Humans have _____ pairs of chromosomes:

Gastrulation is complete when:

During Gastrulation, the blastula folds in on itself to form three layers, the ______, _______ and ______.

An organism with two identical alleles is:

The blastocyst implants in the uterine wall with the assistance of:

The sperm contain enzymes such as ____ that enable the sperm to penetrate the egg:

After a sperm penetrates an ovum, the sperm nucleus is incorporated into the ooplasm triggering the following action:

The difference between a phenotype and genotype is that:

The blastocyst must hatch out of the _________ prior to implantation:

Chromosomes 1 through 22 in humans are “non sex chromosomes” otherwise known as