At 10 days after conception, cellular differentiation of the zygote will begin. This forms a blastocyst (ball of cells) with an outer covering. The outer covering will continue to develop separately from the inner cells to become a membrane responsible for protecting and nourishing the developing fetus. These cells will eventually become the placenta; therefore, the inner zygotic cells will become the embryo. Eventually, the embryo will progress to the fetal stage. This will occur 9 weeks post-conception. A zygote already contains all the genetic information provided by the sperm and egg. As a result, the inner cells would not become chromosomes.

At 10 days after conception, cellular differentiation of the zygote will begin. This forms a blastocyst (ball of cells) with an outer covering. The outer covering will continue to develop separately from the inner cells to become a membrane responsible for protecting and nourishing the developing fetus. These cells will eventually become the placenta; therefore, the inner zygotic cells will become the embryo. Eventually, the embryo will progress to the fetal stage. This will occur 9 weeks post-conception. A zygote already contains all the genetic information provided by the sperm and egg. As a result, the inner cells would not become chromosomes.

During natal development, the brain begins to form many nerve cells. The developing cortex overproduces neurons. As a result, the child is left with the most neurons it will ever have in its lifetime. From ages 3 to 6, the most rapid development occurs in the frontal lobes. This is responsible for enabling the rational behavior that causes preschoolers to be able to focus their attention and control their behavior. The association areas are the last to develop. These areas are linked to cognition, memory, and language. As these areas develop, language, memory, and the ability to think increase at a rapid rate. The occipital lobe is responsible for vision; therefore, it would be expected that the occipital lobe would develop before the association areas. The brainstem is responsible for motor control and background processes. Motor control plays a huge part in infancy and motor development (e.g. walking) is complete within the first year of life.

By definition, secondary sex characteristics are non-reproductive characteristics that develop when adolescents undergo puberty. All of the following choices describe the physical changes that manifest themselves as a boy or girl undergoes puberty.

Puberty is the period during which adolescence begins—it is when we begin to mature sexually. 

As puberty begins, a signal is sent to the master gland (pituitary) that triggers a surge of hormones. These hormones are released with the intention of creating the expected body changes of childhood to adolescence in terms of primary and secondary sex characteristics. The physical development of primary and secondary sex characteristics (e.g. deepening of voice or menarche) are the results of puberty.

Kohlberg's three levels of moral thinking include preconventional, conventional, and postconventional. 

From around the age of 9 until early adolescence Kohlberg believed that a child entered into the conventional phase of morality. At this time, the child would have switched its focus from following rules for self-interest to obeying laws to achieve social approval.

The other options, “preoperational” and “formal operational,” would be incorrect as they are stages from Piaget's theory of cognitive development. 

As the frontal lobe continues to develop there's a rapid growth in brain cells branching to other cells. The creation of pathways and connections betters communication between cells and different regions of the brain. There is also a notable increase in myelin. As the fatty tissue around axons increases, so does the rate of neurotransmission. Together, this allows for better judgment and impulse control as it expands on higher order mental processes and personality.

Teens engage in risky and impulsive behaviors because the development of the frontal lobes lags behind the limbic system, which handles emotions. The development of the frontal lobes is not concerned with maintaining the functions of the limbic system. 

The frontal lobes are not concerned with hormonal distribution, which is controlled by the pituitary gland and hypothalamus.

Frontal lobe development is not associated with senses such as sight and hearing because different areas of the brain control those functions. 

"Subjective age" describes how an individual "feels" about their age regardless of how old he/she actually is. On the other hand, "functional age," "chronological age," and "physical age" refer to an individual's competence, abilities, and actual age, respectively. 

Fetal alcohol syndrome can occur in children born to mothers who drink alcohol heavily during pregnancy. Symptoms can include distinct facial features, developmental delays, low birth weight, learning disabilities, and hyperactivity. Huntington's disease is a genetic disorder that can include uncontrollable movements, cognitive decline, and emotional problems. Autism spectrum disorder involves problems associated with communication, social interactions, and the presence of stereotyped or obsessive interests and behaviors. Turner syndrome and Klinefelter syndrome are both chromosomal disorders. Turner syndrome is only present in females and involves the presence of one X chromosome. Symptoms include delayed puberty, infertility, intellectual disability, heart and joint problems, and short stature. Klinefelter syndrome is only present in males and involves the addition of an X chromosome. Symptoms can include low testosterone, delayed puberty, infertility, difficulty sustaining attention, and distinct facial features.