Which of the following best describes active transport across a cell membrane?
A
Movement of molecules down their concentration gradient without energy.
B
Movement of water across a semi-permeable membrane.
C
Movement of molecules against their concentration gradient, requiring ATP.
D
Movement of small, nonpolar molecules directly through the lipid bilayer.
✓ Correct Answer: Option C
Active transport moves substances from an area of lower concentration to an area of higher concentration (against their gradient). This process requires energy, typically supplied by the hydrolysis of ATP.
💡 Why is C) the correct answer?
The correct answer to the question "Which of the following best describes active transport across a cell membrane?" is Option C: Movement of molecules against their concentration gradient, requiring ATP..
The other options — A) Movement of molecules down their concentration gradient without energy., B) Movement of water across a semi-permeable membrane., D) Movement of small, nonpolar molecules directly through the lipid bilayer. — are incorrect for this IB Exam Prep question. As explained above: Active transport moves substances from an area of lower concentration to an area of higher concentration (against their gradient). This process requires energy, typically supplied by the hydrolysis o…
📚 About This IB Exam Prep Practice Question
This 3-level IB Exam Prep question from the Biology topic is part of BrainForge Quiz's free exam preparation library.
Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.
How to use this page: Read the question above, consider all four options (A through D),
then check the highlighted correct answer and explanation. For active timed practice, start a
free IB Exam Prep practice test
or use flashcards for spaced repetition review.