Chapter 9, Problem 2RQ

What chromosomal abnormality can result from dispermy?

Why do unrelated children with a disorder such as Down syndrome resemble each other more closely than they do their siblings?

What are the advantages of semelparity? of iteroparity? Are there disadvantages?

Figure 12.6 What are the genotypes of the individuals labeled 1, 2, and 3?

Explain what a cline is and provide examples.

Figure 7.2 If a mutation occurs so that a fungus is no longer able to produce a minus mating type, will it still be able to reproduce? Figure 7.2 (a) In animals, sexually reproducing adults form haploid gametes from diploid germ cells. (b) Fungi, such as black bread mold (Rhizopus nigricans), have haploid-dominant life cycles. (c) Plants have a life cycle that alternates between a multicellular haploid organism and a multicellular diploid organism. (credit c fern: modification of work by Cory Zanker; credit c gametophyte: modification of work by Vlmastra/Wikimedia Commons)

About 4 percent of people of Northern European descent have a cystic fibrosis allele, but only about 1 in 2,500 of these people actually has the disorder. What is the most likely reason for this finding?

Why dont genetic markers on the Y chromosome undergo recombination? Why is this lack of recombination a necessity for these markers to be used in tracing migrations?

Can you postulate a reason or reasons why children with Down syndrome are 20 times more likely to develop leukemia than children in the general population?