Question

Which statement describes the net movement of carbon dioxide during internal respiration?

1) Carbon dioxide moves from the cells to the bloodstream
2) Carbon dioxide moves from the bloodstream to the cells
3) Carbon dioxide moves from the lungs to the bloodstream
4) Carbon dioxide moves from the bloodstream to the lungs

Answer 1

During internal respiration, carbon dioxide moves from the cells into the bloodstream due to the gradient created by cellular respiration. It is transported to the lungs in several forms and expelled during exhalation.

Step-by-step explanation:

The net movement of carbon dioxide during internal respiration is described by the statement that carbon dioxide moves from the cells to the bloodstream. This occurs because cellular respiration continuously produces carbon dioxide, creating a gradient where the partial pressure of carbon dioxide is higher in the cells than in the blood. This difference in partial pressure causes carbon dioxide to diffuse out of the cells and into the bloodstream, where it is then transported back to the lungs. The forms of carbon dioxide transport include dissolution directly into the blood, binding to hemoglobin forming carbaminohemoglobin, or being carried as a bicarbonate ion.

Transport of carbon dioxide is crucial because it maintains the balance of gases necessary for proper function of the body's cells. The binding of carbon dioxide to hemoglobin is reversible, allowing for it to be released into the alveoli of the lungs and then expelled from the body during exhalation.

Answer 2

Carbon dioxide moves from the cells to the bloodstream. option 1 is correct.

Step-by-step explanation:

During internal respiration, the net movement of carbon dioxide occurs as a result of cellular metabolism. The process of cellular respiration takes place within the cells, where glucose is oxidized to produce energy. As a byproduct of this metabolic activity, carbon dioxide is generated in the cells. The produced carbon dioxide then diffuses from the cells into the interstitial fluid and eventually into the bloodstream.

In the bloodstream, carbon dioxide is carried in multiple forms. Approximately 7-10% of carbon dioxide dissolves directly in the plasma, while the majority combines with water to form carbonic acid H2CO3. This reaction is facilitated by the enzyme carbonic anhydrase. The carbonic acid quickly dissociates into bicarbonate ions HCO3- and hydrogen ions H+. This bicarbonate ion is the primary form in which carbon dioxide is transported in the blood.

The net movement of carbon dioxide, therefore, is from the cells to the bloodstream, as a consequence of cellular respiration. It's crucial for maintaining the acid-base balance in the body and ensuring efficient gas exchange in the lungs, where carbon dioxide is eventually expelled during external respiration.So, option 1 is correct.