Cell Transport and Signaling Quiz

Which type of transport is primarily responsible for the movement of chloride ions (Cl⁻) across cell membranes?

• Simple diffusion

• Facilitated diffusion

• Active transport

• Osmosis

How can charged particles (ions) reach equilibrium across a membrane even when their concentrations remain unequal?

• By using osmosis to balance ion levels

• Through equal distribution of all ions across the membrane

• By establishing an electrical gradient that balances the chemical gradient

• By converting into neutral molecules that diffuse freely

What is the main difference between a symport and a uniport transport protein?

• Symports move molecules through the membrane using ATP, while uniports do not.

• Symports transport only one type of molecule, while uniports transport multiple types.

• Symports move two molecules in the same direction, while uniports move one molecule at a time.

• Symports work through osmosis, while uniports work through diffusion.

How do potassium (K⁺) channels achieve high selectivity for potassium ions over other ions like sodium (Na⁺)?

• They actively pump potassium using ATP

• The channel’s pore is physically too large for sodium or other ions to pass through

• The membrane potential attracts only potassium ions

• The specific amino acid sequence in the selectivity filter is specific for potassium

Why do potassium (K⁺) ions have hydration shells when in solution?

• Because potassium ions chemically react with water

• Because water molecules are repelled by the positive charge of potassium

• Because the positive charge of potassium attracts the partially negative oxygen atoms in water

• Because potassium ions dissolve by breaking into smaller ions

Tags

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Which of the following is an example of a primary active transporter?

• Sodium/potassium pump

• Chloride channel

• Sodium/glucose symporter

• Aquaporin

How does ATP hydrolysis contribute to the function of the sodium/potassium pump (Na⁺/K⁺-ATPase)?

• It causes a conformational change in the pump, allowing the movement of sodium and potassium ions.

• It directly provides energy to transport sodium and potassium ions down their concentration gradients.

• It facilitates the binding of sodium ions to the pump without changing the pump’s shape.

• It is used to create a concentration gradient for glucose transport via a secondary transporter.

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Why is it problematic that chloride ions cannot be transported out of epithelial cells in cystic fibrosis patients?

• It prevents the production of mucus, leading to reduced lung function/clearance.

• It disrupts the active transport of nutrients into cells, resulting in malnutrition.

• It leads to an overproduction of water in the lungs, causing pulmonary edema.

• It causes an imbalance in water movement, leading to thick mucus that obstructs airways.

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Insulin signaling is an example of which type of cell signaling?

• Autocrine signaling

• Paracrine signaling

• Endocrine signaling

• Juxtacrine signaling

Tags

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In gap junctions, what is typically transported through connexins?

• Small ions

• Large proteins and nutrients

• Genetic material like RNA and DNA

• Water and lipids