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Human males typically have XY chromosomes and females have XX chromosomes, but there are rare instances in which a male can inherit an XXY or an XYY, or a female can have three X chromosomes. Explain how an error in meiosis can cause these aberrations.

In one fruit species, the gene for a dark color is dominant over its allele for light color. At another gene locus, the gene for short shape is dominant over its allele for long shape. These two allele pairs assort independently. If a plant with long, light fruit is crossed with a plant that is heterozygous for both of these traits, what percentage of the offspring do you expect will be short and dark?

In one fruit species, the gene for a dark color is dominant over its allele for light color. At another gene locus, the gene for short shape is dominant over its allele for long shape. These two allele pairs assort independently. If a plant with long, light fruit is crossed with a plant that is heterozygous for both of these traits, what percentage of the offspring do you expect will be short and dark?

Figure 12.1 shows a map of four genes on a chromosome.Figure 12.1Between which two genes would you expect the highest frequency of recombination?

Recombination frequencies are determined for a chromosome as follows: Q-S, 30%; R-S 45%; R-T 40%; Q-T 25%. How would the genes be organized on the chromosome?

Figure 13.1Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions?

Construct a map given the following data. What order will the genes be in? The following letters represent genes and the % is the recombination frequency. A-D 8%; A-B 2%; B-C 6%; C-F 8%; D-F 24%; D-C 16%.

Construct a map given the following data. What order will the genes be in? The following letters represent genes and the % is the recombination frequency. A-D 8%; A-B 2%; B-C 6%; C-F 8%; D-F 24%; D-C 16%.

What is the probability that a couple will have three daughters?

Which best explains the process of meiosis?