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17) In some plants, cyanidin, a red pigment (R-), is synthesized enzymatically f

ID: 268330 • Letter: 1

Question

17) In some plants, cyanidin, a red pigment (R-), is synthesized enzymatically from a colorless [whitel precursor compound. Delphinidin, a purple pigment (P), may be made from cyanidin by enzymatic action. True breeding purple plants (RRPP) crossed with true breeding white plants (rrpp) produce only purple plants. When two heterozygous purple plants [RrPp] were crossed, these Fa offspring resulted: Results: 79 purple: 28 red:39 white lal What type of inheritance is operating here? A. Epistasis Sex Linked C.Lethal D. Monohyrid Ibl What genetic ratio best explains the above results. Icl Give the possible genotypes for the F:offspring that were (3: White-rrpe Purple - R-FRed

Explanation / Answer

17.a. The answer is epistasis.

b. The genetic ratio i.e. 9:3:4 (recessive epistasis) explains the above ratio.

c. Purple – R_P_

Red – R_pp

White – rrpp, rrP_

d.

Category

Purple

Red

White

Total

Observed values

79.00

28.00

39.00

146

Exptected Ratio

9

3

4

16

Exprected Values

82.125

27.375

36.5

82.125

27.375

36.5

Deviation

-3.125

0.625

2.5

D^2

9.765625

0.390625

6.25

D^2/E

0.118912

0.014269

0.171233

0.304414

X^2

0.304414

Degrees of freedom

3-1=2

i.

Observed values

79.00

28.00

39.00

146

Exprected Values

82.125

27.375

36.5

ii. 0.304

iii. 3-1 =2

iv. 5.99 (at 2 DF and 0.05 probability)

v. No. Because the calculate chisquare i.e. 0.304 is lessthan the table value i.e. 5.99 at 2 DF and 0.05 probability. Hence this It is accepted.

Category

Purple

Red

White

Total

Observed values

79.00

28.00

39.00

146

Exptected Ratio

9

3

4

16

Exprected Values

82.125

27.375

36.5

82.125

27.375

36.5

Deviation

-3.125

0.625

2.5

D^2

9.765625

0.390625

6.25

D^2/E

0.118912

0.014269

0.171233

0.304414

X^2

0.304414

Degrees of freedom

3-1=2

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