The Sensorimotor stage ranges from zero to two years of age. The phrase “out of sight, out of mind” describes a child before developing true object permanence. True object permanence is the ability of a child to know that even though an object is not visible to them, it still exists (imagine a game of peek-a-boo). In this stage, Piaget also proposed instinctual reflexes, intentional-ism, and coordination of speaking, hearing, and acting.  

Secondary sex characteristics are traits that develop during puberty, and include facial hair, enlarged breasts, pubic hair, and deeper voices. Primary sex characteristics are innate and include sex organs (the ovaries in women and testes in men) and genitalia. 

Longitudinal research is a popular method of conducting developmental psychology studies. This method takes one group of people and tracks the effect of the developmental factor being studied on them over time. This is a time-consuming and often tricky method of research and many researchers may turn to cross-sectional research instead.

Mary Ainsworth's study of attachment styles in parent-child relationships showed that babies with secure attachments to their parents would be distressed when their parents left the room and look for their comfort upon return. Ainsworth held that the baby had unconsciously recognized and accepted their dependence on their caregivers for their needs. The other attachment styles identified in the study were avoidant and anxious/ambivalent, where the babies may not have felt they could depend on their caregivers to fulfill their needs.

Permissive parenting is the most "relaxed" of the parenting styles. It's defined by a lack of consistency in rules and consequences that are usually not enforced, or are enforced in an inconsistent manner. Permissive parenting is on the opposite end of the spectrum from Authoritarian parenting, which features extremely strict rules with strong enforcement of punishment, and little explanation. Most parenting styles fall somewhere between these two polarized points on the spectrum of parenting style.

Authoritarian parents typically create strict rules that are not open to being updated based on the child's input. These parents have high expectations for their children, and are usually not nurturing. 

FAS is a rare, serious, and irreversible disorder that is caused by heavy drinking by the mother during pregnancy. Although FAS is more common than some other results of substance abuse during pregnancy, it is not the only one- there are damaging effects of cocaine use during pregnancy, for example. FAS presents a number of symptoms including low birth weight, malformed skulls, and intellectual disabilities and its effects present immediately. 

“Zygote to embryo to fetus” is the correct order. In development, a zygote is defined as a fertilized egg cell. An embryo forms at about 2 weeks post fertilization. Last, a fetus is the developing human from 9 weeks until birth. 

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. 

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.