As a researcher, you are charged with determining the effects of a new drug. From previous observations, you suspect that this drug reduces the rate of DNA production (replication) in the skin cells of patients using the drug. With the following materials, design an experiment that would determine the effect of the drug on DNA replication. You know that DNA contains phosphate groups. You have radioactive isotopes of phosphate (³²P), skin cell cultures from different patients, the drug in question, and a device that measures radioactivity.

Which cell found in phloem tissue has a nucleus?

A) vessel element
B) tracheids
C) sieve-tube member
D) guard cell
E) companion cell

A lake that is rich in algae and rooted plants but lacks oxygen is

A) oligotrophic.
B) eutrophic.
C) benthic.
D) pelagic.
E) limnetic.

The anterior body cavity consists of the thoracic and abdominopelvic cavities.

A lizard with a striped tail and a normal head is crossed with one having a normal tail and a spotted head. All the F₁ progeny are normal (no stripes or spots) . What progeny are expected from a cross of the F₁ progeny? Assume that the genes conferring stripes and spots were on different chromosomes.

A) Equal numbers of normal, striped, spotted and striped, and spotted
B) 3 striped : 1 spotted
C) 9 striped and spotted : 3 spotted : 3 striped : 1 normal
D) 9 striped : 3 spotted : 1 striped or spotted
E) 9 normal : 3 striped : 3 spotted : 1 striped and spotted

The spinal nerves are formed by the ________.

A) dura mater
B) dorsal and ventral roots
C) pia mater

Hypothermia occurs when ____.

A) temperature falls to the point where brain activity is impaired
B) interstitial fluid begins to freeze
C) shivering response begins
D) breathing rate increases
E) metabolic activity increases