Question

1. compute the following table. state whether these mechanisms are passive or active.

diffusion

osmosis

facilitated diffusion

active transport

endocytosis

exocytosis

Explanation:

• Diffusion: Movement of molecules from high to low concentration. No energy needed.
• Osmosis: Diffusion of water across a semi - permeable membrane. Passive.
• Facilitated Diffusion: Molecules move via transport proteins. Down concentration gradient.
• Active Transport: Moves molecules against gradient. Requires energy (e.g., ATP).
• Endocytosis: Cell engulfs substances. Active (uses energy).
• Exocytosis: Cell expels substances. Active (energy - dependent).

Answer:

Mechanism for Crossing the Cell Membrane	Brief Description	Passive or Active
Osmosis	Water moves across a semi - permeable membrane	Passive
Facilitated Diffusion	Molecules move through transport proteins (down concentration gradient)	Passive
Active Transport	Molecules move against concentration gradient (uses energy like ATP)	Active
Endocytosis	Cell engulfs substances (e.g., phagocytosis, pinocytosis)	Active
Exocytosis	Cell expels substances (e.g., secretion of proteins)	Active