Question

You are told that a cross between two parents with genotype Rr, (where R= round seeds and r= wrinkled seeds) results in the following progeny: 5474 round and 1850 wrinkled. Calculate a 2 value for this data. What is the probability of obtaining these results? (Show your work in full using a table to show values for observed/expected etc.)

x² =_______ Probability of obtaining results= _______<p<________ Accept or Reject

Answer 1

This is a monohybrid cross that shows :dominant :recessive = 3:1 ratio

Following is the chi square test :

Phenotype	Observed (O)	Expected (E)	O-E	(O-E)2	(O-E)2 /E
Round (R)	5474	3/4 *7324 =5493	-19	361	0.066
Wrinkled(r)	1850	1/4 * 7324 =1831	19	361	0.197
Total	7324	7324			0.263

Calculated ² = 0.263

Degrees of freedom(d.o.f) = categories - 1 = 2-1 =1

probability = 0.05

The tabulated/critical  ² value under probability 0.05 and d.o.f = 1 comes to 3.84

Since the calculated 2 value (0.263) < tabulated 2 value (3.84),we can say that the observed values are consistent with that of expected values and the data fits the ratio.Hence we accept the null hypothesis.