Question 1

Which of the following best describes the principle of independent assortment as observed by Mendel in his pea plant experiments?

Accepted Answer

Alleles of different genes segregate independently of one another during gamete formation.

Question 2

A geneticist is studying two genes, each with two alleles (A/a and B/b), located on different chromosomes. What is the probability that an offspring from a cross AaBb × AaBb will have the genotype aabb? Use the multiplication rule.

Accepted Answer

$$\frac{1}{16}$$

Question 3

Which of the following statements about loci and alleles is correct?

Accepted Answer

A locus is a specific position on a chromosome, and alleles are different versions of a gene found at that locus.

Question 4

In a trihybrid cross involving three independently assorting genes (AaBbCc × AaBbCc), what is the probability of obtaining an offspring with the genotype AABBcc? (Use the multiplication rule.)

Accepted Answer

$$\frac{1}{64}$$

Question 5

A researcher is analyzing the results of a genetic cross and wants to determine if the observed data fit the expected Mendelian ratio. Which statistical test should they use?

Accepted Answer

Chi-squared ($$\$$chi^2$$) test

Question 6

Given the following observed (O) and expected (E) values for a dihybrid cross: O = [90, 30, 30, 10], E = [75, 25, 25, 15], calculate the $$\$$chi^2$$ value using the formula $$\$$chi^2$$ = \sum \frac{$$(O-E)^2$$}{E}$$.

Accepted Answer

$$\$$chi^2$$ = 6.67$$

Question 7

If the degrees of freedom (df) for a chi-squared test is calculated as the number of categories minus one, what is the df for a test with 5 phenotypic categories?

Accepted Answer

df = 4

Question 8

Which of the following best illustrates the addition rule in probability as applied to genetics?

Accepted Answer

The probability of an offspring being either homozygous dominant or homozygous recessive is the sum of their individual probabilities.

Question 9

A population has the following allele frequencies for a gene with two alleles: $$p = 0.7$$ for allele A and $$q = 0.3$$ for allele a. What is the expected frequency of heterozygotes (Aa) under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 0.42$$

Question 10

In a medical genetics case, a patient is heterozygous for two genes (Ocr t/Ocr and ADH 23*2/ADH 28*3). If these genes assort independently, what is the probability that a gamete will contain the Ocr t and ADH 23*2 alleles?

Accepted Answer

$$\frac{1}{4}$$

Question 11

Which of the following genotype symbols correctly represents a heterozygote for a gene with alleles B*I and 23*2?

Accepted Answer

B*I/23*2

Question 12

A trihybrid cross (AaBbCc × AaBbCc) is performed. Using the branching method, what is the probability of obtaining an offspring with at least one dominant allele at each locus?

Accepted Answer

$$\frac{63}{64}$$

Question 13

Which scenario best demonstrates the use of the multiplication rule in genetics?

Accepted Answer

Calculating the probability of an offspring inheriting allele A from one parent and allele B from another, when the genes are on different chromosomes.

Question 14

A scientist observes the following phenotypic ratio in a dihybrid cross: 9:3:3:1. What does this ratio indicate about the genes involved?

Accepted Answer

The genes assort independently and are located on different chromosomes.

Question 15

If a cross between two heterozygous individuals (Aa × Aa) produces 100 offspring, how many would you expect to be homozygous recessive (aa) under Mendelian inheritance?

Accepted Answer

25

Question 16

A researcher is using the chi-squared test to analyze genetic data. If the calculated $$\$$chi^2$$ value is less than the critical value at a given significance level, what should the researcher conclude?

Accepted Answer

Accept the null hypothesis; the data fit the expected ratio.

Question 17

Which of the following is NOT a correct application of the addition rule in genetics?

Accepted Answer

Calculating the probability of an offspring inheriting both A and B alleles from the same parent.

Question 18

In a population, the frequency of allele A is 0.6 and allele a is 0.4. What is the expected frequency of genotype AA?

Accepted Answer

$$p^2 = 0.36$

Question 19

A genetic counselor is analyzing a pedigree for a rare trait. If the trait is determined by a single gene with two alleles, and both parents are heterozygous, what is the probability that their child will not express the trait if it is recessive?

Accepted Answer

$$\frac{3}{4}$$

Mendelian Inheritance and Probability in Genetics

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