Notes

Three beakers, all the same size, are set up with cool tap water and duckweed in them. The first beaker contains 100 mL of water and 20 fronds of duckweed. The second beaker contains 200 mL of water and 50 fronds of duckweed. The third beaker contains 300 mL of water and 40 fronds of duckweed. = the number of duckweed plants in each beaker.

The issue of whether human activities cause global climate change is a controversial topic. Which limitation to climate research could most likely be overcome through scientific design? = Data from a wide range of time periods must be analyzed.

Alli and her classmates want to know which species of oak produces the acorns that squirrels prefer. Which possible procedure is likely to produce the most reliable results? = Divide up and observe squirrels in ten locations for two hours, then dig up and identify each type of acorn buried by squirrels, repeating daily for two weeks.

Which scientific design has the fewest limitations? = using dissection to study the general structure of lily flowers

A drug researcher could avoid risking human health in tests of new drugs by = applying the new drugs to cultures of human cells and observing the effects.

In an experiment, the weight that mice gain is the dependent variable and the temperature of the environment is the independent variable. What must be held constant to obtain valid experimental results? = the type of food given to the mice

Gene is investigating what makes bread moldy. He put two identical slices of bread on separate plates. He made one slice moist and kept the other slice dry. He left the uncovered plates on a table for 2 hours. Then, he sealed them in plastic bags and put them in a dark, warm place. He looked at them each day for five days. After five days, he observed that 50 percent of the moist slice was moldy, and none of the dry slice was moldy. If Gene observed the slices for three more days, what would he most likely observe? = There would be more mold on the moist slice.


Which method of sharing data best enables others to quickly see trends in the data? = making graphs of quantitative results


Bacteria cells will stop dividing in a basic (alkaline) environment because of the high pH. Which statement is the best way to restate the hypothesis so that it is more specific? = If the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing.