Answer Following Biology Of Cell Membrane Quiz

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

The sides of the plasma membrane that face the cytoplasm and the outside of the cell have different lipid and protein composition.

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. 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.

5. 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.

6. 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.

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

Facilitated diffusion via glucose transporter proteins

Cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

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.

8. 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 is usually against the concentration gradient of the solute, whereas passive transport is always down the concentration gradient of the solute; Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy; Active transport always requires the use of transport proteins, but passive transport can sometimes be accomplished without a protein.

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.