Chapter 5 Membranes, Reading Questions Section 4-7 mastering bio

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.

B ... the diffusion gradient there is steeper

What substance is transported by aquaporins?

water

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?

Bacteria can't survive in a hypertonic solution because they lose water.

Which of these statements describes what occurs in facilitated diffusion? Facilitated diffusion of solutes occurs through protein pores in the membrane Facilitated diffusion requires energy from the cell to drive a concentration gradient Facilitated diffusion is another name for osmosis Facilitated diffusion of solutes occurs through phospholipid pores in the membrane

Facilitated diffusion of solutes occurs through protein pores in the membrane.

Review the figure below of passive transport, then choose one of the following statements as being descriptive of this process. Passive transport works with the help of proteins to bring molecules from an area of low concentration to an area of higher concentration Passive transport requires energy from the cell to move molecules from an area of high concentration to an area of lower concentration Passive transport always requires the help of proteins to bring molecules from an area of high concentration to an area of lower concentration Passive transport can transport molecules without the assistance of proteins from an area of high concentration to an area of lower concentration

Passive transport can transport molecules without the assistance of proteins from an area of high concentration to an area of lower concentration.

The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? a hypertonic sucrose solution a hypotonic urea solution a hypotonic sucrose solution a hypertonic urea solution

a hypotonic sucrose solution

Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.

actively pump water back into their cells to counter its loss due to osmosis

What condition might result from an excess of aquaporins?

fluid retention in pregnant women

You're on the pilot episode of a new reality show called "The Transport Factor." The host hands you three different amino acids, four different sugars, and two different ions. Then the host shouts, "How many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport?" Quickly, you correctly respond: _____.

nine

The diffusion of water across a selectively permeable membrane is called __________.

osmosis

When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will _____.

remain standing upright

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?

the difference in water concentration across a selectively permeable membrane