B3 - Movement into and out of cells

Question 1

diffusion definition

Answer 1

net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient as a result of their random movement

Question 2

what are the 4 factors that affect diffusion?

Answer 2

-surface area
-temperature
-concentration gradient
-distance

Question 3

osmosis definition

Answer 3

net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane

Question 4

what is the effect of immersing plant cells in solutions of different concentration?

Answer 4

-flaccid in high concentration as water diffuses out of the plant through osmosis
-turgid in low concentration as water diffuses into the plant through osmosis

Question 5

what is the importance of water potential and osmosis in the UPTAKE of water by PLANTS? [5]

Answer 5

-plants take in water by osmosis
-cell contents push against the inelastic cell wall
-turgor pressure (pressure inside the cell) increases
-cell becomes turgid (firm)
-firmness helps to support the plant

Question 6

what is the importance of diffusion for gases and solutes in living organisms

Answer 6

It allows molecules to enter and leave cells into the organism or enter and leave the organism

Question 7

active transport definition

Answer 7

movement of particles from a region of lower concentration to a region of higher concentration, up a concentration gradient using energy from respiration

Question 8

why is active transport important

Answer 8

its a process for movement of molecules or ions across membranes including ion uptake by root hairs

Question 9

whats a partially permeable membrane

Answer 9

membrane that chooses what gets in and out (only small things like water carbon oxygen go through, not big things like proteins)

Question 10

what substances diffuse into cells for respiration

Answer 10

oxygen and glucose

Question 11

what is the difference if the concentration gradient is steep

Answer 11

greater difference

Question 12

passive process definition

Answer 12

energy not required

Question 13

what toxic substance gets diffused out of respiring cells?

Answer 13

carbon dioxide

Question 14

what toxic substance gets diffused out of liver cells?

Answer 14

urea

Question 15

effect of diffusion distance on rate of diffusion

Answer 15

-shorter the distance, fast the rate of diffusion
-less time to travel a short distance
Ex) blood capillaries

Question 16

effect of concentration gradient on rate of diffusion

Answer 16

-greater the difference in concentration, faster the net movement of particles, so faster the rate of diffusion
Ex) carbon dioxide used in photosynthesis

Question 17

effect of surface area on rate of diffusion

Answer 17

-greater the surface area, faster the rate of diffusion
-more space for diffusion and more particles can move in a given period of time
Ex) small intestine wall

Question 18

effect of temperature on rate of diffusion

Answer 18

-higher the temperature, more kinetic energy the particles have so the faster the rate of diffusion

Question 19

what is the importance of water potential and osmosis in the UPTAKE of water by ANIMALS?

Answer 19

-osmosis may swell the cell and the cell may burst
-called lysis

Question 20

what is the importance of water potential and osmosis in the LOSS of water by PLANTS? [5]

Answer 20

-when water is lost by osmosis, they become soft
-turgor pressure in side the cell decreases
-cell becomes flaccid (soft)
-plant wilts because cell is flaccid
-cel becomes plasmolysed cell (cell contents collapsed away from the cell wall

Question 21

what is the importance of water potential and osmosis in the LOSS of water by ANIMALS?

Answer 21

-cell becomes crinkled/shriveled
-this cell is called a crenated cell

Question 22

what does active transport require?

Answer 22

carrier proteins and energy (in the form of ATP)

Question 23

2 examples of active transport

Answer 23

-gut wall
(in small intestine, glucose is actively transported into blood through the gut wall so that the glucose is taken by the blood to needed places)

-root hair cell
(plants use active transport to take in minerals from the soil but usually soil has a lower concentration of the minerals than the plant itself so root hair cell uses active transport to move these mienrals across the cell membrane into the root)