Answer to Question 1
d
Answer to Question 2
Latitude, season, and time of day all have dramatic effects on vitamin D synthesis and status. Heavy cloud cover, smoke, or smog blocks the ultraviolet (UV) rays of the sun that promote vitamin D synthesis. Differences in skin pigmentation, latitude, and smog may account for the finding that African Americans, especially those in northern, smoggy cities, are most likely to be vitamin D deficient and develop rickets. Vitamin D deficiency is especially prevalent in the winter and in the Arctic and Antarctic regions of the world. To ensure an adequate vitamin D status, supplements may be needed. The body's vitamin D supplies from summer synthesis alone are insufficient to meet winter needs.
Abiotic factors influence population densities.
A plot of trophic diversity across the major groups of organisms shows highest trophic diversity amo
How do you set yourself apart in a country so rich that of its 4.6 million people, 79,000 are ...
In the box on upward social mobility on page 82, we discussed how Latinos face a similar situation. ...
Population Ecology "البيئة السكان"
Landscape Evolution in a Basin and Range Region