Suggested Answers and Teaching Tips
CHAPTER 1 INTRODUCTION: EVOLUTION AND THE FOUNDATIONS OF
BIOLOGY
Scientific Skills Exercise
Teaching objective: Students build scientific skills by interpreting data in a pair of bar graphs
and relating the data to the biological system it came from.
Teaching tips: A version of this Scientific Skills Exercise can be assigned in MasteringBiology.
If this is the first exercise the students are doing related to interpreting graphs, then you will need
In these graphs, there are no statistical significance values given for comparisons between
treatments. In the original paper, there was a statistical difference between predation levels of
light brown versus dark brown mice in light-colored soil enclosures with no moon and in dark-
colored soil enclosures under a full moon. The other two combinations, light-colored soil under a
full moon and dark-colored soil with no moon, had no statistically significant difference between
light and dark mice.
Answers:
1. (a) The independent variables for each graph are the coat color of the mice (light or dark
brown) and the presence or absence of moonlight (full moon or no moon). These are on the x–
5. (a) No moon plus dark brown coat had the highest predation level in the light soil enclosure
Interpret the Data
Figure 1.21 In the beach habitat, approximately 27 light models and 73 dark models were
attacked. In the inland habitat, approximately 76 light models and 24 dark models were attacked.
Suggested Answers for End-of-Chapter Essay Questions
See the general information on grading short-answer essays and a suggested rubric at the
beginning of this document.
7. Scientific Inquiry
Many legitimate hypotheses could be proposed to extend the investigation. Here is one example.
If the camouflage color has arisen through the processes of natural selection due to visual
8. Scientific Inquiry
Students are asked to use a PubMed search to identify an abstract of an article authored or co-
9. Focus on Evolution
Sample key points:
Darwin used reasoning based on observations to develop his theory of natural selection as a
mechanism for evolution.
His observations included:
o Heritable variations exist in each population.
Sample top-scoring answer:
10. Focus on Information
Common ancestry explains this observation. The thousand-some-odd genes shared by humans
11. Synthesize Your Knowledge
the background of the tree trunk, because the gecko
itself looks like mossy bark. This coloration likely makes it harder for the gecko to be seen by
predators, thus enhancing its survival. This cryptic coloration pattern probably evolved over
generations. The members of a gecko population that more closely resembled their background