MoS

Question 1

define and describe factors affecting diffusion

Answer 1

-passive movement of molecules from a region of higher concentration to a region of lower concentration
-smaller particle size travel faster
-SA:V more, diffusion faster
-shorter distance between the two regions
-increased temperature

Question 2

define facilitated diffusion and its diff with normal diffusion

Answer 2

-spontaneous passage of molecules or ions, bound to a specific carrier protein, across a biological membrane down a concentration gradient
-rate depends on CG, specific molecules diffuse faster
-bidirectional, one direction
-si

Question 3

define, describe factors affecting and processes involving active transport

Answer 3

-movement of materials through a plasma membrane against a concentration gradient requiring energy in the form of ATP
-temperature, O2 concentration, presence of poison
-excretion of urea from kidney, muscle contraction, nerve impulse transmission, amino acids to gut, mineral salts from plant roots

Question 4

define endocytosis and exocytosis

Answer 4

-the cellular uptake of macromolecules and particulate substances by localised region of the plasma membrane that surrounds the substance and are pinched off to form an intracellular vesicle
-passage of material out from cells, often secretion of enzyme, hormone or mucus