Question

extension questions

1. given the information in the graph, which type of cell transport would be best to move substances into or out of the cell quickly?
2. which type of transport would be the best if the cell needs to respond to a sudden concentration gradient difference?
3. why would the line representing facilitated diffusion level off as the concentration gets higher, while the line representing diffusion continues to go up at a steady rate?
4. why does active transport, on the same graph, start off with such a high initial rate compared to diffusion and facilitated diffusion?

Explanation:

Step1: Analyze question 35

Facilitated diffusion uses transport proteins, which can move substances faster across the cell - membrane compared to simple diffusion. So for quickly moving substances in or out of the cell, facilitated diffusion is a good choice as shown in the graph where its rate is relatively high at lower concentration differences.

Step2: Analyze question 36

Active transport can move substances against the concentration gradient. When there is a sudden concentration - gradient difference, active transport can respond by using energy (ATP) to move substances as needed, regardless of the concentration difference direction.

Step3: Analyze question 37

Facilitated diffusion relies on transport proteins. As the concentration increases, these proteins become saturated. That is, all available transport proteins are occupied with transporting substances, so the rate levels off. Diffusion, on the other hand, is a passive process that depends only on the concentration gradient and has no such protein - based limitation, so its rate continues to increase steadily with the concentration gradient.

Step4: Analyze question 38

Active transport uses energy (ATP) and transport proteins to move substances against the concentration gradient. It can start with a high rate because it is not solely dependent on the concentration difference like diffusion and facilitated diffusion. It can actively pump substances in or out of the cell from the start, regardless of the initial concentration conditions.

Answer:

1. Facilitated diffusion
2. Active transport
3. Transport proteins in facilitated diffusion become saturated as concentration increases, while diffusion has no such limitation.
4. Active transport uses energy and can move substances against the concentration gradient from the start, not relying on concentration differences like the other two.