Cell Membrane

Cell Membrane

SB1d. Plan and carry out investigations to determine the role of cellular transport (e.g., active, passive, and osmosis) in maintaining homeostasis.

9th Grade Biology​

​Cell Membrane Function

• ​The cell membrane is responsible for moving molecules into and out of the cell.

• Semi-permeable or selectively permeable

  • which means only certain molecules can move in or out

Multiple Choice

What is NOT TRUE about the cell membrane

• It controls what enters and leaves the cell

• Semipermeable

• Phospholipid bilayer

• Contains digestive enzymes

Multiple Choice

True or false:  Some things are not allowed to enter the cell at all. 

• True

• False

Multiple Choice

The cell membrane of the red blood cell will allow water, oxygen, and carbon dioxide to pass through. Because other substances are blocked from entering, this membrane is called

• permeable

• non-conductive

• semi-permeable

• perforated

​Cell Membrane Structure

• ​Made up of TWO Layers (bilayer)

  • ​2 Layers of phospholipids

    • ​Hydrophillic heads

    • ​Hydrophobic tails

• ​Have proteins embedded in the membrane to help move things in and out

Multiple Choice

What does "bilayer" mean?

• one layer

• two layers

• laminated

• bilateral

Multiple Choice

What forms the channels and pumps in the phospholipid bilayer?

• carbohydrates

• proteins

• hydrophilic heads 

• lipids

Multiple Choice

Hydrophobic region of the cell membrane?

• E

• B

• C

• A 

Multiple Choice

Hydrophilic portion of cell membrane?

• A

• C

• D

• E 

​Concentration Gradient

• ​Molecules move across the membrane according to the concentration gradient

  • ​High concentration = very crowded

  • ​Low Concentration = less crowded

• ​Molecules will move across the membrane until they have reached EQUILIBRIUM = evenly spaced

Multiple Choice

In what direction do particles naturally diffuse?

• Up the concentration gradient

• Down the concentration gradient

• Across the concentration gradient

• Over the river and through the woods

​Passive Transport

• ​Movement of materials from areas of high concentration to areas of low concentration.

• No energy is required.

• ​3 Types of Passive Transport:

  • ​Diffusion: movement of molecules

  • ​Facilitated Diffusion: movement of molecules with help of protein

  • ​Osmosis: Movement of water

Multiple Choice

Osmosis is the movement of _____ across a membrane.

• food

• energy

• oxygen

• water

Multiple Choice

What type of transport is this?

• facilitated diffusion

• active transport

• diffusion

• osmosis

Multiple Choice

Special proteins help move particles, but NO energy is needed. This is..

• facilitated diffusion

• exocytosis

• active transport

• equilibrium

Multiple Choice

Suppose that you stayed in the bathtub too long, causing your hands and feet to look wrinkled. What kind of passive cell transport causes this effect?

• exocytosis

• facilitated diffusion

• osmosis

• diffusion

​Tonicity

​The concentration of a solution a cell sits in will determine the movement of water in or out.

​Hypertonic: water moves out the cell. Cell will shrink

​Isotonic: water moves evenly. Cell stayst the same size

​Hypotonic: water moves into the cell. Cell will swell

Multiple Choice

The cell below is in a _________ solution.

• Hypotonic

• Hypertonic

• Isotonic

Multiple Choice

The cell below is in a _____________ solution.

• Hypertonic

• Hypotonic

• Isotonic

Multiple Choice

A cell in an isotonic solution will

• swell

• shrink

• stay the same size

• impossible to tell

Multiple Choice

A person with swollen gums rinses his mouth with warm salt water, and the swelling decreases. Which of the following has occurred?

• The water in the gums has moved out due to the high concentration of salt in the solution.

• The salt in the solution has moved against the concentration gradient.

• The saltwater solution lowers the temperature of the water in the gums

• The swollen gums have absorbed the saltwater solution.

​Active Transport

• ​Movement of molecules from area of low concentration to areas of high concentration.

• ​This type of transport requires energy.

• ​3 Types of Active Transport:

  • ​Protein Pump

  • ​Endocytosis: move molecules in

  • ​Exocytosis: move molecules out

Multiple Choice

This picture represents which type of cellular transport?

• passive transport

• endocytosis

• exocytosis

• osmosis

Multiple Choice

Active transport requires ______, moves materials from __________________, and goes _______ the concentration gradient.

• No energy, low to high, against

• ATP, high to low, with

• ATP, low to high, with

• ATP, low to high, against

Multiple Choice

What is the role of ATP in the process of active transport?

• It provides the energy to transport the cell in its environment

• It lengthens the fatty acid chains in the membrane

• It provides the energy that cells need to move molecules against a concentration gradient

• It weakens the membrane, allowing molecules to pass through more easily.

Multiple Choice

What is (are) the main difference(s) between passive transport and active transport?

• Passive transport occurs primarily in single-cell organisms; active transport occurs primarily in multi-cellular organisms

• Active transport requires cellular energy for substances to cross the cell membrane; passive transport does not

• Passive transport does not require any cellular proteins; active transport requires cellular proteins

• Active transport works against gravity (for example, upwards from the roots of a tree); passive transport works with gravity

Multiple Choice

Which is true about active transport?

• It requires energy

• it does not require energy

• It moves substances down the concentration gradient

• it moves material from high to low concentration

Multiple Choice

This picture represents what type of cell transport?

• endocytosis

• exocytosis

• osmosis

• passive transport

Multiple Choice

Cells need to bring in molecules to carry out cellular processes. Often, this requires moving the molecules across the cell membrane against the concentration gradient. How do these molecules get into the cell?

• passive transport by osmosis

• active transport using ATP

• phagocytosis

• passive transport by diffusion