Answer:
<em><u>This is the only phylum of the animal subkingdom Parazoa and represents the least evolutionarily advanced group of the animal kingdom. ... Sponges are the only animals that lack tissues with mass of cell embedded in gelatinous matrix.</u></em>
Germ layer is a primary layer of cells found in the embryo. The three primary germ layers that generate most of the cells in the developing mammalian forelimb are ectoderm, mesoderm and endoderm.
Ectoderm forms the outer component of a mammalian body such as skin, hair, etc. Endoderm forms the inner layer that comprises of the linings of digestive system, lungs and thyroid. Mesoderm is the middle layer that forms the skeletal system, heart, etc.
Neural tube is generated by the inward folding of the ectoderm. This process is called neurulation. Ectoderm also forms neural crest.
Answer:
A mutation that cause changes to short stretches of nucleotides. These mutations affect the specific genes that provide instructions for various functional molecules, including protein . changes in these molecules can have impact on any number of an organism's physical characteristics
