Answer:
eustachian tube i think lol
Explanation:
Difficult to change - nutrients! crops won’t grow on soil that has had all of the nutrients used up. example: after growing corn in the same place for 50 years, corn will not grow anymore because all of the nutrients it needs to grow will no longer be in the soil
8 of them are essential and human bodys can't produce them.they should be got from foods
The sperm plasma then fuses with the egg's plasma membrane, the sperm head disconnects from its flagellum and the egg travels down the Fallopian tube to reach the uterus. In vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside the womb, in vitro.
