Question 1

During the embryonic period, the:

Accepted Answer

During the embryonic period, which lasts from the second week to the eighth week after conception, the organs and major systems of the body form.

Answer: D
 During the first two weeks after conception, the zygote undergoes rapid cell division, which marks the beginning of the embryonic period.

Therefore, both C and D are correct answer choices.

Question 2

Epigenetics refers to:

Accepted Answer

Epigenetics is the study of the mechanisms that control gene expression and the effects of gene expression on behavior and health. It involves the study of heritable changes in gene function that do not involve changes to the underlying DNA sequence. This includes modifications to DNA and chromatin structure that can affect how genes are turned on or off, as well as the influence of environmental factors on gene expression.

Question 3

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

Accepted Answer

The experiment suggests that environmental factors can alter gene expression without changing the underlying DNA sequence, which is consistent with epigenetic modifications. The attentive mother rats likely provided a nurturing environment that triggered epigenetic changes in the offspring's gene expression, leading to a more calm and stress-resistant phenotype. The genetic mutations or inheritance of epigenetic changes from the previous generation are not supported by the results of the experiment.

Question 4

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

Accepted Answer

Mutations, or spontaneous changes in the DNA sequence, can occur and affect the genotype, which can in turn affect the phenotype. These mutations can be inherited or occur randomly during cell division, and can have varying effects on gene expression and protein function. Therefore, mutations are a crucial factor in the relationship between genotype and phenotype.

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. While all cells in the body contain the same set of genes, each cell type expresses only a subset of those genes, allowing them to carry out specific functions. This process of gene expression leads to the development of specialized cell types with distinct characteristics, such as neurons, muscle cells, and blood cells. The other answer choices (A, B, and C) are not correct because they do not accurately explain the process of cell differentiation and the development of distinct cell types.

Question 6

Some teratogens, such as cocaine, cigarette smoke, or alcohol, can damage the developing fetus:

Accepted Answer

Teratogens can damage the developing fetus at any stage before birth, including during the germinal, embryonic, and fetal periods. Cocaine, cigarette smoke, and alcohol are particularly harmful and can cause a range of physical and cognitive disabilities in the child, known as fetal alcohol spectrum disorders. It is important for pregnant women to avoid exposure to teratogens and to seek medical care to ensure the health of their developing fetus.

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 adult rats 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

The phenomenon described in the question is an example of epigenetic change. Epigenetic changes refer to alterations in gene expression that do not involve changes in the DNA sequence of the gene. In this case, the rats' genes did not change, but the chemicals that control their gene expression did change as a result of their environment. This suggests that environmental factors can have a significant impact on gene expression and the traits that develop as a result. The other answer choices (B, C, and D) do not accurately describe the phenomenon observed.

Question 8

A teratogen is a:

Accepted Answer

A teratogen is a harmful agent that can cause abnormal development or birth defects. This can include exposure to chemicals, drugs, or diseases during prenatal development. It is not a specific type of genetic mutation like the options in A, C, and D.

Question 9

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 area of research that Dr. Maxwell investigates, particularly the regulation of gene activity and the determination of cell differentiation, aligns with the field of epigenetics. Epigenetics studies heritable changes in gene expression without changes to the underlying DNA sequence, including factors such as chemical modifications to DNA and associated proteins.

Note: 
A) Genetic mutation research focuses on the identification and characteristics of specific mutations and their associated effects. 
B) Zygotic research studies the molecular and genetic events that occur from fertilization through the formation of the zygote. 
D) The human genome project aimed to sequence and map all genes in the human genome, but does not directly relate to Dr. Maxwell's specific research focus.

Question 10

As a general rule, the greatest vulnerability to _____ occurs during the _____ period of prenatal development.

Accepted Answer

Teratogens are substances, such as drugs, alcohol or viruses, that can cause birth defects or malformations in the developing fetus. The embryonic period is the second period of prenatal development, lasting from 2 to 8 weeks after fertilization, during which the most critical structures and systems of the body form. The developing organism is most susceptible to the harmful effects of teratogens during this period, which makes it the greatest vulnerability to teratogens.

Question 11

An experiment found that newborn rats who were genetically predisposed to be calm and stress-resistant grew up to be nervous, high-strung, and easily stressed adult rats when raised by genetically unrelated, inattentive mothers. These results showed that:

Accepted Answer

The experiment showed that even though the rats were genetically predisposed to be calm and stress-resistant, their upbringing caused epigenetic changes that altered their brain chemistry and behavior. This suggests that environmental factors can have a significant impact on gene expression and subsequent behavior. There is no evidence to support options A, C, or D.

Question 12

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

Accepted Answer

The differences in physical and psychological characteristics in identical twins who developed from the same zygote but exhibit differences can be attributed to epigenetic changes. Epigenetic changes are modifications that occur in gene expression without any alteration in the DNA sequence. These changes can result from environmental factors, such as nutrition and stress. Therefore, the twins' experiences and environment can cause differences in their physical and psychological characteristics despite having identical DNA.

Question 13

During the germinal period:

Accepted Answer

During the germinal period, which lasts from fertilization to about two weeks, the zygote travels down the fallopian tube and implants itself in the mother's uterine wall.

Question 14

Shannon is in the seventh week of her pregnancy. In terms of prenatal development, Shannon's pregnancy is in the _____ period.

Accepted Answer

The embryonic period begins at the end of the germinal period (conception to 2 weeks) and lasts until the end of the eighth week of pregnancy. As Shannon is in the seventh week of her pregnancy, she is in the embryonic period.

Question 15

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 examining the impact of early stress on epigenetic changes in humans have shown that childhood stress or adversity can cause distinct epigenetic changes in brain tissue, particularly in regions related to stress response and anxiety. The other options are not supported by the text.

Question 16

Which of the following is TRUE of the placenta?

Accepted Answer

The placenta is an organ that forms during pregnancy to provide oxygen and nutrients to the developing embryo or fetus. It also acts as a barrier, preventing the mother's blood from mixing with the blood of the developing embryo or fetus. It is fully developed by the end of the first trimester (approximately 12 weeks) of pregnancy, not six months after birth. It is not the same as the fluid-filled sac that houses the developing embryo or fetus, which is called the amniotic sac.

Question 17

Most developmental psychologists believe that gene expression is:

Accepted Answer

Most developmental psychologists believe that gene expression is flexible and responsive to both internal and external factors. While genes provide the blueprint, the environment and experiences can influence the expression of those genes throughout the lifespan. This is known as gene-environment interaction. Therefore, gene expression is not solely determined by the genetic blueprint with which people are born, but also shaped by environmental factors.

Question 18

Which of the following represents the correct order of prenatal development?

Accepted Answer

The correct order of prenatal development is germinal period, embryonic period, and fetal period. The germinal period is the first stage of prenatal development, which lasts for about two weeks from conception to implantation. The embryonic period starts after implantation and lasts until the end of the eighth week. During this period, the major organs and systems of the body begin to develop. The fetal period starts at the beginning of the ninth week and lasts until birth. During this period, the fetus grows and develops further, and the organs and systems continue to mature. Therefore, option C is the correct order of prenatal development.

Question 19

Extending from the placenta on the mother's uterine wall to the embryo's abdominal area, the _____ delivers nourishment, oxygen, and water, and carries away carbon dioxide and other wastes.

Accepted Answer

The umbilical cord is the structure that extends from the mother's uterine wall to the embryo's abdominal area, and it is responsible for delivering nourishment, oxygen, and water to the developing fetus. It also carries away carbon dioxide and other wastes. The amniotic sac is a fluid-filled sac that surrounds and protects the fetus, but it does not deliver nutrients or remove waste. The embryo is the developing organism inside the uterus, but it is not responsible for delivering nutrients. Teratogens are substances or environmental factors that can cause birth defects, but they do not play a role in delivering nutrients to the fetus.

Question 20

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

Accepted Answer

Humans carry vestigial genes for a tail, but these genes are usually never activated. This is because they are suppressed during embryonic development due to other genetic and environmental factors.

Quiz 9: Lifespan Development