Movement and accumulation of ions across a membrane
against their concentration gradient can be explained by:
Explanation:
Active Transport is the movement of ions across a membrane against their concentration gradient using energy (usually ATP) and specific transport proteins. This allows cells to accumulate ions where their concentration is low outside. The other options do not require energy or move ions against their gradient: Osmosis is water movement across a membrane; Facilitated Diffusion uses proteins to assist diffusion down a gradient; Passive Transport is diffusion without energy down its gradient. Thus, movement and accumulation against the gradient is best explained by Active Transport.
🧠 Did You Know?
Active transport can also move ions into cells against large gradients, enabling nerve impulses and nutrient uptake.
💡 NCERT Memory Line:
Active transport uses energy to move substances against their gradient.
Given below are two statements:
Statement I: The forces generated by transpiration can lift a xylem-sized column of water over 130 meters height.
Statement II: Transpiration cools leaf surfaces sometimes 10 to 15 degrees, by evaporative cooling.
In the light of the above statements, choose the most appropriate answer from the options given below:
