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.
As the tissue heals, new scar tissue is created inside of the damaged heart tissue, thus it doesn't pump as well as healthy heart tissue
Answer:
there are 7 breeding pairs
Explanation:
The answer is; 24 hours.
Scientists called the full rotation of the earth a day and divided it into 24 hours on the clock. This means from sunrise to next sunrise. They also divided the earth into latitudes that indicate time zones. When one point on earth rotates and return to the same position in space, it has lapsed 24 hours.
