Function Biology - Chapter 6 Homework

Interpret the model and determine whether each statement is true or false. A - The many black lines represent amino acid tails B - This model shows membrane transport C - The blue ovals represent phospholipid heads D - The blue ovals are hydrophobic E - The model is called a bilayer because there are two main types of molecules present, lipids and proteins. F - The strings of little red dots represent carbohydrates.

A - False B - True? C - True D - False E - False? F - False?

Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of the transport protein? A - lipid soluble molecule B - water C - glucose D - hydrogen ion

A only Small, nonpolar, lipid-soluble molecules can pass rapidly through the phospholipids of the plasma membranes. Ions, such as hydrogen ions, and hydrophilic molecules, such as water and glucose, cannot rapidly pass through the phospholipids of the membrane. To move rapidly through the membrane, they must pass through membrane transport proteins.

A trout moves from a warm environment into a cold environment. Predict how the saturation status of hydrocarbon chains might change to ensure proper membrane fluidity in the new cold environment.

The hydrocarbons would become less saturated to increase the fluidity of the membrane. As the temperature drops, the membrane becomes less fluid, so the membranes become less saturated, which in general increases the fluidity of the membrane in response.

Your classmate has drawn four membrane models to try to remember how the lipid bilayer is built. Help her to select the best model.

The hydrophilic heads are on the outsides of the phospholipid bilayer and the hydrophobic tails face inwards.

Which of the following statements accurately describe how solutes affect a vesicle? Determine whether each statement is true or false. A - When a vesicle containing 0.1 M Na+ is placed in water, the sodium ions will diffuse out and the vesicle will shrink. B - When a vesicle containing 0.1 M Na+ is placed in a 0.1 M Cl− solution, water molecules will no longer move across the lipid bilayer. C - When a vesicle containing 0.5 M Na+ is placed in a 0.3 M Na+ solution, water is imported and the vesicle will swell. D - When a vesicle is placed in a solution that is hypertonic to the inside, the vesicle will shrink.

A - False B - False? C - True? D - True?

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Amphipathic Nature Detergent form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble.

Which statement describes what happens once equilibrium is reached between the interior of a vesicle and the surrounding solution? A - The transport of solute into the vesicle is equal to the transport of water out of the vesicle. B - The transport of water and solute across the vesicle membrane ceases. C - There is no directional movement of solute or water across the membrane. D - The direction of solute transport is the same as the direction of water transport.

C - There is no directional movement of solute or water across the membrane. At equilibrium, the solute or water will continue to move across the membrane, but the rate of movement to the inside of the vesicle will be the same as the rate of movement to the outside.

A red blood cell placed in a hypertonic solution will shrink in a process called crenation. A red blood cell placed in a hypotonic solution will swell and potentially burst in a process called hemolysis. To prevent crenation or hemolysis, a cell must be placed in an isotonic solution such as 0.9% (m/v) NaCl or 5.0% (m/v) glucose. This does not mean that a cell has a 5.0% (m/v) glucose concentration; it just means that 5.0% (m/v) glucose will exert the same osmotic pressure as the solution inside the cell, which contains several different solutes. A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur. Solution A: 3.21% (m/v) NaCl Solution B: 1.65% (m/v) glucose Solution C: distilled H2O Solution D: 6.97% (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl

Crenation: Solution A Solution D Solution E Hemolysis: Solution B Solution C This activity shows why it is very important to use solutions that are isotonic to body fluids in intravenous solutions (IVs). If an IV solution were hypertonic to the body fluids, cells in the body would shrink. If an IV solution were hypotonic to the body fluids, cells in the body would swell.

Which of the following particles could easily diffuse through a cell membrane? A - Sodium Ion (Na+) B - Glucose C - Hydrogen Ion (H+) D - Oxygen (O2)

D - Oxygen (O2) Small nonpolar molecules such as oxygen can diffuse across cell membranes.

Which of the following statements is TRUE with regards to this animation? A - Potassium ions are transported down their concentration gradient. B - The cell is not expending energy. C - The cell does not expend ATP. D - Sodium ions are transported down their concentration gradient. E - Both sodium and potassium are transported against their concentration gradients.

E - Both sodium and potassium are transported against their concentration gradients. Both ions are transported from where their concentration is low to where their concentration is high, and the cell expends energy in the form of ATP to do it.

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

Hypotonic The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst.

Which student's model does the best job of showing membrane structure?

Rekik Rekik's model shows a detailed view of membrane structure, including lipids, proteins, and carbohydrates.

Four students have done a nice job drawing membrane models. The models are drawn at different scales to serve different purposes. Order the students diagrams from most magnifies (enlarged) to least magnified.

Rekik, Thomas, Zubia, Elsa Rekik's model is the most enlarged, showing detailed structure of the membrane. Thomas's model shows less detail, and Zubia's even less. Elsa's model uses a single line to represent a cell membrane because she shows a whole cell at a less magnified scale.

A semipermeable membrane is placed between the following solutions. Solution A: 1.4% (m/v) starch Solution B: 7.62% (m/v) starch Which solution will decrease in volume?

Solution A: 1.4% (m/v) starch The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.

A semipermeable membrane is placed between the following solutions. Solution C: 9% (m/v) NaCl Solution D: 12.4% (m/v) NaCl Which solution will increase in volume?

Solution D: 12.4% (m/v) NaCl The water molecules actually move in both directions, but they move to a greater extent toward Solution D because it has a higher solute concentration than Solution C. This net movement of water molecules causes Solution D to increase in volume and Solution C to decrease in volume.

What would occur if you added NaCl to the outside solution in this container?

The sodium and chloride ions would interact with water molecules outside the vesicle, resulting in water moving to the outside. Since the ions do not readily pass through the membrane, they only interact with water molecules outside the vesicle. This interaction causes water to be drawn from the vesicle to the outside.

Which student's model does the best job of showing facilitated diffusion of a solute?

Thomas? Thomas's model shows the diffusion of a solute from an area of higher concentration through a channel protein to an area of lower concentration.

True or false? Osmosis is a type of diffusion.

True Osmosis is the diffusion of water across a selectively permeable membrane.

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

True The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.

Facilitated diffusion is a type of _____.

passive transport During facilitated diffusion, the cell is not expending the energy to move the particles across the membrane; therefore, facilitated diffusion is a form of passive transport.

Structure A is a _____.

solute

Structure A in the figure is a(n) _____.

transport protein The protein is allowing solute molecules to enter the cells.

Structure B is a _____.

transport protein The transport protein facilitates the movement of solute across the plasma membrane.