Ion Channels and Transporters Practice Questions
18 free Ion Channels and Transporters practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Ion channels are best described as:
- A Protein pores for ion movement
- B Proteins that synthesize ions
- C Enzymes that degrade ionic bonds
- D Lipid membrane molecules
Correct answer: Protein pores for ion movement
Ion channels are membrane proteins that form pores. They allow specific ions to move across membranes passively.
Which transport mechanism allows ions to move down their concentration gradient?
- A Facilitated diffusion
- B Primary active transport
- C Endocytosis
- D Phagocytosis
Correct answer: Facilitated diffusion
Facilitated diffusion allows ions to move along their concentration gradient through channels or carriers. It does not require energy.
Which process requires energy for ion movement?
- A Diffusion
- B Osmosis
- C Active transport
- D Facilitated diffusion
Correct answer: Active transport
Active transport requires ATP to move ions against their concentration gradient. It is essential for maintaining ion balance.
Which protein is responsible for pumping ions against the gradient?
- A Ion channel
- B Carrier protein
- C Enzyme
- D Pump protein
Correct answer: Pump protein
Pump proteins use energy to move ions against the gradient. They are involved in active transport.
Which ion pump is commonly found in plant cell membranes?
- A Proton pump
- B Sodium pump
- C Calcium pump
- D Potassium pump
Correct answer: Proton pump
Proton pumps (H+ pumps) are common in plant cells. They create electrochemical gradients used for transport.
Which type of transport protein changes shape to move ions?
- A Carrier protein
- B Ion channel protein
- C Pump protein
- D Enzyme
Correct answer: Carrier protein
Carrier proteins bind ions and undergo conformational changes. This helps in transporting ions across membranes.
Ion channels are usually:
- A Continuously open
- B Permanently closed
- C Completely non-specific
- D Gated and selective
Correct answer: Gated and selective
Ion channels are gated and selective. They open or close in response to stimuli and allow specific ions.
Which factor controls the opening of ion channels?
- A Temperature only
- B Light only
- C Voltage or chemical signals
- D Mechanical pressure changes
Correct answer: Voltage or chemical signals
Ion channels can be voltage-gated or ligand-gated. They respond to electrical or chemical signals.
Which ion is most commonly transported in plant cells for turgor regulation?
- A Sodium ion (Na+)
- B Chloride ion (Cl-)
- C Potassium ion (K+)
- D Calcium ion (Ca2+)
Correct answer: Potassium ion (K+)
Potassium ions play a major role in maintaining turgor pressure. They regulate stomatal opening and closing.
Which type of transport uses proton gradient for ion movement?
- A Simple diffusion
- B Primary active ion transport
- C Secondary active transport
- D Osmosis
Correct answer: Secondary active transport
Secondary active transport moves a solute against its own gradient by coupling it to an ion flowing down a gradient that a primary pump has already established; in plants and many bacteria that ion is the proton, pumped out by an H+ ATPase. The transporter itself hydrolyses no ATP, which is what makes it secondary: the energy was stored in the proton gradient earlier. Primary active transport spends ATP directly, while simple diffusion and osmosis need no coupled ion at all.
Which of the following is true about facilitated diffusion?
- A Requires ATP
- B Moves solutes against the gradient
- C Uses transport proteins
- D Is slow
Correct answer: Uses transport proteins
Facilitated diffusion uses carrier or channel proteins. It moves substances along the concentration gradient.
Which process maintains ion gradients across membranes?
- A Diffusion
- B Osmosis
- C Active transport
- D Passive transport
Correct answer: Active transport
Active transport maintains ion gradients. It moves ions against their concentration gradient using energy.
Which transport mechanism is fastest for ion movement?
- A Active transport
- B Carrier-mediated transport
- C Endocytosis
- D Ion channels
Correct answer: Ion channels
Ion channels allow rapid movement of ions. They provide a direct pathway across membranes.
Which ion movement is involved in stomatal opening?
- A H+ efflux
- B K+ influx
- C Cl- efflux
- D Ca2+ efflux
Correct answer: K+ influx
K+ influx into guard cells increases osmotic pressure. This causes water entry and stomatal opening.
Which of the following is NOT a transport protein?
- A Ion channel
- B Carrier protein
- C Pump protein
- D 70S ribosome
Correct answer: 70S ribosome
Ribosomes are involved in protein synthesis. They do not participate in transport across membranes.
Which property allows selective ion movement across membranes?
- A Membrane permeability level
- B Ion channel specificity
- C Diffusion
- D Osmosis
Correct answer: Ion channel specificity
Ion channels are selective for specific ions. This ensures controlled transport.
Which of the following best describes carrier proteins?
- A Form open pores in membranes
- B Bind and transport specific molecules
- C Produce and release cellular energy molecules
- D Carry genetic DNA material
Correct answer: Bind and transport specific molecules
Carrier proteins bind specific molecules and change shape to transport them. They are involved in facilitated diffusion and active transport.
Which type of transport moves ions without energy but with protein assistance?
- A Active transport
- B Facilitated diffusion
- C Receptor-mediated endocytosis
- D Phagocytosis
Correct answer: Facilitated diffusion
Facilitated diffusion uses transport proteins but does not require energy. It occurs along the concentration gradient.