Help due tomorrow what is it please help??

Which mantle is under the crust the upper mantle or the lower mantle i think it's upper let me know if i'm right

Match the type of adaptation to the correct example, structural adaptation functional adaptation behavioral adaptation example type of adaptation elephants live in herds to protect their young leaves of a rain forest plant species have a pointed tip that enables rainwater to drain off easily. camels have nostrils that they can close snakes produce venom to kill prey and defend themselves. earthworms coil when touched, as part of a defense mechanism. human skin darkens with increased exposure to sunlight.

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?