CHAPTER 1 THE SCIENTIFIC STUDY OF LIFE

10) Which statement about a hypothesis is incorrect? A) It can be proven true. B) It can be proven false. C) It is a tentative explanation. D) It is based on previous knowledge. E) It must be testable to be useful.

A) It can be proven true. Explanation: Hypotheses can be shown to be false by experimentation, a normal part of the scientific method.

You perform an experiment in which you take 16 pots of strawberry plants and give half of them 1 gram of ammonium nitrate per liter of water and the other half receive only water. Each group is then split in half again, and exposed to either 8 or 16 hours of light each day. You monitor the height of the plants for 4 weeks. You observe that plants grown in ammonium nitrate and 16 hours of light grow taller than no ammonium nitrate and 8 hours of light. 20) Which of the following is/are independent variable(s) in this experiment? A) amount of ammonium nitrate and light B) amount of water C) amount of carbon dioxide D) height of the plants and amount of light E) height of the plants

A) amount of ammonium nitrate and light Explanation: The independent variable is the variable which the experimenter varies to look for responses in the system, rather than what is measured.

32) You want to test Charles Darwin's prediction that an orchid with long pollen tubes has a pollinator with long, thin mouthparts that can reach the bottom of the elongated nectar tube. You place nets over some orchids, which allows pollinators with small, short mouthparts to enter but prevents the entry of pollinators with long, thin mouthparts. Next, you compare the number of seeds produced by plants with and without the nets. In this experiment, seed production is a(n) A) dependent variable. B) hypothesis. C) theory. D) independent variable. E) standardized variable.

A) dependent variable. Explanation: Whatever is actually measured at the end of an experiment is the dependent variable.

19) What statement deals with an aspect of experimentation but with the incorrect explanation? A) The larger the sample size, the more meaningful the results. B) The smaller the sample size, the more meaningful the results. C) A control group is an untreated group and provides a basis for comparison. D) It is important to standardize aspects of an experiment that might affect the outcome, other than the independent variable. E) All answers are correct.

B) The smaller the sample size, the more meaningful the results. Explanation: Smaller sample sizes make for weaker, less certain experimental results.

12) In a scientific experiment, the investigator measures the response of the ________ variable(s). A) independent B) dependent C) control group D) standardized E) dependent and independent

B) dependent Explanation: While the experimenter alters the independent variable, the dependent variable is what results and is measured.

22) In this experiment, the size of the pot is A) an independent variable. B) a dependent variable. C) a standardized variable. D) a placebo. E) a control.

C) a standardized variable. Explanation: Since pot size is uniform, this is a standardized variable.

9) If you were grading a set of exams dealing with the scientific method, which statement would lead to a student losing points? A) It is a general way of answering questions with evidence. B) It is a framework to consider ideas in a repeatable way. C) It begins with observations. D) It does not apply to problems encountered in everyday life. E) It enables the testing of ideas.

D) It does not apply to problems encountered in everyday life. Explanation: The scientific method can be applied to a wide range of problems, including those of daily life.

13) Which of the following is not a "control" in an experimental procedure? A) a placebo B) a known standard of comparison C) a normal group D) an experimental group E) a "zero"-value group

D) an experimental group Explanation: Controls are parts of the experiment which are used as a kind of baseline.

21) Which of the following is/are dependent variable(s) in this experiment? A) amount of ammonium nitrate and light B) amount of carbon dioxide C) amount of water D) height of the plants E) height of the plants and amount of light

D) height of the plants Explanation: Dependent variables are what are measured in response to changing independent variable values.

11) In a scientific experiment, the investigator manipulates the ________ variable(s) to determine whether it causes another variable to change. A) standardized B) control group C) dependent D) independent E) control group and standardized

D) independent Explanation: The independent variable is altered, and then the exeprimental result is seen in the changes in the dependent variable.

37) Why isn't scientific inquiry foolproof? A) Multiple interpretations of the data are possible. B) Definitive answers may not exist. C) Observations can be misinterpreted. D) Unexpected conclusions are not always readily accepted. E) All answers are correct.

E) All answers are correct. Explanation: Scientific inquiry has its limitations.

14) A theory differs from a hypothesis in that a theory A) has more supportive evidence than a hypothesis. B) is broader in scope than a hypothesis. C) has predictive power. D) ties together many existing observations. E) All answers are correct.

E) All answers are correct. Explanation: Theories are of greater certainty, backed by many different experiments, than mere hypotheses.

41) Gravity is a theory because it is A) a tentative explanation of an observation. B) an untestable prediction. C) a changeable element of experiments. D) an opinion or hunch. E) an encompassing explanation of a natural phenomenon that is well accepted.

E) an encompassing explanation of a natural phenomenon that is well accepted. Explanation: So much experimental evidence is behind our ideas about gravity that it rises to the level of a theory.

31) In an experiment, Charles Darwin's prediction about long nectaries and long-tongued moths would be a(n) A) standardized variable. B) theory. C) independent variable. D) dependent variable. E) hypothesis.

E) hypothesis. Explanation: Hypotheses, such as Darwin's about moth tongue length, are really predictions.

38) The scientific method cannot be used to answer questions about immaterial and philosophical issues. TRUE OR FALSE

TRUE Explanation: The scientific method can only deal with questions about the immediate physical world around us.