Question

15 through 20 please

A) live lab animals; B) embryonated bird eggs: C) tissue cell cultures; D) a blood agar 15. Which of the following is a type of cytopathic effect that can be used as evidence of viral infection? A) inclusions in the nucleus; B) multinucleated giant cells (syncytia): C) inclusions in the cytoplasm; D) cells rounding up and transforming into tumor cells; E) all of the choices are correct 16. Which of the following is a function of early T4 phage gene expression? A) capsid synthesis; B) replication of viral nucleic acid: C) alteration of host RNA polymerase so that it will preferentially transcribe viral genes; D) virion assembly 17. The event that occurs in bacteriophage multiplication that does not occur in most animal virus replication is: A) adsorption to the host cells; B) injection of the viral nucleic acid into the host cell; C) host cell synthesis of viral enzymes and capsid proteins; D) assembly of nucleocapsids; E) replication of viral nucleic acid capsid. 18. One of the principal capsid shapes is a 20-sided figure with 12 evenly spaced corners referred to as an A) spiked; B) radial; C) icosahedral; D) helical; E) bilateral 19. The use of a chemical compound to destroy vegetative pathogens on human skin or mucous membrane is best fermedi A) disinfection; B) sterilization; C) antisepsis; D) sanitization 20. Which of the following types of control agents would be used to achieve sterility? A) virucide; B) sporicidal chemicals such as glutaraldehyde; C) pasteurization; D) algicidal compounds for swimming pool such as CuSO4; E) fungicide

Answer 1

Answer 15: “A,B and C” Inclusions in the nucleus, multinucleated giant cells (syncytia), inclusions in the cytoplasm.

Explanation: Cytopathic effects are the changes caused by the infecting virus in the cell morphology. The virus during infection completely takes over the cell’s enzymes and synthesizes its own molecules. In the process, it can form the inclusion bodies which are viral replication by products, or host cell’s damaged organelles or structures. During infection the virus can join the adjacent cells and form multinucleated giant cells.

The formation of tumor cells will take place only when the host cell survives and virus changes the genome of the host cell in such a way that the cell loses control over the cell division and becomes cancerous. Hence it cannot be considered as a Cytopathic effect.

Answer 16: “C” alteration of host RNA polymerase so that it preferably transcribe viral genes.

The virus T4 changes the Sigma Factor of the host, thereby the host promoters are not recognised by the host RNA polymerase, instead the host RNA polymerase recognizes the virus promoter

Answer 17: “B “injection of viral nucleic acids in to host cells.

Bacteriophage inject DNA into the host cell, whereas animal viruses enter by endocytosis or membrane fusion , animal virus cannot inject DNA in host cell.

Answer 18: “C “Icosahedral.

Examples of viruses with an icosahedral structure are the poliovirus, rhinovirus, and adenovirus.

Answer 19: “C “Antisepsis.

Skin and mucous membrane antisepsis helps to removal surface micro flora, which aids in sample collection from the skin surface or mucous membrane

Answer 20: B: sporicidal agents such as Glutaraldehyde

In microbiological terms any agent which kills all forms of life from a particular surface or material i e both vegetative and Sporulating forms of organism.

Glutaraldehyde, as a disinfectant, it is used to sterilize surgical instruments and other areas of hospitals. Glutaraldehyde is effective against a range of microorganisms such bacteria, fungi including spores, hence can be used to obtain sterility.

Virucidal, fungicidal and algalcidal agents will be specific in removal of virus, fungus and algae, but will not act against bacteria and spores.

Pasteurization is a process of flash heating at high temperature, short time, it does not kill the spores.