BIO207H5S Dihybrid and Trihybrid Crosses with Probability Rules

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

In a dihybrid cross, what is the probability of obtaining offspring with the genotype RRYYCC from the selfing of the F1 generation?

1/512

1/64 (correct)

1/256

1/128

What is the probability of an offspring from the cross Aa Bb Cc dd Ee having the genotype Aa Bb Cc dd Ee?

1/64

1/16 (correct)

1/32

1/128

What does the Chi-Square (𝛘2) Goodness-of-Fit Test indicate in genetics?

Rate of mutation in genetic populations

Probability of obtaining specific genotypes

Degree of freedom in genetic crosses

Deviation between observed and expected ratio (correct)

What is the null hypothesis in the context of the Chi-Square (𝛘2) Goodness-of-Fit Test?

There is no difference between observed and expected ratios Signup and view all the answers

What are the degrees of freedom (d. o. f) in the context of the Chi-Square (𝛘2) Goodness-of-Fit Test?

Number of categories minus one Signup and view all the answers

What does the Forked line/Branch Diagram help to illustrate in genetics?

Mendelian principles of segregation and independent assortment Signup and view all the answers

In a chi-square test, if the calculated 𝛘2 value is 4.2, and the critical value at a significance level of 0.05 with 3 degrees of freedom is 7.815, what can be concluded?

The null hypothesis fails to be rejected Signup and view all the answers

What is the probability of having at least four girls in a family of six children, if the probability of having a girl is 1/2?

$\frac{22}{64}$ Signup and view all the answers

What does the critical value P(0.01) signify at 2 degrees of freedom in a chi-square test?

The probability of deviation occurring by chance is less than 1% Signup and view all the answers

What does the binomial expansion help calculate in genetics problems?

Probabilities of various combinations of events Signup and view all the answers

In the binomial expression n = 8, x = 3, and p = 0.4, what does q represent?

Probability of occurrence of other events (n-x) out of n trials Signup and view all the answers

What problem-solving approach involves using the chi-square test for a monohybrid cross?

Assessing significance of deviations Signup and view all the answers

If the critical value P(0.025) at 5 degrees of freedom is 11.070 in a chi-square test, what does this indicate?

The null hypothesis is accepted Signup and view all the answers

What is the critical value P(0.10) at 4 degrees of freedom in a chi-square test?

$3.841$ Signup and view all the answers

What does a calculated 𝛘2 value less than the critical value indicate in a chi-square test?

The null hypothesis fails to be rejected Signup and view all the answers

What do scientists typically assume when P < 0.05 in a chi-square test?

A significant difference exists between observed and expected values. Signup and view all the answers

Study Notes

Dihybrid Cross

In a dihybrid cross, the probability of obtaining offspring with the genotype RRYYCC from the selfing of the F1 generation is unknown in this context.

Probability of Genotype

The probability of an offspring from the cross Aa Bb Cc dd Ee having the genotype Aa Bb Cc dd Ee is unknown in this context.

Chi-Square (𝛘2) Goodness-of-Fit Test

The Chi-Square (𝛘2) Goodness-of-Fit Test indicates whether the observed frequencies differ significantly from the expected frequencies in genetics.
The null hypothesis in the context of the Chi-Square (𝛘2) Goodness-of-Fit Test is that the observed frequencies do not differ significantly from the expected frequencies.
The degrees of freedom (d.o.f) in the context of the Chi-Square (𝛘2) Goodness-of-Fit Test depend on the number of classes minus one.

Forked Line/Branch Diagram

The Forked line/Branch Diagram helps to illustrate the possible genotypes and phenotypes of offspring from a cross between two parents with different genotypes.

Chi-Square Test

If the calculated 𝛘2 value is less than the critical value, it indicates that the observed frequencies do not differ significantly from the expected frequencies.
If the calculated 𝛘2 value is greater than or equal to the critical value, it indicates that the observed frequencies differ significantly from the expected frequencies.

Probability of Events

The probability of having at least four girls in a family of six children, if the probability of having a girl is 1/2, can be calculated using the binomial expansion.

Critical Value

The critical value P(0.01) at 2 degrees of freedom in a chi-square test signifies the probability of observing a result as extreme or more extreme than the one observed, assuming that the null hypothesis is true.
The critical value P(0.10) at 4 degrees of freedom in a chi-square test signifies the probability of observing a result as extreme or more extreme than the one observed, assuming that the null hypothesis is true.

Binomial Expansion

The binomial expansion helps calculate the probability of a certain number of events occurring in a fixed number of trials, given the probability of the event occurring in a single trial.
In the binomial expression n = 8, x = 3, and p = 0.4, q represents the probability of the event not occurring in a single trial (q = 1 - p = 0.6).

Monohybrid Cross

The problem-solving approach that involves using the chi-square test for a monohybrid cross is unknown in this context.

Interpretation of Chi-Square Test

A calculated 𝛘2 value less than the critical value indicates that the observed frequencies do not differ significantly from the expected frequencies.
Scientists typically assume that the null hypothesis is rejected when P < 0.05 in a chi-square test, indicating that the observed frequencies differ significantly from the expected frequencies.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your understanding of Forked line/Branch diagrams for Dihybrid and Trihybrid crosses in genetics, and applying Probability rules. Calculate the Phenotype Ratio for the given crosses and practice problem-solving. This quiz is based on Lecture 2 by Preeti Karwal, Ph.D. in the course BIO207H5S Introductory Genetics Winter 2024.