Note these practice questions are only a guide to the type of question which may be asked in the theory examination.

The examination paper will be in 2 parts

PART A: MULTIPLE CHOICE. It is anticipated that about 50 questions will appear in the examination in this format

PART B: SHORT ANSWER. It is likely you will be asked to answer 5 questions from a choice of 8

The paper is 1.5 hours. 45 minutes has been devoted to each section (A and B).

Section A and Section B are of equal value in terms of total marks allocated for the examination.

Q1. The principle underlying the phase-contrast microscope is

1. the differences in staining of bacteria to produce regions of light and dark
2. the use of a special objective lens
3. the conversion of differences in the phase of light transmitted by different elements in the specimen into differences in intensity using interference
4. the use of a special ocular lens
5. all of the above

Q2. Ion-exchange chromatography

1. uses differences in the sign and magnitude of the net electric charges of amino acids at a given pH
2. consist of columns filled with particles of a synthetic resin containing fixed charged groups
3. fractions can be analysed and recorded automatically in an apparatus called an amino acid analyser
4. all of the above
5. none of the above

Q3. Which purification procedure utilises the characteristics of a proteins’ charge and size

1. ion exchange chromatography
2. gel electrophoresis
3. ultracentrifugation
4. isoelectric focussing
5. electrophoresis

Q4. If a pigment is illuminated with white light, the colour we see is

1. the colour most refracted by the pigment
2. the colour most reflected or transmitted by the pigment
3. the colour most absorbed by the pigment
4. all of the above
5. none of the above

Q5. In microscopy resolution refers to the ability to

a. magnify objects

b. contrast objects

c. resolve two points as separate entities

d. observe microbes

e. all the above

Q6. Factors which may influence resolution in microscopy include

a. wavelength of light used

b. lens system used

c. contrast system used

d. all the above

e. none of the above

Q7. The refractive index of air is

a. 1.0

b. 1.94

c. 0.94

d. 1.4

e. 0.4

Q8.An advantage of phase contrast microscopy is that

1. live specimens can be observed
2. specimens need to be fixed to the slide
3. specimens need to be stained before observation
4. the system has higher resolution than other systems
5. all the above

Q9. The resolving capability of an electron microscope is about 0.003µm which is about

a. 10 times better than attainable by light microscopy

b. 100 times better than attainable by light microscopy

c. 1000 times better than attainable by light microscopy

d. 10000 times better than attainable by light microscopy

e. all the above

Q10.In the event that we spill a chemical or a culture in a laboratory we should immediately

a. wash off any exposed skin with an appropriate fluid

b. inform a supervisor of the incident

c. decontaminate the area with appropriate fluid

d. all the above

e. none of the above

Q11. When reporting laboratory findings it is important to

a. present the data in a recommended format

b. cite all references used in an appropriate format

c. list only references cited in the body of the text

d. all the above

e. none of the above

Q12. The principle underlying the dark field microscope is

a. the use of an iris to direct light to pass through the specimen at an angle

b. the use of a condenser to direct light to pass through the specimen at an angle

c. the use of a special objective lens

d. the use of a special ocular lens

e. all the above

Q13. Scientific reports should contain sufficient detail so that a reader will

a. be able to repeat the experiment and obtain similar results

b. need to personally contact you to find out how to perform the experiment

c. need to contact you to determine the confidence levels of the experimental methods

d. all the above

e. none of the above

Q14. Escherichia coli is a bacterium that is often used to monitor the quality of water. This is because the bacterium is

a. found only in very pure water

b. useful because it destroys viruses

c. is an indicator of faecal contamination

d. all the above

e. none of the above

Q15. When observing a specimen using a microscope it is important to note the magnification used. This is derived by

a. multiplying the power of the objective and condenser lens

b. multiplying the power of the ocular and objective lens

c. multiplying the power of the ocular and condenser lens

d. noting the power of the oil immersion lens

e. noting the power of the ocular lens

Q.16. Bacillus subtilis is a bacterium which is an obligate aerobe and is commonly found in soil. It is most likely to be found in environments where

a. all oxygen has been removed

b. oxygen is present

c. all air has been removed

d. where the atmosphere is nitrogen

e. where the atmosphere is hydrogen sulphide

Q17. An oil immersion lens is capable of higher resolution because oil has a refractive index which is

a. less than air

b. greater than 1

c. about 0.9

d. significantly less than the glass slide

e. none of the above

Q18. A yeast such as Saccharomyces cerevisiae is termed a facultative anaerobe. This means the yeast will grow in conditions

a. where all oxygen has been removed

b. where oxygen is present

c. where the oxygen level is diminishing

d. all the above

e. none of the above

Q19. Staining is a common way of increasing contrast between a specimen and the background. The Gram stain is a very useful staining method used in microbiology in which bacteria may stain Gram positive (purple) and Gram negative (pink). The basis of how this stain works is related to the bacterial

a. endoplasmic reticulum

b. ribosomes

c. cell wall character

d. mitochondria

e. nucleus

Q20. The bright light microscope is used extensively in biology. The limit of resolution of this system of microscopy is in the range of

a. 0.2 mm

b. 0.2 µm

c. 0.2 nm

d. all the above

e. none of the above

Q21. An electron microscope is a high resolution microscopic system capable of forming images of very small objects such as viruses. The increased resolving capacity is due to

a. the use of short wavelength ultra violet light as a light source

b. the use of an electron beam which behaves in a wave fashion

c. the use of a special glass objective lens

d. the use of a special glass ocular lens

e. all the above

Q22. A scanning electron microscope generally has a lower resolving capability than a transmission electron microscope. The scanning electron microscope has a significant advantage in depth of field and consequently generates a 3 dimensional image of a specimen, this capability is predominantly due to the image being formed by

a. electrons passing through the specimen

b. ultraviolet light waves passing through the specimen

c. generation of secondary electrons in the specimen

d. absorbance of the electron source by the specimen

e. all the above

Q23. Compounds absorb light at specific wave lengths because

a. light energy excites protons in the nuclei

b. light energy promotes valence electrons to higher energy levels

c. light energy is absorbed into carbon-carbon bonds

d. each compound has a specific colour requirement for recognition

e. all the above

Q24. In deep mud it is common to find microbes which can survive without any oxygen (in fact it may be toxic to them). These microbes could be defined as

a. anaerobes

b. plankton

c. aerobes

d. obligate aerobes

e. none of the above

Q25. A spectrophotometer measures

a. the change in intensity of white light when it passes through a solution

b. the refractive index of a solution

c. the increase in intensity of monochromatic light when it passes through a

solution

d. all the above

e. none of the above

Q26. An important function of field biologists is to monitor the quality of water which may be used for domestic purposes. Water with a purity suitable for cooking and drinking is referred to as

a. distilled water

b. chlorinated water

c. potable water

d. brine water

e. tap water

Q27. Accuracy during experimental procedures is often governed by the use of appropriate equipment. If a researcher was required to dispense a fluid in 10 aliquots of 100µL each it would be preferable to use a

a. 10mL glass pipette

b. 1mL glass pipette

c. p200 pipetting device

d. p1000 pipetting device

1. ungraduated Pasteur pipette

Q28. Stereomicroscope is a useful tool for observing specimens in a three dimensional image. The reason the image formed is three dimensional is because

1. only large specimens can be observed with this microscope
2. each eyepiece has its own objective lens
3. of a specialised single objective lens that splits the image formed
4. all the above
5. none of the above

Q29. A viable count was performed on an overnight broth culture of an Escherichia coli bacterium. 100µl of a 10^-7 dilution of the original culture was plated on a nutrient agar plate and incubated overnight at 37^oC. The culture revealed 37 colonies. This means an estimate of the bacterial concentration in the original culture (organisms per mL) is

a. 37

b. 3.7 x 10^-7

c. 3.7 x 10⁷

d. 3.7 x 10⁸

e. 3.7 x 10⁹

Q30.Viruses can not be normally seen under a light microscope because

a. they can’t be stained appropriately

b. they don’t survive the fixing process

c. they are too infectious to observe

d. lack of adequate resolution in light microscopes

e. lack of adequate magnification in light microscopes

Q31. Staining is a common procedure used in bacteriology this is because in a light microscope

a. live bacteria can’t be observed

b. most bacteria appear colourless and staining improves contrast

c. non coloured objects can’t be seen

d. only fixed bacteria can be observed

e. all the above

Q32. In the Gram stain a counter stain such as safranin is used because

a. Gram negative bacteria would otherwise appear colourless

b. Gram positive bacteria would otherwise appear colourless

c. Gram negative bacteria would otherwise appear purple

d. Gram positive bacteria would otherwise appear red

e. Gram positive bacteria would otherwise appear colourless

Q33. Bacteria growing in a broth culture may enter a stationary phase of growth. This phase is characterised by

a. slowing of growth because a majority of cells are dying

b. cell reproduction ceasing

c. the number of cells dividing being equal to the number of cells dying

d. cell motility ceasing

e. none of the above

Q34. Bacteria growing in a broth culture may enter a log phase of growth. This phase is characterised by

a. slowing of growth because a majority of cells are dying

b. cell reproduction ceasing

c. the number of cells dividing being equal to the number of cells dying

d. cells growth at the highest possible rate under the conditions

e. none of the above

Q35. Bacteria growing in a broth culture may enter a lag phase of growth. This phase is characterised by

a. slowing of growth because a majority of cells are dying

b. cell reproduction ceasing

c. the number of cells dividing being equal to the number of cells dying

d. slow growth due to cells adapting to new environmental conditions

e. none of the above

Q36. Bacteria growing in a broth culture may enter a death phase of growth. This phase is characterised by

a. slowing of growth because a majority of cells are dying

b. cell reproduction ceasing

c. the number of cells dividing being equal to the number of cells dying

d. cell motility ceasing

e. none of the above

Q37. Enzyme activity appears to be affected by solvent pH. This means to gain maximum enzymatic activity it would be important to maintain a (an)

a. neutral pH

b. physiological pH

c. optimal pH

d. any of the above

e. none of the above

Q38. Which of the following is true?

a. In gel filtration chromatography, larger molecules move faster

b. In gel electrophoresis, larger molecules move faster

c. In ion exchange chromatography, smaller molecules move faster

d. In paper electrophoresis, smaller molecules move faster

e. None of the above

Q39. A mixture of dextran blue and haemoglobin were separated using a Sephadex G100 column. The total volume collected was 27ml, dextran blue from the column in the sixth 2ml fraction collected, and haemoglobin in the eleventh fraction. The void volume of the column (that outside the gel) would be approximately

a. 27mL

b. 6mL

c. 12mL

d. 22mL

e. 15mL

Q40. Which of the following statements is false?

a. kinetic enzyme assays are more reliable than fixed time assays

b. enzyme levels in human blood can be used to help determine disease status

d. all of the above

e. none of the above

e. a and c

Q42. Enzyme assays may be used to

Q43. The Beer-Lambert Law states that

a. A= e cl

b. A= log₁₀(^Io/_I)

c. a plot of absorbance vs concentration is linear

1. all of the above
2. none of the above

Q44. Microbiology may be defined as

1. the study of procaryotes
2. the study of bacteria
3. the study of viruses
4. the study of live agents which normally can not be seen by the unaided eye
5. none of the above

Q45. A viable count was performed on an overnight broth culture of an Escherichia coli bacterium. 100µl of a 10^-6 dilution of the original culture was plated on a nutrient agar plate and incubated overnight at 37^oC. The culture revealed 110 colonies. This means an estimate of the bacterial concentration in the original culture (organisms per mL) is

a. 110

b. 1.1 x 10^-7

c. 1.1 x 10⁷

d. 1.1 x 10⁸

e. none of the above

Q47. Bacterial growth in a closed liquid culture characteristically follows 4 phases. The order of these phases is

1. exponential, lag, stationary, death
2. exponential, stationary, lag, death
3. lag, stationary, exponential, death
4. lag, exponential, stationary, death

1. provide a basis for making conclusions
2. test hypotheses
3. analyse qualitative and quantitative data
4. reduce variability in a system
5. none of the above

1. the closeness of the measured value to the true value
2. the ability to reduce extraneous variation
3. the application of technologically advanced equipment
4. the closeness of repeated measurements on the same entity
5. a measure of central tendency in data

1. we are only dealing with simple binary categories (e.g. presence/absence)
2. incorporates continuous scales of measurement
3. incorporates the nominal scale, but the categories indicate some rank
4. a true zero exists
5. deals exclusively with measurements where there is no true zero (e.g. the pH scale)

1. range
2. mode
3. median
4. mean
5. all of the above

1. the sum of all observations in a dataset divided by the number of observations
2. estimate of how well the sample mean reflects the population mean
3. the highest and lowest observations in a dataset
4. the standard error of the mean
5. the average deviation of observations from the mean

1. the mean, standard deviation and variance are the same
2. the standard error is larger than the mean
3. the mean is greater than the mode
4. the mean, mode and median are the same
5. none of the above

Q54. The best way to present frequency data in graphical format is by a:

1. histogram
2. bargraph
3. line graph
4. line plot
5. linearly-scaled line graph

1. determine the extent of variability in the dataset
2. visualise the mean and standard error of the data
3. illustrate trends and/or derive mathematical relationships
4. summarise results from several experiments
5. provide information on potential outliers in the dataset

Q56. When presenting means in graphical representations it is also generally important to:

1. plot the means in rank order from the smallest to the largest
2. use a linear scale
3. use a bargraph
4. plot some indication of variability, such as standard error or variance
5. all of the above

1. place the title above the table and below the graph
2. place both table and graph titles at the top
3. place the title below the table and above the graph
4. place both table and graph titles at the bottom
5. not worry about the placement of titles

Q58. Ion-exchange chromatography

1. uses differences in the sign and magnitude of the net electric charges of amino acids at a given pH
2. consist of columns filled with particles of a synthetic resin containing fixed charged groups
3. fractions can be analysed and recorded automatically in an apparatus called an amino acid analyser
4. all of the above
5. none of the above

Q59. Which purification procedure utilises the characteristics of a proteins’ charge and size

1. ion exchange chromatography
2. gel electrophoresis
3. ultracentrifugation
4. isoelectric focussing
5. electrophoresis

Q1. Outline how the concentration of a substance such as glucose in an aqueous sample could be determined using a spectrophotometric assay using a colour development system.

Q2. Outline the principles of spectrophotometry.

Q3. Describe what is meant by the terms obligate anaerobe, obligate aerobe, faculttative anaerobe and microaerophilic when referring to types of bacteria

Q4. Describe the principles of the Gram stain. Explain why some bacteria stain pink whilst others stain purple.

Q5. Describe how the optics in a darkfield microscope are used to form an image. Provide an advantage that this microscopic technique provides.

Q6. Describe the phases of growth that are characteristic of microbial growth in a closed liquid culture. In your answer explain why each stage occurs.

Q7. Describe how the optics of a phase contrast microscope are used to form an image. Provide an advantage that this microscopic technique provides.

Q8. Define and describe what you understand the term resolution to mean when used in microscopy. Explain how the wave length of light may influence the resolving capability of a microscope.

Q9. Define the following terms used in microscopy

1. numerical aperature
2. refractive index
3. condenser
4. ocular lens
5. objective lens

Q10. Describe how charge and size can be used to separate charged macromolecules.