Section 1.4 The Cell in its Environment

Selectively permeable

Some substance can pass through the membrane, others cannot.

True or False: As a cell gets larger, it takes longer for a molecule that has entered the cell to reach the middle of the cell.

TRUE - Larger cell means it has farther to go, which takes longer.

The cell membrane is ______________ ______________, which means that some substances can pass through it while others cannot.

The cell membrane is SELECTIVELY PERMEABLE, which means that some substances can pass through it while others cannot.

The cell membrane separates the ________ from the outside _________________.

The cell membrane separates the CELL from the outside ENVIRONMENT.

Osmosis

The diffusion of WATER molecules through a selectively permeable membrane.

Diffusion

The main method by which small molecules move across the cell membrane.

Passive transport

The movement of dissolved materials through a cell membrane WITHOUT using cellular energy.

Active transport

The movement of materials through a cell membrane USING cellular energy.

True or False: Selectively permeable means letting some but not all substances pass through.

True

_____________ ______________________ must move out of cells.

WASTE MATERIALS must move out of cells.

What Causes Diffusion? Molecules are always _______. As they move, the molecules _______ into one another. The more ________ there are in an area, the more ________ there will be. Collisions cause molecules to _____ _____ from one another. Over time the molecules of a substance will continue to _________ _______. Eventually they will spread ________ throughout the area.

What Causes Diffusion? Molecules are always MOVING. As they move, the molecules BUMP into one another. The more MOLECULES there are in an area, the more COLLISIONS there will be. Collisions cause molecules to PUSH AWAY from one another. Over time the molecules of a substance will continue to SPREAD OUT. Eventually they will spread EVENLY throughout the area.

Equillibrium

When the concentration of molecules is equal on both side of the cell membrane.

Why cells are small: It would take much _____ for ___________ & ___________ to travel in a ____________ cell than in a _________ cell. Therefore if cell grows too ___________ it could not function enough to _______________.

Why cells are small: It would take much LONGER for MOLECULES & WASTE to travel in a LARGE cell than in a SMALL cell. Therefore if cell grows too LARGE it could not function enough to SURVIVE.

Osmosis and Diffusion: In osmosis, water molecules move by diffusion from an area of _______ concentration to an area of _____________ concentration.

Osmosis and Diffusion: In osmosis, water molecules move by diffusion from an area of HIGH concentration to an area of LOWER concentration.

Osmosis is ____________________________________________________________________________________________________________________________________________________________

Osmosis is the diffsion of water molecules through a selectively permeable membrane

Explain how osmosis differs from diffusion.

Osmosis is when WATER molecules go through a selectively permeable membrane. Diffusion is when molecules go from higher concentration to lower concentration.

Passive Transport - _____________________________________________________________________

Passive Transport - The movement of dissolved materials through cell membrane WITHOUT using cellular energy.

Compare and contrast active and passive transport.

1. Both move molecules. 2 Active transport is WITH using cellular enegy. Passive transport is WITHOUT using cellular energy.

Two ways of moving things into and out of cells that do NOT need energy are:

1. Diffusion 2. Osmosis

List three ways that substances can move in and out of a cell.

1. Diffusion 2. Osmosis 3. Active Transport

Identify two methods of active transport.

1. Transport proteins 2. Transport by engulfing

List two ways the cell moves things by active transport:

1. Transport proteins 2. Transport by engulfing

Active Transport - ______________________________________________

Active Transport - The movement of materials through the cell membrane USING cellular energy

Active Transport moves substance from _______________ concentration to _____________ concentration.

Active Transport moves substance from LOWER concentration to HIGHER concentration.

Cells let in needed materials such as _____________ & _____________ _____________

Cells let in needed materials such as OXYGEN & FOOD MOLECULES

Cells must let things ___________ & ____________.

Cells must let things ENTER & LEAVE.

Concentration of a substance is the ____________ of the substance in a given ______________.

Concentration of a substance is the AMOUNT of the substance in a given VOLUME.

Diffusion is: ____________________________________________________________________________________________________________________________________________________________.

Diffusion is: The process by which molecules move from an area of higher concentration to an area of lower concentration.

Diffusion of oxygen: The oxygen molecules diffuse from the area of ________ concentration - the _______ _______ - through the cell membrane to the areas of _________ concentration - the ________ of the cell.

Diffusion of oxygen: The oxygen molecules diffuse from the area of HIGHER concentration - the POND WATER - through the cell membrane to the areas of LOWER concentration - the INSIDE of the cell.

Diffusion: ________ method by which __________ __________ move across the cell membrane.

Diffusion: MAIN method by which SMALL MOLECULES move across the cell membrane.

Effects of Osmosis & Figure 24: #1 Equal concentration --> Movement in both directions --> _________ ________ of red blood cell.

Effects of Osmosis & Figure 24: #1 Equal concencentration. ----> Movement in both directions ----> NORMAL SHAPE of red blood cell.

Effects of Osmosis & Figure 24: #2 High salt solution (water concentration low outside) --> water moves ____________ of cell --> red blood cell ___________.

Effects of Osmosis & Figure 24: #2 High salt solution (water concentration low outside) --> water moves OUT of cell --> red blood cell SHRINKS.

Effects of Osmosis & Figure 24: #3 Low salt solution (water concentration high outside) --> water moves ______ the cell --> causing the red blood cell to ____________.

Effects of Osmosis & Figure 24: #3 Low salt solution (water concentration high outside) --> water moves IN the cell --> causing the red blood cell to SWELL.

Examples of Passive Transport: _____________________ & __________________.

Examples of Passive Transport: DIFFUSION & OSMOSIS

True or False: Diffusion and Osmosis are types of active transport.

FALSE Question should say they are Passive transport

True or False: The process by which water moves across a selectively permeable membrane is called diffusion.

FALSE WATER molecules use Osmosis!

True or False: Passive transport requires the cell's own energy.

FALSE Question should say Active Transport

True or False: Osmosis is the process by which molecules tend to move from an area of higher concentration to an area of lower concentration

False WATER molecules use Osmosis. Question did not say WATER!

In ______________, water molecules diffuse through a selectively permeable membrane.

In OSMOSIS, water molecules diffuse through a selectively permeable membrane.

In diffusion, molecules move from an area of __________ concentration to an area of ____________ concentration.

In diffusion, molecules move from an area of HGHER concentration to an area of LOWER concentration.

State one reason that cells are small.

Materials move in and out more quickly than in a large cell.

______________ of sugar in ____________ of water = a concentration of ___________________________________.

ONE GRAM of sugar in ONE LITER of water = a concentration of ONE GRAM PER LITER.