Physical Development - AP Psychology

Out of these three units, genes are the building blocks and the smallest unit. Each gene codes for one or more proteins, though only one protein will be produced from each gene transcript. Genes are comprised of DNA sequences. A single strand of DNA will carry the code for numerous genes. When DNA is condensed and wrapped around histone proteins, it creates the structure of a chromosome. Chromosomes are formed from tightly coiled DNA strands, as well as protein components.

Chromosomes are composed of DNA, which is composed of genes. As such, genes are the least complex element, followed by DNA and chromosomes.

Genes frequently come in different varieties, known as alleles. Certain alleles can be dominant to others, such that the presence of a dominant allele masks the presence of a recessive allele. Every time a dominant allele is present in an individual's genome, that individual will display the trait coded by the dominant form of the gene.

Note that there is no such thing as a "dominant gene" or "recessive gene." Take, for example, the gene that codes for eye color. One does not say that the gene for eye color is dominant or recessive; this suggests that presence of a "recessive eye color gene" would result in no eye color whatsoever. In contrast, one can say that the allele for blue eyes is recessive to the allele for brown eyes, such that an individual with both forms of the allele will always display brown eyes. Note that eye color is, in reality, far more complex that this explanation would suggest.

The Moro reflex is an involuntary type of reflex (response to stimulation) during which a baby will respond to loss of support by spreading out his/her arms (abduction), unspreading the arms (adduction), then usually crying. Another common name for this reaction is the startle reflex.

Babies tend to develop in a pattern called cephalocaudal development. This means that the first areas to develop are the head and neck, and the last are the legs and feet. We also develop smell and taste in the womb, then hearing, then finally sight.

Teratogens are chemicals or viruses that can reach the embryo or fetus during prenatal development and cause great harm. Moderate to high amounts of alcohol consumed by the mother may cause problems for the developing fetus; thus it is an example of a teratogen.

Fetal alcohol syndrome (FAS) is a collection of cognitive abnormalities in young children caused by a mother's heavy drinking during pregnancy. In severe cases of FAS, there may be severe physical deficiencies as well.

The rooting reflex is an infant's tendency to turn his/her head toward something that touches his/her cheek. This allows the baby to find the nipple during breastfeeding.

Menarche, a girl's first menstrual period, is often viewed as the biological marker indicating the beginning of adolescence.

After the conception of a child, the following two weeks are known as the Germinal Period. This is followed by the Embryonic Period, which lasts another 2-8 weeks. After the Embryonic Period is complete, the Fetal Period occurs, and the child is born at its conclusion.

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.

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.

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.

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.

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.

"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.

The Moro reflex occurs in infants up to 6 months old. This reflex occurs when infants feel like they are falling, and specifically involves the infant spreading and unspreading his arms while crying out for help.