You Add an Unknown Phage to a Mixture of F⁺

question 52

Multiple Choice

You add an unknown phage to a mixture of F⁺ and F^- cells of E. coli and plate out the bacteria. The bacterial colonies that grow are all F^-. How can you explain this phenomenon?

• A) The phage bound to a receptor on the sex pilus, and therefore only infected the F⁺ cells (leaving the F^- cells alone).
• B) The phage bound to a receptor on the F^- cells, leaving only them alive and allowing the F⁺ cells to die off.
• C) The phage integrated (lysogenized) the F^- cells, giving them a selective advantage over the F⁺ cells.
• D) F⁺ cells are uniquely susceptible to phage attack for unknown reasons.

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Definitions:

Chi-square Distribution

A probability distribution used in statistical significance tests, which is built on the sum of squared standard normal deviates.

Confidence Interval

A variety of numerical values, obtained from statistical analysis of a sample, which probably includes the value of an unseen population characteristic.

Standard Deviation

A measure of the amount of variation or dispersion of a set of values, calculated as the square root of the variance.

Variance

A measure of the dispersion of a set of data points in a population, showing how much the data diverge from the average value.