Cell Membrane Permeability and Diffusion

The four main factors that affect the rate of diffusion are: 1) the concentration gradient, 2) the surface area to volume ratio, 3) the distance over which diffusion occurs, and 4) the temperature.

Active transport is a process where a cell uses energy from respiration to take up substances against a concentration gradient, whereas diffusion is the movement of substances down a concentration gradient and does not require additional energy.

The cell membrane must be partially permeable, allowing water to move through but not other solutes, for osmosis to occur.

<p>Multicellular organisms like animals and plants begin as a single fertilized egg cell (zygote) that then divides through mitosis into two cells, then four, eight, and so on, until the adult body contains millions of cells.</p> Signup and view all the answers

<p>Diffusion happens because of the kinetic energy of the particles. Higher temperatures provide the particles with more kinetic energy, which increases the rate of diffusion.</p> Signup and view all the answers

<p>During active transport, the cell uses energy from the breakdown of ATP to power the 'pumps' (large protein molecules in the cell membrane) that move substances against a concentration gradient.</p> Signup and view all the answers

<p>Diffusion is the movement of substances from an area of higher concentration to an area of lower concentration.</p> Signup and view all the answers

<p>The concentration gradient is the difference in concentration of a substance between two areas, and it drives the movement of molecules from high concentration to low concentration.</p> Signup and view all the answers

<p>Carbon dioxide moves out of the cell because its concentration inside the cell is higher than outside, resulting in a net movement of molecules out of the cell.</p> Signup and view all the answers

<p>Oxygen moves into the cell by diffusion during cellular respiration, as it is used up inside the cell, creating a concentration gradient from outside to inside.</p> Signup and view all the answers

<p>Carbon dioxide moves out of the cell, while oxygen moves into the cell, down their respective concentration gradients.</p> Signup and view all the answers

<p>The rate of diffusion can be affected by factors such as the concentration gradient, temperature, surface area, and the permeability of the membrane.</p> Signup and view all the answers