Question 1

In addition to interactions among genes, and between genotype and environmental influences, another crucial factor in therelationship between genotype and phenotype is:

Accepted Answer

Mutations can occur randomly and spontaneously, leading to changes in genotype that can result in different phenotypes. This is an important factor to consider when examining the relationship between genotype and phenotype.

Question 2

If Gerry's genotype contains a copy of the dominant freckles gene:

Accepted Answer

The expression of the dominant freckles gene can be triggered by a specific environmental factor, such as sunlight, meaning that even though Gerry has the gene, he may not necessarily develop freckles unless he is exposed to sunlight.

Question 3

A male has an _____ combination in the _____.

Accepted Answer

In humans, males have an XY combination in the 23rd pair of chromosomes, while females have an XX combination. Choice A is incorrect because XX is a female combination, and choice B is incorrect because the 1st pair of genes does not refer to chromosomes. Choice C is incorrect because XX is still a female combination and not a male combination.

Question 4

Humans carry all of the genes necessary to develop a tail but we typically don't develop tails because:

Accepted Answer

Humans carry the genes necessary to develop a tail but they are never activated because of genetic mechanisms that suppress them during development.

Question 5

The diverse characteristics of different cells in the body develop because:

Accepted Answer

The diverse characteristics of different cells in the body develop because different genes are "expressed" or activated. This means that each cell type contains the same set of genes, but they are expressed differently based on the cell's function and development. For example, a muscle cell will express genes involved in muscle contraction while a nerve cell will express genes involved in neurotransmitter release.

Question 6

Unlike Donna, who usually gets a nice tan when exposed to sunlight, Derek has a tendency to sunburn easily. Donna and Derek obviously have different sensitivities to the same environmental factor. This example illustrates their different_____.

Accepted Answer

Donna and Derek's different sensitivities to sunlight suggest that they have different genetic predispositions. Genes play a role in determining skin sensitivity to UV radiation, which can result in varying degrees of tanning and sunburn. Epigenetic and karyotypic factors are less likely to be involved in this particular example.

Question 7

In an experiment, it was found that newborn rats who were genetically predisposed to be skittish, nervous, and high-strung would develop into calm, exploratory, and stress-resistant adultrats when raised by genetically unrelated, attentive mothers.The researchers concluded that:

Accepted Answer

The fact that the genetically predisposed rats developed into a different behavior phenotype when raised by genetically unrelated, attentive mothers indicates that the genes controlling their behavior were not mutated. Instead, it suggests that the chemical tags that control gene expression, which are influenced by environmental factors, were altered leading to changes in behavior. This is an example of epigenetic changes, which can be inherited and are reversible.

Question 8

The _____ pair of chromosomes, called the sex chromosomes,determines a person's biological sex.

Accepted Answer

The 23rd pair of chromosomes, also known as the sex chromosomes, determines a person's biological sex. This pair consists of two chromosomes, X and Y. Individuals with two X chromosomes are female, while individuals with one X and one Y chromosome are male. Therefore, option C is the correct answer.

Question 9

Which of the following factors was listed in your textbook as a possible trigger for gene activity?

Accepted Answer

All of the listed factors (internal chemical changes, external environmental factors, and the activity of other genes) can potentially trigger gene activity. Gene expression is a complex process that is influenced by both internal and external factors, as well as by the interplay between different genes within the same organism. Therefore, there is no single factor that can be identified as the sole trigger for gene activity.

Question 10

A female has an _____ combination in the _____.

Accepted Answer

Females have two X chromosomes, which are located on the 23rd pair of chromosomes. Therefore, the correct option is XX; 23rd pair of chromosomes. The other choices are incorrect as males have XY combination and the X chromosomes are not located on the 1st pair of chromosomes.

Question 11

Sheena and Tina are identical twins who developed from asingle zygote and share identical DNA. Nevertheless, as they develop, differences in physical and psychological characteristics become evident. These differences are due to:

Accepted Answer

Epigenetic change refers to modifications that occur to DNA or its associated proteins that do not change the underlying DNA sequence but can affect gene expression and, therefore, contribute to differences in physical and psychological characteristics between identical twins. Choices A, C, and D do not accurately reflect the cause of differences between identical twins, as they share the same genetic blueprint and do not have allele variation or genotypic change.

Question 12

The term phenotype refers to:

Accepted Answer

The phenotype of an organism refers to its observable characteristics or traits, which are determined by the interaction of genetic and environmental factors. This includes things like physical appearance, behavior, and other traits that can be observed or measured. The other options do not accurately describe the concept of phenotype. A is incorrect because a dominant gene on the X chromosome would affect inheritance patterns, but not necessarily an organism's observable traits. B is incorrect because a computer-enhanced image of an organism's chromosomes would show its genotype, not its phenotype. D is incorrect because the complete set of an organism's genes is its genotype, which may or may not be fully expressed in its phenotype.

Question 13

Most developmental psychologists believe that gene expressionis:

Accepted Answer

Developmental psychologists believe that gene expression is flexible and responsive to both internal and external factors. This means that while genes provide a blueprint for development, environmental factors such as experiences, nutrition, and stress can influence how genes are expressed or "turned on" and impact development. This concept is known as epigenetics, which has highlighted the dynamic and complex interplay between genetics and environment in shaping human development.

Question 14

In an experiment, it was found that newborn rats who were genetically predisposed to be calm and stress-resistant grew upto be nervous, high-strung, and easily stressed adult rats when raised by genetically unrelated, inattentive mothers. The explanation for these results was that:

Accepted Answer

Epigenetic changes had taken place that changed their brain chemistry and literally "reprogrammed" their future behavior.

Question 15

In an experiment, it was found that newborn rats who were genetically predisposed to be skittish, nervous, and high-strung would develop into calm, exploratory, and stress-resistant adultrats when raised by genetically unrelated, attentive mothers.Although the rats' DNA did not change, the chemicals that controlled their gene expression did change, a phenomenon called:

Accepted Answer

Epigenetic changes refer to alterations in the expression of genes without changes in the actual DNA sequence. In this case, while the rats' DNA did not change, the chemicals that controlled their gene expression did change, leading to a change in behavior. This supports the phenomenon of epigenetic change. Allele variation, recessive gene mutation, and dominant gene mutation refer to changes in the actual DNA sequence, which is not the case in this experiment.

Question 16

According to the text, studies examining the impact of early stress on epigenetic changes in humans have shown that childhood stress or adversity:

Accepted Answer

The text states that studies have shown that childhood stress or adversity can cause distinct epigenetic changes in brain tissue.

Question 17

People with a particular genetic configuration will be more orless sensitive to particular environmental factors. This is referred to as a person's _____ to develop in a particular way.

Accepted Answer

Genetic configuration refers to a person's unique combination of genes. A genetic predisposition means that a person is more likely to develop a certain trait or condition because of their specific genes. The other options do not accurately describe this concept.

Question 18

One problem with the genotype-as-a-blueprint analogy is that:

Accepted Answer

The genotype-as-a-blueprint analogy suggests that a person's genes determine their physical and behavioral characteristics in a predictable manner. However, this overlooks the role that environmental factors (such as diet, exposure to toxins, and social experiences) can play in shaping the phenotype that is displayed. Therefore, option A is the best choice as it shows that genes can be influenced by environmental factors.

Question 19

In his research, Dr. Maxwell investigates how gene activity is regulated within a cell, what signals switch genes "on" or "off,"and in particular, what determines whether a given cell will become a skin cell, a nerve cell, or a heart muscle cell. His area of research is called:

Accepted Answer

The research topic of Dr. Maxwell, specifically investigating what signals regulate gene activity and determine cell differentiation, falls under the field of epigenetics. Genetic mutation research and the human genome project may be related to understanding gene activity, but do not focus specifically on the regulation of gene expression. Zygotic research refers to the study of early development from the fertilized egg to the emergence of an organism, which is not directly related to Dr. Maxwell's research interest in gene regulation.

Question 20

Epigenetics refers to:

Accepted Answer

Epigenetics is the study of the mechanisms that control gene expression and its effect on behavior and health. It involves the study of changes in gene expression that do not involve changes to the underlying DNA sequence, but rather modifications of the DNA molecule or associated proteins that influence whether a gene is turned on or off. These changes can be influenced by environmental factors, such as diet, stress, and exposure to toxins, as well as by developmental and other factors.

Quiz 9: Lifespan Development