Lesson Cell Transport

Modeling Cell Transport:

Scientists use models to help make sense of the world.

A Model uses a familiar object to represent something unfamiliar or

unable to be seen. A cell membrane is microscopic and “see-through”

or transparent.

The Cell Membrane

also called The Plasma Membrane

● It controls what enters and leaves the cell.
● A membrane is similar to a thin covering.
● It forms a barrier between the cytoplasm and the

outside environment.

WHAT IS THE CELL MEMBRANE MADE OF?

The cell strives to maintain a stable environment in order to survive. It needs to
control what enters and leaves to maintain homeostasis. There is water on both
sides of a cell, the cell membrane is made up of a phospholipid bilayer. Each
phospholipid molecule has a head and two tails. The head "loves" water
(hydrophilic) and the tails "hate" water (hydrophobic). The water-hating tails
are on the interior of the membrane, whereas the water-loving heads point
outwards, toward either the cytoplasm or the fluid that surrounds the cell.

Cell Membrane - Like a Butter Sandwich?

You can relate the cell membrane to a sandwich model.

The bread in your sandwich would absorb water if you placed it on a wet
counter in the kitchen. The bread would be considered hydrophilic, or water
loving, since it soaks up the water.

Lipids are hydrophobic since they are made of oil. Oil repels water. So in our
butter model, the butter represents the nonpolar tails of the phospholipids.

Passive
Transport
Uses no energy
and…goes with the
flow!

Active Transport
Goes against the
flow and uses ATP
Energy!

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Multiple Choice

Completely able to pass through a membrane

• semipermeable

• selectively permeable

• permeable

• impermeable

Multiple Choice

Not able to pass through a membrane

• semipermeable

• selectively permeable

• permeable

• impermeable

Multiple Select

Some things (but not all) are able to pass through a membrane

Choose two...

• impermeable

• semipermeable

• selectively permeable

• permeable

Multiple Select

The cell membrane's purpose is (check all that apply)

• structure and support

• make proteins

• maintain homeostasis (stable environment)

• determine what can enter and leave the cell

Multiple Choice

Fill in the blank:

Osmosis is the movement of ________ across a cell membrane from high to low.

• Carbon dioxide

• Starch

• Water

• Oxygen

Multiple Choice

In an isotonic solution which way will the water flow

• it will not flow at all

• it will flow into the cell

• it will flow both ways at equal rates

• out of the cell

Multiple Choice

What would happen to a cell placed in a hypertonic solution

• The cell would shrink

• The cell would expand and possibly burst

• The cell would remain the same

• The cell would dance and do the Nay Nay!

Multiple Choice

Homeostasis means...

• a change on each side

• permeable membrane

• the same, normal, or stable

• different levels

Multiple Choice

Completely able to pass through a membrane

• semipermeable

• selectively permeable

• permeable

• impermeable

Match

Match the following words to their definitions:

• solute

• solvent

• concentration

• solution

substance being dissolved

a dissolving liquid

quantity of solute present

a homogenous mixture

• substance being dissolved

• a dissolving liquid

• quantity of solute present

• a homogenous mixture

Multiple Choice

Hydrophilic means

• water loving

• water hating

Multiple Choice

Hydrophobic means

• water loving

• water hating

Multiple Choice

After examining this diagram showing the concentration of water inside and outside of the cell, identify the tonicity of the solution.

• hypertonic

• hypotonic

• isotonic

Multiple Choice

What type of solution is this cell in?

• Isotonic

• Hypertonic

• Hypotonic

• diffused

Multiple Choice

Nemo and other ocean dwelling fish cannot survive in freshwater because......

• freshwater is hypertonic to Nemo's cells and will result in water leaving them causing the cells to shrink

• freshwater is hypotonic to Nemo's cells and will result in water leaving them causing the cells to shrink

• freshwater is hypertonic to Nemo's cells and will result in water entering them causing the cells to swell and burst

• freshwater is hypotonic to Nemo's cells and will result in water enter them causing the cells to swell and burst

Multiple Choice

This egg has shrunk, what type of solution was it placed in?

• hypotonic solution

• hypertonic solution

• isotonic solution

Multiple Choice

Which Type of solution is the middle cell placed in?

• Hypertonic

• Hypotonic

• Isotonic

• Robotonic

Multiple Choice

What type of solution allows water to enter the plant cell?

• hypotonic solution

• hypertonic solution

• isotonic solution

• active transport

Multiple Choice

What type of solution is this cell in?

• Isotonic

• Hypertonic

• Hypotonic

• diffused