Corrections to Problem Book, 21st edition, 2015, to turn it into the Learners' Manual of 2016.

This is the page you need if you have the 21st edition, 2015. 

If you have an earlier edition, you will need to look at previous corrections. See the current corrections page or the old-probbook corrections page for links to previous corrections.

Minor Changes:
A few typos were corrected, and many minor changes in formatting were made to make reading easier. These changes do not alter the text, and are not listed below.
Some small changes in terminology were made in  7-10 (& its answer), 9-2, 9-4, 9-5-D, 9-11-D. These do not change the meaning of the questions or their answers.

Significant Changes:
1. Title of Book was changed to 'A Learner's Manual' to emphasis the primary purpose of doing the problems -- to learn!!

2. Additional advice on using 'A Learner's Manual' was added at the beginning, and the advice pages were renumbered pages i to iv. 
Because of the added advice pages, the numbering of the pages containing problems and answers has changed.
Page N in the 22nd edition = page N + 4 in the earlier editions.

3. The following questions have been slightly rewritten to make them clearer:

1-6, 3-5, 4-12 (B-F), 5-11, 6-12-D,  7R-1, part III (added some hints),  11-12-A, 12R-6-E, & 14-7-C. 
These changes should have no significant effect on the questions or their answers. If you are curious about the details, look at a copy of the 22nd edition.

4. For the following problems, it asks you to be sure to check the answer to part A (or some other part that is specified) before doing the rest:

2-11, 2-17, 3-12, 5-11 (check the picture in the key before doing the problems), 6-5, 7-12, 7-21-B, 7R-1, part IV, & 9-19. 

In general, it is a good idea to be sure you are correct before going on to do additional parts or problems that build on earlier questions. You don't want to  base your logic (in subsequent parts) on incorrect assumptions. 

5. The answers to the following questions have been rewritten to make the explanations clearer, or to adjust the answers to fit the (slightly) revised questions. 

3R-3D, 5R-2-B (regarding V), 5R-5-A, 7-8,  7-21-D, 7R-1 part V, 7R-4 part B, 9-9-B,  9-10, 13-7, 13-14,  & 13-17.
These changes should have no significant effect on the meaning of the answers. If you are curious about the details, look at a copy of the 22nd edition.

6. No new problems were added to the current edition, but a part D has been added to 9-15. Here is 9-15, part D:

Question:  Could this be a rare condition?
Answer:  Yes.  This mutation may be common in the family shown, but could well be rare in the population at large. The most frequent allele or phenotype is not always the dominant one. Dominant conditions are not always common, and recessive conditions are not always rare.  (Disease causing mutations are generally rare, whether they are dominant or recessive.)  This will be discussed more later when we get to population genetics (Prob. Set #14.)