Part a - differentiating between cleavage, gastrulation, and organogenesis determine which terms, phrases, and images describe each phase of development. drag each item to the appropriate bin.

In cleavage, the first phase where the newly fertilized egg called the zygote is divided into many cells exponentially (and yet remains intact because of the presence of the zona pellucida). Therefore, the words that needs to be in the "cleavage" bin are "blastula" and "cytoplasm partitioned into many cells". 

In gastrulation, ultimately, there is the formation of the gastrula. Embryonic germ layers (ectoderm, mesoderm, and endoderm) as well as the blastopore (the opening of the central embryonic cavity) will form. 

In organogenesis, organs will be derived from the germ layers formed in gastrulation. There will be the formation of the neural tube which will give rise to the primitive nervous system as well as the somites that will give rise to the muscles.