Exam 21: Human Development and Genetics

A person who has two similar genes for a particular trait is said to be ____________________ for that trait.

If a trait may appear in the phenotype when only one gene for it is present,that trait is called:

For the ABO blood types in people,the O allele is ____________________ and the A and B alleles are ____________________.

The placental hormone that maintains the corpus luteum during early pregnancy is ____________________.

After birth,the baby's ductus venosus ____________________,because the umbilical cord has been cut and blood no longer enters the baby from the ____________________.

Normal implantation of a blastocyst takes place in the ____________________ of the uterus.

In the embryo,the bones and muscles are derived from the ____________________.

For people,curly hair is dominant and straight hair is recessive.Genetics problem: Mom has straight hair and Dad is homozygous for curly hair.The chance that their child will have straight hair is:

Genetics problem: Mom is type O and Dad is heterozygous for type A.The percent chance that a child of theirs will have type A blood is ____________________.

During an average gestation period,the period of embryonic growth lasts ____________________ weeks,and the period of fetal growth lasts ____________________ weeks.

During the ____________________ stage of labor,the placenta is delivered.

In the early embryo,the ectoderm gives rise to the:

Genetics problem: Both Mom and Dad are heterozygous for type B blood.The percent chance that a child of theirs will have type O blood is ____________________.

The morula stage of early embryonic development may be described as a ____________________ of cells.

During pregnancy,the placental hormones that inhibit ovulation are ____________________ and ____________________.

Which statement is NOT true of genes?

The sex chromosomes in ____________________ are called XX,and in ____________________ are called XY.

A human cell contains ____________________ (number)chromosomes,and 22 pairs of these are called ____________________.

Which of the following statements are true of fertilization and embryonic development? (Read carefully and select all of the correct statements.)

A trait that is ____________________ requires two genes for its expression,and a trait that is ____________________ requires only one gene for its expression.