Unless is similar in meaning to if not and can be used instead of if not in certain types of conditional sentences. You won't get in to see the show, if you don't have reserved seats. Unless you have reserved seats, you won't get in to see the show.
Best Answer: Internal fertilization is when the sperm is directly deposited into the female, who produces eggs and fertilizes them in her body.External fertilization is when the sperm and eggs are released outside of the body and meet outside of the body, not like how chithra described.Birds do not have external fertilization, the fertilization still occurs in the body, they just do not produce live young.xternal fertilization is when the sperm and eggs are released outside of the body and meet outside of the body, not like how chithra described. Birds do not have external fertilization, the fertilization still occurs in the body, they just do not produce live young.
In vitro fertilisation. In vitro fertilisation (or fertilization; IVF) is a process of fertilisation where an egg is combined with sperm outside the body, in vitro (in glass).