“Study Guide”
Chapter 3 Cell Processes and Energy
(Students: Use these pages below to help you understand the “Study Guide” you
are completing for homework.”)
Continue to next pages.
Movement of Particles
 Diffusion is …. the main method by which small molecules move across the cell
membrane from an area of greater concentration to area of lower concentration.
 “Eggsample”
= Example (Haha! A little play with
words!) – Turn to figure 8 at the top of pg. 82 and study this diagram along
with the explanation called, “Diffusion in Action”. This means to read and study
ALL the captions that belong with ‘Figure 8’!  Happy studying!
 Next,
look below & study the pictures of the 3
beackers and 3 test tubes and notice how a highly
concentrated drop of blue food coloring goes
through diffusion.
 Below, study how two different drops of food
coloring have been diffusing over time.
Movement of Particles Through Cell Linings
 Osmosis is …the diffusion of water molecules therough a selectively permeable
membrane. Cell depend on osmosis because ALL cellular processes NEED
WATER to have their processes work properly and help each cell live!!!
Eggsplaination (haha again!) =
 The above diagram (NOT on the sheet from class, but still very helpful! ) is a great
picture to illustrate OSMOSIS! Study it well. The blue water molecules from the left
side of the ‘membrane’ ( the dashed black line) are a larger concentration compared
to the blue water molecules from the right side of the black dashed line (membrane),
so…. The left side blue molecules will MOVE ACROSS & THROUGH THE
OPENINGS OF THE MEMBRANE TO GET TO THE RIGHT SIDE where there is
MORE SPACE for the blue molecules to fit! Hooray! The blue molecules ‘should’
technically balance-out where almost equal amounts of water molecules will happen
on each of the two sides of the black dashed membrane line.
 The above diagram also shows orange dots to represent salt molecules, which are
larger and on the left there’s fewer salt molecules compared to the right side of the
black dashed line membrane. So which way do you think the salt may move? To
the left, correct?!  The salt will try to balance-out in the solution of salt water as
well. This would make for ‘good dissolving’ to have occurred. Hooray! BE
CAREFUL THOUGH, because once we examine and ‘think about the salt molecules
moving across a membrane’ it’s more about regular ‘DIFFUSION’ of particles (not
the special kind of diffusion known as ‘osmosis’!!!!!!!!!!). Interesting, right?! 
 Selectively permeable membrane is….a way to describe one
physical property of the cell membrane and each membrane is actually
chemically ‘selecting’ which particles (molecules and/or atoms) are allowed to
move into and out of each cell. Things like oxygen and food molecules
(carbohydrates, lipids, and proteins) AND water are some VERY IMPORTANT
molecules that need to move into each cell for its survival. Also, certain
molecules MUST leave each cell also, like carbon dioxide, which is a compound
that is produced in your cells as a waste product. Our cells must rid of the
carbon dioxide for our cells to survive (happily the carbon dioxide certain
organisms like animals get rid of, the plants in the plant kingdom will have their
cells take-in the carbon dioxide… plant cells give-off oxygen as one of their
waste products. Lucky for us, we can inhale the oxygen that the plants
exhale!!!!!!!!!!!! Cool – it’s an example of what we call, ‘symbiosis’ between
various types of organisms!!!)
This diagram below will help you with the
‘EFFECTS of OSMOSIS on Cells”
(ALSO use pg. 83 to help you understand the
‘Effects of Osmosis on Cells’)
Explanation of 3 Red Blood Cells Above =
 The first picture of the red blood cell on the left side, above is a NORMAL RED
BLOOD CELL (Hello Greg! Our blood cell from class is Greg!:) ). Notice how
water molecules (black dots) are equally spaced inside the cell AND outside the
cell. A great picture of ‘HOMEOSTASIS’ as well is this first pic of a red blood
cell.
 The middle picture of the red blood cell is showing the water molecules in the
process of LEAVING THE cell, so the cell SHRINKS/ SHRIVELS-Up! ;0 oh no!!
In other words, the water molecules are going through osmosis from the inside to
the outside.
 The 3rd picture/ to the far right of the red blood cell is enlarging, getting ready to
possibly burst open!!!!!!!!!! This is because water molecules have already
diffused/ went through osmotic process from the outside of the cell where there
used to be more concentration of water molecules TO the inside of the cell where
there was less water molecules but more space to fit-in the on-coming water
molecules flooding into the cell. These water molecules kept entering INTO the
cell and that is how it is enlarging!!!!!! ;0
 Passive and Active Transport (Study the colorful
diagrams below to help you understand ‘passive’
and ‘active’ transporting. Cool!)
 Passive Transport is…the movement of dissolved materials through a cell
membrane without using cellular energy. (pg. 84 in textbook)
 Active Transport is…the movement of materials through a cell membrane using
cellular energy. Active transport requires the cell to use its own energy, while passive
transport does not. (textbook pg. 84)
 Engulfing is…a form of active transport. Typically, organisms like amoebas,
perform the process of ‘engulfing’. This means the amoeba, being a single-celled
organism, makes its membrane surround a smaller organism/ it’s food and then it
gets to ‘eat’ and ‘drink’ this way!