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.
<u>Answer</u>:
Smaller planets would dissipate heat more rapidly and this criteria doesn't satisfy the conditions of existence of life.
<u>Explanation</u>:
The existence of life on Earth was possible because it fulfilled the criteria needed for the conditions of generating life in a planet. Its distance from sun is appropriate, it is made up of rock, it is big enough to have a core which is molten and it has a magnetic field. If it was a smaller planet, then it would have a liquid hot core that dissipate heat at a rapid rate. This condition doesn't support the criteria of life's existence.
False. The myocardium receives oxygen from the coronary arteries. Coronary arteries are found on the outside of the heart and supply oxygenated blood to the heart tissue.
