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AP Biology Practice Quiz: Mendelian Genetics

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 9 questions to check your progress.

Question 1 of 9

Which of the following statements best describes Mendel’s Law of Segregation?

All Questions (9)

Which of the following statements best describes Mendel’s Law of Segregation?

A) Alleles for a single trait separate from each other during the formation of gametes.

B) Genes for different traits are sorted into gametes independently of one another.

C) The fusion of haploid gametes restores the diploid number of chromosomes.

D) Traits from two parents blend together to create an intermediate phenotype in the offspring.

Correct Answer: A

Based on the provided content, Mendel's laws describe the inheritance of genes. The Law of Segregation specifically states that the two alleles for a heritable character separate (segregate) from each other during gamete formation so that they end up in different gametes.

Mendel’s Law of Independent Assortment is fundamentally dependent on which of the following conditions?

A) The genes for the traits are located very close together on the same chromosome.

B) The organism is homozygous for both traits being studied.

C) The genes for the traits are located on different chromosomes.

D) The process of fertilization involves two genetically identical gametes.

Correct Answer: C

The provided content explicitly states that Mendel’s laws of segregation and independent assortment apply to genes located on different chromosomes. This allows the alleles for each gene to be sorted into gametes independently of the alleles for the other gene.

According to the principles of Mendelian genetics, what is the primary role of fertilization in the life cycle of a diploid organism?

A) To create haploid gametes through the process of segregation.

B) To ensure that alleles for different traits assort independently.

C) To reduce the chromosome number by half in preparation for reproduction.

D) To restore the diploid chromosome number through the fusion of haploid gametes.

Correct Answer: D

The content specifies that fertilization involves the fusion of haploid gametes. This process restores the diploid chromosome number and creates a new individual with a unique combination of alleles from both parents.

In a pea plant heterozygous for both tallness and seed color (TtYy), the genes for these traits are on different chromosomes. Which principle explains why a gamete could receive the alleles T and y together?

A) The law of segregation

B) The law of independent assortment

C) The restoration of the diploid number

D) The fusion of haploid gametes

Correct Answer: B

The Law of Independent Assortment states that genes on different chromosomes are inherited independently of each other. Therefore, whether a gamete gets the 'T' or 't' allele has no influence on whether it gets the 'Y' or 'y' allele, allowing for combinations like 'Ty'.

If an organism has a diploid number of 24 chromosomes, how many chromosomes would be present in its gametes and in its zygote, respectively?

A) 24 in gametes, 24 in the zygote

B) 12 in gametes, 24 in the zygote

C) 24 in gametes, 48 in the zygote

D) 12 in gametes, 12 in the zygote

Correct Answer: B

Gametes are haploid, meaning they have half the number of chromosomes of a diploid cell (24/2 = 12). Fertilization involves the fusion of two haploid gametes to form a diploid zygote, restoring the full chromosome number (12 + 12 = 24).

In a cross between two parents with genotypes Gg and Gg, the rules of probability can be used to predict the genotypic ratio of the offspring. What is the probability that an offspring will have the genotype Gg?

A) 1/4

B) 1/2

C) 3/4

D) 1

Correct Answer: B

Using the rules of probability, there are two ways to get a Gg offspring: the first parent contributes 'G' (1/2 probability) and the second contributes 'g' (1/2 probability), OR the first parent contributes 'g' (1/2) and the second contributes 'G' (1/2). The total probability is (1/2 * 1/2) + (1/2 * 1/2) = 1/4 + 1/4 = 1/2.

Which of the following processes, as described by Mendelian genetics, is most directly responsible for creating new combinations of alleles and increasing genetic variation among sexually reproducing organisms?

A) The expression of a dominant allele over a recessive one.

B) The separation of alleles for a single gene into different gametes.

C) The independent sorting of genes on different chromosomes into gametes.

D) The fusion of haploid gametes during fertilization.

Correct Answer: D

While segregation and independent assortment create variation in the gametes, the content specifies that the fusion of these gametes during fertilization is what 'create[s] new combinations of alleles, increasing genetic variation' in the resulting offspring by combining the genetic material from two different parents.

A failure of Mendel's Law of Segregation during meiosis would most likely result in which of the following?

A) A gamete containing two alleles for the same gene.

B) A zygote with a haploid number of chromosomes.

C) Genes on different chromosomes failing to assort independently.

D) The creation of four genetically identical daughter cells.

Correct Answer: A

The Law of Segregation dictates that the two alleles for a gene separate into different gametes. If this law failed, a gamete could improperly receive both alleles for a gene (e.g., 'Gg') instead of just one ('G' or 'g'). This is a form of nondisjunction.

The predictable 9:3:3:1 phenotypic ratio in a dihybrid cross, involving genes on different chromosomes, is a statistical outcome that can be analyzed using rules of probability. This ratio is a direct consequence of:

A) The law of segregation acting alone.

B) The process of fertilization restoring the diploid number.

C) The combined effects of the law of segregation and the law of independent assortment.

D) The law of independent assortment acting alone.

Correct Answer: C

The 9:3:3:1 ratio is produced because alleles for each gene segregate into gametes (Law of Segregation), and the two genes are inherited independently of each other (Law of Independent Assortment). Both laws must apply for this specific ratio to be predicted by the rules of probability.