MB chapter 7

water balance in plant cell

best in hypotonic solution-uptake of water is balanced by pushing back on the cell isotonic- flaccid or limp hypertonic-plasmolyzed- lose water

A cell that neither gains nor loses water while sitting in a solution is probably sitting in

an isotonic environment

Which of the following correctly describes some aspect of exocytosis or endocytosis? See Concept 7.5 (Page 139) View Available Hint(s) Which of the following correctly describes some aspect of exocytosis or endocytosis? See Concept 7.5 (Page 139) Exocytosis and endocytosis temporarily change the surface area of the plasma membrane. The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane. These two processes require the participation of mitochondria. Endocytosis and exocytosis involve passive transport. Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol.

Exocytosis and endocytosis temporarily change the surface area of the plasma membrane. The fusion or budding of transport vesicles at the plasma membrane either adds or removes proteins and phospholipids, thus temporarily changing the surface area.

Biologists use the fluid mosaic model to describe membrane structure.

The diverse proteins found in and attached to membranes perform many important functions. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.

You can recognize the process of pinocytosis when

the cell is engulfing extracellular fluid

Which of the following cell structures exhibits selective permeability between a cell and its external environment? View Available Hint(s) Which of the following cell structures exhibits selective permeability between a cell and its external environment? endoplasmic reticulum lysosomes the plasma membrane chloroplasts mitochondria

the plasma membrane

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?

endocytosis

Which of the following statements about diffusion is true? View Available Hint(s) Which of the following statements about diffusion is true? It involves only the movement of water molecules. It occurs when molecules move from a region of lower concentration to a region of higher concentration. It is a passive process. It requires expenditure of energy by the cell. It always requires integral proteins of the cell membrane.

it is a passive process Diffusion is the tendency of molecules to spread out in the available space. A substance will diffuse from an area of higher concentration to an area of lower concentration without energy input.

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.

only channels provide a continuous path across the membraneallow water molecules and small ions to flow quickly across the membrane only carriers transport primarily small polar organic moleculesundergo a change in shape to transport solutes across the membrane both channels and carriers are integral membrane proteinsprovide a hydrophilic path across the membranetransport solutes down a concentration or electrochemical gradient

Which of the following processes includes all others? Which of the following processes includes all others? diffusion of a solute across a membrane facilitated diffusion transport of an ion down its electrochemical gradient passive transport osmosis

passive transport

Which of the following enables a cell to pick up and concentrate a specific kind of molecule? View Available Hint(s) Which of the following enables a cell to pick up and concentrate a specific kind of molecule? facilitated diffusion channel proteins receptor-mediated endocytosis passive transport osmosis

receptor-mediated endocytosis In receptor-mediated endocytosis, only a specific molecule, called a ligand, can bind to the receptor. Without receptor binding occurring first, endocytosis does not proceed.

Diffusion across a biological membrane is called

passive transport

Active transport requires an input of energy and can also generate voltages across membranes. Based on this information, which of the following statements is true? View Available Hint(s) Active transport requires an input of energy and can also generate voltages across membranes. Based on this information, which of the following statements is true? The source of energy for active transport of a solute up its gradient can be ATP or a concentration gradient of a second solute. This second gradient of solutes maintains no net difference in voltage across the membrane. Active transport can use ATP as its energy source and ensures that there is no voltage across the cell membrane. Active transport uses channel proteins and ensures that the interior of the cell is always positive compared to the exterior of the cell. Active transport moves solutes down their concentration gradients and always uses ATP as the source of energy to do this. The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell membrane.

The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell membrane.

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

facilitated diffusion is a type of

passive transport

Endocytosis moves materials _____ a cell via

into ... membranous vesicles

The permeability of a biological membrane to a specific polar solute depends primarily on which of the following? See Concept 7.2 (Page 132) View Available Hint(s) The permeability of a biological membrane to a specific polar solute depends primarily on which of the following? See Concept 7.2 (Page 132) the amount of cholesterol in the membrane the types of transport proteins in the membrane the phospholipid composition of the membrane the presence of unsaturated fatty acids in the membrane the types of polysaccharides present in the membrane

the types of transport proteins in the membrane

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?

in the interior of the membrane

Select the correct statement about osmosis. Select the correct statement about osmosis. Osmosis is the diffusion of water molecules across a selectively permeable membrane. Osmotic equilibrium cannot be reached unless solute concentrations equalize across the membrane. If a dead cell is placed in a solution hypotonic to the cell contents, osmosis will not occur.

osmosis is the diffusion of water molecules across a selectively permeable membrane

Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? S

water, oxygen, carbon dioxide, lipids

Which of the following statements is true regarding potential energy? Which of the following statements is true regarding potential energy? Water acquires potential energy as it runs downhill. Potential energy is the energy matter could have if it were in a different location or structure. Potential energy is the energy possessed by matter due to its location or structure. Matter has a natural tendency to acquire more potential energy until a maximum is reached.

If you had trouble with this question, review the following material: Energy is defined as the capacity to cause change — for instance, by doing work. Potential energy is the energy that matter possesses because of its location or structure. Matter has a natural tendency to move from higher states of potential energy toward the lowest possible state of potential energy, such as water running downhill from a dam. As water runs downhill, the energy released can be used to do work. potential energy is the energy process by matter due to its location or structure.

Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Plant cells continuously produce a proton gradient by using the energy of ATP hydrolysis to pump protons out of the cell. Why, in the absence of sucrose, do protons not move back into the cell through the sucrose-proton cotransport protein?

The movement of protons through the cotransport protein cannot occur unless sucrose moves at the same time.

Which of the following statements about the sodium-potassium pump is correct? he sodium-potassium pump moves Na+ and K+ in the same direction, resulting in a net negative charge outside the cell. The sodium-potassium pump moves sodium out of the cell and co-transports protons into the cell, which is the source of energy for the movement of the potassium into the cell. The sodium-potassium pump moves Na+ and K+ in opposite directions, resulting in a net negative charge inside the cell. The sodium-potassium pump transports Na+ and K+ across the plasma membrane in the same direction at the expense of ATP hydrolysis. The sodium-potassium pump uses an existing proton gradient to drive the movement of sodium and potassium ions.

The sodium-potassium pump moves Na+ and K+ in opposite directions, resulting in a net negative charge inside the cell.

Which of the following molecular movements is due to diffusion or osmosis? Which of the following molecular movements is due to diffusion or osmosis? Cells of the pancreas secrete insulin into the bloodstream. When a plant cell is placed in concentrated salt water, water moves out of the cell. The sodium-potassium pump pumps three sodium ions out of a neuron for every two potassium ions it pumps in.

When a plant cell is placed in concentrated salt water, water moves out of the cell.

If you are going to bake potatoes, and your potatoes are soft and dehydrated, they can be soaked in __________ to make them more firm before baking.

a hypotonic solution such as tap water

water balance in animal cell

best in isotonic hypotonic- gain water, swell, possibly burst, lysed hypertonic- shriveled

Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane? View Available Hint(s) Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane? active transport and the rough ER exocytosis and smooth ER and rough ER endocytosis and Golgi flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi receptor-mediated endocytosis and smooth ER and Golgi

exocytosis and smooth ER and rough ER

Active and passive transport of solutes across a membrane typically differ in which of the following ways?

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.

Seawater is hypertonic to cytoplasm in vertebrate cells and in plant cells. If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.

Which of the following pairs correctly matches a membrane transport process to its primary function? View Available Hint(s) Which of the following pairs correctly matches a membrane transport process to its primary function? phagocytosis: secretion of large particles from the cell by fusion of vesicles with the plasma membrane exocytosis: the movement of water and solutes out of the cell by vesicle fusion with the plasma membrane pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane osmosis: passive diffusion of water and small solutes across a membrane None of the listed responses is correct.

pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane

When a person is dehydrated, his or her IV fluids

should be isotonic because either a hypertonic or hypotonic IV would damage red blood cells.

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? View Available Hint(s) Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? Phospholipids form a single sheet in water. Phospholipids form a structure in which the hydrophobic portion faces outward. Phospholipids are completely unable to interact with water. Phospholipids form a selectively permeable structure. They are triacylglycerols, which are commonly available in foods.

Phospholipids form a selectively permeable structure. Their structure allows some substances to penetrate easily and blocks others.

Glucose can be moved into cells via an active transport mechanism when the concentration of glucose inside the cell is higher than the concentration of glucose outside of the cell. This active transport mechanism moves glucose and sodium into the cell at the same time. The glucose moves up its gradient and the sodium moves down its gradient. Which of the following statements about this mechanism is accurate?

To pump glucose up its concentration gradient, sodium moves down its concentration gradient, and the distribution of sodium ions across the membrane forms an electrochemical gradient that drives this mechanism.

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?

Water molecules move between the two solutions, but there is no net movement of water across the membrane.

Paramecium is a genus of protists that lives in water. It has organelles called contractile vacuoles that continually eliminate the excess water gained through osmosis. Knowing that Paramecia gain water through osmosis, we can deduce that they normally live in

freshwater lakes and ponds

A human cell placed into a hypertonic solution is likely to

lose water by osmosis

A white blood cell engulfing a bacterium is an example of

phagocytosis

A human cell placed in a hypotonic environment would

take up water through osmosis

Many bacteria and fungi have a difficult time surviving on our food if the food is very salty. The best explanation for this is

that the salt in the food creates a hypertonic environment for the bacteria and fungi

Which of the following is a correct difference between active transport and facilitated diffusion? View Available Hint(s) Which of the following is a correct difference between active transport and facilitated diffusion? Facilitated diffusion involves transport proteins, and active transport does not. Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. Active transport involves transport proteins, and facilitated diffusion does not. Active transport requires energy from ATP, and facilitated diffusion does not. Facilitated diffusion requires carrier proteins, but active transport requires channel proteins.

Active transport requires energy from ATP, and facilitated diffusion does not.