Question

the contracting and relaxing of muscle is regulated by the amount of calcium present in the cells of muscle fibers. these cells must be able to move the calcium ions from areas with low concentrations to areas with high concentrations. what process would be necessary for this movement to occur?
o a osmosis
o b active transport
o c passive transport
o d facilitated diffusion

question 16 (4 points)
(02.04 mc)
when a cell has to endure lasting changes in its environment that require it to actively transport more molecules than normal through the cell membrane, what effect will this have on the mitochondria of the cell? the cell will need
o a fewer mitochondria since the transport proteins will also create atp
o b more mitochondria to meet the increased energy demand
o c more mitochondria to repair damage to the atp molecules
o d fewer mitochondria since there will be fewer molecules left in the cell

question 17 (4 points)
(02.04 mc)
which of the following accurately describes an example of how materials can move across the cell membrane through active transport?
o a a protein acts as a channel to allow large, hydrophilic molecules to diffuse across the cell membrane
o b a protein acts as a pump and moves calcium ions from an area of low concentration to an area of high concentration
o c the cell membrane folds to surround a substance and bring the substance inside the cell during exocytosis
o d water moves by osmosis from higher concentration to lower concentration by passing through proteins called aquaporins

Explanation:

Question 15:

Muscle cells need to move calcium ions against the concentration - gradient (from low to high concentration). Active transport is the process that moves substances against their concentration gradient using energy (ATP). Osmosis is the movement of water, passive transport moves substances down the concentration gradient, and facilitated diffusion is a type of passive transport.

Question 16:

Active transport requires energy in the form of ATP. Mitochondria are the power - houses of the cell and produce ATP. When a cell has to do more active transport, it needs more energy, so it will need more mitochondria to meet the increased energy demand.

Question 17:

Active transport moves substances against their concentration gradient using energy. A protein acting as a pump and moving calcium ions from an area of low concentration to an area of high concentration is an example of active transport. Option a is facilitated diffusion, option c is endocytosis, and option d is osmosis.

Answer:

Question 15: b. Active transport

Question 16: b. more mitochondria to meet the increased energy demand

Question 17: b. A protein acts as a pump and moves calcium ions from an area of low concentration to an area of high concentration