dhe position of the flowers on the stem of the pea plant is determined by a pair of alleles. Those that grow axially are produced by the action of a dominant T allele and those that only grow at the tip of the stem through the action of a recessive t allele. Purple flowers are produced by a dominant B allele and white flowers by a recessive b allele. A heterozygous plant with purple flowers and axillary leaves is crossed with a pure line of the same phenotype. What genotypic and phenotypic ratios are expected in F1 progeny?

1. a). The position of the flower on the stem of the garden pea is governed by a pair of alleles. Flowers growing in the axis (upper angle between petiole and stem) are produces by the action of a dominant allele 'T', those growing only at the tip of the stem by its recessive allele 't'. Colored flowers are produced by a dominant gene 'C', and white flowers by its recessive allele 'c'. A dihybrid plant with colored flowers in the leaf axis is crossed to a pure strain of the same phenotype. What genotypic and phenotypic ratios are expected in the F1 progeny?

b). In summer squash, white fruit color is governed by a dominant allele (W) and yellow fruit color by the recessive (w). A dominant allele at another locus (S) produces disc-shaped fruit and its recessive allele (s) yields sphere-shaped fruit. If a homozygous white disc variety of genotype 'WWSS' is crossed with a homozygous yellow sphere variety (wwss), the F1 are all white disc dihybrids of genotype 'WwSs'. If the F1 is allowed to mate at random, what would be the phenotypic ratio expected in the F2 generation?

Hi, Can you please explain clearly. Thank you.

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."

1. In the fruit fly, Drosophila melanogaster, the normal wildtype has long wings and red eyes (both are dominant traits).Recessive forms of these genes result in vestigial wings and browneyes. A red-eyed, vesigial winged male is crossed with abrown-eyed, long winged female.

(a) Assuming each parent is homozygous for the dominant alleles,write out the cross and give the genotype and phenotype of theoffspring.

(b) If each parent is a heterozygote for the dominant alleles,what are the genotypes, phenotypes and ratios of the potentialoffspring?

2. In peas, the allele for tall plant (T) is dominant to theallele for short plants and the allele for purple flowers (P) isdominant to white flowers (p). Write out the results of thefollowing crosses and determine the phenotypic ratios for each:

(a) TtPp x TtPp

(b) Ttpp x ttpp

(c) ttPp x Ttpp

(d) TTpp x ttPP