Answer:
A. Cholecalciferol, or vitamin D3, is necessary for the normal absorption of calcium and phosphate ions. Vitamin D3 is made by cells in the epidermis due to exposure to sunlight. Without enough exposure to sunlight, the body won't produce enough vitamin D3
Explanation:
Hydroxyapetite is the organic mineral in the bone that maintain the mechanical strengthening of the bone, by interacting with collagen fibres. Calcium and Phosphate ions are the two major components of this bone materials. Generally 90%of bone is calcium , while 80% is phosphate. Phosphate stimulate growth of Oesteocytes. And the latter is important for bone mineralization. Together they maintain bone mineralization and maintenance,thereby preventing bone resorption.
Absorption of Ca and P. into the blood stream to reach the bones cells is conducted by Vit D. Dietary supply is not the only route through which Vit D get to the blood stream. Exposure of the skin to UVB rays of the early morning sunlight is another route.
Vitamin D plays major role in absorption of Ca and P in the body.
Vit. D is naturally synthesized in humans when the skin is exposed to early morning sunlight (UVB). It is usually produce in inactive forms,and undergoes hydroxylation( i.e addition of hydroxyl group -OH) in the liver to be biologically active .
Its active forms acts on the epithelial cells of the intestinal wall to facilitate calcium absorption into the blood stream to reach the bone cells .it also stimulate absorption of Phosphate.
Since these two minerals ensures, mechanical strength, prevention of bone resorption, there availability in the bone must be maintained by Vit, D supply from exposure to sunlight.
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Answer:
It is expected to observe a low genetic variation within populations and high genetic variation between populations.
Explanation:
The pika's populations are geographically isolated among them, it drastically will increase the genetic variation among populations, especially due to the random process of genetic drift (and also to mutations). On the other hand, this geographical isolation also contributes to decreasing the genetic variation within populations due to the endogamy among their members. The combination of both genetic features (i.e., a low genetic variation within populations and high genetic variation between populations) are expected to produce high genetic diversity effects and a low population structure.
Answer: false
Explanation: because it mutation can help or not help in many ways think of a mocking bird if its beck was short it would have a less chance of surviving. if the mockingbird had a longer beck it would surviving .This leads up to natural selection.
It's called a mutation.
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