2019 · Q78
Which one of the following is active transport ?
General KnowledgeBiology
- AIt is the movement of a substance against a diffusion gradient with the use of energy from respiration.
- BIt is the movement of a substance against a diffusion gradient without the use of energy.
- CIt is the movement of a substance against a diffusion gradient with the use of energy from photosynthesis.
- DIt is the movement of a substance along a diffusion gradient with the use of energy from respiration.
Explanation
Active transport moves ions or molecules against their concentration (diffusion) gradient, which requires metabolic energy — ATP produced by respiration. Diffusion, osmosis and facilitated diffusion are passive and need no energy. Hence energy from respiration.