Testosterone oxido-reductase is a liver enzyme that regulates testosterone levels in alligators. One
study compared testosterone oxido-reductase activity between male and female alligators from
Lake Woodruff, a relatively pristine environment, and from Lake Apopka, an area that has suffered
severe contamination. The graph above depicts the findings of that study.
The data in the graph best support which of the following claims?
A Environmental contamination elevates total testosterone oxido-reductase activity in females.
B Environmental contamination reduces total testosterone oxido-reductase activity in females.
C Environmental contamination elevates total testosterone oxido-reductase activity in males.
D Environmental contamination reduces total testosterone oxido-reductase activity in males.
2. A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved
carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher
determines the rates of synthesis of several organic compounds found in the Spirogyra before and
after several weeks in the water solution. Which of the following graphs best illustrates a likely
result of the experiment?
3. A group of students designed an experiment to determine the effect of compost on the germination
and growth of plants. The students set up experimental plots by mixing different ratios of soil and
compost. They planted 20 pea and 20 melon seeds in each plot and watered each plot regularly.
The students recorded the number of seeds that germinated, and as the plants grew, they recorded
plant length, number and size of leaves, and general health observations.
The following observations were recorded.
• In all treatments, more pea seeds germinated than melon seeds.
• There was a week of rainy weather at three weeks.
• Melon plants developed a fungal growth at four weeks.
• Melon plants grew longer than pea plants, but many melon leaves showed signs of yellowing as
the weeks passed.
The students concluded that pea plants grew better in compost than did melon plants.
Which of the following best addresses the validity of the conclusion made by the students?
The conclusion is valid because the independent and dependent variables in the experiment were
A
controlled.
B The conclusion is valid because the experimental design included a large sample size.
The conclusion is invalid because other variables in the experiment (both biotic and abiotic)
C
affected the results.
The conclusion is invalid because the units of measurement were not given in the experimental
D
design.
4. A response of an organism to seasonal change is
A phototropism
B photoperiodism
C circadian rhythm
D photolysis
E the biological clock
A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri
dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped.
The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of
dark. All other conditions were the same for both dishes. The dishes were examined after 7 days and the
opaque cover was permanently removed from dish A. Both dishes were returned to the light and
examined again at 14 days. The following data were obtained.
5. According to the results of this experiment, germination of tobacco seeds during the first week is
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