Answer: ATP (energy) and carrier proteins.
- A A concentration gradient mainly
- B No energy
- C ATP (energy) and carrier proteins
- D Mainly a semi-permeable membrane
Correct answer: C. ATP (energy) and carrier proteins
Explanation: Active transport moves substances against the concentration gradient using ATP energy and specific carrier proteins.
Animal cell structure with major organelles labeled. Image: LadyofHats (Mariana Ruiz), Public Domain, via Wikimedia Commons.
Concept context
Cell theory, prokaryotic vs eukaryotic cells, organelles and their functions. Foundation of all biology.