D2.3 - water potential

Question 1

crenation

Answer 1

having a shrunken shape with notched or indented edges

Question 2

hypotonic

Answer 2

a low solute concentration solution

Question 3

hypertonic

Answer 3

a high solute concentration solution

Question 4

osmolarity

Answer 4

measurement of the solute concentration of a solution

Question 5

solvation

Answer 5

process in which a solute molecule attracts solvent molecules

Question 6

what occurs during solvation?

Answer 6

attraction between polar water molecules and solute molecules, leading to hydrogen bonding

Question 7

what do positively charged ions form bonds with?

Answer 7

form hydrogen bonds with partial negative charge on the oxygen of water molecules

Question 8

what do negatively charged ions form bonds with?

Answer 8

form hydrogen bonds with partial positive charge on the hydrogen atoms of water molecules

Question 9

what do polar molecules form bonds with?

Answer 9

form hydrogen bonds between partial positive charges on solute molecules and partial negative charge of the oxygen atoms of water molecules or between the partial negative charges of solute molecules and the partial positive charge of the hydrogen atoms of water molecules

Question 10

osmosis

Answer 10

movement of water from a hypotonic to hypertonic solution

Question 11

what can affect osmolarity of cells?

Answer 11

• species
• level of hydration
• tissue type or age
• soil type

Question 12

what happens in a hypotonic solution?

Answer 12

net movement occurs into the cell by osmosis

Question 13

what happens in a hypertonic solution?

Answer 13

net movement occurs out of the cell by osmosis

Question 14

what happens in an isotonic solution?

Answer 14

dynamic equilbrium occurs - no net movement

Question 15

dynamic equilibrium

Answer 15

no net movement of water, but molecules continue to pass in both directions across the membrane

Question 16

what is the effect of an isotonic medium on the cell wall?

Answer 16

no net movement so no effect on cell structure

Question 17

what is the effect of an hypotonic medium on the cell wall?

Answer 17

water moves into cells, causing swelling and bursting

Question 18

what is the effect of an hypertonic medium on the cell wall?

Answer 18

water moves out of the cell, causing shrinking and crenation

Question 19

how do multicellular organisms prevent harmful cell changes?

Answer 19

maintain an isotonic tissue fluid that surrounds the cells

Question 20

how do contractile vacuoles expel water?

Answer 20

1. water enters due to osmosis
2. excess water enters contractile vacuole
3. contractile vacuole swells
4. contractile vacuole moves to the edge of the cell
5. contractile vacuole bursts and expels water

Question 21

what is the relationship between concentration gradient and volume of water expelled?

Answer 21

the greater the concentration gradient, the greater the volume of water expelled and the more frequently the vacuoles are emptied

Question 22

why do freshwater unicellular organisms absorb water?

Answer 22

absorb water by osmosis as freshwater is hypotonic

Question 23

what is the effect of an hypertonic medium on cells without a cell wall?

Answer 23

water moves into the cells by osmosis and instead of bursting, turgor pressure is generated

Question 24

what is the effect of an hypotonic medium on cells without a cell wall?

Answer 24

water moves out of the cell by osmosis, but instead of shrinking, the plasma membrane pulls away from inside of the cell (plasmolysis)

Question 25

what is the effect of an isotonic medium on cells without a cell wall?

Answer 25

no effect on cell structure as no net movement

Question 26

what are two medical applications of isotonic solutions?

Answer 26

• bathing of organs ready for transplantation
• intravenous fluids given as part of medical treatment