Chapter 1: Evolution and the Foundations of Biology
Why can a hypothesis never be proven to be true? A: There may always be alternative untested hypotheses that might also account for the results. B: Time limitations prevent us from collecting enough data to be 100 percent sure. C: Experimental error is involved in every research project. D: Science is limited by our senses. E: Science "evolves"; hypotheses and even theories are always changing.
A: There may always be alternative untested hypotheses that might also account for the results. 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 percent 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.
Which of the following statements is an example of correct inductive reasoning? A: 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. B: Because worms lack bones, they are classified as invertebrates. C: An elephant is "warm-blooded" because it is a mammal. D: A paramecium moves by means of the rhythmic motion of its cilia. E: Many birds fly so we conclude that bats are birds.
A: 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.
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 ___________. A: control group B: controlled variable C: replicate group D: dependent variable E: experimental group
A: control group 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.
The process that accounts for the unity and the diversity of life is: A: evolution B: the scientific method C: systems biology D: deductive reasoning E: inductive reasoning
A: evolution
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: that the drug has little effect on viral transmission at the given dosage B: nothing because no control group was used in the test of the drug C: nothing because no independent variable could be identified D: that the drug enhances disease progression E: that the drug is 5 percent effective and testing on humans should begin
A: that the drug has little effect on viral transmission at the given dosage
Which of the following is a prokaryotic domain? A: Eukarya B: Archaea C: Fungi D: Protists E: The domain Bacteria, the domain Archaea, and the domain Eukarya all contain at least some prokaryotic members.
B: Archaea Prokaryotic organisms belong to the domain Archaea. Archaea, together with bacteria, are among the simplest kinds of organisms: the microscopic, mostly single-celled 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 Eukarya.
Which of the following would be an experimental means to investigate whether bean plants require an environmental source of sodium? A: Measure how fast sodium enters the plant. B: Compare the growth and survival of bean plants in a growth medium containing sodium and in an identical growth medium completely lacking sodium. C: Measure the total amount of sodium in a few bean plants. D: Look for sodium in leaf tissues using autoradiography. E: Analyze root contents for sodium.
B: Compare the growth and survival of bean plants in a growth medium containing sodium and in an identical growth medium completely lacking sodium.
Which of the following observations and inferences led Charles Darwin to his theory of natural selection as a mechanism for evolution? A: Individuals of a population are unequal in their likelihood of surviving and reproducing. B: Darwin synthesized his theory of natural selection from all of the listed observations and inferences. C: A population of any species has the potential to produce far more offspring than will survive to produce offspring of their own. D: Individuals in a population of any species vary in many heritable traits. E: Individuals with heritable traits best suited to the local environment will generally produce a disproportionate number of healthy, fertile offspring.
B: Darwin synthesized his theory of natural selection from all of the listed observations and inferences.
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 ______________. A: a small sample size B: uncontrolled variables C: a lack of replication D: an unfalsifiable hypothesis E: nonsystematic observation and analysis of data
B: uncontrolled variables
Which of the following sequences correctly lists life's hierarchy of levels of organization from lowest to highest? A: Organ, tissue, organ system, organism, population B: Molecule, biosphere, cell, organ, organism C: Molecule, organelle, cell, tissue, organ, organism D: Organism, community, population, ecosystem, biosphere E: Tissue, cell, organ, organism, community
C: Molecule, organelle, cell, tissue, organ, organism
What is the appropriate term for a group of all the individuals that can mate with each other living within a specified area? A: Habitat B: Community C: Population D: Ecosystem E: Species
C: Population 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.
Which of the following is an example of qualitative data? A: The six pairs of robins hatched an average of three chicks. B: The plant's height is 25 cm. C: The fish swam in a zigzag motion. D: The contents of the stomach are mixed every 20 seconds. E: The temperature decreased from 20 degrees C to 15 degrees C.
C: The fish swam in a zigzag motion.
How is the information encoded in DNA actually used by organisms? A: DNA is the molecular building block of proteins. B: DNA leaves the nucleus and interacts directly with other molecules in the cytoplasm. C: The information in DNA is transcribed to RNA and then translated into protein. D: DNA serves as a template upon which proteins are assembled. E: DNA is translated into protein and then transcribed to RNA.
C: The information in DNA is transcribed to RNA and then translated into protein. The information in DNA is transcribed to RNA and then translated into protein. In transcription, the information in the sequence of DNA nucleotides specifies the sequence of nucleotides in a related molecule called mRNA. The mRNA is then translated into a chain of protein building blocks called amino acids. It is, therefore, not correct to say that DNA serves as a template upon which proteins are assembled, nor is it correct to say that DNA itself is the molecular building block of proteins. DNA is separated from the process of protein assembly by the mRNA intermediary. It is incorrect to say that DNA is translated into protein and then transcribed into RNA. DNA is always transcribed into RNA, and then the RNA code is translated into a specific protein with a unique shape and function. It is also incorrect to say that DNA leaves the nucleus and interacts directly with molecules outside the nucleus; DNA remains in the nucleus (of eukaryotic cells).
All the organisms on your campus make up ______________. A: a domain B: an experimental group C: a community D: a population E: an ecosystem
C: a community 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.
With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of _____________ and traits that differ among organisms as evidence of _____________. A: systems biology; reductionism B: descent from a common ancestor; loss of energy as heat C: descent from a common ancestor; adaptation through natural selection D: coincidence; adaptation E: qualitative data; quantitative data
C: descent from a common ancestor; adaptation through natural selection With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of descent from a common ancestor and traits that differ among organisms as evidence of adaptation through natural selection. Collection of both qualitative and quantitative data has supported evolution as a core theme of biology. When an organism uses chemical energy to perform work, such as muscle contraction or cell division, some of that energy is lost to the surroundings as heat, but this is a universal process and does not account for differences in traits possessed by different organisms. Shared traits may result from a shared common ancestor or convergent evolution (the evolution of similar features in independent evolutionary lineages due to similar environmental pressures), but coincidence is usually not a factor in determining shared traits. Systems biology and reductionism are ways of approaching biological problems, not explanations of organismal traits, so this answer is incorrect.
Energy ______________ an ecosystem, whereas chemical elements ______________. A: is burned in; are wasted B: is lost in; are created C: flows through; cycle within it D: is recycled in; flow through it E: cannot be created nor destroyed in; disappear
C: flows through; cycle within it Energy flows through an ecosystem, whereas chemical elements cycle within it. 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. There is a one-way flow of energy in an ecosystem: During photosynthesis, plants convert energy from sunlight to chemical energy (stored in food molecules such as sugars), which is used by plants and other organisms to do work and is eventually lost from the ecosystem as heat. In contrast, chemicals cycle between organisms and the physical environment. Energy is not burned; it is converted from one form to another. This is not the same as recycling of energy since the energy is ultimately lost from the ecosystem as heat. It is incorrect to say that chemical elements are created, lost, or disappear in an ecosystem. Chemical elements are recycled as a result of interactions between organisms.
A controlled experiment is one that ______________. A: is supervised by an experienced scientist B: is repeated many times to make sure the results are accurate C: tests experimental and control groups in parallel D: keeps all variables constant E: proceeds slowly enough that a scientist can make careful records of the results
C: tests experimental and control groups in parallel A controlled experiment is one that tests experimental and control groups in parallel. Without a control factor, researchers have no basis for comparison of their results and cannot determine what effect, if any, an experimental factor may have. The pace at which an experiment proceeds is typically not important and is not related to a control group. Although repetition of results is important in scientific experiments, it is not related to the importance of a control group. In any scientific experiment, it is very difficult to keep all variables constant. Researchers usually "control" unwanted variables not by eliminating them but by canceling out their effects using control groups. The experience of a scientist isn't related to the importance of a control group in an experiment.
What is DNA? A: A code for protein synthesis B: The substance of heredity C: A double helix made of four types of nucleotides D: All of the listed responses are correct. E: A component of chromosomes
D: All of the listed responses are correct. All of the listed responses are correct. DNA is the substance of heredity organized into structures called chromosomes. Each chromosome contains one very long DNA molecule with hundreds or thousands of genes, each a stretch of DNA arranged along the chromosome. Transmitted from parents to offspring, genes are the units of inheritance. The molecular structure of DNA accounts for its ability to store information. A DNA molecule is made up of two long chains, called strands, arranged in a double helix. Each chain is made up of four kinds of chemical building blocks called nucleotides, abbreviated A, T, C, and G. DNA provides the blueprints for making proteins, which are major players in building and maintaining the cell and carrying out its activities.
Eukaryotic organisms that decompose dead organisms and absorb dissolved nutrients from their surroundings would be found in which kingdom? A: Plantae B: Bacteria C: Archea D: Fungi E: Animalia
D: Fungi
At which point is a scientific investigator most likely to use deductive reasoning? A: During initial observation(s) B: After the careful analysis of both the qualitative and the quantitative data recorded in the study C: In rephrasing an alternative hypothesis D: In establishing a test of a hypothesis E: During the formulation of a hypothesis
D: In establishing a test of a hypothesis
What is the primary source of energy that makes life on Earth possible? A: Decomposition of plants and other organic matter B: Carbon dioxide C: Sugars D: Heat E: The sun
E: The sun
Emergent properties of living systems are defined as properties that ___________________. A: define the cell's surroundings B: none of the listed responses is correct. C: are evident during only one portion of the life cycle of an organism D: are apparent only when an organism is studied at the molecular level E: are due to the arrangement and interactions of parts as complexity increases
E: are due to the arrangement and interactions of parts as complexity increases