Question

Number of Plants With:	P1 Generation	P1 Generation Percentage	F1 Generation	F1 Generation Percentage
Purple stem and dwarf stem height	5		3
Purple stem and normal stem height	4		4
Non-purple stem and dwarf stem heigh	0		0
Non-purple stem and normal stem height	0		2
Total Number of Plants	9		9

Number of Plants With:	F2 Generation Prediction	F2 Generation Percentage Prediction	F2 Generation Actual	F2 Generation Percentage Actual
Purple stem and dwarf stem height			10
Purple stem and normal stem height			17
Non-purple stem and dwarf stem heigh			6
Non-purple stem and normal stem height			14
Total Number of Plants			47

1. Is the Purple Stem trait dominant or recessive? Support your conclusion with examples from your laboratory observations.

2. Is the dwarf stem trait dominant or recessive? Support your conclusion with examples from your laboratory observations.

3. Based on your observations, what are the phenotype and genotype of the P1 plant? What did you deduce to be the genotype and phenotype of the P2?

4. Based on your observations, draw the Punnett square for the cross of the P1 and P2 parental plants.

5. Based on your observations, draw the Punnett square for the cross of the F1 plants.

a. Based on the Punnett square above, what is the percentage of offspring that are predicted to have purple stems and dwarf stem 3 © 2019 Carolina Biological Supply Company height? How did this compare to the results that you obtained in this lab?

b. Based on the Punnett square above, what is the percentage of offspring that are predicted to have non-purple stems and dwarf stem height? How did this compare to the results that you obtained in this lab?

c. Based on the Punnett square above, what is the percentage of offspring that are predicted to have purple stems and normal stem height? How did this compare to the results that you obtained in this lab?

d. Based on the Punnett square above, what is the percentage of offspring that are predicted to have non-purple stems and normal stem height? How did this compare to the results that you obtained in this lab?

Can you please fill in empty chart data and answer questions. Will rate, thank you.

Answer 1

To solve this problem, we're going to go backwards, from F2. The second generation shows 21.28% Purple stem and Dwarf stem height; 36.17% Purple and Normal; 12.77% Non purple and Dwarf, and 29.78% Non purple and Normal. When analyzing this, we observe 57.45% of Purple versus 43.55% of Non-Purple, as well as 34.05% of Dwarf versus 65.05 of normal. This indicates that Normal is dominant over Dwarf. The percentages of Purple and Non-Purple are very similar, which, in principle, would suggest co-dominance.But at least one of the P1 parental generation should be heterozygous for Not Purple, since the phenotype appears in F1, despite not being in any of the parents. Thus, co-dominance is ruled out, and the dominance of the Purple allele is clear.

We already have two clues: 1.- Purple is dominant over non-purple; 2.- Normal is dominant over dwarf. We will call P the purple character; p the Non-Purple; N the Normal and n the Dwarf. The possible combinations then for P1 are:

	PN	Pn	pN	pn
PN	PPNN Purple Normal	PPNn Purple Normal	PpNN Purple Normal	PpNn Purple Normal
Pn	PPNn Purple Normal	PPnn Purple Dwarf	PpNn Purple Normal	Ppnn Purple Dwarf
pN	Ppnn Purple Dwarf	PpNn Purple Normal	ppNN NO Purple Normal	ppNn No Purple Normal
pn	PpNn Purple Normal	Ppnn Purple Dwarf	ppNn No Purple Normal	ppnn No Purple Dwarf

If both parents were heterozygous, we would obtain :3 Dwarf Purple (18.75%); 9 Normal Purple (56.25%); 1 Not Dwarf Purple (6.25%) and 3 Not Normal Purple (18.75%) for F1. but the percentages were 33.33%; 44.44% ; 0% and 23.23% respectively. So we have to plate the scenario of a single heterozygous parent

	PN	Pn	pN	pn
PN	PPNN Purple Normal	PPNn Purple Normal	PpNN Purple Normal	PpNn Purple Normal
Pn	PPNn Purple Normal	PPnn Purple Dwarf	PpNn Purple Normal	Ppnn Purple Dwarf

With a P1 homozygous for Purple, but heterozygous for Normal/Dwarf, it is obtained: 6 Purple Normal (75%) and 2 Purple Dwarf (25%). No No-Purples are obtained

	PN	Pn	pN	pn
PN	PPNN Purple Normal	PPNn Purple Normal	PpNN Purple Normal	PpNn Purple Normal
pN	Ppnn Purple Dwarf	PpNn Purple Normal	ppNN NO Purple Normal	ppNn No Purple Normal

With a P1 homozygous for Normal, but heterozygous for Purple/no-Purple, we obtain 5 Purple Normal (62,5%), 2 No-Purple Normal (25%) and 1 Purple Dwarf (12,5%). We did not get No Purple and Dwarf, as in the F1 observed. So the genotype of a P1 is a P1 homozygous for Normal, but heterozygous for Purple/no-Purple, and the other is heterozygous for both of them.

The table is then left:

	P1	P1 percentage	F1	F1 percentage
Purple Dwarf	5	55,56%	3	33,33%
Purple Normal	4	44,44%	4	44,44%
No Purple Dwarf	0	0%	0	0,00%
No Purple Normal	0	0%	2	22,23%

For F2, the table is:

	F2 Prediction	F2 % Prediction	F2Actual	F2 Actual %
Purple Dwarf	9	18,75%	10	21,28%
Purple Normal	26	56,25%	17	36,17%
No Purple Dwarf	3	6,25%	6	12,77%
No Purple Normal	9	18,75%	14	29,78 %