Microbiology Chapter 11 Review

Please order the following microbes or microbial forms in terms of their resistance to control methods, beginning with those that are most resistant.

1. Prions 2. Bacterial Endospores 3. Mycobacterium tuberculosis 4. Gram-negative Bacteria 5. Enveloped Virsues

Please select the four primary targets of antimicrobial control agents.

Cell wall Cell membrane Protein and nucleic acid synthesis Protein structure and function

Please select the choices which indicate the effects of heat on microbes.

Denatures protein Oxidizes the cellular structures

Please select the statement that describes the antimicrobial activity of alcohols.

Disrupt membrane lipids and denature proteins

Please choose the microbial control method that neither inhibits nor kills microbes, but instead physically removes them from liquids or air.

Filtration

Please choose the answer that correctly fills in the blanks of this sentence in order. _______radiation has good penetrating power and can be used for cold sterilization, whereas _______ radiation doesn't penetrate well and is more often used for disinfection purposes.

Ionizing; nonionizing

Please choose the answer that best completes the blanks of this sentence in the correct order. ______ radiation causes broad scale damage to DNA whereas UV light specifically causes formation of _______ dimer formation in DNA.

Ionizing; pyrimidine

Please select the factors below that influence the effectiveness of an antimicrobial agent.

Temp., Number of Microorganisms, Presence of Organic Matter, Concentration of dosage of the agent

Please choose the statement that identifies the major disadvantage of both cold and desiccation in terms of microbial control.

These methods are bacteriostatic rather than bactericidal.

An antimicrobial agent's adverse effect on cells is known as its mode of action.

True

Another potential target is the cell membrane, whose surface tension can be reduced by various microbicidal agents resulting in a loss of selective permeability in the cell.

True

Physical and chemical agents can also interfere with protein synthesis through disruption of ribosome activity, protein function through the denaturation of a protein's native state, and finally disrupting the synthesis or structure of nucleic acids.

True

Potential cellular targets of various physical and chemical forms of antimicrobials include the cell wall, whose synthesis can be blocked by these agents or whose structure can be altered as well.

True

Such antimicrobials exhibit a range of cellular targets, the least selective being the most effective against the widest range of microbes and the most selective agents exhibiting specificity in terms of cellular targets and microbial types they are effective against.

True

Please select those characteristics of a chemical control agent that make it a desirable agent.

Water or alcohol soluble and stable Cidal to a wide range of microbes, but nontoxic to humans and animal tissue Rapidly effective in low concentrations Inexpensive

A chemical labeled as ________ will inhibit bacterial growth but will not kill them.

bacteriostatic