Name 2 PTsl A hybrid corn plant with green leaves was testcr

Name 2. PTsl A hybrid corn plant with green leaves was test-crossed with a plant having yellow striped leaves. When 250 seedlings were grown, 140 of the seedlings had green leaves and 110 had yellow-striped leaves. Suggest a as hypothesis that could explain the data above, assigning allele designations necessary. Then use the chi-squared test and the table below to decide whether this result differs significantly from the expected ratios that you postulate. (Note: the number of the table is arbitrary; you are not required to fill up all the rows in Observed (o) Expected (e) Difference (o-e) (o-e i (o-el le Sum (chi squared value) Degrees of freedom Using the information from the P value, explain whether this uare test leads you to reject your model or not. ll. CELL CYCLE, CELL DIVISION, MITOSIS AND MEIOSIs 3. 11,5 PTS] In a diploid organism the haploid chromosome number (N) s 8 how many chromatids present in a cell (a) mitotic metaphase? (b) meiotic metaphase I? (c) meiotic metaphase II?

Solution

2.

Assume that the gene coding for green leaves is, G and the gene coding for yellow leaves is, g; G is dominant over g.

Test cross of green leaves (Gg) with yellow leaves (gg) produce the offspring with the following genotypes:

Gg* gg --à Gg (1/2, green), gg (1/2, yellow)

Thus, the expected frequency of green leaves and yellow leaves is 125 each.

CHI - SQUARE (X²):

X² = (O - E)² / E

Where O = Observed frequency

E = Expected frequency

Genotype

O

E

(O-E)

(O-E)^2

(O-E)^2/E

Gg

140

125

15

225

1.8

gg

110

125

-15

225

1.8

250

250

0

450

3.6

The chi-square value is = 3.6

Degrees of freedom is = n-1 = 2-1 =1

The calculated P value is 0.05778, which is not significant at p< 0.05. So, we accept the null hypothesis.

The difference between the expected an observed phenotypic ratios is not significant and the genes are assorting independently.

Genotype	O	E	(O-E)	(O-E)^2	(O-E)^2/E
Gg	140	125	15	225	1.8
gg	110	125	-15	225	1.8
	250	250	0	450	3.6