The notochord will eventually develop into the  

In order for a muscle to contract for movement, what is required?

solid ball of cells is called the 

The type of muscle that lines the digestive system and involves movement of food is

hollow ball of cells is called the

single fertilized cell is called the

The cortical granules contain what

The basic unit of contraction is called a

The Digestive system is produced by which germ layer

  The following species, X, Y, Z, U and V share a common ancestor T.  A grouping of the species T, X, Y and Z would make up a