Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
After two months of
development, the embryo is called a fetus. The endometrium is formed in part
from the inner lining of the uterus and in part from other membranes. It is
through the placenta that that the embryo/fetus is nourished while in the
umbilical cord and three blood vessels are carried away.
4 is the correct answer hope you get it right!!!
Capillaries are one cell thick and so this makes them very thin. capillaries are also arranged in networks known as capillary beds, and thus multiple capillaries are spread over a large area.