Indicate the answer choice that best completes the statement or answers the ques
ID: 189970 • Letter: I
Question
Indicate the answer choice that best completes the statement or answers the question I. When the net movement of water in and out a cell is zero, that solution is said to be: a. osmotic b. isotonic c. hypotonic d. hypertonic e. pressurized 2. Which statement best describes the activity of the sodium-potassium pump? a. It transports hydrogen ions out of the cell. b. It transports water directly out of the cell. c. It transports 2 sodium ions into the cell in exchange for 3 potassium ions. d. It transports 3 sodium ions out of the cell in exchange for 2 potassium ions. e. It transports 2 sodium ions out of the cell in exchange for 2 potassium ions. 3. Since sodium-potassium pumps transport sodium ions out of a cell and potassium ions into a cell, what type proteins are they? of carrier a. ion pumps uniporters e. symporters d. antiporters e. ABC transporter . You light a scented candle in the guest bathroom. Within a few minutes you can already smell the candle's scent hroughout the hallway. What process is occurring? a. dialysis b. osmosis c. simple diffusion d. active transport e. facilitated diffusion How are integral proteins unique in cell membranes? a. They have no hydrophobic portions. b. They are weakly bound to the surface of the membrane. c. They are only located on the inner side of a membrane. d. They are firmly bound to the membrane and can only be released with a detergent. e. They are completely embedded within the lipid bilayer with no exposure to the internal cell environmen vright Cengage Learning. Powered by Cognero.Explanation / Answer
Ans. #1. Correct option- Isotonic. Two solutions separated by semipermeable membrane are said to be isotonic when there is no net movement of water molecules between them.
# There is net movement of water between the two solution in case of both hypotonic and hypertonic solutions. The solution of higher concentration is called hypertonic whereas that of lower concertation is called hypotonic.
# The term “osmotic” and “pressurized” themselves are not sufficient to determine the direction of net movement of water between two solution.
#2. Correct option- d. Na+-K+ pump transports 3 Na+ out of the cell and imports 2 K+ into the cell.
# It does not transport H+ across the cell.
#3. Correct option- a. Ion pump. Na+-K+ pump is an ion pump that “pumps (using energy derived from ATP hydrolysis)” sodium and potassium ions against their concertation gradient.
# Uniport, symport and antiport – all these mechanisms transport molecules along the concertation gradient. Whereas ion pumps transport molecules against the concertation gradient.
# ABC transporters also use energy from ATP hydrolysis to facilitate transport of molecules across the membrane. But, ABC transporter (ABC class of ATP-powered ion & small molecule pumps) and Na+-K+ pump (P class of ATP-powered ion & small molecule pumps) belong to different protein families.
#4. Correct option- c. Simple diffusion. Diffusion (simple diffusion) is the net movement of a molecule from its higher to lower concentration to establish a dynamic concentration equilibrium (i.e. the process continues till the molecules are equally distributed through the given space) without requiring any protein transporter. Moreover, the presence of plasma membrane as boundary is not necessary.
# Osmosis is the transport of water molecules across the plasma membrane. There is no plasma membrane as boundary. Moreover, there is movement of perfume molecules but not water molecules.
# Active transport and facilitated diffusion require protein transporters as well as plasma membrane as boundary. Both these conditions lack in diffusion of perfume.
# Dialysis: During dialysis (say, of blood), solid particles (urea, glucose, ions, etc.) also move their higher to lower concertation through a dialysis membrane. There is no dialysis membrane involved during diffusion of perfume molecules.
#5. Correct option. d. Integral membrane proteins are proteins spanning the lipid bilayer. They have hydrophobic regions embedded in the hydrophobic core of the cell membrane. They can only be separated by disintegrating the cell membrane, say by application of detergents.
# They have hydrophobic regions.
# They are firmly embedded in lipid bilayer. So, can’t be separated from membrane unless it is disintegrated.
# They span across the lipid membrane.