Question

Flower color in buffalo clover is either white or some shade of pink to red. Pollen from a red individual was applied to white flowers in 1999. This seed was germinated in 2000 and four red plants were obtained in the progeny. These four red plants were allowed to self pollinate in summer 2000 to produce the next generation. Populations of progeny from each of the four plants were grown in the greenhouse in spring 2001 and the following data were obtained. Propose a hypothesis and calculate a Chi Square for each plant and the pooled data, and determine if these data fit your hypothesis.

Cross Plant    Red   White

6/2X10/4 #1   21   8

6/2X10/4 #2 53 18

6/2X10/4 #3   49 18

6/2X10/4 #4    60   21

Pooled            183 65

Answer 1

As we can see from the result of F1 cross that ratio of F2 generation population is 3:1:; Red: White

Plant 1	Observed o	Expected e	Deviation d (Observed- expected)	Deviation square d2	d2/e
Red	21	21.75	-0.75	0.5625	0.025862
White	8	7.25	0.75	0.5625	0.077586
Total	29				0.103448
Plant 2	Observed o	Expected e	Deviation d (Observed- expected)	Deviation square d2	d2/e
Red	53	53.25	-0.25	0.0625	0.001174
White	18	17.75	0.25	0.0625	0.003521
Total	71				0.004695
Plant3	Observed o	Expected e	Deviation d (Observed- expected)	Deviation square d2	d2/e
Red	49	50.25	-1.25	1.5625	0.031095
White	18	16.75	1.25	1.5625	0.093284
Total	67				0.124378
Plant 4	Observed o	Expected e	Deviation d (Observed- expected)	Deviation square d2	d2/e
Red	60	60.75	-0.75	0.5625	0.009259
White	21	20.25	0.75	0.5625	0.027778
Total	81				0.037037
Pool data	Observed o	Expected e	Deviation d (Observed- expected)	Deviation square d2	d2/e
Red	183	186	-3	9	0.048387
White	65	61.5	3.5	12.25	0.199187
Total	248				0.247574

Since there are two alleles which are involved in the cross so the degree of freedom will be 2-1 = 1.

For df =1 the 5% level of significance, the value is 3.64. which allow us to accept the hypothesis and put data fits in Mendel's monohybrid heterozygous cross.