AP Biology : AP Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #92 : Inheritance

Which occurs when a heterozygous genotype produces blended traits?

Possible Answers:

Monosomy

Codominance

Incomplete dominance

Pure genotype

Trisomy

Correct answer:

Incomplete dominance

Explanation:

Incomplete dominance involves expression of an intermediate phenotype. The heterozygotes express a phenotype that is a blend of both the dominant and recessive phenotypes. One common example is a flower with white petals and a flower with red petals sexually reproduce to create flowers with pink petals. 

Example Question #93 : Inheritance

Which of these is an example of polygenic inheritance?

Possible Answers:

Freckles

Color blindness

Skin color

Sickle cell anemia

Duchenne muscular dystrophy 

Correct answer:

Skin color

Explanation:

Polygenetic inheritance is where multiple genes affect a single trait. Human skin color depends on three sets of alleles: Aa, Bb, and Cc. A cross between two parents with any combination of these three alleles determines skin color; there is no single skin color gene.

Example Question #1 : Apply 3 Laws Of Inheritance To Meiosis

Which is not true during meiosis?

Possible Answers:

Each gamete receives a random number of alleles for each gene from each parent

Each gamete receives one allele for each gene from each parent

Each gamete receives two alleles for each gene from only one parent

Each gamete receives two alleles for each gene from each parent

Correct answer:

Each gamete receives one allele for each gene from each parent

Explanation:

According to the Law of Segregation, each gamete receives one allele for each gene from each parent. During Meiosis, each parent’s two copies of each allele are separated from each other, then the gamete receives one copy of each allele from each parent (for a total of two alleles).

 

Example Question #2 : Apply 3 Laws Of Inheritance To Meiosis

The law of independent assortment states that ______________________. 

Possible Answers:

genes that are on the same chromosome are inherited together

each gamete receives one allele for each gene from each parent

genes that are further apart will be less likely to be inherited together 

inheritance of a specific gene is not influenced by other genes

Correct answer:

inheritance of a specific gene is not influenced by other genes

Explanation:

This is the definition of the law of independent assortment; during meiosis, the inheritance of one gene does not influence whether another, separate gene will also be inherited by that gamete.

Example Question #3 : Apply 3 Laws Of Inheritance To Meiosis

 According to Mendel’s Law of Dominance, the phenotype of a heterozygote will be ______________________ . 

Possible Answers:

determined by the dominant allele

determined by the recessive allele

a mixture of the phenotypes of both parents

determined by the mother’s genotype

Correct answer:

determined by the dominant allele

Explanation:

According to the Law of Dominance, each individual has two alleles for each trait and only the dominant allele contributes to the phenotype.

 

Example Question #4 : Apply 3 Laws Of Inheritance To Meiosis

During what process do homologous chromosomes segregate into different gametes? 

Possible Answers:

DNA replication

Meiosis

DNA synthesis

Cytokinesis

Correct answer:

Meiosis

Explanation:

According to the Law of Segregation, during Meiosis, homologous chromosomes segregate into different gametes.

 

Example Question #301 : Cell Functions

Which law of inheritance is incorrectly matched to its explanation?

Possible Answers:

Law of dominance; in a heterozygote individual, only the dominant allele will influence the phenotype

Law of segregation; each gamete receives both copies of gene from its parent

Law of independent assortment; inheritance of one gene does not influence inheritance of another gene

Law of segregation; each gamete receives only one copy of each gene from its parent

Correct answer:

Law of segregation; each gamete receives both copies of gene from its parent

Explanation:

The laws of inheritance include the laws of segregation (each gamete receives only one copy of each gene from its parent), dominance (in a heterozygote individual, only the dominant allele will influence the phenotype), and independent assortment (inheritance of one gene does not influence inheritance of another gene)

Example Question #302 : Cell Functions

In a dihybrid cross of seed color and seed shape, Y (yellow) is dominant to y (green) and R (rounded) is dominant to r (wrinkled). An individual with genotype YyRr is crossed with an individual with genotype YYRr. The inheritance of the alleles for seed color does not affect inheritance of genes for seed shape. Which law supports this statement?

Possible Answers:

Law of dominance

Law of segregation

Law of random mating

Law of independent assortment

Correct answer:

Law of independent assortment

Explanation:

The law of independent assortment states that inheritance of one gene does not influence inheritance of another gene. Thus, inheritance of seed color does not affect the inheritance of seed shape.

Example Question #1 : Understanding Crossing Over

Crossing over occurs during which stage of meiosis?

Possible Answers:

Prophase I

Anaphase I

Metaphase I

Prophase II

Correct answer:

Prophase I

Explanation:

During prophase I homologous chromosomes will line up with one another, forming tetrads. During this lining up, DNA sequences can be exchanged between the homologous chromosomes. This type of genetic recombination is called crossing over, and allows the daughter cells of meiosis to be genetically unique from one another.

Crossing over can only occur between homologous chromosomes. Cells become haploid after meiosis I, and can no longer perform crossing over.

Example Question #1 : Understanding Crossing Over

What is the evolutionary purpose of cells that undergo crossing over?

Possible Answers:

To produce gametes that are genetically identical

To keep mutations from forming

To increase genetic diversity

To produce two cells instead of one

To keep the redundancy of the cell high

Correct answer:

To increase genetic diversity

Explanation:

Crossing over is a process that happens between homologous chromosomes in order to increase genetic diversity. During crossing over, part of one chromosome is exchanged with another. The result is a hybrid chromosome with a unique pattern of genetic material. Gametes gain the ability to be genetically different from their neighboring gametes after crossing over occurs. This allows for genetic diversity, which will help cells participate in survival of the fittest and evolution.

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