Question 1

Genetic recombination as a result of crossing over occurs more readily in genes

Accepted Answer

Genetic recombination as a result of crossing over occurs more readily in genes that are located far apart on the same chromosome. This is because genes located close together on the same chromosome tend to be inherited together due to linkage, while genes that are farther apart have a greater chance of being separated during meiosis via crossing over.

Question 2

The reason for the darker fur on the tail, ears, nose, and legs of a Siamese cat is

Accepted Answer

The darker fur on these specific areas of a Siamese cat is due to the activity of a heat-sensitive enzyme involved in melanin production. This enzyme is only active in cooler parts of the body, such as the extremities, which causes the melanin to be produced in those areas and results in darker fur. This is an example of temperature-sensitive pigment expression, which is unique to Siamese cats.

Question 3

Which of the following is NOT a known effect in the expression of Marfan syndrome?

Accepted Answer

Excessive absorption of oxygen causing the blood cells to swell is not a known effect in the expression of Marfan syndrome. The other options, lanky body type, weakened blood vessels, lack of elasticity in the aorta, and loose joints, are all characteristics commonly associated with Marfan syndrome.

Question 4

The difference between people who handle stress well and those who become deeply depressed is based on all BUT

Accepted Answer

The answer of The difference between people who handle stress...

Question 5

In genetic analyses, researchers know that linkage of genes will introduce exceptions to the principle of

Accepted Answer

Linkage between genes on the same chromosome can disrupt the principle of independent assortment, which states that genes on different chromosomes will assort independently into gametes. Linked genes, however, will tend to be inherited together in the same gametes, leading to exceptions to independent assortment. Linkage does not affect the principles of dominance, segregation, recessiveness, or chromosomal inheritance.

Question 6

Which of the following is false about Marfan syndrome?

Accepted Answer

All the statements provided are true about Marfan syndrome.

Question 7

From the relative positions of genes on the chromosome illustration below, we expect

Accepted Answer

The answer of From the relative positions of genes on...

Question 8

Genes that are located on the same chromosome

Accepted Answer

Genes that are located on the same chromosome are said to be linked and tend to be inherited together, meaning they will usually appear together in the gamete. However, they may be separated during crossing over, which is a process that can result in the exchange of genetic material between homologous chromosomes during meiosis. Therefore, all of these statements are true.

Question 9

The role of environmental factors on gene expression is illustrated by

Accepted Answer

All of these examples illustrate the role of environmental factors on gene expression. The varying plant height of genetically identical yarrow plants when grown at different elevations highlights the impact of environmental factors such as light and availability of nutrients on gene expression. The varying body forms of Daphnia affected by the presence of predators likewise shows how environmental factors can impact gene expression through natural selection. The depression response that some persons make to very stressful situations illustrates how gene expression can be influenced by environmental factors like traumatic events. Finally, the fur pattern of Himalayan rabbits is affected by temperature-induced changes in gene expression, which is again an example of the influence of environmental factors on gene expression.

Question 10

Which of the following statements is false?

Accepted Answer

The closer together genes are on a chromosome, the less likely crossing over will occur between them, as there is less physical space for recombination events to take place.

Question 11

All of the genes located on a given chromosome constitute

Accepted Answer

All of the genes located on a given chromosome are physically linked together and tend to be inherited together, forming a linkage group. Therefore, choice D is the best answer. A karyotype is an image of a complete set of chromosomes, so it does not apply to a single chromosome. A bridging cross and wild-type allele are not relevant to the question.

Question 12

If the F₁gametes show a distribution pattern like that shown in the illustration below, then they present an example of

Accepted Answer

The answer of If the F₁gametes show a distribution...

Question 13

The color of Siamese cats is controlled by

Accepted Answer

The color of Siamese cats is controlled by a temperature-sensitive allele, which means that the colder parts of the cat's body (extremities) produce darker fur due to increased pigment production. This is an example of environmental influence on gene expression, not genetic inheritance.

Question 14

Pleiotropic genes

Accepted Answer

Pleiotropic genes are genes that influence more than one aspect of an individual's phenotype. This means that a single gene has multiple effects on different traits, such as eye and hair color or height and weight.

Question 15

If the paternal chromosome has alleles L, M, and n and the maternal chromosomes have l, m, and N, then the chromosome that cannot be produced by crossing over is

Accepted Answer

The answer of If the paternal chromosome has alleles L,...

Question 16

The variation of the color in Siamese cats is due to

Accepted Answer

The color variation in Siamese cats is due to temperature-sensitive enzyme activity, which is an environmental effect on phenotypes. The enzyme responsible for pigment production is active in cooler areas of the body, leading to darker fur in those regions.

Question 17

If alleles L, M, and N are on the maternal chromosome and l, m, and n are on the paternal chromosome, the only way that a gamete from a heterozygote will produce a gamete with alleles l, m, and N is through

Accepted Answer

Crossing over is the only process that can produce a gamete with a combination of alleles that are not present in the parental chromosomes. This process, which occurs during meiosis, involves the exchange of genetic material between homologous chromosomes, resulting in new combinations of alleles. In this case, crossing over between the M and m alleles on the maternal and paternal chromosomes, respectively, would lead to the production of a gamete with alleles l, m, and N. The other processes listed (nondisjunction, segregation, independent assortment, and chromosome aberration) do not directly result in the production of new combinations of alleles.

Question 18

If two genes are on the same chromosome,

Accepted Answer

Genes on the same chromosome are said to be linked, meaning they are physically close to each other on the same chromosome. The group of genes that are linked together on a chromosome is called a linkage group. Therefore, Choice C is the correct answer.

Question 19

A bell-shaped curve of phenotypic variation is indicative of

Accepted Answer

A bell-shaped curve of phenotypic variation is a result of continuous variation, where there is a range of phenotypes within a population that is influenced by the combination of genetic and environmental factors.

Question 20

If two genes are almost always found in the same gamete,

Accepted Answer

Two genes that are almost always found in the same gamete are likely to be located close together on the same chromosome. This is because genes that are located on the same chromosome tend to be inherited together due to the process of genetic linkage, where the physical proximity of genes on a chromosome affects their likelihood of being inherited together.

Quiz 11: Observing Patterns in Inherited Traits