This document discusses types of fertilization, sexual reproduction, and the male and female reproductive systems. There are two types of fertilization: external fertilization, where gamete fusion occurs outside the female body as seen in frogs and fish, and internal fertilization, where gamete fusion occurs inside the female body as seen in cats and dogs. Sexual reproduction involves the genetic material from two organisms combining through processes like meiosis and fertilization to form a new organism. The male reproductive system includes testes, vas deferens, urethra, and penis. The female reproductive system includes ovaries, oviducts, uterus, cervix, and vagina. Development of the embryo involves complex physical changes and processes during formation