FREE AND STUDY GAMES ABOUT MICROBIOLOGY LAB

PDF Download

FREE AND STUDY GAMES ABOUT MICROBIOLOGY LAB

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -56 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: what type of cell would you find lipoplusaccharide in its cell wall? gram negative or gram positive?

Answer:

gram- negative

Question 2: which reagent serves this purpose in the gram stain procedure?

Answer:

In the Gram stain, Gram's iodine is used to form a complex with crystal violet, trapping it into gram-positive cells (and therefore, they are purple even after decolorization

Question 3: what is the mordant in the spore stain

Answer:

Heat is the mordant in the endospore stain. It causes the endospore to expand allowing stain to penetrate the structure.

Question 4: explain why bacterial capsule is considered a virulence factor

Answer:

Because the capsule inhibits the immune system (see #1) and facilitates attachment to host cells/tissues, it has a greater capacity to cause disease. Any factor that increases the capacity to cause disease is called a virulence factor.

Question 5: explain how capsule is visualized without the use of eyes that adhere to the capsule

Answer:

Capsule stains do not penetrate the capsule but rather form an opaque background surrounding the cell, highlighting the presence of the capsule.

Question 6: in the ziehl-neelsen acid fast stain what is the mordant?

Answer:

Heat is the mordant in the Ziel-Neelsen method.

Question 7: what color of endospores after gram staining? after spore staining?

Answer:

After Gram staining, the endospore is colorless. After the endospore stain, it is green.Question 8: how would you differentiate between oral streptococci yeast and spirochaetes in your sample?

Answer:

Streptococci are ovoid cells that occur in pairs or chains; yeasts are large ovoid cells that have characteristic buds

Question 9: function does the capsule have for streptococcus mutants

Answer:

Streptococcus mutans forms a capsule that allows the bacterium to attach to the surface of a tooth. This results in the formation of a biofilm called plaque.Question 10: what biological molecules can make up the bacterial capsule or slime layer

Answer:

Capsules are composed of polysaccharides or proteins.

Question 11: why do acidic dyes not stain bacterial cells

Answer:

Acidic dyes are negatively charged, and therefore, they are repelled by negatively charged bacterial cells. Instead, they stain the background of a slide.

Question 12: if you were working with and unlabeled simple stained smear would you be able to identify the bacterial species by observing the slide under a microscope? why or why not?

Answer:

Simple staining only indicates the shape, size, and arrangement of a bacterial species. Many different species have similar characteristics, and therefore, this would not be enough to determine the species

Question 13: what is the difference between basic and acidic dyes

Answer:

Basic and acidic dyes differ in their charges, and therefore, they will be attracted to different parts of a slide when used to stain a specimen.

Question 14: why is the gram stain considered a differential stain

Answer:

The Gram stain differentiates two types of bacteria based on the composition of their cell walls. It uses a primary stain, a mordant, a decolorizer, and a secondary stain to allow for the visualization of these structural differences.

Question 15: Staphylococcus will be

Answer:

spherical cells,.Question 16: how do gram positive and gram negative differ in cellular structure and how does this contribute to their differential staining properties part 2

Answer:

in the presence of the decolorizer as compared to gram-negative cell, which has a thin layer of peptidoglycan in its cell wall.Question 17: of these three hrnerp of bacteria which does not produce endospores?clostridium, mycobacterium or bacillus?

Answer:

Mycobacterium does not produce endospores.

Question 18: M. catarrhalis should be

Answer:

pink (gram-negative) cocci in pairs (diplococci).

Question 19: which step in the gram stain procedure is mort prone to error and if done incorrectly how might this step affect the end result part 2

Answer:

If too much decolorizer is used, gram-positive cells will lose the primary stain and be counterstained pink. If too little decolorizer is used, gram-negative cells will not lose the primary stain and will remain purple after counterstaining

Question 20: functions of endospores in bacteria

Answer:

Endospores are resting stages that allow bacteria to survive conditions unfavorable for growth.

Question 21: what makes mycobacterium resistant to staining

Answer:

Mycobacterium has a waxy cell wall that contains mycolic acid, a complex lipid that prevents stains from penetrating the cell.Question 22: what step normally associated with staining bacterial cells is omitted when the dimensions of the cells are determined and why?

Answer:

Heat fixation is normally omitted when determining dimensions of bacterial cells because heat will cause cells to shrink.Question 23: external structure on the endospore acts as a protective barrier? what is its composition?

Answer:

Endospores have a protective barrier on their exterior composed of protein.

Question 24: example of a negative stain

Answer:

Nigrosin and India ink are examples of negative stains.

Question 25: m smegmatus and s epidermidis (kinyoun method)

Answer:

Acid-fast cells (M. smegmatis) will be pink to red; non-acid-fast cells (S. epidermidis) will be blue.