the first answer as blood needs to be oxygenated to be passes round the body then when its deoxgenated it will return to the heart to be pumped around the body again
Answer:
Vitamin D3 is synthesized in keratinocytes of the two epidarmal layers namely <u>stratum basale </u>(bottom layer) and <u>stratum spinosum</u>.
Explanation:
In the two epidermal layers of the skin namely <u>stratum basale</u> and <u>stratum spinosum</u>, 7-dehydrocholesterol (pro-vitamin D3) is converted to vitamin D3. This process takes place in the presence of ultravoilet radiations. Briefly, upon exposure, the pro-vitamin D3 is photolyzed to pre-vitamin D3. The pre-vitamin D3 then isomerized to form vitamin D3.
Hi There, The answer is Robert Hooke