Ch. 1 Chapter 1- Introduction- Evolution and the Foundations of Biology Dynamic Study Module.docx

1. Why can a hypothesis never be proven to be true? A hypothesis can never be proven to be true because there may always be alternative untested hypotheses that might also account for the results. In science, a hypothesis is a tentative answer to a well-framed question; it is an explanation on trial. The hypothesis is usually a rational accounting for a set of observations, based on the available data and guided by inductive reasoning. A scientific hypothesis leads to predictions that can be tested by making additional observations or by performing experiments. A hypothesis can be rejected with certainty, but we can’t be 100% sure a hypothesis is correct regardless of the amount of data collected in a scientific experiment. Science relies on the senses for observation of particular phenomena, but numerous tools, such as microscopes, allow us to investigate beyond the limits of our senses. Some degree of experimental error is involved in any scientific investigation but is taken into account in a well-designed experiment and analysis. Although a hypothesis can never be proved beyond the shadow of a doubt, testing it in various ways can significantly increase our confidence in its validity. Often, rounds of testing and changing hypotheses, and even theories, lead to a scientific consensus—the shared conclusion of many scientists that a particular hypothesis explains the known data well and stands up to experimental testing. 2. Radon is a radioactive gas that seeps into homes from the soil. It is thought to be a cause of lung cancer. A research team investigates this hypothesis. Researchers gather large amounts of data on basement radon concentrations and lung cancer rates and conclude that the more radon there is in a home, the more likely are people living in the home to develop lung cancer. After the study is published, other researchers criticize it by asserting that the studied neighborhoods with higher radon concentrations also have a higher percentage of older people and a higher percentage of cigarette smokers than the low-radon neighborhoods. Both advanced age and cigarette smoking increase the risk of lung cancer. This criticism, if correct, shows that the radon study suffered from . Radon is a radioactive gas that seeps into homes from the soil. It is thought to be a cause of lung cancer. A research team investigates this hypothesis. Researchers gather large amounts of data on basement radon concentrations and lung cancer rates and conclude that the more radon there is in a home, the more likely are people living in the home to develop lung cancer. After the study is published, other researchers criticize it by asserting that the studied neighborhoods with higher radon concentrations also have a higher percentage of older people and a higher percentage of cigarette smokers than the low-radon neighborhoods. Both advanced age and cigarette smoking increase the risk of lung cancer. This criticism, if correct, shows that the radon study suffered from uncontrolled variables. In this case, the uncontrolled variables were the percentage of older people and cigarette smokers in the two neighborhoods being compared: the high-radon neighborhood and the lowradon neighborhood. When variables of possible relevance are not controlled, the conclusions of a study may be invalid. It is incorrect to say that a lack of replication is the answer; data were collected from multiple homes. It is also incorrect to say the study suffered from an unfalsifiable hypothesis; the hypothesis could be falsified by data showing a lack of association between radon concentrations and lung cancer rates. It is also incorrect to say that the study suffered from nonsystematic observation and analysis of data—no criticism was made to suggest a problem with how the data were collected and analyzed. Finally, we have no information suggesting a small sample size so this would not be the best answer. 3. Which of the following would be an experimental means to investigate whether bean plants require an environmental source of sodium? Comparing the growth and survival of bean plants in a growth medium containing sodium and in an identical growth medium completely lacking sodium would be an experimental means to investigate whether bean plants require an environmental source of sodium. In hypothesis-based scientific inquiry, an experiment must have an experimental group and a control group. In this case, growing bean plants with sodium would constitute the experimental group, and growing bean plants without an environmental source of sodium would constitute the control group. None of the other answer choices listed include the comparison of a control group and an experimental group. 4. What is the appropriate term for a group of all the individuals that can mate with each other living within a specified area? Population is the term for a group of all the individuals that can mate with each other living within a specified area. The term species does not require specification of a certain area and could include multiple populations. An ecosystem is all the living things in a particular area along with all the nonliving components of the environment with which life interacts, such as soil, water, atmospheric gases, and light. A community is all of the populations of species in a given area. Habitat is the environment occupied by members of a population. 5. Which of the following statements is an example of correct inductive reasoning? The statement “We conclude that all animals require organic molecules as nutrients because, over centuries of study, we have found no animals that can survive without organic molecules acquired through feeding” is an example of correct inductive reasoning. By definition, induction moves from a set of specific observations to a general conclusion. None of the other answer choices fits this definition. 6. A company was testing a new drug it thought would help decrease the risk of transmission of a particular virus from mother to fetus. In an experiment to test the drug, an investigator gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with the virus. At the same time, 400 other pregnant rats were inoculated with the virus but not administered the drug. Of the rat pups born to the females that received both the virus and the drug, 203 showed no symptoms of infection; 205 rat pups born to the virus-only females showed symptoms. From these data, we can best conclude . A company was testing a new drug it thought would help decrease the risk of transmission of a particular virus from mother to fetus. In an experiment to test the drug, an investigator gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with the virus. At the same time, 400 other pregnant rats were inoculated with the virus but not administered the drug. Of the rat pups born to the females that received both the virus and the drug, 203 showed no symptoms of infection; 205 rat pups born to the virus-only females showed symptoms. From these data, we can best conclude that the drug has little effect on viral transmission at the given dosage because an approximately equal number of pups were infected in each group. It is incorrect to say that the drug is 5 percent effective and testing on humans should begin because the effect was not demonstrated and, even if it were, the drug might not function the same way in humans. It is incorrect to say that there was no independent variable because the independent variable in this experiment was the administration of the drug to only one of the two groups of pregnant rats inoculated with the virus. The pregnant rats that were inoculated with the virus but did not receive the new drug represent the control group for the experiment. There is no evidence in the data that the drug enhances disease progression. 7. All the organisms on your campus make up . All the organisms on your campus make up a community. The array of organisms inhabiting a particular ecosystem is called a biological community. A community includes many kinds of plants, various animals, and enormous numbers of diverse microorganisms, which are living forms, such as bacteria, that are too small to see without a microscope. Each of these forms of life is called a species. An ecosystem consists of all the living things in a particular area along with all the nonliving components of the environment with which life interacts, such as soil, water, atmospheric gases, and light. A population consists of all the individuals of a species living within the bounds of a specified area. An experimental group is a set of subjects that has (or receives) the specific factor being tested in a controlled experiment. A domain is a taxonomic category above the kingdom level. 8. Two garden plots were planted with corn. The soil was similar in each, and equal amounts of water were applied to each plot. One plot was fertilized, and the other was not. The experimenters measured the yield as bushels of corn from each plot. The corn in the plot that did not receive the fertilizer was the . Two garden plots were planted with corn. The soil was similar in each, and equal amounts of water were applied to each plot. One plot was fertilized, and the other was not. The experimenters measured the yield as bushels of corn from each plot. The corn that did not receive the fertilizer was the control group—the group that did not receive the experimental treatment. In this case, the experimental treatment was the addition of fertilizer, so the experimental group was the corn that received fertilizer. The corn itself was not a variable in this experiment, so to call it the controlled variable or the dependent variable is incorrect. Finally, there was no replicate group in the experiment, so this answer choice is incorrect. 9. Which of the following is the fundamental unit of structure and function in living organisms? The cell is the fundamental unit of structure and function in living organisms. Some organisms, such as bacteria, are single cells. Others, including plants and animals, are multicellular. In a multicellular organism, there is a division of labor among specialized cells instead of each cell performing all the functions of life. Organelles are various functional components, such as chloroplasts, that are present in cells. Tissues are composed of many cells of similar structure and function. Organs consist of two or more tissues that work together to perform a particular function. Organisms are individual living things; some are composed of only a single cell, but many are not. 10. Which of the following is a prokaryotic domain? Prokaryotic organisms belong to the domain Archaea. Archaea, together with bacteria, are among the simplest kinds of organisms: the microscopic, mostly singlecelled prokaryotes. These organisms comprise domain Archaea and domain Bacteria. It is not correct to say that Eukarya, Fungi, or protists are part of one of the two prokaryotic domains. Domain Eukarya contains all eukaryotic organisms and includes kingdom Fungi, kingdom Animalia, and kingdom Plantae as well as organisms from several different groups collectively known as protists. It is also not correct to say that the domain Bacteria, the domain Archaea, and the domain Eukarya all contain at least some prokaryotic members because there are no prokaryotes in the domain