Modern Biology Midterm

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Questions from chapters 1,2,3,7,8,9,11.

A hypothesis is a statement that can be

tested and proven false

Where are the most reliable scientific results published?

In peer-reviewed science magazines and journals

In a scientific study evaluating the beneficial effects of caffeine on the elderly, who would be the best subjects to test?

Elderly men and women

Studies involving the benefits or risks of drinking coffee may be obscured by

side effects of the caffeine, how the coffee was roasted or processed, other chemicals in coffee, and the age of the people studied

Studies involving coffee drinking have shown

a link to pancreatic cancer, no link to pancreatic cancer, a link to decreased fertility, a lowering of the incidence of ovarian cancer

Two studies were conducted to determine if a new drug was effective at reducing tumor size in patients with lung cancer. One study examined men and found that the drug reduced tumor size by 45%, while the other study, conducted on women, concluded the drug had no effect. Is it possible that the results of both studies are correct?

Yes, the results of both studies may be correct because there may be significant differences in how the drug affects men compared to women

Imagine that you read a study of the effects of exercise on the prevalence of heart disease in women ages 35 to 65. Although you believe the experiment was carried out in an appropriate manner, you still do not believe the results. You decide to conduct your own study to see for yourself. To determine if the results of the first study were valid, would you want to do everything the same way as the first study or would you change several of the variables, such as studying men, or looking at different age groups?

To be most comparable, you would conduct your new study in the exact same manner as the previous study. If you were to change any of the variables, then the results might change as well; thus, you would not be able to compare your new results to the first study.

Two researchers wish to examine the effect of caffeine on alertness. One researcher has the participants drink a cup of coffee with 100 mg of caffeine, while the other researcher has the participants take a capsule with 100 mg of caffeine. In all other respects, these two studies are identical. Which method do you think will answer the question best? Why? Are there any complicating factors that could compromise the results of one of the studies?

The study in which participants are given caffeine in pill form will best answer the question about the effect of caffeine on alertness. Even though the amounts of caffeine are equal, there could be other compounds in coffee that could influence the results.

Two studies were carried out to determine if children in daycare got more ear infections than children who stayed at home. The first study compared ear infection rates in 50 Canadian girls ages 1 to 2, half of whom attended daycare and half of whom stayed home. The second study compared ear infection rates in 1000 Swedish boys ages 3 to 4, half of whom attended daycare and half of whom stayed home. The results of these two studies differed greatly. Which of the following is LEAST likely to be the cause of such differences?

Different mothers

What factors may influence the outcome of an experiment, such as the caffeine study you read about in your textbook?

the number of people involved in the study, the demographics of the test subjects, the length of time the study was done, the way individuals are chosen for the study

Would it be possible for a scientist to bias a scientific study?

Yes, if the scientist chose specific individuals to include in the study

How can two studies on the same topic have conflicting conclusions?

There may be other factors that can influence the outcome of the study that were not considered in the experimental design.

An experiment was performed using 1000 non-smoking males ages 18 to 22. Which of the following experimental groups would most likely produce the most similar results?

800 non-smoking males ages 20 to 25

Researchers ran three experiments using the following populations:
• 250 non-smoking men ages 18 to 25
• 500 smoking and non-smoking men and women ages 20 to 55
• 300 smoking women ages 45 to 60

Would you expect the results of these three experiments to be the same?

No, because the three experimental groups were different in age, gender, and whether or not they smoked; so there are many different factors that may have had an effect on the results of the experiment.

Observations used in testing hypotheses should not include

anecdotal evidence

When tested, a hypothesis may be

not supported, supported, falsifiable, testable

All of the following are true of a scientific hypothesis except

it is an opinion

Which of the following places the steps of the scientific process in the correct order?

Questions→read literature→hypothesis→experiment→conclusions

Why can't science answer questions about the existence of a supernatural being?

Science requires a hypothesis that is testable and falsifiable. There is no way to test the existence of a supernatural being, nor is it possible to prove that a supernatural being does not exist. It is not a testable and falsifiable hypothesis.

A scientific hypothesis must have two very important features. What are they?

A scientific hypothesis must be testable and falsifiable

What does it mean to say that a scientific study has undergone "peer review"? Why is this important?

When a study has undergone peer review it means that other scientists have examined the study to make sure the experiment was carried out properly and that the conclusions are appropriate. This is important to weed out studies with questionable methods and results to ensure scientific accuracy and reliability.

Why do scientists say that a hypothesis is "supported" and never say that a hypothesis has been "proven"?

Because it is impossible to test a hypothesis under every possible scenario, there is no way to "prove" a hypothesis. Thus, a hypothesis can only be supported.

What are the steps used in the process of a scientific study?

Making initial observations that generate questions, studying the literature, generating hypotheses that are both testable and falsifiable, testing the hypothesis with experiments and analyzing the data, and making conclusions that are supported by data

What is the importance of peer review in the scientific process?

It ensures that a study has been appropriately designed and correctly interpreted

What conclusions can be drawn from a hypothesis?

If evidence rejects the hypothesis, then it can be removed from the list of possible answers to the original question. If there is data to support the hypothesis, then it is accepted until further testing suggest otherwise.

Evidence that is not based on systematic scientific study is known as _____________ evidence.

anecdotal

If the results of an experiment contradict your hypothesis, you must ___________ the hypothesis.

reject

Scientific journals send out new but unpublished research articles to other scientists working in the same research area. Those scientists read the article and make comments regarding the research. This is known as

peer review

A hypothesis must be __________________ and ____________________.

testable; falsifiable

You have the following known observations: Smoking causes accumulation of materials in the lungs, thereby decreasing the lungs' oxygen absorbing capability. Long-term smoking causes more accumulation of materials in the lungs. Decreased lung capacity increases the workload of the heart. Which of the following hypotheses can you make from these observations?

Long-term smokers may have poorer heart health than non-smokers.

A hypothesis is often called an educated guess. Why is it a guess and why is it educated?

It is a guess because it is only one possible answer to a question that has been formulated. It is educated because that question and the possible answer are both based on prior knowledge gained from previous observation and research.

What is peer review?

Peer review is the process by which articles submitted to scientific journals for publication are reviewed by other scientists working in the same subject area as the authors of the article. Peer review helps ensure that poorly designed research is not published.

A controlled experiment describes

having separate control and experimental groups

In a controlled experiment, the control and experimental groups differ in

the independent variable

A placebo is given to

the control group

Increasing the sample size

provides more reliable data

In a clinical trial with 400 subjects, the most reliable results would be obtained if ___ subjects were in the experimental group and ___ in the control.

200; 200

A study is conducted to see if walking reduces joint stiffness in people suffering from arthritis of the knee. Half the participants are instructed to walk an additional 1 mile every day, while the other half are told to go about their normal daily routine with no additional exercise. In this study, the group that walks an extra mile every day is referred to as

the experimental group

A study was conducted to determine if the growth rate of babies differs between babies that are bottle-fed and babies that are breast-fed. In this experiment, growth rate is referred to as

the dependent variable

Two groups of people are given a drug that they are told will make them drowsy. However, only one group actually receives this drug, while the other group secretly receives a sugar pill. Strangely, both groups report feeling very tired 30 minutes later. The group receiving the sugar pill is said to be experiencing

the placebo effect

What is a placebo treatment and why is it important in a properly designed experiment?

A placebo treatment is a fake treatment given to the control group to mimic the experience of the experimental group. It is important to keep as many factors as possible identical between the experimental and control groups so that only the variable being studied is different. By doing this, you ensure that the result you observe is due to the experimental factor and not to any other unknown factor.

Describe the features of an experimental group versus a control group in an experiment whose hypothesis is "coffee improves memory."

The experimental group will contain subjects who are observed under the conditions being tested. In this case, experimental and control groups would both have their memories tested in some way. The experimental group would be individuals who have had caffeinated coffee versus the control group, who would have had decaf coffee (no caffeine).

What is the importance of a placebo?

It allows the researcher to treat control and experimental groups differently while allowing them to believe they are being treated exactly the same.

A scientific study looked at the effect of tanning beds on DNA damage. The scientists took skin cells and exposed them to UV radiation (the type used in indoor tanning beds) for different lengths of time: some for 1 minute, some for 5 minutes, some for 15 minutes, and some for 30 minutes. They then looked for signs of DNA damage and compared the results to cells that had never been exposed to UV light. What is the independent variable in this experiment?

the length of time the cells are exposed

A scientific study looked at the effect of tanning beds on DNA damage. The scientists took skin cells and exposed them to UV radiation (the type used in indoor tanning beds) for different lengths of time: some for 1 minute, some for 5 minutes, some for 15 minutes, and some for 30 minutes. They then looked for signs of DNA damage and compared the results to cells that had never been exposed to UV light. What is the control in this experiment?

the untreated cells

A scientific study looked at the effect of tanning beds on DNA damage. The scientists took skin cells and exposed them to UV radiation (the type used in indoor tanning beds) for different lengths of time: some for 1 minute, some for 5 minutes, some for 15 minutes, and some for 30 minutes. They then looked for signs of DNA damage and compared the results to cells that had never been exposed to UV light. What is the independent variable in this experiment?

the amount of DNA damage

In a well designed experiment the sample size

is large enough to have statistical significance

Statistical significace

is the degree of confidence you can have that your results are real versus due to chance and is more likely to be reliable if you have a large sample size versus a small sample size.

You finish a research project and submit your findings in an article to a scientific journal for peer review. The reviewers decide that they do not think your experimental results were convincing enough to prove or disprove your hypothesis. What is your next step?

Design and carry out better experiments to prove or disprove your hypothesis, perhaps using a larger sample size

A controlled experiment

must have a dependent variable, independent variable, falsifiable and repeatable.

You are running an analysis on different food items to test for the presence of the major biological macromolecules starch, proteins, and lipids. For each test you examine four food items and distilled water. What is the role of the distilled water?

It is the control

Numerous studies have shown that the more often a person performs a workout routine that increases heart rate, the better their overall heart health is. You have two groups of individuals who are willing to participate in a heart-health experiment. Fifty are non-smoking males, ages 18 to 22, who work out three times/week. Fifty are non-smoking males, ages 18 to 22, who do not work out on a regular basis. In the experiment, they will step up and down on an 8-inch-high cinder block 120 times/minute for 3 minutes. Researchers will examine their heart rate before starting, immediately after they finish, and every minute after finishing until their heart rate returns to their original rate. Two common measures of heart health are the percentage increase in heart rate caused by exercise and the time the heart rate takes to return to the base rate. Based on these parameters, what is your hypothesis regarding the heart health and test performance of the two groups?

The non-exercising group will have a greater increase in heart rate and a longer recovery time, indicating an overall lower level of heart health.

You are tasked with testing the following hypothesis: Left-handed people have better hand-eye coordination than right-handed people. Based on a review of literature, you have read that one common test of hand-eye coordination is measuring the percentage of times that someone can drop a coin into a small container from a height of 3 feet. To perform this experiment, you have a group of 25 left-handed males, 25 right-handed males, 25 left-handed females, and 25 right-handed females. Design an experiment to test your hypothesis and be sure to define your independent and dependent variables.

Experimental design may vary but should include a gender and handedness balance. It is important that each individual has multiple attempts to drop the coin into the container. The dependent variable is the number of times each person is successful in getting the coin into the container. The independent variables are gender and handedness. The best experimental designs will also incorporate the concepts of participants' ages and heights.

Increase in sample size increases

reliability of data

A significant result from a scientific study indicates

a non-random result

You examine several studies on the effect of a new drug to treat diabetes. Which of the following would give you the most confidence in the results?

Three studies done the same way, each with 1000 people

Why does having a large sample size give more reliable results?

The larger the sample size, the less likely the results are due to chance alone.

Which of the following is not a scientific theory?

Results from an experiment with 3000 subjects

A study determining if caffeine enhances memory was done by two different researchers but with the exact same experimental design except for sample size. Researcher A showed that in 25% of people, it affected memory; but researcher B showed that in 50% of people, it affected memory. Assume that the demographics of the subjects were the same in each study (i.e., age, race, socioeconomic background. etc.). Further testing showed that researcher A's results were more accurate. Can you think of a reason their results would be so different if the conditions were the same, and why researcher A was more accurate?

Researcher A had a larger sample size than researcher B

Experiments with a small sample size are ________ likely to produce statistically significant results than experiments with a large sample size.

Less

You are reviewing the results of five similar experiments, but each had a different sample size. Which of the following experiments had the most reliable results?

The experiment with a sample size of 100,000

What is the difference between a hypothesis and a theory?

A hypothesis is an explanation that may or may not have undergone scientific testing, while a theory is a hypothesis that has undergone numerous tests over many years and has accumulated a large body of evidence in support of the explanation.

Does science ever prove a hypothesis or theory?

Science never "proves" a hypothesis or a theory because no idea can be tested under every possible circumstance. Thus, the best science can do is rigorously test a hypothesis, and with rigorous testing comes increased support in favor of the hypothesis.

A scientific theory

is a hypothesis that has been upheld by many experiments

A correlation in a scientific study indicates

a possible link between two variables

Epidemiologists

study the incidence of diseases and risk factors in populations

Epidemiological studies

are used when experimental manipulation of people is unethical

You conduct an experiment to test the effectiveness of a new drug in controlling blood sugar levels in diabetics. Unfortunately, half the participants experienced nausea. Nausea would be considered

a side effect

It is not possible to control for all variables in an experiment. Can you think of anything that could interfere in getting clear-cut results when interpreting data in an experiment like the coffee study described in your textbook?

The side effects of caffeine may mask the real effect of caffeine. This could interfere with data analysis and cause us to draw the wrong conclusions.

A negative correlation in a scientific study means

One variable increases while the other decreases

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