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Papers covered; August 2013 May 2013

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Microorganisms MCQ's 2013 Answered

Question 1 of 40

1

The cardinal temperatures are the:

Select one of the following:

  • Minimum temperatures

  • Optimum temperatures

  • Maximum temperatures

  • Minimum, optimum, and maximum temperatures taken together.

Explanation

Question 2 of 40

1

Carl Woese of the University of Illinois and his collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

Select one of the following:

  • Microscopic examination of the staining characteristics of the cell wall.

  • Metabolic characteristics such as the production of methane gas

  • Ecological characteristics such as the ability to survive extreme temperatures

  • Molecular characteristics such as ribosomal RNA sequences

Explanation

Question 3 of 40

1

Which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?

Select one of the following:

  • extreme halophiles

  • extreme thermophiles.

  • methanogens

  • nitrogen-fixing bacteria that live in root nodules

Explanation

Question 4 of 40

1

Photoautotophs use:

Select one of the following:

  • Light as an energy source and CO2 as a carbon source

  • Light as an energy and methane as a carbon source

  • CO2 as both an energy source and a carbon source

  • All of the above.

Explanation

Question 5 of 40

1

Addition of blood to a culture medium only allows the haemolytic bacteria that grow on the plate to be picked out. This is an example of a:

Select one of the following:

  • Selective medium

  • Differential medium

  • Complex medium

  • Synthetic medium

Explanation

Question 6 of 40

1

Almost all medically important microbes are:

Select one of the following:

  • Chemolithoautotrophs

  • Photoorganoheterotrophs

  • Photolithoautotrophs

  • Chemoorganoheterotrophs

Explanation

Question 7 of 40

1

With regards to bacterial plasmids which statement is the CORRECT one?

Select one of the following:

  • A plasmid is extra chromosomal DNA that encodes only resistance to antibiotics

  • A plasmid is a part of the bacterial chromosome

  • A plasmid is single stranded DNA found in some bacteria

  • A plasmid is an extra chromosomal DNA molecule

Explanation

Question 8 of 40

1

Bacterial Genomics is:

Select one of the following:

  • A study of the entire bacterial genome

  • Sequencing of the bacterial chromosome

  • A study of essential genes and genetic elements

  • Sequencing of DNA samples obtained from the environment

Explanation

Question 9 of 40

1

All viruses:

Select one of the following:

  • Enter cells by receptor-mediated endocytosis

  • Replicate their genomes in the nucleus of the cell

  • Replicate their genomes in the cytoplasm of the cell

  • Surround their progeny genomes with capsid proteins inside infected cells

Explanation

Question 10 of 40

1

Underline the TRUE statement below:

Select one of the following:

  • Viruses do not infect microorganisms

  • All viruses are enveloped

  • All viruses cause disease

  • All viruses are parasites

Explanation

Question 11 of 40

1

Anthrophilic dermatophytes (fungi causing cutaneous infections of humans) are primarily associated with:

Select one of the following:

  • Soil

  • Animals

  • Plants

  • Humans

Explanation

Question 12 of 40

1

Phytophthora ramorum is the causal pathogen of:

Select one of the following:

  • Potato blight

  • Sudden Oak Death

  • Coffee rust

  • Ash dieback

Explanation

Question 13 of 40

1

The Bacille-Calmette-Guérin (BCG) vaccine is:

Select one of the following:

  • Heat-killed Mycobacterium tuberculosis

  • Attenuated live Mycobacterium tuberculosis

  • Mycobacterium bovis

  • Attenuated live Mycobacterium bovis

Explanation

Question 14 of 40

1

Which of the following is transmitted via the faecal-oral-route?

Select one of the following:

  • Malaria

  • Typhoid

  • Plague

  • Meningitis

Explanation

Question 15 of 40

1

With regard to the differences between bacterial and eukaryotic cells which statement is the CORRECT one?

Select one of the following:

  • Bacterial cells do not contain mitochondria.

  • Bacterial cells are always larger than eukaryote cells.

  • Bacteria do not contain a chromosome.

  • Eukaryotic cells are sensitive to β-lactam antibiotics.

Explanation

Question 16 of 40

1

Koch’s postulates MOST CORRECTLY relate to which one of the following statements?

Select one of the following:

  • The isolation of a bacterium in culture from an infection alone indicates that it caused the disease.

  • Isolation and cultivation of a microorganism from a diseased animal, then inoculation into another healthy animal to cause the same disease followed by re-isolation of the same microorganism indicates that it is the cause of the disease.

  • The observation of virus particles in tissue from a human with disease indicates that it has caused the disease.

  • Inoculation of a bacterium into an animal and observation of disease alone indicates that it is the cause of the disease observed.

Explanation

Question 17 of 40

1

Which statement is CORRECT with respect to Lipopolysaccharide (LPS)?

Select one of the following:

  • LPS is found in Gram positive cells.

  • LPS is found in Gram negative cells in the cytoplasmic membrane.

  • LPS is found in the outer-membrane of Gram negative cells.

  • LPS is associated with found inside all bacterial cells.

Explanation

Question 18 of 40

1

A culture of E.coli is diluted by a factor of 10-6 and, after plating out 100 μl on an agar plate, 57 colonies grew after incubation at 37oC overnight. The original culture therefore contained how many viable E. coli cells per ml?

Select one of the following:

  • 5.7 x 10(7)

  • 5.7 x 10(8)

  • 5.7 x 10(6)

  • 5.7 x 10(5)

Explanation

Question 19 of 40

1

With respect to differences between members of the archaeal and bacterial domains/kingdoms, which is the CORRECT statement?

Select one of the following:

  • Both have peptidoglycan in their cell walls

  • No bacteria and only some Archaea are capable of methanogenesis

  • Archaea and bacteria are sensitive to β-lactam antibiotics

  • Bacteria have similar RNA polymerase to that of Archaea

Explanation

Question 20 of 40

1

Which statement is CORRECT with respect to peptidoglycan?

Select one of the following:

  • There are multiple molecules of peptidoglycan in bacterial cell walls.

  • Only Gram positive cells possess peptidoglycan.

  • There is only a single molecule of peptidoglycan in a bacterial cell wall.

  • Peptidoglycan is only found in Gram negative cell walls.

Explanation

Question 21 of 40

1

Which of the following is a macronutrient?

Select one of the following:

  • Manganese

  • Magnesium

  • Zinc

  • Cobalt

Explanation

Question 22 of 40

1

Which of the following forms of oxygen are generally toxic to living organisms?

Select one of the following:

  • Superoxide anion

  • Hydrogen peroxide

  • Hydroxyl radical

  • All of the above

Explanation

Question 23 of 40

1

Carrier mediated transport is necessary when:

Select one of the following:

  • Diffusion will not allow adequate amounts of a substance to enter the cell

  • Movement into the cell is against a concentration gradient

  • The level of nutrients in nature is very low

  • All of the above

Explanation

Question 24 of 40

1

The size (as determined by the sedimentation factor) of the most useful RNA molecule for prokaryotic evolutionary studies is:

Select one of the following:

  • 5S

  • 16S

  • 18S

  • 23S

Explanation

Question 25 of 40

1

Which of these environmental factors influences microbial growth?

Select one of the following:

  • pH

  • Water potential

  • Oxygen

  • All of the above

Explanation

Question 26 of 40

1

The signature sequence is used extensively in the:

Select one of the following:

  • Phylogenetic probe

  • Reclassification of misclassified organisms

  • Defining of a specific group within a domain

  • All of the above

Explanation

Question 27 of 40

1

A Wild-type strain is:

Select one of the following:

  • A bacterial or viral strain with minimum of mutations in its genome

  • An arbitrarily chosen strain; other strains compared with it

  • A strain adapted to laboratory conditions

  • A strain that dominates the natural environment

Explanation

Question 28 of 40

1

Bacterial genes:

Select one of the following:

  • Are stretches of double stranded RNA

  • Have introns

  • Are often organised into operons

  • Are always present in two copies

Explanation

Question 29 of 40

1

Viruses may encode their genomes as:

Select one of the following:

  • DNA

  • RNA

  • Negative strand RNA

  • All of the above

Explanation

Question 30 of 40

1

Poliovirus:

Select one of the following:

  • Has a double-stranded DNA genome

  • Has a capsid that is composed of 240 copies of a single protein

  • Replicates primarily in the upper respiratory tract

  • Belongs to the enterovirus genus of the picornavirus family

Explanation

Question 31 of 40

1

Which of the following statements is NOT true about rust fungi?

Select one of the following:

  • They are obligate pathogens

  • They are host specific pathogens

  • They have an active saprophytic phase

  • They form basidiospores as part of their life cycle

Explanation

Question 32 of 40

1

Which of the following is NOT part of the plant disease triangle:

Select one of the following:

  • Susceptible host

  • Climate change

  • Active pathogen

  • Suitable environment

Explanation

Question 33 of 40

1

Which of the following is primarily a respiratory pathogen?

Select one of the following:

  • Vibrio cholera

  • Mycobacterium tuberculosis

  • Salmonella typhi

  • Mycobacterium leprae

Explanation

Question 34 of 40

1

Modification of RNA polymerase confers bacterial resistance to:

Select one of the following:

  • Beta-lactam antibiotics

  • Rifampicin

  • Quinolone antibiotics

  • Metronidazole

Explanation

Question 35 of 40

1

Pasteur is attributed with which one of the following discoveries?

Select one of the following:

  • Was the first to see microorganisms under a microscope

  • First to discover and use agar

  • That there could be life without air

  • The first chemical antibiotics

Explanation

Question 36 of 40

1

The length of a typical E.coli cell is approximately:

Select one of the following:

  • 20 μm

  • 2 μm

  • 200 nm

  • 20 nm

Explanation

Question 37 of 40

1

With respect to differences between members of the archaeal and bacterial domains/kingdoms, which is the CORRECT statement?

Select one of the following:

  • Both have peptidoglycan in their cell walls

  • No bacteria and only some Archaea are capable of methanogenesis

  • Archaea and bacteria are sensitive to β-lactam antibiotics

  • Bacteria have similar RNA polymerase to that of Archaea

Explanation

Question 38 of 40

1

Which statement is CORRECT with respect to the E.coli chromosome?

Select one of the following:

  • It is negatively supercoiled

  • It is positively supercoiled

  • There are typically several origins of replication

  • It consists of over 50 million base pairs

Explanation

Question 39 of 40

1

A culture of E.coli is diluted by a factor of 10-6 and, after plating out 100 μl on an agar plate, 56 colonies grew after incubation at 37oC overnight. The original culture therefore contained how many viable E. coli cells per ml?

Select one of the following:

  • 5.6 x 10(7)

  • 5.6 x 10(8)

  • 5.6 x 10(6)

  • 5.6 x 10(5)

Explanation

Question 40 of 40

1

Bacterial flagella bring about cell motion by which mechanism?

Select one of the following:

  • Wave-like movement of the flagellum

  • Rotation of the cell

  • Rotation of the flagellum in one direction only

  • Rotation of the flagellum that is reversible

Explanation

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