16.3 Total C

Elizabeth is conducting an investigation to study how molecules are transported into and out of a cell. Elizabeth builds a model of a cell using a U-shaped tube. A barrier, which is permeable to water, but not sugar, is placed on the bottom of the tube to model the cell membrane. Elizabeth adds two different solutions to each side of the tube. The solute in each solution is sugar and the solvent is water. The initial levels of solution in Side A and Side B are equal. The concentration of sugar in Side A is lower than the concentration of sugar in Side B. What is Elizabeth likely to observe?

• Water molecules will move from Side A to Side B. The solution level on Side A will fall and the solution level on Side B will rise.
• Water molecules will move from Side B to Side A. The solution level on Side A will rise and the solution level on Side B will fall.
• Sugar molecules will move from Side A to Side B. The solution level on Side A will fall and the solution level on Side B will rise.
• Sugar molecules will move from Side B to Side A. The solution level on Side A will rise and the solution level on Side B will fall.

Which are examples of active transport across the cell membrane?

• osmosis and diffusion
• diffusion and facilitated diffusion
• osmosis and chemiosmosis
• endocytosis and exocytosis

Wes places red blood cells in a petri dish with pure water and observes them under a microscope. He drew a model to illustrate his observations. What is the most likely explanation for Wes’s observations?

• The red blood cells were placed into an isotonic solution. Water moved into and out of the cells to maintain homeostasis.
• The red blood cells were placed into an isotonic solution. Water moved into the cells until the cells burst.
• The red blood cells were placed in a hypertonic solution. Water moved from the inside of the cells to the outside of the cells to maintain homeostasis.
• The red blood cells were placed in a hypotonic solution. Water moved from the outside of the cells to the inside of the cells until the cells burst.

The pancreas produces enzymes that aid in digestion. By what process are these digestive enzymes excreted from pancreas cells?

• osmosis
• exocytosis
• endocytosis
• diffusion

The movement of matter across a cell membrane against a concentration difference is called ______________________, and it requires (aquaporins / energy / homeostasis / osmotic pressure).

• active transport
• passive transport
• facilitated diffusion
• osmosis

What is homeostasis in relation to cellular function?

• The process of cell division
• The maintenance of relatively constant internal conditions
• The breakdown of cellular components
• The production of energy within cells

What is the primary function of aquaporins in cell membranes?

• To transport sugar molecules
• To facilitate the movement of water molecules
• To prevent osmosis
• To transport sodium ions

Osmosis is defined as:

• The movement of sugar through a membrane
• The diffusion of ions against a concentration gradient
• The diffusion of water through a selectively permeable membrane
• The active transport of molecules

In osmosis, water molecules move:

• Only from high to low concentration
• Only from low to high concentration
• In both directions, but with net movement toward higher solute concentration
• Only when energy is applied

When two solutions are isotonic, this means:

• One solution has more solutes than the other
• The solutions have equal solute concentrations
• Water cannot move between the solutions
• Active transport is occurring