Scientific Skills Questions and Answers from Chp. 11, 12, 13

Now what are the phenotypic frequencies of the surviving offspring?

0, 2, 9, 16, 14, 6, 1

What is the probability range that your data fit the expected 1:1:1:1 ratio of phenotypes?

0.50 < p < 0.70

Using the ratio of 1:1:1:1, calculate the expected number of each phenotype out of the 900 total offspring. Drag the correct values onto the data table. Labels may be used once, more than once, or not at all.

225, 225, 225, 225

What does this example indicate about the distribution of phenotype frequencies in a population?

A lethal combination of alleles in a population will result in phenotype frequencies that do not have a normal distribution.

What is the %T in wheat DNA?

Approximately 28%

What is the best explanation for the curve's shape?

Equal numbers of light-skin and dark-skin alleles result in a majority of the offspring having intermediate phenotypes.

How does the shape of this curve compare with the curve in Figure 2? (Select Figure 2 from the drop-down menu.)

It is now skewed toward a higher number of dark-skin alleles.

Do your results support the hypothesis that the stem color and petal length genes are unlinked and assorting independently, or do the observed values differ from the expected values enough to reject this hypothesis?

The hypothesis is supported. Because 0.50 < p < 0.70, the differences between the observed and expected values are not statistically significant.

What is the hypothesis that you are testing?

The two genes are unlinked and are assorting independently, leading to a 1:1:1:1 ratio of phenotypes in the offspring.

Does the distribution of bases in sea urchin DNA and salmon DNA follow Chargaff's rules?

Yes, because the %A approximately equals the %T and the %G approximately equals the %C in both species.

Calculate the average percentage for each base in your completed table. Do Chargaff's equivalence rules still hold true when you consider those six species together?

Yes, the average for A approximately equals the average for T, and the average for G approximately equals the average for C.

What pattern does the distribution of frequency values show in this histogram?

a normal distribution, characterized by frequencies that are symmetrically distributed around one central peak value

Between which values on the df = 3 line does your calculated X2 value lie?

between 1.42 and 2.37

Which phenotype has the highest frequency?

the phenotype that results from having 3 dark-skin alleles