Understanding Key Concepts in Cellular Transport

Passive transport refers to the movement of substances across the cell membrane without the need for energy input from the cell itself.

A concentration gradient refers to the difference in concentration of a substance across a space, not necessarily an increase or decrease in concentration or a uniform distribution.

Equilibrium refers to a state where the concentration of a substance is equal throughout a space, indicating a balance. It is not about constant movement or complete stillness, nor does it involve exponential increases or rapid decreases in concentration.

Diffusion is the process of particles moving from an area of high concentration to an area of low concentration due to random thermal motion, leading to equal distribution of particles.

Osmosis specifically refers to the movement of water molecules through a selectively permeable membrane. The incorrect answers are not related to the definition of osmosis.

A hypertonic solution has a higher concentration of solutes compared to the inside of a cell, leading to water leaving the cell and causing it to shrink.

A hypotonic solution has a lower solute concentration compared to the cell, leading to water moving into the cell causing it to swell.

An isotonic solution is one in which the concentration of solutes is the same inside the cell as outside, leading to no net movement of water and thus no change in cell volume.

An ion channel is a specialized protein that forms a pore in a cell membrane through which ions can pass, affecting the cell's electrical properties.

Carrier proteins are specifically designed to transport substances across cell membranes, aiding in various cellular functions.

Facilitated diffusion is a type of passive transport, meaning it does not require the cell to expend energy. It involves the movement of substances with the concentration gradient with the help of transport proteins.

Active transport involves the use of energy to move a substance against its concentration gradient, unlike passive transport which occurs with the concentration gradient. It is crucial for maintaining proper balance and functionality within cells.

Endocytosis specifically refers to the movement of substances into a cell, not out of it, breakdown of substances, or cell replication.

Exocytosis specifically refers to the process where substances are moved outside of a cell through vesicles.

A receptor protein specifically binds to signal molecules to allow cells to respond to those signals, which is essential for communication and coordination within the body.

Second messengers are molecules that relay signals received at receptors on the cell surface to target molecules inside the cell. They facilitate communication between the cell membrane and cytoplasm, enabling various cellular responses to external stimuli.