Question

how to find chi-squared of this data?

Gametophytes:

            Green: 116

            Pale: 146

and

Sporophytes

            Green: 168

            Pale: 72

is this the observed or expected data??

or what is the observed or expected data?

Answer 1

Under ideal conditions, gametophyte give rise to sporophyte. The number of gametophyte and sporophyte should be equal.

Total number of gametophyte and sporophyte = 116 + 146 + 168 + 72 = 502

Expected number for 4 phenotypes = 502/4 = 125.5

Null hypothesis = one gametophyte gives rise to one sporophyte and therefore the number of gametophyte and sporophyte should be equal

	Observed#	Expected#	(O-E)^2/E
Green G	116	125.5	0.719
Pale G	146	125.5	3.35
Green S	168	125.5	14.39
Pale S	72	125.5	22.8

Calculated chi square value = 0.719 + 3.35 + 14.39 + 22.8 = 41.259

Degrees of freedom = 4 - 1 = 3

p value < 0.01 (1%)

If p value is less than 5%, then we reject null hypothesis. Instead we place an alternative hypothesis.

According to alternative hypothesis, every gametophyte is not able to give rise to a sporophyte because the environmental conditions may not be favourable.

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