Question 1

Which of the following statements best describes the relationship between ozone in the stratosphere and the presence of CFCs?

Accepted Answer

Ozone is a naturally occurring molecule in the stratosphere and is formed by the interaction of UV radiation with oxygen molecules. However, CFCs cause additional ozone breakdown in the stratosphere. CFCs contain chlorine and fluorine, which react with ozone molecules, causing them to break apart and reducing the amount of ozone in the stratosphere. This leads to a thinning of the ozone layer, which allows more harmful UV radiation to reach Earth's surface.

Question 2

In an experiment examining the level of UV-B radiation on the incidence of skin cancer, the level of UV-B radiation would be the _____________.

Accepted Answer

The level of UV-B radiation is being manipulated in the experiment, and any changes in the incidence of skin cancer are being measured in response to this manipulation. Therefore, the level of UV-B radiation is the independent variable.

Question 3

In an experimental study, what is TRUE about the independent variable?

Accepted Answer

The independent variable is the variable that the researcher manipulates or changes in order to see its effect on some other variable (the dependent variable). Therefore, choice C is correct. Choices A, B, D, and E are incorrect because they do not accurately describe the nature or role of the independent variable.

Question 4

In an experimental study, what is TRUE about the dependent variable?

Accepted Answer

The dependent variable is a measured response that is typically charted on the y-axis (vertical axis) of a graph in an experimental study. It is used to assess the effects of the independent variable (the variable being manipulated) on the outcome of the study.

Question 5

Susan Solomon used an observational study because:

Accepted Answer

The atmosphere is too vast and complex to control in a laboratory setting, making an observational study the most appropriate method for studying it.

Question 6

Infographic 2.5.

-Refer to Infographic 2.5. Does an increase or decrease in the concentration of chlorine monoxide (ClO) in the stratosphere support Solomon's hypothesis that free chlorine molecules (Cl₂) from CFCs would break up into chlorine atoms that destroy ozone?

Accepted Answer

The answer of  Infographic 2.5.

-Refer to Infographic 2.5. Does...

Question 7

Scientists generally require a level of certainty of at least ______ to be sure their conclusions are correct.

Accepted Answer

Scientists generally require a level of certainty of at least 95% to be sure their conclusions are correct. This means that there is only a 5% chance that their results occurred by chance or coincidence. This level of confidence is achieved by using statistical tests and analyzing large samples of data.

Question 8

Prior to Susan Solomon's experiments, the information available to NASA ozone-modeler Paul Newman led him to believe that the loss of ozone in the Antarctic spring was due to excess solar activity. What was the new information that Solomon discovered that led Newman to reject his hypothesis in favor of her polar cloud hypothesis? Is it possible that Solomon's hypothesis could be rejected in the future?

Accepted Answer

The answer of Prior to Susan Solomon's experiments, the information...

Question 9

A researcher wants to know how effective a new suntan lotion is at preventing skin cancer caused by UV radiation. She uses mice as test subjects to model the effects for humans. Which of the following is the best control for this experiment?

Accepted Answer

The best control in this experiment is to have a group of mice that receives no suntan lotion while the test group receives the new lotion. This allows the researcher to compare the effects of the new lotion to the natural effects of UV radiation on the skin. Option A is not a control group because the mice in the control group are not receiving the same treatment as the test group. Option B is not a good control group because it alters the independent variable, the amount of UV radiation the mice receive. Option D is not a good control group because it introduces a confounding variable, genetic susceptibility, that could affect the results. Option E is not a good control group because it introduces a new variable, lotion in their drinking water, that has not been tested for its effectiveness in preventing skin cancer.

Question 10

The group in an experimental study that is manipulated such that it differs from the control group in only one way is the _________.

Accepted Answer

The group that is manipulated in an experimental study and differs from the control group in only one way is called the test group. This group is used to test the effect of the manipulation or treatment being studied, and its results are compared to those of the control group, which does not receive the treatment or manipulation.

Question 11

When conducting an experimental study, scientists manipulate the ________ variable and measure the _____________ variable to see if it is affected.

Accepted Answer

In an experimental study, the scientist manipulates the independent variable and measures the dependent variable to see if it is affected. Choice B correctly identifies the independent variable as the one being manipulated and the dependent variable as the one being measured.

Question 12

What kind of study, observational or experimental, was Susan Solomon's experiment that provided support for her hypothesis that CFCs were leading to depletion of ozone in the stratosphere?

Accepted Answer

The answer of What kind of study, observational or experimental,...

Question 13

In the following example, what is the independent variable? Hypothesis: Mice on a restricted low-caloric diet will live longer than mice that can eat as much as they want.
Experiment: A large population of genetically identical mice is divided into two groups. Half receive as much food as they care to eat each day. The other half receives 20% less food than a typical mouse eats each day. The day of death (lifespan) is recorded for all mice. All mice live in the same room, in the same type of cage, with access to water.

Accepted Answer

The independent variable is the amount of food available, as it is being manipulated by providing two different amounts to the two groups of mice. The dependent variable is the lifespan of each mouse, which is being measured as the outcome of the experiment. The other options (B, C, and D) are not relevant to the independent variable being tested in this experiment.

Question 14

Studying the effects of CFCs on ozone in the atmosphere is an example of which of the following?

Accepted Answer

Studying the effects of CFCs on ozone in the atmosphere is an observational study because scientists do not manipulate or intentionally change any variables. They simply observe and record the effects of CFCs on ozone in the atmosphere over time.

Question 15

Which type of experiment collects data in the real world, without manipulating the subject of study?

Accepted Answer

Observational experiments involve collecting data in the real world without manipulating the subject of study. This type of study can be used to observe and describe relationships between variables or to gather information about a particular phenomenon. Examples of observational studies include surveys, naturalistic observations, and case studies.

Question 16

Which of the following provided support for Solomon's hypothesis that CFCs were contributing to ozone depletion?

Accepted Answer

Both options C and D provide support for Solomon's hypothesis. Option C shows that NOₓ levels were decreasing, indicating that it was not the cause of ozone depletion. Option D shows that high levels of ClO were observed in the stratosphere, which is consistent with the mechanism proposed by Solomon that CFCs were releasing chlorine atoms that were destroying ozone molecules. Therefore, the combination of options C and D strongly supports Solomon's hypothesis, and choice E is the best answer.

Question 17

Which type of study is appropriate for demonstrating the cause-and-effect relationship between an independent variable and a dependent variable?

Accepted Answer

An experimental study is the best choice for demonstrating a cause-and-effect relationship between an independent variable (the cause) and a dependent variable (the effect). In an experimental study, the researcher can manipulate the independent variable and control for other variables that may influence the outcome, thus providing strong evidence for causality. Observational and natural studies may suggest a correlation between variables, but they cannot establish causal relationships. Anecdotal evidence is based on individual experiences and cannot be used to draw general conclusions. Inferential studies involve making predictions or inferences based on data, but they do not necessarily demonstrate causality.

Question 18

Which of the following statements is TRUE of CFCs?

Accepted Answer

CFCs (chlorofluorocarbons) are industrial chemicals that were once commonly used as refrigerants, solvents, and propellants in spray cans. They were also responsible for depleting the ozone layer. Option B is incorrect as UV-C is the type of ultraviolet radiation between UV-A and UV-B. Option C is incorrect as CFCs are not used to cook food at the McMurdo research station. Option D is incorrect as CFCs are actually responsible for depleting the ozone layer.

Question 19

When data are shown in a graph, the independent variable should be plotted on the _______.

Accepted Answer

The independent variable, also known as the explanatory variable, is typically plotted on the x-axis in a graph. The dependent variable or response variable is usually plotted on the y-axis.

Question 20

The multiple lines of evidence in support of the "CFC hypothesis" have elevated it to the status of __________.

Accepted Answer

The "CFC hypothesis" is a well-supported explanation for the depletion of the ozone layer, but it has not yet been elevated to the status of a law or proven fact. As a scientific explanation, it falls under the category of a theory - an overarching framework that explains a set of related phenomena based on multiple lines of evidence.

Quiz 2: Science Literacy and the Process of Science- Science and the Sky: Solving the Mystery of the Disappearing Ozone