CHAPTER 33 ANIMAL NUTRITION
Scientific Skills Exercise
Teaching objective: Students build scientific skills by interpreting data from an experiment
investigating the roles of appetite regulation genes using mice with various genetic mutations.
Teaching tip: A version of this Scientific Skills Exercise can be assigned in MasteringBiology.
Answers:
1. In pairings (b) (d), a mouse lacking ob gene activity was paired with a mouse that was either
(b) also lacking ob gene activity, (c) wild type, or (d) lacking db gene activity. Pairings (a) and
4. As in (b), the pairing in (d) affected mass gain in ob/ob mutants, but in (d) the result was a
severe and destructive mass loss. This indicates that db/db mutant mice not only produce the
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.
8. Scientific Inquiry
Excess iron uptake results in blood iron levels that are higher than normal. You might
9. Focus on Evolution
The high oxygen demands of active endotherms, such as mammals, require nearly continuous
breathing. Most other amniotes cannot breathe while chewing food because the connection
10. Focus on Organization
Sample key points:
Cells synthesize proteins from amino acids, not from whole proteins in food or other sources.
the cell surface.
Sample top-scoring answer:
The emergent properties of proteins in an animal body result from the synthesis of particular
proteins at a particular time and location. All proteins are assembled from amino acids, which
11. Synthesize Your Knowledge
Hummingbirds, like other animals, are heterotrophs and need to obtain from their diet chemical