and other inclusive bodies. Also the arrnagement of the
flagella, the general motility of the species and the gram reaction of the species are taken into
consideration.
__ In terms of Bio chemistry, the species are classified based on their reactions to a series of
biochemical tests.
In terms of nutritional requirements the species are classified based on their growth
conditions; if they grow aerobically or anaerobically.
Question Ten: Identify the main differences between animal, plant and
bacterial cells.
____Bacterial cells: Bacteria are single-celled or prokaryotes. The bacterial cell has no well
defined nucleus and there is an absence of membrane bound organelles. The bacterial cells
have smaller 70S ribosomes.
Plant cells: Plant cells are eukaryotic and are structurally similar to animal cells except a few
minor variations. They have a well defined nucleus and differ from animal cells with the
presence of chloroplasts, vacuole and a cell wall.
Animal cells: The animal cells are smaller than plant cells. They have the same membrane
bound organelles like plant cells but lack chloroplasts, vacuole and a cell wall.

Running head: WRITTEN QUESTIONS 8
Question Eleven: Draw and explain the following components of a cell.
(cytoplasm, vacuole, mitochondria, nucleus)
Cytoplasm: Cytoplasm is the material within the cell that houses the gel like
cytosol and all the organelles within the cell. It comprises of water upto 80% and
a small portion of salt.
Vacuole: It is an organelle that is present mainly in the plant cells. It comprises of
several compartments containing water, enzymes and other organic and inorganic
substances.
Mitochondria: It is the power house of the cell. It is an organelle with a double
membrane and has the following structures: the outer membrane, intermembrane
space, inner membrane, cristae and matrix.
Question Twelve: Explain the process of disinfection and sterilisation. Use at
least two examples of each in their practical use in production.
__Disinfection: It is the process in which the majority of microbes are killed, but not all. The
microbial population is reduced to a number that may not cause infections. Some strains of
organisms and spores may likely survive. It is mainly carried out by the use of chemicals like
aldehydes, alcohols, chlorine compounds and other phenolics.
Sterilisation: In this process all the microbes are removed or killed, even the spores that re
resistant. It is carried out by steam autoclave or by dry heat, radiation, vapors and gases.
Question Thirteen: Explain the different ways quality assurance of media is
carried out both when it is prepared and when it is used.
_The quality assurance of media should be carried out in the following ways:
(i) Quality control during media preparation- Media should be prepared correctly,
sterilized and labelled

Running head: WRITTEN QUESTIONS 9
(ii) Control of chemical and physical parameters: The colour and pH should be tested
and containers examined.
(iii) . Growth promotion testing: This is not required for standard media,
but for other media these tests help estimated the number of colony
forming units.
Question Fourteen: Identify at least 4 factors a microbiologist needs to
consider when selecting a sampling plan for testing products and explain
why.
A sampling plan is applied to a microbial batch only after specific methods of
examinations of the requirement (number of units). The factors to consider are:
(i) Number of units required
(ii) If the sampling procedure is the most suitable one for the batch
(iii) The microbiological criteria to be followed
(iv) The sampling plan to be followed: A variable sampling plan or attribute
sampling plan or tho class or three class plan.
Question Fifteen: You own a small deli that has food displayed in a
refrigerated cabinet. You slice meats on a slicer and prepare other
ingredients by slicing on a chopping board. You use tongs to select the food
for the customer and place it in containers for take away services. In this
exercise you are to complete the following cleaning schedule for the deli
including:
a) Equipment / surface to be cleaned
b) Person responsible
c) Procedure
d) Frequency

Running head: WRITTEN QUESTIONS 10
e) Cleaning agent
f) Why you chose the agent on this piece of equipment
g) How can you confirm the effectiveness of the cleaning
Question Sixteen: What are the possible consequences of not following a
strict cleaning regime?
When a strict cleaning regime is not followed, the samples can get contaminated that might
lead to a loss in the costs
 When workplaces and desks are not cleaned and disinfected, it increases the risk of
contamination of specimen in the bay area.
 Lack of regular in-depth cleaning of the equipments may increase the risk of
contamination of samples while storing. Therefore, old samples must be disposed
periodically and an in-depth cleaning of the equipments should be carried out atleast
twice a year.
 If the dust and other remanets are not cleaned regularly, they can accumulate
microbes that cause allergies.
Question Seventeen: Briefly describe the legal responsibilities in maintaining
a food production area clean and sanitised? Hint:
http://www.comlaw.gov.au/Details/F2012C00774
_____
Question Eighteen: How should media be labelled and stored after
preparation?
The storage of media depends on the apparatus and they type of media used.
 Nutrient broth or agar in screw capped bottles can be stored for six
months in lower temperatures (12-16 °C).

Running head: WRITTEN QUESTIONS 11
 Agar plates should be stored in sealed containers at 2-8 °C
 Media should never be frozen
 It should always be stored away from light
All the media should be labelled based on the shelf life and the holders should be
date- stamped accordingly.
Question Nineteen: Look up food standards code for microbiology found at:
http://www.comlaw.gov.au/Details/ F2012C00862
For each of the examples listed below review the results and determine if the
sample would be accepted or rejected.