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Papers covered; May 2010

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Microorganisms MCQ's 2010

Question 1 of 25

1

A microbe growing in a functioning refrigerator is probably a:

Select one of the following:

  • Psychrophile

  • Mesophile

  • Thermophile

  • Hyperthermophile

Explanation

Question 2 of 25

1

Active transport in 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 3 of 25

1

The size of the most useful RNA molecule for prokaryotic evolutionary studies is:

Select one of the following:

  • 5S

  • 16S

  • 18S

  • 23S

Explanation

Question 4 of 25

1

Siderophores:

Select one of the following:

  • Act as a solvent for iron and transport it into the cells

  • Are a key component of cytochromes

  • Help maintain osmotic balance in seawater microbes

  • Develop when errors in membrane synthesis occur

Explanation

Question 5 of 25

1

Chemical energy is released when organic or inorganic compounds are:

Select one of the following:

  • Reduced

  • Incorporated into larger molecules

  • Synthesized

  • Oxidized

Explanation

Question 6 of 25

1

MacConkey agar selects for:

Select one of the following:

  • Gram-negative bacteria

  • Gram-positive bacteria

  • Both Gram-positive and Gram-negative bacteria

  • Haemolytic microorganisms

Explanation

Question 7 of 25

1

The bacterial genome is:

Select one of the following:

  • Mostly diploid but includes several haploid regions

  • A single circular DNA molecule

  • Mostly haploid

  • A double stranded RNA molecule

Explanation

Question 8 of 25

1

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

Select one of the following:

  • Plasmids are extra chromosomal DNA that encode only resistance to antibiotics

  • Plasmids are a part of bacterial chromosome

  • Plasmids are single stranded DNA found in some bacteria

  • Plasmids are extra chromosomal DNA molecules

Explanation

Question 9 of 25

1

The genomes of positive-sense RNA viruses:

Select one of the following:

  • Can give rise to infectious virus if transfected into their host tissue culture cells

  • Are fully or partially translated immediately following uncoating in host cells

  • Need to be transcribed to produce mRNA molecules immediately after uncoating

  • Always carry a polymerase molecule in their mature capsid that functions after infection

Explanation

Question 10 of 25

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 11 of 25

1

Which of the following organisms is NOT a true fungus (i.e. it is classified in the Kingdom Protoctista):

Select one of the following:

  • Phytophthora infestans

  • Botrytis cinerea

  • Agaricus bisporus

  • Taphrina deformans

Explanation

Question 12 of 25

1

Black sigatoka is a:

Select one of the following:

  • Fungal root disease of bananas

  • Fungal foliar disease of bananas

  • Fungal fruit disease of apples

  • Fungal foliar disease of potatoes

Explanation

Question 13 of 25

1

Which of the following is transmitted to humans by arthropods?

Select one of the following:

  • Tuberculosis

  • Malaria

  • Cholera

  • Typhoid

Explanation

Question 14 of 25

1

Which of the following is a host component important in specific immune recognition of extracellular microbes?

Select one of the following:

  • Antigen

  • Antibody

  • Phagocyte

  • Lipopolysaccharide

Explanation

Question 15 of 25

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 usually larger than eukaryote cells

  • Bacteria do not contain a chromosome

  • Bacterial cells are not sensitive to β-lactam antibiotics

Explanation

Question 16 of 25

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 a human alone indicates that it causes disease

  • Determination in a series logical steps the agent that causes disease

  • The observation of bacterial cells in tissue from a human with disease indicates that the observed bacterium has caused the disease

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

Explanation

Question 17 of 25

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 all bacterial cells

Explanation

Question 18 of 25

1

A culture of E. coli is diluted by a factor of 10-6 and, after plating out 100 μl on an agar plate, 63 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:

  • 6.3 x 10(7)

  • 6.3 x 10(8)

  • 6.3 x 10(6)

  • 6.3 x 10(5)

Explanation

Question 19 of 25

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 20 of 25

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 25

1

Fungi primarily contribute to soil and plant health by:

Select one of the following:

  • Degrading sand particles to release Si

  • Facilitating desiccation of water-logged soils

  • Degrading organic matter and releasing nutrients

  • Preventing bacterial growth

Explanation

Question 22 of 25

1

Fungi tend to live at interfaces. Which of these statements is untrue:

Select one of the following:

  • This can be where nutrients are most concentrated

  • Solid surfaces may provide anchorage

  • Other microbes, that leak useful metabolites, may inhabit such niches

  • There is typically less water on physical surfaces and fungi avoid water

Explanation

Question 23 of 25

1

Fungal growth and cell division is not normally accompanied by:

Select one of the following:

  • Biomass aquisition

  • Reduced vitality

  • Nucleic acid replication

  • Enhanced ability to compete with other microbial species

Explanation

Question 24 of 25

1

One factor that is not used to prevent or reduce fungal spoilage of processed foods is:

Select one of the following:

  • Addition of benzene

  • Low water-activity

  • Refrigeration

  • Heat-sterilization

Explanation

Question 25 of 25

1

Saprophytic activity is essential for biosphere health because it:

Select one of the following:

  • Facilitates nutrient cycling and waste degradation

  • Kills host organisms and thereby averts overpopulation

  • Facilitates species evolution via endosymbiosis

  • Involves mineralization of inorganic rocks in the lithosphere

Explanation

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