Passive Transport and Osmosis

Osmosis-Passive

Transport

Biology-on level

Learning objective for today’s lesson

❖ Standard B4.B : investigate and explain cellular

processes, including homeostasis, energy
conversions, transport of molecules, and synthesis of
new molecules.

Passive transport check in:

1. Simple diffusion- unassisted movement of small

neutral molecules through a cell membrane (High →
Low)

Passive Transport Check IN:

2. Facilitated Diffusion- protein assisted movement of
large charged molecules through the Cell Membrane (
High → Low)

NO ENERGY (ATP) USE
NEEDED BY THE
CELL TO MAKE
PASSIVE TRANSPORT
HAPPEN

Multiple Choice

In simple diffusion, which way are the small molecules moving through the cell membrane?

• High to Low

• Up and Down

• Low to High

• Down and Up

Concentration Gradient

High concentrations have a lot
molecules tightly packed

A good visual visualize them as
a solution with a deep color

-

Low concentrations have less
molecules and are spread out

A good visualize them as a
solution with a lighter color

Diffusion: the movement of molecule from an area of
HIGH concentration to an area of LOW
concentration (across the plasma membrane/lipid
bilayer)

THE INK IS HIGHLY
CONCENTRATED IN ONE
PLACE WHEN ADDED-

IT SPREADS OUT INTO THE
WATER WHERE THERE IS NO
CONCENTRATION OF INK
UNTIL DYNAMIC
EQUILIBRIUM IS ACHIEVED
(Balanced/Even distribution)

Moving WITH the concentration gradient (HIGH to LOW) is…

Passive and requires NO ENERGY.

There are 3 types of PASSIVE Transport across the Cell
Membrane: simple, facilitated, and OSMOSIS

All of these “Go with flow”

Fill in the Blanks

Moving with the concentration gradient (High to Low) is

and requires NO energy.

“How does WATER move across the cell membrane?”

Osmosis

The diffusion of water specifically across

semipermeable membrane.

Multiple Choice

What type of cell membrane does osmosis diffusion of water?

• Permeable

• Impermeable

• Semipermeable

Osmosis

Solution is made of solutes dissolved in a solvent
(water= universal solvent)

KOOL-AID is the solute

WATER is the solvent

Concentration: the amount of solute (stuff) dissolved

into a solvent (liquid)

CONCENTRATION is how much
Kool-Aid you put in

Adding more Kool-Aid mix without
adding water increases the
concentration of the Kool-Aid solute

Fill in the Blanks

Which is the solute in Kool-Aid?

Fill in the Blanks

Which is the solvent in Kool-Aid

Tonicity

Tonicity is the concentration of a solution in a cell as
compared to another nearby solution.

It determines how water moves across the membrane.

Water is constantly trying to main HOMEOSTASIS for
the solution

DURING OSMOSIS THE WATER
MOVES, NOT THE SOLUTES!
THE WATER HELPS THE SOLUTION
ACHIEVE DYNAMIC EQUILIBRIUM
(HOMEOSTASIS)

Tonicity

Wherever there is an imbalance, water wants to
move towards that direction to establish
equilibrium.

Multiple Choice

When there is a imbalance in water moves _______that direction to create __________.

• away; non-equilibrium

• towards; equilibrium

• away; equilibrium

• toward; non-equilibrium

Isotonic

ISOTONIC solutions contain the same concentration of
solutes in the cell and solution-they are essentially at
homeostasis

Water will cycle in and out of the cell
since the environment inside the cell
and outside the cell have the same
concentration

Isotonic

A solution that has the SAME concentration
of solutes as the environment of the cell.

●Water moves IN & OUT of the cell.

NO NET MOVEMENT OF WATER

ISOTONIC (ISO=same)

Means “same strength”

If water concentration is EQUAL inside &
outside

Then: NO VISIBLE CHANGE (water
moves evenly in & out)

Draw

Draw what is happening to the cell in SALTY water. Remember to use arrows.*HINT LOOK AT YOUR NOTES ON HOW TO DRAW THE ARROWS

Hypertonic

If a solution has a higher concentration of solutes (less water)
outside then the cell has inside then it is said to be
HYPERTONIC.

Water will flow out of the cell and into the
surrounding environment in an attempt
to bring them both to equilibrium so that
their concentrations match.

Hypertonic

A solution that has a HIGH concentration
of solutes than the environment of the
cell.

●Net movement of water OUT OF the
cell

CAUSES THE CELL TO SHRINK

HYPERTONIC (hyper=above)

Means “above strength”

If WATER concentration is LOWER outside the
cell

Then: water will move out of the cell

CELL WILL SHRINK (loses volume/mass)

HYPER is HIGH the cell will shrink

Draw

Draw what is happening to the cell in VERY salty water. Remember to use arrows.*HINT LOOK AT YOUR NOTES ON HOW TO DRAW THE ARROWS

Hypotonic

If a solution has a lower concentration of solutes (thus
more water) outside then the cell has inside then it is said
to be HYPOTONIC.

Water will flow into the cell from the
surrounding environment in an attempt to
bring them both to equilibrium so that
their concentrations match.

Hypotonic

A solution that has a LOWER concentration
of solutes than the environment of the cell.

●Net movement of water INTO the cell

CAUSES THE CELL TO SWELL

HYPOTONIC (hypo = low)

Means “below strength”

If WATER concentration is HIGHER outside
the cell

Then: water will move into the cell

CELL WILL SWELL (volume/mass increase)

HYPO is LOW the cell will SWELL!

Draw

Draw what is happening to the cell in PURE water. Remember to use arrows.*HINT LOOK AT YOUR NOTES ON HOW TO DRAW THE ARROWS

Match

Match the following

• Hypertonic solution

• Hypotonic solution

• Isotonic solution

the cell will shrink

the cell will swell

the cell will have no change

• the cell will shrink

• the cell will swell

• the cell will have no change

Summary
HYPOtonic: Water moves into cell
and it becomes swollen, like a
HIPPO (HYPO)

ISO: Water cycles in and out, cell
stays the same (HOMEOSTASIS)

HYPERtonic: Water moves out of
the cell and it shrinks

Summary

Simple diffusion

Facilitated diffusion

And Osmosis are all PASSIVE
TRANSPORT

All passive transport process
work based on concentrations
gradient flow, so no energy is
ever needed to be used by a cell

Poll

How did the egg look for Day 2?

• Swelled up

• Shrink

• Nothing happen