Exam 21: Human Development and Genetics

If a trait may appear in a person's phenotype only when two genes are present for it,the trait is called ____________________.

The expression of the genes a person has for a particular trait is called the ____________________.

Blood is carried from the fetus to the placenta by the:

Which statement is NOT true of the events surrounding fertilization?

The embryonic membrane that forms the first blood cells is the:

A person has two genes for each genetic trait,and these genes are called ____________________ and ____________________.

Which of the following statements are true of genes and chromosomes? (Read carefully and select all of the correct statements.)

A human zygote contains how many chromosomes?

During the ____________________ stage of labor,the cervix dilates.

A zygote begins a series of cell divisions called:

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

In the placenta,nutrients are taken into fetal vessels by the process of ____________________.

The appearance or expression of a particular trait in a person is called the:

During the third stage of labor,____________________.

The average gestation period lasts:

A person's phenotype for a particular trait refers to the ____________________.

A homologous pair of chromosomes contains genes for:

The sex chromosomes in women are called ____________________.

Which of these embryonic structures is NOT paired with the correct primary germ layer from which it develops?

A gene is the genetic code for ____________________.