Answer:
Sertoli cells
Explanation:
The Sertoli cells nourish and protect the developing sperm cells, and spermatogenesis—the developmental pathway from germ cell to mature sperm—occurs in the recesses of the Sertoli cells (Figure 19.17)
Following a cut or scrape ....
A Mitosis.
....repairs your skin
Answer:
c. Ductus venosus, vena cava, heart, ductus arteriosus, arteries
Explanation:
The circulatory system consists of the heart and blood vessels. In a fetus, the circulation of blood is different from circulation after delivery largely due to the fact that the lungs are not in use, rather, the fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord.
Blood from the placenta is carried to the fetus by the umbilical vein. While some of this blood enters the fetal ductus venosus and is carried to the inferior vena cava, some others enter the liver. The blood from the inferior vena cava then moves into the right atrium of the heart. The foramen ovale, an opening between the right and left atrium in the fetus directs most of the blood flow from the right into the left atrium, thereby, bypassing pulmonary circulation. Most of the blood from the right atrium flows into the left ventricle and is pumped through the aorta to the rest of the body.
Some of the blood from the right atrium however, enters into the right ventricle and is pumped into the pulmonary artery. The ductus arteriosus which is a special connection between the pulmonary artery and the aorta in a fetus, directs most of this blood away from the lungs and into the arteries.
Explanation:
Dinosaurs are living organisms that depends on the environment for survival. As the asteroid hits the Yucatan Peninsula area about 66 million years a couple of things can happen:
Frictional heating of the surface as the earth collided with the asteroid. This heating will cause surface temperature to rise globally and can induce the phenomenon of global warming. This can lead to release of water from reservoirs on the earth surface and hence flooding.
The impact can lead to increase in surface pressure beyond normal and that which life has adjusted to.
Debris in form of dust will be released into the atmosphere and a global air pollution will occur. Gases useful for life will be highly polluted by the vast amount of dusts and other particles discharged into the atmosphere.
