In Fig. 4.1, use the letter C together with a label line to show where crossing over happens.
Describe how crossing over can lead to genetic variation in a population.
Explain what is meant by the F1 generation.
The scientists applied the chi-squared ($\chi^2$) test to see how closely their data matched the expected phenotypic ratio of $9 : 3 : 3 : 1$. The chi-squared formula is $\chi^2 = \sum \frac{(O - E)^2}{E}$, where $O$ represents the observed value and $E$ represents the expected value. Complete Table 4.1 and use the chi-squared formula to work out the $\chi^2$ value for these data.
The critical value at the $0.05$ probability level with three degrees of freedom is $7.81$. Using the result you calculated in (b)(ii), explain whether the study results agree with the expected ratio of phenotypes in the F2 generation.
Suggest two reasons why phenotypic ratios in the F2 generation may not always be the same as the expected ratios.