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A researcher has selfed an autotetraploid plant with the genotype D/D/d/d, and in the resulting progeny she observes a 35:1 phenotypic ratio. What can she conclude from this observation?

The progeny from this cross do not demonstrate a standard Mendelian phenotypic ratio.
In the 35:1 phenotypic ratio, the 1 represents the phenotype of the d/d/d/d progeny.
During meiosis in the D/D/d/d parent plant, it is likely that only bivalents, no quadrivalents or trivalents, formed.
It is likely that in this plant species, gametes associate with one another randomly.
All of the answers are correct.

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Jamar Ferry
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28 Sep 2019

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Related questions

**Please answer ALL 10 QUESTION**

1. A species of flowering plant includes plants with blooms that range from bright golden yellow to very pale yellow; no flowers carrying the yellow pigment allele appear white. The allele for yellow flower color:

a. must be a suppressor of another allele.

b. demonstrates incomplete penetrance.

c. demonstrates variable expressivity.

d. must be a modifier of another allele.

e. demonstrates variable penetrance.

2. Coat color in mice is determined by two alleles acting at a single locus: B is dominant and results in mice with black coats, and b is recessive and results in mice with white coats. In a litter of 12 mice, nine are black (B/–) and three are white (b/b). What is the penetrance of the B coat color allele?

a. zero

b. 25 percent

c. 50 percent

d. 75 percent

e. 100 percent

3. Semisterility in nearly 50 percent of the progeny they produce is often an indication that:

a. the parents are translocation heterozygotes.

b. both parents carry pericentric inversions.

c. both parents carry polytene chromosomes.

d. one of the parents carries a chromosomal deletion that removes a telomere.

e. one of the parents carries a chromosomal deletion that removes a chromosome's centromere.

4. A researcher is studying melanoma cells derived from a patient's skin tumor. He determines that all melanoma cells are 2n + 1, but the chromosome number in all normal skin cells is 2n. The 2n + 1 melanoma cells likely arose from:

a. mitotic nondisjunction.

b. meiotic nondisjunction.

c. mitotic recombination.

d. parthenogenesis.

e. colchicine treatment.

5. Why won't a balancer chromosome in Drosophila produce viable crossover products when paired with a wild-type chromosome?

a. Balancer chromosomes contain multiple inversions.

b. Balancer chromosomes contain multiple deletions.

c. Balancer chromosomes have no centromere.

d. Balancer chromosomes have no telomeres.

e. None of the answers is correct.

6. A doctor notes that a patient's genome contains 100 potentially harmful recessive mutations; however, the patient is heterozygous for all of the loci considered and thus does not demonstrate any abnormal phenotypes. The 100 recessive mutations the doctor discovered represent the patient's:

a. bivalents.

b. monosomy.

c.genetic load.

d. amphidiploidy.

e.nondisjunction.

7.The term describing the relationship between the number of copies of a gene and how much product is made from the gene is:

a. gene-dosage effect. gene balance.

b. dosage compensation.

c. transcription.

d. aneuploidy.

8. The gene for upright ears in rabbits has two alleles. The E allele is dominant and results in upright ears, and the recessive e allele results in droopy ears. Of 100 rabbits surveyed, 87 had a genotype for upright ears (E/–). However, only 72 of these 87 rabbits had upright ears; the remaining 15 rabbits had completely droopy ears. This suggests that the allele for upright ears:

a. has incomplete penetrance.

b. has complete penetrance.

c. demonstrates variable expressivity.

d. is lethal.

e. is incompletely dominant.

9. A researcher has selfed an autotetraploid plant with the genotype D/D/d/d, and in the resulting progeny she observes a 35:1 phenotypic ratio. What can she conclude from this observation?

a. The progeny from this cross do not demonstrate a standard Mendelian phenotypic ratio.

b. In the 35:1 phenotypic ratio, the 1 represents the phenotype of the d/d/d/d progeny.

c. During meiosis in the D/D/d/d parent plant, it is likely that only bivalents, no quadrivalents or trivalents, formed.

d. It is likely that in this plant species, gametes associate with one another randomly.

e. All of the answers are correct.

10. A researcher is studying fur color in a new species of bats. He notices that fur color, which is due to the presence of a dominant allele (G), ranges from light gray to very dark gray. In addition, some bats that carry a G allele have no fur pigmentation whatsoever; their coats appear white. This is an example of:

a. only variable expressivity.

b. only incomplete penetrance.

c. both variable expressivity and incomplete penetrance.

d. recessive allele lethality.

e. pleiotropy.

1. A species of flowering plant includes plants with blooms that range from bright golden yellow to very pale yellow; no flowers carrying the yellow pigment allele appear white. The allele for yellow flower color:

a. must be a suppressor of another allele.
b. demonstrates incomplete penetrance.
c. demonstrates variable expressivity.
d. must be a modifier of another allele.
e. demonstrates variable penetrance.

2. Coat color in mice is determined by two alleles acting at a single locus: B is dominant and results in mice with black coats, and b is recessive and results in mice with white coats. In a litter of 12 mice, nine are black (B/–) and three are white (b/b). What is the penetrance of the B coat color allele?

a. zero
b. 25 percent
c. 50 percent
d. 75 percent
e. 100 percent

3. Semisterility in nearly 50 percent of the progeny they produce is often an indication that:

a. the parents are translocation heterozygotes.
b. both parents carry pericentric inversions.
c. both parents carry polytene chromosomes.
d. one of the parents carries a chromosomal deletion that removes a telomere.
e. one of the parents carries a chromosomal deletion that removes a chromosome's centromere.

4. A researcher is studying melanoma cells derived from a patient's skin tumor. He determines that all melanoma cells are 2n + 1, but the chromosome number in all normal skin cells is 2n. The 2n + 1 melanoma cells likely arose from:

a. mitotic nondisjunction.
b. meiotic nondisjunction.
c. mitotic recombination.
d. parthenogenesis.
e. colchicine treatment.

5. Why won't a balancer chromosome in Drosophila produce viable crossover products when paired with a wild-type chromosome?

a. Balancer chromosomes contain multiple inversions.
b. Balancer chromosomes contain multiple deletions.
c. Balancer chromosomes have no centromere.
d. Balancer chromosomes have no telomeres.
e. None of the answers is correct.

6. A doctor notes that a patient's genome contains 100 potentially harmful recessive mutations; however, the patient is heterozygous for all of the loci considered and thus does not demonstrate any abnormal phenotypes. The 100 recessive mutations the doctor discovered represent the patient's:

a. bivalents.
b. monosomy.
c.genetic load.
d. amphidiploidy.
e.nondisjunction.

7.The term describing the relationship between the number of copies of a gene and how much product is made from the gene is:

gene-dosage effect.
gene balance.
dosage compensation.
transcription.
aneuploidy.

8. The gene for upright ears in rabbits has two alleles. The E allele is dominant and results in upright ears, and the recessive e allele results in droopy ears. Of 100 rabbits surveyed, 87 had a genotype for upright ears (E/–). However, only 72 of these 87 rabbits had upright ears; the remaining 15 rabbits had completely droopy ears. This suggests that the allele for upright ears:

a. has incomplete penetrance.
b. has complete penetrance.
c. demonstrates variable expressivity.
d. is lethal.
e. is incompletely dominant.

9. A researcher has selfed an autotetraploid plant with the genotype D/D/d/d, and in the resulting progeny she observes a 35:1 phenotypic ratio. What can she conclude from this observation?

a. The progeny from this cross do not demonstrate a standard Mendelian phenotypic ratio.
b. In the 35:1 phenotypic ratio, the 1 represents the phenotype of the d/d/d/d progeny.
c. During meiosis in the D/D/d/d parent plant, it is likely that only bivalents, no quadrivalents or trivalents, formed.
d. It is likely that in this plant species, gametes associate with one another randomly.
e. All of the answers are correct.

10. A researcher is studying fur color in a new species of bats. He notices that fur color, which is due to the presence of a dominant allele (G), ranges from light gray to very dark gray. In addition, some bats that carry a G allele have no fur pigmentation whatsoever; their coats appear white. This is an example of:

a. only variable expressivity.
b. only incomplete penetrance.
c. both variable expressivity and incomplete penetrance.
d. recessive allele lethality.
e. pleiotropy.

In pea plants, the appearance of flowers along the main stem isa dominant phenotype called "axial" and is controlled by an alleleT. The recessive phenotype, produced by an allele t, hasflowers only at the end of the stem and is called "terminal."

Pod form displays a dominant phenotype "inflated," controlled byan allele C, and a recessive "constricted" form, producedby the c allele.

A cross is made between a pure-breeding axial, constricted plantand a plant that is pure-breeding terminal, inflated.

Part A

The F1 progeny of this cross are allowed to self-fertilize. Whatis the expected phenotypic distribution among the F2 progeny?

*The answer for this one is 9:3:3:1. I understand this part.

Part B

Suppose that all of the F2 progeny with terminal flowers, i.e.,plants with terminal flowers and inflated pods and plants withterminal flowers and constricted pods, are saved and allowed toself-fertilize to produce a partial F3 generation. What is theexpected phenotypic distribution among these F3 plants?

(Remember to take into consideration the frequency of eachgenotype in the F2 as well as the probability of specific offspringthat result from self-fertilizing each F2 genotype.)

*I don't understand this part. It wants wants an answer in termsof "terminal inflated : terminal constricted."

Part C

If an F1 plant from the initial cross described above is crossedwith a plant that is terminal, constricted, what is the expecteddistribution among the resulting progeny?

*I understand this part. The answer is axial inflated : axialconstricted : terminal inflated : terminal constricted =1:1:1:1

Part D

If the plants with terminal flowers produced by the cross inPart C are saved and allowed to self-fertilize, what is theexpected phenotypic distribution among the progeny?

*I also don't understand this part. They want an answer in termsof "terminal inflated : terminal constricted."

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