Staining of bacteria Objective Question

1.Which care should be taken care while using slides for staining?

  • a) Slide must be free from grease
  • b) Slide must be handled through edges
  • c) One should try to spread the water drop evenly over the surface of slide to check its greasiness
  • d) All of the above

2.Which kind of water should be used to make smear?

  • a) Distilled water with neutral or slightly alkaline pH
  • b) Freshly distilled water, if possible
  • c) If water is not fresh enough, boiling or addition of neutral phosphate buffer is advisable
  • d) All of the above

3.Fixation helps to:

  • a) Preserve the internal and external structures of cells and microorganisms
  • b) Inactivate enzymes that might disrupt all structures
  • c) Toughens cell structure, so that they do not undergo change during and post staining
  • d) All of the above

4.Ethanol, Acetic acid, Mercuric chloride, Formaldehyde and Glutaraldehyde are used as:

  • a) Intensifiers
  • b) Mordants
  • c) Fixatives
  • d) Decolorizers

5.Accentuators differ from Mordants as:

  • a) They act by combining with the dye
  • b) They do not act by combining with the dye
  • c) They ionize the dye
  • d) They degrade the dye

6.The compounds that can be used for decolorizing in different ways are:

  • a) Use of an excess of mordants
  • b) Use of acids and alcohols
  • c) Use of oxidizing agents
  • d) All of the above

7.Progressive staining is done when:

  • a) Staining is done in a definite order and decolorizing is not essential
  • b) Staining is done in an indefinite order and decolorizing is not essential
  • c) Staining is done in a definite order and decolorizing is essential
  • d) Staining is done in an indefinite order and decolorizing is essential

8.Heat fixation is carried out at:

  • a) 70 °C for 10 – 20 seconds
  • b) 50 °C for 10 – 20 seconds
  • c) 70 °C for 1 – 2 seconds
  • d) 150 °C for 1 – 2 seconds

9.In specimen preparation the samples are fixed before staining by:

  • a) Titanium
  • b) Ethanol
  • c) Water
  • d) Heat

10.In specimen preparation the samples are fixed before staining by:

  • a) Titanium
  • b) Ethanol
  • c) Water
  • d) Heat

11.Which mordant is used in Gram staining?

  • a) Alcohol
  • b) Formaldehyde
  • c) Iodine
  • d) Phenol

12.Preparation and staining of specimens for Light microscope includes:

  • a) Fixation
  • b) Mordanting
  • c) Decolorization and staining specific structures
  • d) All of the above

13.A process by which the internal and external structures of bacterial cells are preserved and fixed in position is called:

  • a) Fixation
  • b) Preservation
  • c) Staining
  • d) Decolorization

14.Chemical fixatives penetrate cells and react with cellular components making them:

  • a) Inactive
  • b) Immobile
  • c) Insoluble
  • d) All of the above

15.Accentuators are also known as:

  • a) Detoxifiers
  • b) Intensifiers
  • c) Emulsifier
  • d) Mordants

16.The pH value at which electric charges are expressed is known as the:

  • a) Isoelectric point
  • b) Isoelectric focusing
  • c) Both a and b
  • d) None of the above

17.The usual diametric size of a smear is:

  • a) 2000 mm
  • b) 200 mm
  • c) 20 mm
  • d) 2 mm

18.Mechanism of fixation means that the:

  • a) Reactive group easily binds with the stain
  • b) Non-reactive group easily binds with the stain
  • c) Both a and b
  • d) None of the above

19.In the mechanism of heat-fixation, fixation denatures the:

  • a) DNA
  • b) RNA
  • c) Cellular protein
  • d) Enzyme

20.In the mechanism of fixation, the cellular protein is denatured by:

  • a) Folding the globular protein
  • b) Unfolding the globular protein
  • c) Targeting the globular protein
  • d) None of the above

21.In the chemical fixation process, the chemical penetrates the cells and reacts with:

  • a) Nucleic acid
  • b) Proteins
  • c) Lipids
  • d) Both b and c

22.A chemical agent that increases the affinity between the dye particles and the bacterial cells is known as:

  • a) Decolorizing agent
  • b) Fixative
  • c) Mordant
  • d) All of the above

23.Which mordant is responsible for the thickness of the cell or organelles in staining?

  • a) Congo red
  • b) Iodine
  • c) Rose Bengal
  • d) Saffranin

24.Figure out the odd terminology in terms of a decolorizing agent:

  • a) Acetone
  • b) Alcohol
  • c) Acid-alcohol
  • d) None of the above

25.The compound used for removing the color of a dye or a stain is called:

  • a) Mordant
  • b) Recolorizing agent
  • c) Decolorizing agent
  • d) Colorizing agent

26.Which of the following is a Differential staining?

  • a) Acid fast
  • b) Capsule fast staining
  • c) Negative fast staining
  • d) Cell wall staining

27.Which of the following is a Gram-negative organism group?

  • a) E. coli, Treponema palladium, Micrococcus luteus
  • b) E. coli, Enterobacter aerogenes, Corynebacterium diphtheria
  • c) E. coli, Serratia marcescens, Coxiella burnetii
  • d) E. coli, Streptococcus pneumonia, Clostridium tetani

28.The lipids present in bacteria may be in the form of:

  • a) Mycolic acid esters
  • b) Mycosides
  • c) Glycolipids
  • d) All of the above

29.Which of the following is NOT an acid-fast bacterium?

  • a) Nocardia asteroides
  • b) Corynebacterium diphtheria
  • c) Mycobacterium phlei
  • d) Clostridium tetani

30.Gram staining was developed by:

  • a) Danish physician: Christian Gram
  • b) Dutch physician: Christian Gram
  • c) Dutch lens maker: Leeuwenhoek
  • d) French microbiologist; Louis Pasteur

31.Which of the following is an excellent way to study the size and shape of bacteria?

  • a) Gram stain
  • b) Acid fast stain
  • c) Simple stain
  • d) Negative stain

32.Which lipid soluble dye is selectively used to stain lipid inclusions in cells?

  • a) Sudan Black B
  • b) Rose Bengal
  • c) Neosine
  • d) Nigrosine

33.The reason for Sudan Black B dye to selectively stain PHB is:

  • a) It does not dissolve in aqueous interior of the cell
  • b) It is a lipid soluble dye
  • c) Both a and b
  • d) None of the above

34.Examples of Monochrome stain are:

  • a) Crystal violet
  • b) Methylene blue
  • c) Carbol-fuschin
  • d) All of the above

35.A staining method of microbes in which a single staining agent is used is referred to as:

  • a) Monochrome staining
  • b) Positive staining
  • c) Simple staining
  • d) All of the above

36.Relief staining is also known as:

  • a) Positive staining
  • b) Negative staining
  • c) Both a and b
  • d) None of the above

37.Monochrome staining procedure may be:

  • a) Positive
  • b) Negative
  • c) Direct
  • d) All of the above

38.Which staining procedure incorporates a positive ion in the dye:

  • a) Positive staining
  • b) Negative staining
  • c) Both a and b
  • d) None of the above

39.In the negative staining procedure, the negative dye ion is repelled by:

  • a) Negatively charged chromophore
  • b) Positively charged chromophore
  • c) Both a and b
  • d) None of the above

40.The main stages of differential staining are:

  • a) Mordanting
  • b) Decolorization
  • c) Both a and b
  • d) None of the above

41.Differential staining is a technique that employs more than one staining solution and allows the differentiation:

  • a) Between two kinds of organisms
  • b) Between particular structures of microorganisms
  • c) Both a and b
  • d) None of the above

42.In Gram staining alcohol acts on:

  • a) Periplasm
  • b) Teichoic acid
  • c) Membrane lipids
  • d) Peptidoglycan

43.The differential staining property of Gram staining is mainly due to:

  • a) Difference in lipid content in Gram positive and Gram-negative bacteria
  • b) Difference in cell wall thickness in Gram positive and Gram-negative bacteria
  • c) Difference in peptidoglycan layer in Gram positive and Gram negative bacteria
  • d) All of the above

44.In Gram staining, Safranin acts as:

  • a) Primary stain
  • b) Conjugate stain
  • c) Counter stain
  • d) None of the above

45.The mechanism of Gram staining is based on:

  • a) Phytochemical nature of cell wall
  • b) Biochemical nature of cell wall
  • c) Physicochemical nature of cell wall
  • d) None of the above

46.During ethanol treatment in Gram staining:

  • a) Crystal violet is dissolved in alcohol in Gram negative bacteria due to high lipid content in the outer layer
  • b) Crystal violet is retained in Gram positive bacteria due to less lipid content and thick peptidoglycan wall
  • c) Both a and b
  • d) None of the above

47.The factors affecting Gram staining are:

  • a) Age of bacterial cell
  • b) Decolonization and excessive fixation
  • c) pH and over crowding
  • d) All of the above

48.Acid fast staining is specifically done for the identification of:

  • a) Bacillus species
  • b) Mycobacterium species
  • c) Escherichia species
  • d) Clostridium species

49.Acid fast bacteria have:

  • a) High lipoidal waxy content in the cell wall
  • b) High protein content in the cell wall
  • c) High poly-saccharide content in the cell wall
  • d) High amino acid content in the cell wall

50.Acid fast property of bacteria was first discovered by:

  • a) Paul Ehrlich in 1882
  • b) Paul Ehrlich in 1982
  • c) Joseph Lister in 1876
  • d) Robert Koch in 1876

51.Property of acid fastness depends on:

  • a) Impermeability of bacterial surface to the stain
  • b) Ability of the stain to bind to a particular bacterial component
  • c) Presence of lipids and mycolic acid esters
  • d) All of the above

52.Types of lipids present in acid fast bacteria are:

  • a) Mycolic acid esters
  • b) Waxes D and glycolipids
  • c) Sulpholipids and mycosides
  • d) All of the above

53.Basic fuchsin used in acid fast staining is:

  • a) More soluble in phenol than in water
  • b) More soluble in phenol than in acid-alcohol
  • c) Both a and b
  • d) More soluble in acetone than in water

54.In acid fast staining, ZNCF is:

  • a) More soluble in cellular waxes than in the decolorizing agent
  • b) Less soluble in cellular waxes than in the decolorizing agent
  • c) More soluble in water than in the decolorizing agent
  • d) Less soluble in water than in the decolorizing agent

55.By Ziehl-Neelson’s method, acid fast bacteria appear:

  • a) Red in color
  • b) Blue or green in color
  • c) Orange or pink in color
  • d) Violet in color

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