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Two true breeding strains of peas, one with (T gene) vines and violet (V gene) f

ID: 19028 • Letter: T

Question

Two true breeding strains of peas, one with (T gene) vines and violet (V gene) flowers and the other with dwalf (t) vines and white (v) flowers, were crossed. All the F1 were tall and produced violet flowers. When the plants were test-crossed to the dwarf, white parents strains, the following offspring were obtained-38 tall, violet; 53 tall, white; 57 dwarf, violet; 52 dwarf, white.
QUESTIONS
2.) Do a chi square analysis of the test cross data to test the hypothesis that the two genes are unlinked and assort independently. Determine the P value for the data. what is your conclusion concerning this hypothesis and why.

Explanation / Answer

Two true breeding strains of peas,

one with (T gene) vines and violet (V gene) flowers

and the other with dwalf (t) vines and white (v) flowers, were crossed.

All the F1 were tall and produced violet flowers.

TV X tv

Tt Vv----------- tall and produced violet flowers

Tt Vv         x   tt vv      

When the plants were test-crossed to the dwarf, white parents strains, the following offspring were obtained-38 tall, violet; 53 tall, white; 57 dwarf, violet; 52 dwarf, white.
test cross ----------1:1:1:1

Observed

Expected

o-e

(o-e)^2 /e

tall, violet

38

50

-12

2.88

tall, white

53

50

3

0.18

dwarf, violet

57

50

7

0.98

dwarf, white.

52

50

2

0.08

total

200

556

4.12

table value 5% levle of significance= 3.91

calculated value =4.12

calculated value is more than table value, hence the null hypothesis is rejected

The population-offspring ---------are not according test cross ratio

Observed

Expected

o-e

(o-e)^2 /e

tall, violet

38

50

-12

2.88

tall, white

53

50

3

0.18

dwarf, violet

57

50

7

0.98

dwarf, white.

52

50

2

0.08

total

200

556

4.12