What is a symporter?

• A carrier that moves two substances the same way
• A carrier that swaps two substances opposite ways
• A pump that burns ATP by itself

Which step spends ATP when a gut cell absorbs glucose?

• The symporter pulling glucose in
• The sodium potassium pump pushing sodium out
• Glucose drifting through the membrane alone

Which substance flows down its gradient to drag glucose into the cell?

• Potassium
• Glucose
• Sodium

Put the events in a gut cell in the correct order.

• Symporter acts first, then the pump builds a gradient
• Glucose enters alone, then sodium follows it
• Pump pushes sodium out, then symporter brings glucose in

A poison blocks the sodium potassium pump. What happens to glucose uptake?

• It stops, because the sodium gradient fades away
• It speeds up, because ATP is saved for glucose
• It stays normal, because glucose needs no gradient

How does an antiporter differ from a symporter?

• It burns ATP while a symporter does not
• It moves only one substance at a time
• It swaps two substances in opposite directions

If the pump is blocked, sodium piles up inside the cell and glucose absorption fails.

Circle one:   True   False

A student says ileum glucose uptake is primary active transport because ATP is needed. What is the mistake?

• Glucose uptake needs no energy of any kind
• The pump and not the symporter moves the glucose
• ATP and glucose steps sit in different proteins, so it is secondary