1. Why are the progeny of a testcross generally used to map loci? Why not the F2
ID: 48316 • Letter: 1
Question
1. Why are the progeny of a testcross generally used to map loci? Why not the F2 progeny from an F1 x F1 cross?
Select one:
a. In a testcross more of the progeny would be expected to display the dominant phenotype than in the progeny of an F1 x F1 cross.
b. The progeny of an F1 x F1 cross would be found in a 9:3:3:1 ratio when two genes are involved, whereas the progeny of a testcross would result in a 1:1:1:1 ratio.
c. A testcross is more useful for mapping genes that are located near each other but when genes are quite far apart on the same chromosome, an F1 x F1 cross actually is more useful.
d. It is easier to classify recombinant and parental offspring of a testcross than with the progeny of an F1 x F1 cross.
e. Only recombinant offspring would be found in the progeny of an F1 x F1 cross.
2. A cell possessing two nuclei derived from different cells through cell fusion is called
Select one:
a. recombinant.
b. None of the above is correct.
c. nonrecombinant.
d. a heterokaryon.
e. a haplotype.
3. Recombination occurs through
Select one:
a. crossing over and chromosome interference.
b. chromosome interference and independent assortment.
c. complete linkage and chromosome interference.
d. crossing over and independent assortment.
e. somatic-cell hybridization and chromosome interference.
3. Two genes, A and B, are located 30 map units apart. The dihybrid shown below is mated to a tester aa bB. What proportion of the offspring is expected to be dominant for both traits?
Select one:
a. a.0%
b. b.15%
c. e.70%
d. c.30%
e. d.35%
Explanation / Answer
1.d. It is easier to classify recombinant and parental offspring of a testcross than with the progeny of an F1 x F1 cross.
2. d. a heterokaryon.
3. d. crossing over and independent assortment.
4. e. d.35%
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.