Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments.The Earth's magnetic field is somewhat caused by the composition of the earth's core which is rich in iron minerals. There is a solid inner core that is made of iron which makes up to 2/3 of the moon's size. The charged metal of the iron produces electric currents, consequently resulting to Earth's magnetic field.
<span>Osteoclasts
</span><span>Are derived from stem cells that produce macrophages
Secrete acids and protein-digesting enzymes</span>
<span>Gene experssion are influenced by enviroment. the best example is skin color in case of human for e.g if person with fair color or white complexion goes to africa or any part where sun exposure is more his or her color gets dark .the darking of skin is due to melanin production. see here person is same only difference is in enviromental condition due to which gene which are responsible for the production of melanin are produced.
I hope u understood it</span>
