4.3, 4.4, 4,5: Osmosis and active transport

Question 1

Osmosis

Answer 1

The diffusion of water molecules across a partially permeable membrane from an area of high water potential to an area of lower water potential

Question 2

Water potential

Answer 2

The potential (likelihood) of water molecules to diffuse out of or into a solution

Question 3

Isotonic

Answer 3

Two solutions have the same water potential

Question 4

Rate osmosis
factors
3

Answer 4

water potential gradient
thickness of the exchange surface
surface of the exchange surface

Question 5

Active transport requires

Answer 5

energy

Question 6

Active transport

Answer 6

required energy to move molecules and ions across membranes and usually against a concentration gradient

Question 7

Differences between active transport and facilitated diffusion
2

Answer 7

AT= usually low to high conc.
FD= always high to low conc.

AT= requires energy

Question 8

… are involved in active transport

Answer 8

carrier proteins

Question 9

Co-transporters

Answer 9

type of carrier protein which bind to 2 molecules at a time

Question 10

Co-transporters

how do they work

Answer 10

The conc. gradient of one of the molecules is used to move the other molecules against its own conc. gradient

Question 11

Example of Co-transporters

Answer 11

sodium ions and glucose

Na ions move into the cell down their conc gradient which moves glucose into the cell against its conc. gradient

Question 12

Factors affecting rate of active transport

Answer 12

speed of individual carrier proteins
number of carrier proteins present
rate of respiration and availability of ATP

Question 13

Co-transport

Answer 13

The transport of one substance coupled with the transport of another substance across a plasma membrane in the same direction through the same protein carrier