lab 9 - heredity and genetics i

Question 1

what is the difference between dominant and recessive traits?

Answer 1

a dominant allele expresses its traits even if only one copy is present

a recessive allele is expressed only if two copies are present (homozygous)

Question 2

how do you calculate degrees of freedom (df)?

Answer 2

df = number of phenotypic categories - 1

Question 3

how do you determine the observed ratio?

Answer 3

by counting the phenotypes of offspring in your experiment

Question 4

how do you calculate the expected ratio?

Answer 4

multiply the total offspring by the proportion predicted by Mendel’s laws

Question 5

what does the p-value represent?

Answer 5

the probability that the observed data fits the expected data due to chance

Question 6

what is the significance threshold for p-values?

Answer 6

p is greater than or equal to 0.05 = fail to reject null hypothesis

p is less than 0.05 = reject the null hypothesis

Question 7

Mendel’s Law of Independent Assortment?

Answer 7

genes for different traits segregate independently during the formation of gametes, creating genetic variation

Question 8

phenotype

Answer 8

observable traits (brown eyes)

Question 9

genotype

Answer 9

the genetic makeup of the trait (Bb for brown eyes)

Question 10

degrees of freedom in a chi-square test

Answer 10

df = number of categories -1

Question 11

what phenotypic ratio is expected for dihybrid crosses for Mendel’s Law?

Answer 11

9:3:3:1

Question 12

what does it mean to reject the null hypothesis?

Answer 12

Rejecting the null hypothesis means that the data provides enough evidence to show that there is an effect or difference, suggesting the null hypothesis (which says “no effect” or “no difference”) is not true.