exchanging substances

Question 1

what is diffusion ?

Answer 1

Particles spreading out from a high concentration to a low concentration

Question 2

what is osmosis ?

Answer 2

Water molecules across a PARTIALLY PERMUABLE MEMBRANE from a region of high water concentration to a region of lower water concentration

Question 3

What is active transport ?

Answer 3

This is when substances go against the concentration gradient and travel from a low concentration to a higher concentration.

Question 4

how have exchange surfaces adapted to maximise effectiveness ?

Answer 4

1) They have a thin membrane that gives substances a short distance to diffuse
2) They have a large surface area so lots of substances can diffuse at once
3) Exchange surfaces in animals have lots of blood vessels to get substances in and out of the blood quickly