Nimo

Study smarter with Nimo

Personalised revision that adapts to you. Ace your revision with unlimited practice questions that are designed to help you learn faster. We're slowly rolling out to more and more students.

Try Nimo

Factors affecting diffusion across cell membranes

Cell biology • Transport in cells

Key concepts

What you'll likely be quizzed about

  • Diffusion refers to the net movement of particles from areas of high concentration to areas of low concentration without external energy input.
  • Substances that diffuse across membranes include oxygen and carbon dioxide, which move between alveoli and blood, as well as urea, a waste product that moves from cells into the blood.
  • Efficient diffusion occurs across membranes that are thin and moist, such as in alveoli, villi, and gills, which provide large surface areas for rapid exchange.

Flashcards

Test your knowledge with interactive flashcards

Name three substances transported by diffusion in animals.

Click to reveal answer

Oxygen, carbon dioxide, and urea move by diffusion between cells and the blood.

Key notes

Important points to keep in mind

Diffusion is the net movement from high to low concentration, and it is a passive process.

A steeper concentration gradient results in faster diffusion; removal of diffused molecules maintains this gradient.

Higher temperature increases particle kinetic energy, thus speeding up diffusion.

A larger membrane surface area provides more simultaneous diffusion sites, leading to a higher rate.

Thin diffusion distance (one-cell-thick) accelerates diffusion; exchange surfaces tend to be thin and moist.

Small molecules and gases like O2, CO2, and urea diffuse, while larger or charged particles may require carrier proteins or active transport.

Built with v0