A geneticist crosses a tomato plant heterozygous for both stem color and leaf shape ( $P p L l$ ) with a double homozygous recessive partner ( $ppl l$ ).

The genes are hypothesized to assort independently, which predicts a $1:1:1:1\,$ phenotypic ratio among the offspring.

Out of 400 offspring collected, the following phenotypes are observed:

Purple stem, cut leaf: 120
Purple stem, potato leaf: 80
Green stem, cut leaf: 75
Green stem, potato leaf: 125

Which of the following choices correctly shows the calculated chi-squared ( $χ2\chi^2$ ) value and the degrees of freedom ( $df$ ) that should be used to test this genetic hypothesis?

$χ2=20.50\chi^2 = 20.50$ ; $df = 4$

$χ2=5.13\chi^2 = 5.13$ ; $df = 3$

$χ2=20.50\chi^2 = 20.50$ ; $df = 3$

$χ2=5.13\chi^2 = 5.13$ ; $df = 4$

A geneticist crosses a tomato plant heterozygous for both stem color and leaf shape ( $P p L l$ ) with a double homozygous recessive partner ( $ppl l$ ).

The genes are hypothesized to assort independently, which predicts a $1:1:1:1\,$ phenotypic ratio among the offspring.

Out of 400 offspring collected, the following phenotypes are observed:

Purple stem, cut leaf: 120
Purple stem, potato leaf: 80
Green stem, cut leaf: 75
Green stem, potato leaf: 125

Which of the following choices correctly shows the calculated chi-squared ( $χ2\chi^2$ ) value and the degrees of freedom ( $df$ ) that should be used to test this genetic hypothesis?

$χ2=20.50\chi^2 = 20.50$ ; $df = 4$

$χ2=5.13\chi^2 = 5.13$ ; $df = 3$

$χ2=20.50\chi^2 = 20.50$ ; $df = 3$

$χ2=5.13\chi^2 = 5.13$ ; $df = 4$

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