Download Fluid Movement in Cells - St. John Paul II Collegiate

Fluid Movement in Cells
The cell membrane is a selectively
permeable membrane that encloses the
contents of a cell.
Selectively permeable means only certain
materials to cross the membrane. It
regulates the passage of substances into
or out of the cell. The membrane
regulates the passage of nutrients into
the cell and wastes out of the cell.
- A permeable membrane allows
everything to cross it.
- Impermeable lets nothing cross it.
See front board diagrams.
BLM 2-12
Diffusion
Show with beaker and food colouring.
Diffusion is the phenomenon whereby
substances become evenly distributed or
interspersed. Example: perfume – spray
it  then what happens?
Diffusion is caused by the random
movement of individual molecules. This
movement results in a net movement of
the molecules from a region where they
are at a high concentration to a region of
lower concentration. See front board.
BLM 2-13
BLM 2-14
Question?
What would happen if there were no such
thing as diffusion?
Answer:
 Cells wouldn’t function (some nutrients
couldn’t enter the cell, and some wastes
couldn’t leave the cell).
 You wouldn’t be able to smell cooking
odors.
 Insects wouldn’t pollinate flowers.
The most common substance inside and
around cells is water. Water particles
are small and can easily move into and out
of cells by diffusion. The diffusion of
water through a selectively permeable
membrane is called osmosis.
Osmosis results in a net movement of
water from a solution that has a higher
water concentration to one that has a
lower water concentration. In other
words, water will move from a solution of
lower solute concentration to one of
higher solute concentration.
Perform the lab on page 132.
Hand in data table and questions on page
133 #1-5.
A cell placed in a solution with more
solute in the environment will shrivel up.
A cell placed in a solution with less solute
in the environment will swell up.
A carrot has plant cells with a higher
solute concentration than water. As a
result, the water tends to diffuse into
them.
Fluid Movement in Plants
It is with the assistance of tissues,
plants can transport water and nutrients
throughout the whole plant. Plants have 2
types of tissues, called vascular tissue,
which connect the roots to the leaves
(like a circulatory system with veins and
arteries).
1)
Xylem tissue – transports water
and minerals absorbed by root cells to
every cell in the plant.
2)
Phloem tissue – transports sugars
produced in leaves to the whole plant.
Plants get water (and nutrients) from the
soil. Nutrients dissolve in water and
enter the plant roots. At the plant roots
are root hairs – which increase the root
surface area available for absorbing
water and minerals.
When the concentration of water in the
soil is greater than the concentration of
water in the root cells, water enters
these root hairs by osmosis.
As more water enters the root hairs, it
creates pressure that pushes water up
the plant through the xylem tissue.
At the other end of the xylem are leaves
which have stomata – which are tiny
openings in the leaf. They open and close
to allow water to escape the plant and to
exchange gases with the environment.
When the stomata are open, water exits
the plant. This loss of water from a plant
through evaporation is called
transpiration. Transpiration helps to move
water up the stem – it pulls water up the
stem.
Water in the xylem is pushed up the
stem by pressure in the roots (osmosis
also pushes water up a plant).
Lab on page 136.
BLM 2-15.
Summarize your understanding of osmosis
and diffusion in a poster.
Page 137 #1-7