Exploring the Structure and Function of Cell Membranes Quiz

1. Which of the following statements about a typical plasma membrane is correct?

The plasma membrane is a rigid structure that does not exhibit any flexibility or dynamic movement.

The plasma membrane is permeable to all substances, allowing free movement in and out of the cell.

The plasma membrane is composed solely of carbohydrates with no lipid or protein components.

The correct statement highlights the asymmetrical nature of the plasma membrane, which is essential for its functions in communication and transport processes.

Explanation

The correct statement highlights the asymmetrical nature of the plasma membrane, which is essential for its functions in communication and transport processes.

2. Which of the following best describes the structure of a biological membrane?

Two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

A) a single layer of phospholipids with proteins embedded throughout.

B) no phospholipids present, only proteins.

C) multiple layers of proteins without any phospholipids.

The correct answer describes the structure of a typical cell membrane, which consists of a lipid bilayer with proteins. Option 'a' describes a different structure, while options 'b' and 'c' are outright incorrect as membranes are primarily composed of lipids and not just proteins.

Explanation

The correct answer describes the structure of a typical cell membrane, which consists of a lipid bilayer with proteins. Option 'a' describes a different structure, while options 'b' and 'c' are outright incorrect as membranes are primarily composed of lipids and not just proteins.

3. What factors may influence the permeability of a biological membrane to a specific solute?

The pH of the solution; the solute concentration

The time of day; the amount of light present

The size and polarity of the solute; the types of transport proteins in the membrane

The temperature of the solution; the color of the solute

The correct answer considers the physical traits of the solute and transport proteins, while the incorrect answers provide unrelated or inaccurate factors.

Explanation

The correct answer considers the physical traits of the solute and transport proteins, while the incorrect answers provide unrelated or inaccurate factors.

4. What role do transport proteins play in facilitated diffusion?

Transport proteins pump solutes against the concentration gradient.

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

Transport proteins anchor the membrane to the cell wall.

Transport proteins break down solutes into smaller molecules.

Facilitated diffusion involves the passive movement of molecules across a membrane with the help of transport proteins. These proteins create channels or carrier proteins that offer a pathway for the solute to move through the hydrophobic interior of the membrane. This process does not require energy input and is driven by concentration gradients.

Explanation

Facilitated diffusion involves the passive movement of molecules across a membrane with the help of transport proteins. These proteins create channels or carrier proteins that offer a pathway for the solute to move through the hydrophobic interior of the membrane. This process does not require energy input and is driven by concentration gradients.

5. How is the movement of glucose into a cell against a concentration gradient most likely achieved?

Facilitated diffusion via glucose transporter proteins

Simple diffusion through the lipid bilayer

Active transport of glucose using the energy of ATP hydrolysis

The movement of glucose into a cell against a concentration gradient requires the co-transport of glucose with another molecule (like a proton or sodium ion) that has been pumped across the membrane using the energy of ATP hydrolysis. This process is known as secondary active transport and is essential for cells to take up essential molecules like glucose despite a lower concentration inside the cell compared to the outside environment.

Explanation

The movement of glucose into a cell against a concentration gradient requires the co-transport of glucose with another molecule (like a proton or sodium ion) that has been pumped across the membrane using the energy of ATP hydrolysis. This process is known as secondary active transport and is essential for cells to take up essential molecules like glucose despite a lower concentration inside the cell compared to the outside environment.

6. How do active and passive transport of solutes across a membrane typically differ?

Passive transport requires cellular energy, while active transport does not

Active transport moves solutes in the same direction as passive transport

Active transport can occur without the use of transport proteins

Active transport and passive transport of solutes across a membrane differ in various ways, including the direction of movement, energy requirement, and involvement of transport proteins.

Explanation

Active transport and passive transport of solutes across a membrane differ in various ways, including the direction of movement, energy requirement, and involvement of transport proteins.

7. Which of the following is least likely to be important in holding the components of a biological membrane together?

Hydrophobic interactions between lipid tails in the bilayer.

Electrostatic interactions between membrane proteins and ions in the extracellular fluid.

Strength of hydrogen bonds between lipid head groups and water molecules surrounding the membrane.

Covalent interactions between the phospholipid and protein components of the membrane

The correct answer states that covalent interactions are least likely to be important in holding biological membrane components together since they are primarily formed by non-covalent interactions such as hydrophobic interactions, electrostatic interactions, and hydrogen bonds.

Explanation

The correct answer states that covalent interactions are least likely to be important in holding biological membrane components together since they are primarily formed by non-covalent interactions such as hydrophobic interactions, electrostatic interactions, and hydrogen bonds.

8. How could a cell increase the concentration of calcium in the cytoplasm if the concentration of calcium in the surrounding fluid is 0.1 mM and in the cytoplasm is 2.0 mM?

Simple diffusion

Osmosis

Active transport

Facilitated diffusion

Active transport is the process by which a cell can move molecules against their concentration gradient requiring energy. In this case, active transport would be needed to move calcium ions from an area of lower concentration to an area of higher concentration.

Explanation

Active transport is the process by which a cell can move molecules against their concentration gradient requiring energy. In this case, active transport would be needed to move calcium ions from an area of lower concentration to an area of higher concentration.

9. Which of the following is an example of active transport?

Movement of oxygen into the blood through alveoli.

Diffusion of carbon dioxide out of the cell.

Pumping of sodium ions out of the cell via the sodium-potassium pump.

Osmosis of water into a plant root cell.

The sodium-potassium pump is an example of active transport because it requires ATP to move ions against their concentration gradients, maintaining cell potential and balance.

Explanation

The sodium-potassium pump is an example of active transport because it requires ATP to move ions against their concentration gradients, maintaining cell potential and balance.

10. What happens to a red blood cell when placed in a hypotonic solution?

It shrinks as water leaves the cell.

It swells and may burst as water enters the cell.

Its membrane becomes impermeable to water.

It remains unchanged.

In a hypotonic solution, water moves into the red blood cell due to osmosis, causing it to swell and possibly burst. This illustrates the importance of osmotic balance for cell survival.

Explanation

In a hypotonic solution, water moves into the red blood cell due to osmosis, causing it to swell and possibly burst. This illustrates the importance of osmotic balance for cell survival.

Exploring the Structure and Function of Cell Membranes Quiz

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