Which of the following occurs because of the law of independent assortment? a Two heterozygous mutations on separate chromosomes have a 25% chance of winding up in a single gamete cell b Two mutations close together on the same chromosome will remain linked together through meiosis c Two alleles of the same gene will not occur in the same gamete d One allele of a gene masks or overrides the effect of a different allele of that gene

Which of the following occurs because of the law of independent assortment? a Two heterozygous mutations on separate chromosomes have a 25% chance of winding up in a single gamete cell b Two mutations close together on the same chromosome will remain linked together through meiosis c Two alleles of the same gene will not occur in the same gamete d One allele of a gene masks or overrides the effect of a different allele of that gene

Concepts of Biology

1st Edition

ISBN:9781938168116

Author:Samantha Fowler, Rebecca Roush, James Wise

Publisher:Samantha Fowler, Rebecca Roush, James Wise

Chapter8: Patterns Of Inheritance

Section: Chapter Questions

Problem 1ACQ: Figure 8.9 In pea plants, round peas (R) are dominant to wrinkled peas (r). You do a test cross...

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A pea plant has the genotype TtRr. The independent assortmentof these two genes occurs at ________ because chromosomescarrying the ________ alleles line up independently of the chromosomes carrying the ________ alleles.a. metaphase of meiosis I, T and t, R and rb. metaphase of meiosis I, T and R, t and rc. metaphase of meiosis II, T and t, R and rd. metaphase of meiosis II, T and R, t and r
On rare occasions, an organism may have three copies of achromosome and therefore has three copies of the genes on thatchromosome (instead of the usual number of two copies). Forsuch a rare organism, the alleles for each gene usually segregateso that a gamete will contain one or two copies of the gene. Let’ssuppose that a rare pea plant has three copies of the chromosomethat carries the height gene. Its genotype is TTt. The plant is alsoheterozygous for the seed color gene, Yy, which is found on adifferent chromosome. With regard to both genes, how manytypes of gametes can this plant make, and in what proportions?(Assume that it is equally likely that a gamete will contain oneor two copies of the height gene.)
The plant blue-eyed Mary grows on Vancouver Islandand on the lower mainland of British Columbia. Thepopulations are dimorphic for purple blotches on theleaves—some plants have blotches and others don’t. NearNanaimo, one plant in nature had blotched leaves. Thisplant, which had not yet flowered, was dug up and takento a laboratory, where it was allowed to self. Seeds werecollected and grown into progeny. One randomly selected (but typical) leaf from each of the progeny is shown inthe accompanying illustration.a. Formulate a concise genetic hypothesis to explainthese results. Explain all symbols and show all genotypicclasses (and the genotype of the original plant).
Mutations in DNA that result in altered proteins can causehereditary diseases. Pedigree studies and genetic testing mayclarify the risk of disease. At the chromosome level, nondisjunctionduring meiosis can result in gametes with too few or too manychromosomes, most of which produce inviable offspring.Imprinting refers to inactivation of alleles depending on whichparent the alleles come from; offspring in whom imprinting occursappear haploid for the affected gene even though they are diploid. During spermatogenesis, is there any difference in outcome between first- and second-division nondisjunction?
What are mitosis and meiosis? These two processes arehow parent cells produce daughter cells. However, they have two entirely differentgoals. What are the key steps of these two types of cellular reproduction? How does thebehavior of chromosomes during meiosis generate variation and explain Mendel’s lawof independent assortment?
A system of sex determination known as haplodiploidy is found in honeybees. Females are diploid, andmales (drones) are haploid. Male offspring resultfrom the development of unfertilized eggs. Sperm areproduced by mitosis in males and fertilize eggs in thefemales. Ivory eye is a recessive characteristic inhoneybees; wild-type eyes are brown.a. What progeny would result from an ivory-eyedqueen and a brown-eyed drone? Give both genotype and phenotype for progeny produced fromfertilized and nonfertilized eggs.b. What would result from crossing a daughter fromthe mating in part (a) with a brown-eyed drone?
On average, what proportion of the genome in the following pairs ofhumans would be exactly the same if no crossing over took place? (Forthe purposes of this question only, we will ignore the special case of theX and Y sex chromosomes and assume that all genes are located onnonsex chromosomes.)a. Father and childb. Mother and childc. Two full siblings (offspring that have the same two biological parents)d. Half siblings (offspring that have only one biological parent incommon)e. Uncle and niecef. Grandparent and grandchild
. In nature, the plant Plectritis congesta is dimorphic forfruit shape; that is, individual plants bear either winglessor winged fruits, as shown in the illustration.Wingless fruit Winged fruitPlants were collected from nature before floweringand were crossed or selfed with the following results:Number of progenyPollination Winged WinglessWinged (selfed) 91 1*Winged (selfed) 90 30Wingless (selfed) 4* 80Winged × wingless 161 0Winged × wingless 29 31Winged × wingless 46 0Winged × winged 44 0*Phenotype probably has a nongenetic explanation.Interpret these results, and derive the mode ofinheritance of these fruit-shaped phenotypes. Usesymbols. What do you think is the nongeneticexplanation for the phenotypes marked by asterisks inthe table?
Pea plants with purple pollen and long-shaped pollen were crossed with each other withthe following offspring: 296 purple long-shaped pollen; 19 with purple round-shapedpollen; 27 with red long-shaped pollen; 85 with red round-shaped pollen. Explain thisbizarre outcome!
Assuming that such a fly would be viable, what would be the sexof a fruit fly with the following chromosomal composition?A. One X chromosome and two sets of autosomesB. Two X chromosomes, one Y chromosome, and two sets ofautosomesC. Two X chromosomes and four sets of autosomesD. Four X chromosomes, two Y chromosomes, and four sets ofautosomes
Which of the following statements accurately describes a differencebetween mitosis and meiosis?a. Mitosis may produce diploid cells, whereas meiosis produceshaploid cells.b. Homologous chromosomes synapse during meiosis but do notsynapse during mitosis.c. Crossing over commonly occurs during meiosis, but it does notcommonly occur during mitosis.d. All of the above are correct.e. Both a and c are correct
in the experiment of following chromosomal dna mvement througgh meiosis, why. do you use non-sister chromatids to demobstrate crossing over? what combinatiobns of alleles could result from a crossover between BD and bd chromosomes? Identify two ways that meiosis contributes to genetic recombination. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cell?