Which of the following is not true about a gram-positive cell wall? a) It mainta

Question

Which of the following is not true about a gram-positive cell wall? a) It maintains the shape of the cell b) It is sensitive to lysozyme c) It protects the cell in a hypertonic environment d) It contains teichoic acids e) None of the above 32. Which type of organism must grow inside of other cells? a) Bacterium b) Fungus c) Protozoan d) Virus e) Ticks 33. What format is used in writing the genus and species name of an organism? a) Both the genus and species are capitalized b) Both the genus and species are in lower case c) The genus is capitalized and the species is in lower case d) The species is capitalized and the genus is in lower case e) None of the these 34. Filaments of fungi are known as: a) Septa b) Hyphae c) Conidia d) Spores e) Mycelium 35. A medium that allows most organisms to grow and distinguishes organisms based in their chemical properties is known as: a) Selective medium b) Transport mediunm 36. c) Growth medium d) Differential medium e) TSA medium

Explanation / Answer

32. Cell wall of gram negative bacteria helps maintain the shape of the cell and is sensitive to lysozyme and penicillin. Most gram-negative bacteria also contain teichoic acids, a bacterial co-polymer of glycerol phosphates and carbohydrates that provides rigidity to the cell wall. So, we see options a), b), and d) are all true about cell wall of gram-negative bacteria, and option e) does not apply. Now, like the cell wall of most bacteria, cell wall of gram negative bacteria can also NOT protect it in a hypertonic environment. This is because cells can exchange solute ions and water across the cell wall and if placed in hypertonic environment they will shrivel or loose water through osmosis. Therefore, your answer is c).

33. All the given organisms bacteria, fungi, protozoa, and a tick can live independently as well as a parasite inside (or on) a host organism. However, virus is the only microorganism that cannot live without a host and it must grow inside the cells of other organisms. Therefore, your answer is d).

34. In writing the genus and species name of an organism- The genus and species names are written together, both the names are italicized, and genus name is capitalized. Therefore, your answer is c).

35. The filaments of fungi are known as hyphae, while the network of hyphae is called mycelium. Septa are the cross-walls that divide the hyphae inside the fungal cells. Conidia are spores that are produced asexually by fungi, and spores are the ones through which fungi reproduce. Therefore, your answer is b)

36. Growth medium is the general term for any type of medium allowing growth of organisms. Selective and differential media are used to isolate or identify particular organisms. They let only specific types of organisms to grow. Transport media is for temporary storage and transportation of the specimen. TSA or tryptone soya agar medium is a general-purpose, nonselective medium that provides enough nutrients to allow a wide variety of organisms to grow. It is used for several puposes such as enumeration of microbial colonies, distinguishing microbes based on their chemical properties, etc. Therefore, your answer is e)

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