Biology: The scientific study of Life Chapter Review

In life's hierarchy of organization, new properties emerge at each level.

Biological organization unfolds as follows: biosphere ^ ecosystem ^ community ^ population ^ organism ^ organ system ^ organ ^ tissue ^ cell ^ organelle ^ molecule. Emergent properties result from the interactions among component parts.

What is life?

Biology is the scientific study of life. Properties of life include order, reproduction, growth and development, energy processing, regulation, response to the environment, and evolutionary adaptation. The cell is the structural and functional unit of life.

In an ecosystem, how is the flow of energy similar to that of matter, and how is it different?

Both energy and matter are passed through an ecosystem from producers to consumers to decomposers. But energy enters most ecosystems as sunlight and leaves as heat. Chemicals are recycled from the soil or atmosphere through plants, consumers, and decomposers and returned to the air, soil, and water

7. Which of the following is a true statement of observational data? a. It is always qualitative, not quantitative. b. It is used to form hypotheses, but not to test them. c. It can include comparisons of fossils as well as DNA sequences. d. It is the type of data used for the independent variable in a controlled experiment

C. It can include comparisons of fossils as well as DNA sequences

Theme: Life depends on the flow of information.

DNA is responsible for heredity and for programming the activities of a cell by providing the blueprint for proteins. Information from the external and internal environment includes the stimuli, signals, and pathways that regulate body processes and gene expression.

11. Explain the role of heritable variations in Darwin's theory of natural selection

Darwin described how natural selection operates in populations whose individuals have varied traits that are inherited. When natural selection favors the reproductive success of certain individuals in a population more than others, the proportions of heritable variations change over the generations, and a population becomes better adapted to its environment. Should the environment change, however, natural selection may favor different traits.

Theme: evolution is the core theme of biology

Darwin synthesized the theory of evolution by natural selection.

Theme: Life depends on interactions within and between systems.

Emergent properties are the result of interactions between the components of a system. Systems biology models the complex behavior of biological systems.

Theme: Life depends on the transfer and transformation of energy and matter.

Energy flows through an ecosystem in one direction—entering as sunlight, converted to chemical energy by producers, passed on to consumers, and exiting as heat. Ecosystems are characterized by the cycling of matter from the atmosphere and soil through producers, consumers, decomposers, and back to the environment.

The fruits of wild species of tomato are tiny compared with the giant beefsteak tomatoes available today. This difference in fruit size is almost entirely due to the larger number of cells in the domesticated fruits. Plant biologists have recently discovered genes that are responsible for controlling cell division in tomatoes. Why would such a discovery be important to producers of other kinds of fruits and vegetables? To the study of human development and disease? To our basic understanding of biology?

If these cell division control genes are involved in producing the larger tomato, they may have similar effects if transferred to other fruits or vegetables. Cancer is a result of uncontrolled cell division. One could see if there are similarities between the tomato genes and any human genes that could be related to human development or disease. The control of cell division is a fundamental process in growth, repair, and asexual reproduction—all important topics in biology.

12. Describe the process of scientific inquiry and explain why it is not a rigid method.

In pursuit of answers to questions about nature, a scientist often uses a logical approach involving these key elements: observations about natural phenomena; questions derived from observations, reading scientific literature, and communicating with other scientists; hypotheses posed as tentative explanations of observations; logical predictions of the outcome of tests if the hypotheses are correct; actual tests of hypotheses; and analysis of results. Scientific research is not a rigid method because hypothesis generation and testing is often repetitive and nonlinear. Intuition, chance, and luck are also part of the scientific process

Life defies a simple, one-sentence definition

Life is recognized by what living things do

15. Explain what is meant by this statement: Natural selection is an editing mechanism rather than a creative process.

Natural selection screens (edits) heritable variations by favoring the reproductive success of some individuals over others. It can only select from the variations that are present in the population; it does not create new genes or variations.

What is science?

Science uses an evidence-based process of inquiry to investigate the natural world. The scientific approach involves observations, hypotheses, predictions, tests of hypotheses via experiments or additional observations, and analysis of data. A scientific theory is broad in scope and supported by a large body of evidence.

Hypotheses can be tested using observational data.

Scientists tested hypotheses about the evolutionary relationships of red pandas. Recent studies comparing DNA sequences classify the red panda as the only living species in its family.

Theme: structure and function are related.

Structure is related to function at all levels of organization.

Biologists arrange the diversity of life into three domains.

Taxonomists name species and classify them into broader groups. Domains Bacteria and Archaea contain organisms with simple cells. Domain Eukarya includes various protists and the kingdoms Fungi, Plantae, and Animalia

Biology, technology, and society are connected in important ways.

Technological advances stem from scientific research, and research benefits from new technologies.

13. Contrast technology with science. Give an example of each to illustrate the difference.

Technology is the application of scientific knowledge. For example, the use of solar power to run a calculator or heat a home is an application of our knowledge, derived by the scientific process, of the nature of light as a type of energy and how light energy can be converted to other forms of energy. Another example is the use of genetic engineering to insert new genes into crop plants. Genetic engineering stems from decades of scientific research on the structure and function of DNA from many kinds of organisms.

Suppose that in an experiment similar to the camouflage experiment described in Module 1.5, a researcher observed and recorded more total predator attacks on dark-model mice in the inland habitat than on dark models in the beach habitat. From comparing these two pieces of data, the researcher concluded that the camouflage hypothesis is false. Do you think this conclusion is justified? Why or why not?

The researcher needed to determine the percent of total attacks in each habitat that occurred on dark models. It may be that there were simply more predators in the inland habitat than in the beach habitat. The experiment needed proper data analysis.

Hypotheses can be tested using controlled experiments.

The use of control and experimental groups can demonstrate the effect of a single variable. Hypotheses can be tested in humans with clinical trials, as well as retrospective or prospective observational studies.

14. Biology can be described as having both a vertical scale and a horizontal scale. Explain what that means.

The vertical scale of biology refers to the hierarchy of biological organization: from molecules to organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere. At each level, emergent properties arise from the interaction and organization of component parts. The horizontal scale of biology refers to the incredible diversity of life, past and present. Biologists seek to classify groups of organisms to reflect their evolutionary relationships.

19. The news media and popular magazines frequently report stories that are connected to biology. In the next 24 hours, record the ones you hear or read about in three different sources and briefly describe the biological connections in each story.

Virtually any news report or magazine contains stories that are about biology or at least have biological connections. How about biological connections in advertisements?

The graph below shows the results of an experiment in which mice learned to run through a maze. a. State the hypothesis and prediction that you think this experiment tested. b. Which was the control group and which the experimental? Why was a control group needed? c. List some variables that must have been controlled so as not to affect the results. d. Do the data support the hypothesis? Explain.

a. Hypothesis: Giving rewards to mice will improve their learning. Prediction: If mice are rewarded with food, they will learn to run a maze faster b. The control group was the mice that were not rewarded. Without them, it would be impossible to know if the mice that were rewarded decreased their time running the maze only because of practice. c. Both groups of mice should not have run the maze before and should be about the same age. Both experiments should be run at the same time of day and under the same conditions. d. Yes, the results support the hypothesis because the data show that the rewarded mice began to run the maze faster by day 3 and improved their performance (ran faster than the control mice) each day thereafter.

5. Which of the following best demonstrates the unity among all living organisms? a. structure correlated with function b. DNA and a common genetic code c. emergent properties d. natural selection

b. DNA and a common genetic code

Which of the following statements best distinguishes hypotheses from theories in science? a. Theories are hypotheses that have been proven. b. Hypotheses usually are narrow in scope; theories have broad explanatory power. c. Hypotheses are tentative guesses; theories are correct answers to questions about nature. d. Hypotheses and theories are different terms for essentially the same thing in science

b. Hypotheses usually are narrow in scope; theories have broad explanatory power.

2. All the organisms on your campus make up a. an ecosystem. b. a community. c. a population. d. the biosphere

b. a community.

3. Which of these is not a property of all living organisms? a. capable of reproduction b. uses energy c. composed of multiple cells d. responds to the environment

c. composed of multiple cells

9. Which of the following best describes the logic of scientific inquiry? a. If I generate a testable hypothesis, my experiments will support it. b. If my prediction is correct, it will lead to a testable hypothesis. c. If my observations are accurate, they will support my hypothesis. d. If my hypothesis is correct, I can expect certain test results.

d. If my hypothesis is correct, I can expect certain test results.

A controlled experiment is one that a. proceeds slowly enough that a scientist can make careful records of the results. b. keeps all variables constant. c. is repeated many times to make sure the results are accurate. d. tests experimental and control groups in parallel.

d. tests experimental and control groups in parallel.

8. A biologist studying interactions among the bacteria in an ecosystem could not be working at which level in life's hierarchy? (choose carefully and explain your answer.) a. the population level b. the molecular level c. the organism level d. the organ level

d. the organ level

Evolution

is the process of change that has transformed life on Earth

Evolution is connected to our everyday lives.

Evolutionary theory is useful in medicine, agriculture, and conservation. Humancaused environmental changes are powerful selective forces that affect the evolution of many species.

The process of science is repetitive, nonlinear, and collaborative.

Forming and testing hypotheses is at the core of science. This endeavor is influenced by three spheres: exploration and discovery; analysis and feedback from the scientific community; and societal benefits and outcomes.