2.B.2 Membrane Practice Quiz

Active transport is the mechanism that requires energy. Unlike passive transport mechanisms such as diffusion, facilitated diffusion, and osmosis, active transport involves the movement of molecules or ions against their concentration gradient, from an area of lower concentration to an area of higher concentration. This process requires the expenditure of energy in the form of ATP (adenosine triphosphate) to transport the molecules or ions across the cell membrane.

Endocytosis is the correct answer because it refers to the process by which a vesicle is formed at the plasma membrane to bring substances into the cell. During endocytosis, the plasma membrane invaginates and forms a vesicle that surrounds the substances outside the cell. This vesicle then pinches off from the plasma membrane and moves into the cytoplasm, allowing the substances to be transported into the cell. Exocytosis, on the other hand, is the process by which vesicles fuse with the plasma membrane to release substances out of the cell. Plasmolysis refers to the shrinking of the cytoplasm due to water loss, and hemolysis refers to the rupture or destruction of red blood cells.

If a solution outside a cell is more concentrated and causes the cell to lose water to its environment, it is referred to as hypertonic. This means that the external solution has a higher solute concentration compared to the cell's contents, resulting in water moving out of the cell to balance the concentration gradient.

When a cell is placed in a hypertonic solution, it means that the concentration of solutes in the surrounding solution is higher than inside the cell. In order to balance the concentration, water molecules will move out of the cell into the surrounding solution through a process called osmosis. This causes the cell to shrink or become dehydrated. Therefore, the correct answer is "Water will move out of the cell into the surrounding solution."

When a cell is placed in a hypotonic solution, it means that the concentration of solutes outside the cell is lower than inside the cell. As a result, water will move into the cell from the surrounding solution through a process called osmosis. This occurs because water tends to move from an area of low solute concentration to an area of high solute concentration in order to equalize the concentrations on both sides of the cell membrane.

Active transport is the process by which a cell can move substances against their concentration gradient, from an area of lower concentration to an area of higher concentration. In this case, the concentration of calcium in the cell (0.3%) is higher than the concentration in the surrounding fluid (0.1%). Therefore, the cell would need to use active transport to obtain more calcium by actively pumping it into the cell against the concentration gradient.

When the concentration of the solute is lower inside the cell than outside it, energy is required for the transport of molecules from inside the cell across the cell membrane to the extracellular fluid. This is because the molecules need to move against the concentration gradient, from an area of lower concentration to an area of higher concentration. Energy is needed to drive this process, usually in the form of ATP, to ensure that the molecules can be transported effectively.

In osmosis, water moves from an area of lower solute concentration to an area of higher solute concentration. An isotonic solution is one where the solute concentration is equal on both sides of the membrane, so there is no net movement of water. Therefore, water will move towards the solution with the greater solute concentration, which is the correct answer.