Biology | Answers to Review Questions

Author Dr. George B. Johnson, Washington University
Author Dr. Peter H. Raven, Missouri Botanical Gardens & Washington University
Contributor Dr. Susan Singer, Carleton College
Contributor Dr. Jonathan Losos, Washington University

Answers to Review Questions

Chapter 1 (p. 18)

1. Living things are characterized by a high degree of orderliness, the ability to respond to stimuli, the ability to grow and develop and reproduce, the passing on of genetic material, and possession of control processes that regulate and coordinate life functions.

2. Deductive reasoning employs analysis of specific data or sets of data upon which to base conclusions and is used to test the validity of ideas or hypotheses. Inductive reasoning stems from careful observation of specific phenomena, upon which certain conclusions are made. (Inductive conclusions can then be tested deductively!) A hypothesis is a suggested explanation that accounts for observations about a particular area of science.

3. Variables are elements of an experiment or observation that vary, such as temperature, exposure time, amount of light, etc. In a controlled experiment, all variables except one are held constant through several trials, thereby ensuring that any result seen in the experiment is a direct result of the single variable being investigated. All legitimate scientific experiments have controls.

4. A hypothesis becomes a theory after a prolonged period of rigorous and repeated experimentation, during which the hypothesis cannot be proved wrong. While these theories, such as those of evolution, relativity, and gravity are accepted as "absolute truth" for convenience, the true scientist acknowledges that there is no "absolute truth," and that any theory may be potentially disproved at some later point in time.

5. Basic research is that research carried out for "the sake of knowledge," and is typically encountered in universities. Applied research is an extension of basic research, taking information generated by basic research and extending (applying) it to such industries as biotechnology, agriculture, medicine, or engineering.

6. Darwin observed that organisms that were both better adapted to their environment and that left a larger amount of offspring tended to be more successful. Those that were successful lived, reproduced, and passed the "successful genes" to their offspring. Over time, gradual accumulations of these changes from generation to generation could give rise to new species under the right conditions. Since Darwin, scientists have found an expanded fossil record, more accurate estimation of the age of the earth, the mechanisms of heredity, an examination of comparative anatomy, and advances in molecular biology.

7. A homologous structure is one that develops the same way embryologically as another, even though the two homologous structures may not resemble each other in two separate species, such as the wing of a bat and front flipper of a porpoise. Analogous structures look similar and have the same function, even though they may be completely unrelated embryologically, such as the wing of a bat and the wing of a butterfly.

8. Because life evolved throughout the levels of organization, a purely historical approach becomes a study of levels of organization. The levels-of-organization approach to the mass of biological information is probably the most effective means of viewing the whole picture. Most other approaches tend to fall short by greatly limiting the study of the lower levels of organization or ignoring them altogether.