What are the major differences in cleavage between protostomes and deuterostomes?

1.Define and describe the first three stages of early development: fertilization, cleavage, and gastrulation.
2.What are the major differences in cleavage between protostomes and deuterostomes?
3.The major outcomes of gastrulation are the establishment of three primary germ layers, the establishment of the anterior to posterior body axis (head to tail orientation), and the formation of the archenteron, or primitive gut. Describe how these major events occur. In which clades do each of these features appear in animal evolution? How does the gut tube change through animal evolution? In which clades do these changes occur? What are the differences between protostomes and deuterostomes in how the gut tube forms?
4.What is the importance of body size in biological systems? Why is surface area to volume ratio important? Can you think of examples from other groups of organisms (besides vertebrates, which were all of the examples in the web lecture) in which surface area to volume ratios might be important?
5.Why is diffusion important in biology? What are some examples of biological processes that rely on diffusion? (See if you can think of some plant or algae examples.) What are some of the ways that organisms can increase the rate of diffusion across their surfaces? How can this help with the surface area to volume ratio problem?