Answer:
a. heart development.
Explanation:
As the third week of fetal development starts, the process of formation of blood vessels begins. Also, the splanchnic mesoderm in the head end of the embryo forms heart on days 18 and 19. Since it develops heart, this part of the mesodermal cells is called the cardiogenic area. The underlying endoderm sends the induction signals to these mesodermal cells to form a pair of endocardial tubes that gradually develop into a single primitive heart tube.
This primitive heart begins to beat by the end of the third week of development. Therefore, any drug that affects fetal development during the first 20 days of the pregnancy might affect the development of the heart.
Answer:
to produce food for the plant
The column of mercury in the barometer is lowest when the barometer is ion location 4. Atmospheric pressure measured by the barometer decreases with an increase in altitude. Atmospheric pressure is caused by the column of air above the ground level at any given point on the earths surface thus an increase in altitude leads to a decrease in this column leading to a decrease in atmospheric pressure.
