For a Science Fair Project,two Students Decided to Repeat the Hershey

question 62

Multiple Choice

For a science fair project,two students decided to repeat the Hershey and Chase experiment,with modifications.They decided to label the nitrogen of the DNA rather than the phosphate.They reasoned that each nucleotide has only one phosphate and two to five nitrogens.Thus,labeling the nitrogens would provide a stronger radioactive signal than labeling the phosphates.Why won't this experiment work?

• A)There is no radioactive isotope of nitrogen.
• B)The phosphate in normal DNA is naturally radioactive.
• C)Although there are more nitrogens in a nucleotide,labeled phosphates actually have 16 extra neutrons;therefore,they are more radioactive.
• D)Amino acids (and thus proteins)also have nitrogen atoms;thus,the radioactivity would not distinguish between DNA and proteins.

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Definitions:

Affordances

The properties of objects or environments that allow individuals to perform actions on them.

Bottom-Up Perception

A processing approach where sensory input is first analyzed into its components and then integrated to form a perception.

Perceptual Learning

A process through which practice or experience leads to improvements in the processing of sensory information.

Featural Analysis

A process in object recognition and perception involving the breakdown and analysis of sensory input into fundamental features or components.