Exam 2: A: Genetic Bases of Child Development

The same genotype for intelligence leads to the same phenotypes for intelligence. This is called reaction range.

Genes are made up of nucleotide bases.

Although environmental factors are important, they usually affect each child in a unique way, which makes siblings differ.

The autosomes determine the sex of the child.

About 50 percent of the differences in children's scores on intelligence tests are due to heredity.

In twin studies, it is assumed that heredity influences a characteristic if fraternal twins are more alike than identical twins.

Experiences determine which phenotypes emerge, and genotypes influence the nature of experiences.

The behavioural consequences of genetic instructions depend on the environment in which those interactions develop.

A homozygous individual has two alleles that are the same.

Heredity and environment interact dynamically throughout development.

Each sperm and egg contain 46 chromosomes.

One problem with twin studies is that the experiences of identical twins may be more similar than the experiences of fraternal twins so that heredity appears to have a greater influence.

The extra 21st chromosome that is found with Down syndrome usually comes from the father's sperm.

Chromosomes consist of deoxyribonucleic acid (DNA).

Heredity-environmental influences at any given point are affected by prior heredity-environmental exchanges.

About 80 percent of in vitro fertilization attempts succeed.

Individuals with the sickle-cell allele are more resistant to malaria.

In vitro fertilization involves combining the sperm and egg in a laboratory dish.

If one identical twin is clinically depressed, the other twin has a 25 percent chance of becoming depressed.

The presence of abnormal autosomes is a major cause for spontaneous abortions during the period of the zygote.