According to the Big Bang theory, the universe was once very dense and is now expanding.
Sunlight is the original source of almost all energy in most ecosystem.
Increase and decrease in oestrogen and progesterone.
Answer:
The Human Immune system helps fight bacteria and germs and viruses because without the Immune system we could die it is what protects us from The flu and sometimes cov id with a weak immune system we might no survive.
Explanation:
The surface area of a sphere can be approximated as follows: Surface area = 4πr2; where r is the radius of the sphere; π is a constant that is roughly equal to 3.
