Diffusion - Introduction
This unit we are learning about the structure and function of cells. The plasma membrane, for example, is an important structure of all cells and it is responsible for regulating the passage of materials into and out of the cell. Plasma membranes are differentially (selectively) permeable, meaning some substances are allowed to enter and exit the cell, while the movement of other materials is either carefully regulated or blocked. Two ways in which materials can move
freely
across the cell membrane are
diffusion
and
osmosis
.
Diffusion
is the movement of
solutes
(material dissolved in liquid) from an area of high concentration to an area of low concentration. If these areas are separated by a membrane, that membrane may or may not be permeable to the solute. The membrane is always permeable to water though and the movement of water across a membrane is a special form of diffusion called
osmosis
.
We will be using
dialysis tubing
to simulate a semipermeable membrane. This tubing allows small molecules (e.g., water, ions, glucose) to pass while preventing large molecules (e.g., macromolecules like proteins, starch, glycogen) from moving across. Be sure you have read over the suggested material before starting this exercise and that you have reviewed the following video:
Diffusion and Osmosis (Links to an external site.)
When you are ready to begin, open the
Unit 3 Experiment Answer Sheet
and answer the questions associated with the first exercise.
Osmosis - Introduction
In our second exercise this unit, we will to take a closer look at
osmosis
; the movement of water across a membrane. The direction water moves depends on the relative concentration of
solute
molecules on either side of the membrane (in this case, these solutes are not able to cross the membrane). Furthermore, the presence or absence of cell walls (e.g., in plant cells) influences how cells respond to osmotic fluctuations in their environment. This exercise will examine the forces that determine whether water moves into or out of a cell.
We will be using the following website in this exercise. Be sure you are able to access and use this website before starting.
The Biology Place. No Date. Osmosis: Movement of Water across Membranes (Links to an external site.)
Open the
Unit 3 Experiment Answer Sheet
and complete the questions for this exercise.
.
Diffusion - IntroductionThis unit we are learning about the .docx
1. Diffusion - Introduction
This unit we are learning about the structure and function of
cells. The plasma membrane, for example, is an important
structure of all cells and it is responsible for regulating the
passage of materials into and out of the cell. Plasma membranes
are differentially (selectively) permeable, meaning some
substances are allowed to enter and exit the cell, while the
movement of other materials is either carefully regulated or
blocked. Two ways in which materials can move
freely
across the cell membrane are
diffusion
and
osmosis
.
Diffusion
is the movement of
solutes
(material dissolved in liquid) from an area of high
concentration to an area of low concentration. If these areas are
separated by a membrane, that membrane may or may not be
permeable to the solute. The membrane is always permeable to
water though and the movement of water across a membrane is a
special form of diffusion called
osmosis
.
We will be using
dialysis tubing
to simulate a semipermeable membrane. This tubing allows
small molecules (e.g., water, ions, glucose) to pass while
2. preventing large molecules (e.g., macromolecules like proteins,
starch, glycogen) from moving across. Be sure you have read
over the suggested material before starting this exercise and that
you have reviewed the following video:
Diffusion and Osmosis (Links to an external site.)
When you are ready to begin, open the
Unit 3 Experiment Answer Sheet
and answer the questions associated with the first exercise.
Osmosis - Introduction
In our second exercise this unit, we will to take a closer look at
osmosis
; the movement of water across a membrane. The direction
water moves depends on the relative concentration of
solute
molecules on either side of the membrane (in this case, these
solutes are not able to cross the membrane). Furthermore, the
presence or absence of cell walls (e.g., in plant cells) influences
how cells respond to osmotic fluctuations in their environment.
This exercise will examine the forces that determine whether
water moves into or out of a cell.
We will be using the following website in this exercise. Be sure
you are able to access and use this website before starting.
The Biology Place. No Date. Osmosis: Movement of Water
across Membranes (Links to an external site.)
Open the
Unit 3 Experiment Answer Sheet
and complete the questions for this exercise.
