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Past papers; August 2014 May 2014

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Microorganisms MCQ's 2014 Answered

Question 1 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 2 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 3 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

  • Only some Archaea are capable of methanogenesis

  • Archaea are sensitive to β-lactam antibiotics

  • Bacteria have similar RNA polymerase to that of Archaea

Explanation

Question 4 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 5 of 40

1

A culture of E. coli is diluted by a factor of x 10-5 and, after plating out 100 µl on an agar plate, 78 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:

  • 7.8 x 10(7)

  • 7.8 x 10(8)

  • 7.8 x 10(6)

  • 7.8 x 10(5)

Explanation

Question 6 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

Question 7 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 8 of 40

1

Which of the following is only transmitted by direct person-to-person contact?

Select one of the following:

  • Malaria

  • Plague

  • Gonorrhoea

  • . Tuberculosis

Explanation

Question 9 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 glucose as a carbon source

  • CO2 as both an energy source and a carbon source

  • All of the above.

Explanation

Question 10 of 40

1

Biochemical synthesis of new cell material is called:

Select one of the following:

  • Metabolism.

  • Anabolism.

  • Catabolism.

  • Synthatabolism.

Explanation

Question 11 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 12 of 40

1

Incorporation of atmospheric N2 to NH4+ occurs via the process of:

Select one of the following:

  • Nitrogen fixation.

  • Nitrification.

  • Denitrification.

  • None of the above, atmospheric N2 cannot be incorporated into NH4+

Explanation

Question 13 of 40

1

Which of these environmental factors influence microbial growth?

Select one of the following:

  • pH

  • Water potential

  • Oxygen

  • All of the above

Explanation

Question 14 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 15 of 40

1

‘Necrosis’ is a symptom of infection of a plant with a pathogenic organism. Necrosis is:

Select one of the following:

  • Yellowing of infected or surrounding tissue

  • Uncontrolled cell division resulting in the formation of a gall

  • Death of infected or surrounding cells

  • Premature leaf fall

Explanation

Question 16 of 40

1

Phytophthora infestans is a fungus-like organism which:

Select one of the following:

  • Causes disease of a wide range of woody hosts

  • Causes potato blight

  • Causes ringworm

  • Causes black sigatoka disease of banana

Explanation

Question 17 of 40

1

Bacterial genes:

Select one of the following:

  • often contain introns

  • often organised in operons

  • always encode proteins

  • always shorter than 1,000 base pairs

Explanation

Question 18 of 40

1

The Bacterial chromosome is:

Select one of the following:

  • Circular DNA

  • Linear DNA

  • Either circular or linear DNA

  • Double stranded RNA

Explanation

Question 19 of 40

1

The genome of measles virus is composed of :

Select one of the following:

  • Double stranded DNA

  • Single stranded DNA

  • Single stranded RNA

  • DNA and RNA

Explanation

Question 20 of 40

1

The poliovirus mature virus particle:

Select one of the following:

  • Contains 240 copies of a single protein

  • Contains 60 copies of four proteins

  • Has a dsDNA genome

  • Has a single stranded negative–sense genome

Explanation

Question 21 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 contain mitochondria

  • Bacterial cells are usually larger than eukaryote cells

  • Bacteria do not contain a chromosome

  • Only bacterial cells are sensitive to β-lactam antibiotics

Explanation

Question 22 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 23 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 found inside all bacterial cells

Explanation

Question 24 of 40

1

A culture of E. coli is diluted by a factor of 10(-5) and, after plating out 100 µl on an
agar plate, 142 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:

  • 1.42 x 10(7)

  • 1.42 x 10(8)

  • 1.42 x 10(6)

  • 1.42 x 10(5)

Explanation

Question 25 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

  • Only some Archaea are capable of methanogenesis

  • Archaea are sensitive to β-lactam antibiotics

  • Bacteria have similar RNA polymerase to that of Archaea

Explanation

Question 26 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 the Gram negative cell wall

Explanation

Question 27 of 40

1

Which of the following is transmitted to humans by arthropods?

Select one of the following:

  • Tuberculosis

  • Malaria

  • Cholera

  • Typhoid

Explanation

Question 28 of 40

1

The antibiotic rifampicin interferes with which of the following?

Select one of the following:

  • Peptidoglycan synthesis

  • DNA gyrase

  • Lipid synthesis

  • RNA polymerase

Explanation

Question 29 of 40

1

Catalase is indispensable to

Select one of the following:

  • Obligate anaerobes

  • Aerotolerant anaerobes

  • Aerobes

  • All of the above

Explanation

Question 30 of 40

1

The CORRECT way to write this microbe’s name is

Select one of the following:

  • bacillus subtilis (italics)

  • Bacillus subtilis

  • Bacillus Subtilis (italics)

  • Bacillus subtilis (italics)

Explanation

Question 31 of 40

1

Chemical energy is released when organic or inorganic compounds are:

Select one of the following:

  • Reduced

  • Incorporated into larger molecules

  • Oxidized

  • Synthesized

Explanation

Question 32 of 40

1

A microbe isolated from deep in the ocean could best be characterized as a:

Select one of the following:

  • Psychrophile.

  • Mesophile.

  • Barophile and psychrophile

  • Barophile.

Explanation

Question 33 of 40

1

Which of the following is both a selective and a differential medium?

Select one of the following:

  • Nutrient broth.

  • MacConkey agar.

  • Blood agar.

  • Tryptic soya broth.

Explanation

Question 34 of 40

1

The signature sequence is used extensively in:

Select one of the following:

  • Developing phylogenetic probes for fluorescent in situ hybridisation.

  • Analyzing the G+C content of DNA.

  • Isolating microorganisms from the environment.

  • All of the above

Explanation

Question 35 of 40

1

Mature virus particles (Virions) ALWAYS contain:

Select one of the following:

  • non-structural proteins

  • a protease enzyme

  • a DNA or RNA genome

  • a reverse transcriptase

Explanation

Question 36 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 37 of 40

1

Organisms belonging to the genus Phytophthora are:

Select one of the following:

  • True fungi

  • Fungus-like organisms

  • Slime moulds

  • Rusts

Explanation

Question 38 of 40

1

Which of the following is NOT a correct statement about true fungi

Select one of the following:

  • True fungi are eukaryotic

  • All true fungi are multi-cellular

  • True fungi are heterotrophic

  • Most true fungi have chitin cell walls

Explanation

Question 39 of 40

1

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

Select one of the following:

  • A plasmid is a regulatory gene

  • A plasmid is a short RNA molecule

  • A plasmid is an extra chromosomal DNA molecule

  • A plasmid is a non coding region found in some bacterial genomes

Explanation

Question 40 of 40

1

A Wild-type bacterial strain is:

Select one of the following:

  • A strain with a limited number of mutations

  • An arbitrarily chosen strain

  • A strain without plasmids

  • A strain which is sensitive to antibiotics

Explanation

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