1.7 Cells in 1.7 Cells in their their

EnvironmentEnvironmentRead p. 22 to 23.Read p. 22 to 23.

As you read, think about how As you read, think about how nutrients enter cells.nutrients enter cells.

Add “diffusion” to your Add “diffusion” to your vocabulary list.vocabulary list.

Page Word Definition Sketch or Example

23 Diffusion The movement of molecules from an area of higher concentration to an area of lower concentration. Think of a waterfall: it moves from high to low.

Observe your teacher adding Observe your teacher adding crystals of potassium crystals of potassium

permanganate to two beakers of permanganate to two beakers of water.water.

• What is the difference between the two beakers?

• The purple colouring spreads out much more quickly in the beaker with the hot water because those molecules are moving faster, and experiencing more collisions.

• Diffusion happens more quickly when there is more energy in the system.

• The teacher will squirt a spray of perfume at the front of the room.

• Raise your hand when you can smell it. • Does diffusion occur through air as well

as liquids?

Diffusion means…Diffusion means…• Spreading out• This is one way nutrients can enter cells

and • Wastes can leave.

Molecules can enter and Molecules can enter and leave cells because of the…leave cells because of the…

• Pores in the cell membrane.

When something has pores, When something has pores, it is…it is…

• “permeable.”• Things can pass through it.

Add “selectively permeable” Add “selectively permeable” to your vocabulary list.to your vocabulary list.

Page Word Definition Sketch or Example

22 Selectively Permeable

Page Word Definition Sketch or Example

22 Selectively Permeable

Allowing certain things to enter or leave the cell. Based partly on size, but also on shape, and electric charge.

Observe the Demonstration:Observe the Demonstration:• Can the salt crystals pass through:• A. the glass?• B. the fabric?• C. the gauze?

Could it be possible to make Could it be possible to make the salt pass through the the salt pass through the

fabric?fabric?• Dissolve the salt in water

Which of the “membranes” in Which of the “membranes” in the activity is most like a cell the activity is most like a cell

membrane. membrane.

How is a cell membrane even How is a cell membrane even better than these materials?better than these materials?

A cell membrane can pull in A cell membrane can pull in needed molecules even if they needed molecules even if they seem to big to fit through the seem to big to fit through the

pore.pore.

C.Y. U. p. 24 1,2,3,5 and 7.C.Y. U. p. 24 1,2,3,5 and 7.• Use full sentences, indicating the

question in the answer.