12. Meiosis

Which of the following processes occurs when homologous chromosomes cross over in meiosis I?

Crossing over involves each of the following EXCEPT:

How many genetically unique gametes can be created in an organism with 4 chromosomes?

During which of the following processes does independent assortment of chromosomes occur?

What is an outcome of genetic recombination? a. the synapsing of homologs during prophase of meiosis I b. the new combination of maternal and paternal chromosome segments that results when homologs cross over c. the new combinations of chromosome segments that result when self-fertilization occurs d. the combination of a haploid phase and a diploid phase in a life cycle

A wild-type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild-type, 778; black vestigial, 785; black normal, 158; gray vestigial, 162. What is the recombination frequency between these genes for body color and wing size? Is this consistent with the results of the experiment in Figure 15.9?

A planet is inhabited by creatures that reproduce with the same hereditary patterns seen in humans. Three phenotypic characters are height (T=tall, t=dwart), 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.

Nondisjunction that leads to problems in offspring can occur in: a. mitosis b. meiosis I only c. meiosis I and II d. mitosis, meiosis I, and meiosis II