Module 11 Terms - Water Movement: Osmosis, Tonicity, and Osmoregulation Flashcards

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1
Q

Solutes

A

Dissolved substances

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2
Q

Molarity

A

The concentration of a solute in a solution

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3
Q

Osmosis

A

The movement of water across a selectively permeable membrane in response to a difference in solute concentration

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4
Q

Water potential

A

All of the chemical and physical forces that affect the movement of water, such as osmosis, pressure, and gravity

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5
Q

Osmotic pressure

A

The tendency of water to move from one solution into another by osmosis (higher solute concentration = higher osmotic pressure)

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6
Q

Tonicity

A

A term used to describe osmotic pressure and the direction of water movement; describes how strongly water is pulled into one solution compared to another. A relative term used for comparisons

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7
Q

Hypertonic

A

A solution with a higher solute concentration than another solution

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8
Q

Hypotonic

A

A solution with a lower concentration than another solution

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9
Q

Isotonic

A

A solution with the same concentration as another solution

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10
Q

Contractile vacuoles

A

Organelles that take up excess water from inside the cell and then, by contraction, expel it into the external environment

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11
Q

Pressure potential

A

The effect of pressure on the movement of water

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12
Q

Solute potential

A

The effect of solutes on the movement of water

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13
Q

Osmoregulation

A

The regulation of osmotic pressure inside cells and organisms

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14
Q

What is high and low water potential and what does it mean?

A

If a solution has high water potential, it has a high concentration of free water molecules; conversely, if the solution has low water potential, it has a low concentration of free water molecules and tends not to move to other places.

Water has a tendency to move from areas of high water potential to low water potential.

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15
Q

What is the water potential equation?

A

Ψ = Ψs + Ψp

Ψ is water potential
Ψs is solute potential
Ψp is water potential

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16
Q

What are bars in terms of water potential?

A

Bars are basically just the quantified water potential, with the highest being 0 (pure water) and anything more negative than that having lower water potential.

Thus, if area 1 has a water potential of -40 bars and area 2 has a water potential of -5 bars, the water will flow from area 2 to area 1, because water moves from areas of high water potential (more positive in terms of bars) to areas of lower water potential (more negative in terms of bars).

17
Q

How does solute potential (Ψs) work?

A

If more solutes are added to a solution, the solute potential drops—in other words, it becomes more negative

Thus, if you added salt to pure water with a solute potential of 0, the solute potential would become more negative, say, -5 bars

18
Q

How does pressure potential (Ψp) work?

A

Pressure potential is basically the amount the solution is being pushed out of an area.

For example, if there is a lot of water in a plant cell, its cell walls will push against the water, making it want to go out of the cell. A positive pressure potential means there is a force acting on the water that motivates the water to exit an area

Make sure to remember that on problems where there is an open beaker or no other forces acting on the solution, Ψp is 0!

19
Q

What is the solute potential equation?

A

Ψs = -iCRT

i = ionization constant (anywhere from 1-2), depending if the solute will split into two molecules or not in solution
C = concentration (molarity)
R = pressure constant (ALWAYS 0.0831 liter bars/mole K)
T = temperature (273 + °C)