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Papers covered; May 2012 NO RESIT PAPER

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Microorganisms MCQ's 2012

Questão 1 de 40

1

Which of the following is a macronutrient?

Selecione uma das seguintes:

  • Manganese

  • Magnesium

  • Zinc

  • Cobalt

Explicação

Questão 2 de 40

1

Denitrification is a process by which:

Selecione uma das seguintes:

  • Nitrogen gas is fixed by microorganisms

  • Nitrates are reduced to nitrogen gas

  • Nitrates are reduced to ammonia

  • Nitrogen is assimilated into cellular material

Explicação

Questão 3 de 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?

Selecione uma das seguintes:

  • 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

Explicação

Questão 4 de 40

1

Catalase is indispensable to:

Selecione uma das seguintes:

  • Obligate anaerobes

  • Aerotolerant anaerobes

  • Aerobes

  • All of the above

Explicação

Questão 5 de 40

1

Addition of blood to a culture medium allows haemolytic bacteria to be picked out. This is an example of a:

Selecione uma das seguintes:

  • Selective medium

  • Differential medium

  • Synthetic medium

  • Defined medium

Explicação

Questão 6 de 40

1

Which of these environmental factors influence microbial growth?

Selecione uma das seguintes:

  • pH

  • Water potential

  • Oxygen

  • All of the above

Explicação

Questão 7 de 40

1

Mutations are:

Selecione uma das seguintes:

  • Chemical modifications of DNA or RNA molecules

  • Any changes of bacterial genome as compared with a wild type

  • Events resulting from genetic exchange between bacterial plasmids

  • Sequencing errors

Explicação

Questão 8 de 40

1

A Wild-type bacterial strain is:

Selecione uma das seguintes:

  • A strain with a limited number of mutations

  • An arbitrarily chosen strain

  • A strain without plasmids

  • A strain which is sensitive to antibiotics

Explicação

Questão 9 de 40

1

Viruses may encode their genomes as:

Selecione uma das seguintes:

  • DNA

  • RNA

  • negative strand RNA

  • All of the above

Explicação

Questão 10 de 40

1

Virus particles:

Selecione uma das seguintes:

  • Are always smaller than bacterial cells

  • Can replicate independently of a host cell if provided with a nutrient medium

  • Can use some of the enzymes expressed in the host cell to aid their replication

  • Are always eliminated by the host immune system

Explicação

Questão 11 de 40

1

The symptom ‘chlorosis’ which develops when some fungi infect plants is due to:

Selecione uma das seguintes:

  • Cell death

  • Nutrient imbalance

  • Impaired photosynthesis

  • Excess plant hormones

Explicação

Questão 12 de 40

1

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

Selecione uma das seguintes:

  • True fungi are eukaryotic

  • All true fungi are multi-cellular

  • True fungi are heterotrophic

  • Most true fungi have chitin cell walls

Explicação

Questão 13 de 40

1

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

Selecione uma das seguintes:

  • Heat-killed Mycobacterium tuberculosis

  • Attenuated live Mycobacterium tuberculosis

  • Mycobacterium bovis

  • Attenuated live Mycobacterium bovis

Explicação

Questão 14 de 40

1

Which of the following is transmitted to humans by arthropods?

Selecione uma das seguintes:

  • Tuberculosis

  • Malaria

  • Cholera

  • Typhoid

Explicação

Questão 15 de 40

1

Pasteur is attributed with which one of the following discoveries?

Selecione uma das seguintes:

  • 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

Explicação

Questão 16 de 40

1

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

Selecione uma das seguintes:

  • 20 μm

  • 2 μm

  • 200 nm

  • 20 nm

Explicação

Questão 17 de 40

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 18 de 40

1

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

Selecione uma das seguintes:

  • It is negatively supercoiled

  • It is positively supercoiled

  • There are typically several origins of replication

  • It consists of over 50 million base pairs

Explicação

Questão 19 de 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?

Selecione uma das seguintes:

  • 7.8 x 10(7)

  • 7.8 x 10(8)

  • 7.8 x 10(6)

  • 7.8 x 10(5)

Explicação

Questão 20 de 40

1

Bacterial flagella bring about cell motion by which mechanism?

Selecione uma das seguintes:

  • 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

Explicação

Questão 21 de 40

1

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

Selecione uma das seguintes:

  • Nitrogen fixation

  • Nitrification

  • Denitrification

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

Explicação

Questão 22 de 40

1

Active transport is necessary when:

Selecione uma das seguintes:

  • 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

Explicação

Questão 23 de 40

1

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

Selecione uma das seguintes:

  • 5S

  • 16S

  • 18S

  • 23S

Explicação

Questão 24 de 40

1

Siderophores:

Selecione uma das seguintes:

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

  • Are a key component of cytochromes

  • Help maintain osmotic balance in seawater microbes

  • Develop when errors in membrane synthesis occur

Explicação

Questão 25 de 40

1

Chemical energy is released when organic or inorganic compounds are:

Selecione uma das seguintes:

  • Reduced

  • Incorporated into larger molecules

  • Synthesized

  • Oxidized

Explicação

Questão 26 de 40

1

MacConkey agar selects for:

Selecione uma das seguintes:

  • Gram-negative enteric bacteria

  • Gram-positive bacteria

  • Both Gram-positive and Gram-negative bacteria

  • Haemolytic microorganisms

Explicação

Questão 27 de 40

1

The Bacterial chromosome is:

Selecione uma das seguintes:

  • Circular DNA

  • Linear DNA

  • Either circular or linear DNA

  • Double stranded RNA

Explicação

Questão 28 de 40

1

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

Selecione uma das seguintes:

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

  • Plasmids are a part of the bacterial chromosome

  • Plasmids are single stranded DNA found in some bacteria

  • Plasmids are extra chromosomal DNA molecules

Explicação

Questão 29 de 40

1

Which is the TRUE statement below:

Selecione uma das seguintes:

  • Viruses do not infect microorganisms

  • All viruses are enveloped

  • All viruses cause disease

  • All viruses are parasites

Explicação

Questão 30 de 40

1

The poliovirus mature virus particle:

Selecione uma das seguintes:

  • Contains 240 copies of a single protein

  • Contains 60 copies of four proteins

  • Has a dsDNA genome

  • Has a single stranded negative–sense genome

Explicação

Questão 31 de 40

1

Phytophthora infestans is a fungus-like organism which:

Selecione uma das seguintes:

  • Causes disease of a wide range of woody hosts

  • Causes potato blight

  • Causes ringworm

  • Causes black sigatoka disease of banana

Explicação

Questão 32 de 40

1

Zoophilic dermatophytes are:

Selecione uma das seguintes:

  • normally associated with animals and humans

  • normally only associated with humans

  • mainly associated with the soil

  • mainly associated with contaminated water

Explicação

Questão 33 de 40

1

Which of the following is primarily a respiratory pathogen?

Selecione uma das seguintes:

  • Vibrio cholerae

  • Mycobacterium tuberculosis

  • Salmonella typhi

  • Mycobacterium leprae

Explicação

Questão 34 de 40

1

Which of the following is NOT an acquired mechanism of antibiotic resistance in bacteria?

Selecione uma das seguintes:

  • Beta-lactamase production

  • Efflux pump antibiotic export

  • Lack of peptidoglycan

  • RNA polymerase single nucleotide change

Explicação

Questão 35 de 40

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 36 de 40

1

Koch’s postulates most correctly relate to which one of the following statements?

Selecione uma das seguintes:

  • The isolation of a bacterium in culture from a human alone indicates that it causes disease

  • Determination in a series of 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

Explicação

Questão 37 de 40

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 38 de 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, 94 colonies grew after incubation at 37oC overnight. The original culture therefore contained how many viable E. coli cells per ml?

Selecione uma das seguintes:

  • 9.4 x 10(7)

  • 9.4 x 10(8)

  • 9.4 x 10(6)

  • 9.4 x 10(5)

Explicação

Questão 39 de 40

1

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

Selecione uma das seguintes:

  • 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

Explicação

Questão 40 de 40

1

Which statement is CORRECT with respect to peptidoglycan?

Selecione uma das seguintes:

  • 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

Explicação

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