The UV is needed by the skin to make previtamin D3. Previtamin D3 or cholecalciferol made from the skin will be changed in the liver into 25- hydroxyvitamin D3 and then sent to the kidney to be changed into 1,25- dihydroxyvitamin D3. The last change in the kidney will active the vitamin D. Vitamin D has a role in the calcium absorption which was will strengthen the bone tissue.
Answer:
the answer is B, I believe
The answer: snakes! Snakes lay eggs and have lungs.
Answer: the root is not a referred to as a layer of the hair
Explanation: Medulla, Cortex, and cuticle are 100% layers but the root doesn’t seem to be one