Answer:
American's portion sizes have become larger in the last decade due to the expanding of food industries and marketing campaigns that tell us to eat more.
Explanation:
The growth of food industries in the last decades to obtain more money in combination with the media influence has led us to eat more, thus why the size of our portions has increased their size.
Another theory states that people always want to eat more, and the industry has only fulfilled this demand, but it is not clear why, in the past, this did not happen.
Answer:
B) increased exchange surface provided by their membranes
Explanation:
Alveoli are tiny air sacs that are responsible for exchanging oxygen (O2) and carbon dioxide (CO2) in the lungs. Alveoli have elastic fibers in order to expand and recoil depending on the volume of air breathed in. The alveolar epithelial cells (pneumocytes) may adopt a shape that serves to increase the surface area of gas exchange. On the other hand, intestinal epithelial cells have microvilli, which are microscopic projections in the plasma membrane. Microvilli serve to increase the cell's surface area, thereby facilitating the absorption of nutrients and water.
