Exam 15: The Chromosomal Basis of Inheritance

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?

What does a frequency of recombination of 50% indicate?

A 0.1% frequency of recombination is observed

A space probe discovers a planet inhabited by creatures that reproduce with the same hereditary patterns seen in humans. Three phenotypic characters are height (T = tall, t = dwarf), head appendages (A = antennae, a = no antennae), and nose morphology (S = upturned snout, s = downturned snout). Since the creatures are not "intelligent," Earth scientists are able to do some controlled breeding experiments, using various heterozygotes in testcrosses. For tall heterozygotes with antennae, the offspring are: tall-antennae, 46; dwarf-antennae, 7; dwarf-no antennae, 42; tall-no antennae, 5. For heterozygotes with antennae and an upturned snout, the offspring are: antennae-upturned snout, 47; antennae-downturned snout, 2; no antennae-downturned snout, 48; no antennae-upturned snout, 3. Calculate the recombination frequencies for both experiments.

Which of the following statements is True?

Calico cats are female because

Which of the following is a map of a chromosome that includes the positions of genes relative to visible chromosomal features, such as stained bands?

They have a daughter who is a dwarf with normal color vision. What is the probability that she is heterozygous for both genes?

Two genes of a flower, one controlling blue (B)versus white (b)petals and the other controlling round (R)versus oval (r)stamens, are linked and are 10 map units apart. You cross a homozygous blue-oval plant with a homozygous white-round plant. The resulting F1 progeny are crossed with homozygous white-oval plants, and 1,000 F2 progeny are obtained. How many F2 plants of each of the four phenotypes do you expect?

D, F, and J are three genes in Drosophila. The recombination frequencies for two of the three genes are shown in Figure 15.3. Gene Pair Recombination Frequency D-F 50\% D-J 25\% F-J ? -Genes D and F could be

Figure 15.4 -The pedigree in Figure 15.4 shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

Down syndrome has a frequency in the U.S. population of ~ 1/700 live births. In which of the following groups would you expect this to be significantly higher?

If a human interphase nucleus contains three Barr bodies, it can be assumed that the person

At which phase(s)is it preferable to obtain chromosomes to prepare a karyotype?

A woman is found to have 47 chromosomes, including 3 X chromosomes. Which of the following describes her expected phenotype?