What is the difference between primary waves and secondary waves

In sexual reproducing animals once fertilization of the egg takes place, the exists as a single cell until cell division begins. a) egg b) larva c) sperm d) zygote

How is the national wildlife refuge system similar to the pacific region coastal program? a. both programs are concerned with providing habitats for wildlife b. both programs are primarily concerned with preserving fish species c. both programs have set aside 150 million acres of land d. both programs are under the u.s. fish and wildlife service

In the diagram below, the northern hemisphere would be in what season at position a a.fall b. winter c.summer d.spring