Evaluating Scientific Design

Question 1

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?

Revolt · Accepted Answer

the type of food given to the mice

Question 2

Biologists use ball-and-stick models to study complex molecules by representing atoms with balls and bonds with sticks. DNA is a biological molecule that contains millions of atoms. What is a limitation of using a ball-and-stick model to represent a complete DNA molecule?

Revolt · Accepted Answer

DNA has so many atoms that the size and cost of a model could be too great.

Question 3

A kind of variable that a researcher purposely changes in an investigation is

Revolt · Accepted Answer

independent.

Question 4

Chen displayed the results of her experiment in the graph that is show below.What is the dependent variable in her experiment?

Revolt · Accepted Answer

amount of duckweed

Question 5

Gene investigated the effect of moisture on the rate of growth of mold on bread. 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?

Revolt · Accepted Answer

There would be more mold on the moist slice.

Question 6

Which statement best describes the relationship between a dependent variable and an independent variable in a scientific investigation?

Revolt · Accepted Answer

The dependent variable changes in response to changes in the independent variable.

Question 7

Many scientists are involved in research studying global climate change. Which limitation to climate research could most likely be overcome through scientific design?

Revolt · Accepted Answer

Data from a wide range of time periods must be analyzed.

Question 8

Nalah labels ten rats with the numbers 1 through 10. Then, she records how long it takes each rat to run through a maze. She finds it difficult to graph her data in a line graph. What change could she make to her experimental design that would allow her to plot a clearly displayed data trend in a single line graph?

Revolt · Accepted Answer

Repeat the experiment ten times. Label the y-axis “Time” and the x-axis “Trial.” Plot the average time for all ten rats for each trial of the experiment.

Question 9

What is true of experimental designs that are used in scientific research?

Revolt · Accepted Answer

The designs follow a general method that is familiar to all scientists.

Question 10

Which scientific design has the fewest limitations?

Revolt · Accepted Answer

using dissection to study the general structure of lily flowers

Evaluating Scientific Design Answers

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