Microbiology Lab [ LAB EXAM 1 ] Review Questions And Answers Verified Solutions.

If a bacterial cluster appears as a square of four cocci, this arrangement is called as _________ - correct answers tetrad A streptococcus arrangement shows __________ - correct answers cocci in chains a chain of round bacteria - correct answers streptococcus irregular group of round bacteria with no specific arrangement - correct answers staphylococcus group of cocci arranged in cluster of 8 - correct answers sarcinae diplobaccilus - correct answers two rod shaped bacteria attached together study of cell shape and arrangement is called ________ - correct answers morphology The proper procedure for smear preparation is: - correct answers Make smear--air dry--heat fix Use of two dyes - correct answers differential staining Use of a single stain - correct answers simple staining Basic stains with a positively charged chromatogen - correct answers Methylene blue and Crystal violet Negatively charged chromatogens - correct answers acidic stains Differential staining - correct answers Decolorizing agent In staining procedure used to identify Mycobacterium smegmatis, the decolorizer used is _______ - correct answersacid alcohol Primary stain in Acid-fast staining - correct answerscarbol fuchsin Primary stain in Gram staining - correct answersCrystal violet Counter stain in Acid fast staining - correct answersMethylene blue Counter stain in Gram staining - correct answersSafranin Acidic stain - correct answersNigrosin At the end of Gram staining, Gram positive bacteria stain purple while Gram negative bacteria stain red. - correct answersTRUE What is the purpose of using decolorizing agent in Gram staining? - correct answersa. In Gram negative cells alcohol increases the porosity of cell wall by dissolving the lipid in outer layer, removing the CV-I complexes b. In Gram positive cells alcohol dehydrates cell wall and shrinks the pores, making it difficult to remove CV-I complexes. both a and b are correct Why are bacteria not stained in negative staining? - correct answersBoth the bacterial cell wall and the dye are negatively charged, so they repel each other Amphitrichous flagellar arrangement show presence of a cluster of flagella at one end only - correct answersFALSE All bacteria have flagella - correct answersFALSE Presence of flagella contributes to bacterial pathogenecity. - correct answers TRUE What is the concentration of agar in the motility test media? - correct answers0.3%-0.5% turns red in reduced form - correct answers Tritetrazolium chloride concentration of agar - correct answers0.3%-0.5% depression slide - correct answers hanging drop technique brownian movement - correct answers non motile bacteria