Grade 8 biology Diffusion A type of passive transportnot requiring energy involving the movement of particles from an area of higher concentration to an area of lower concentration ID: 586499
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Slide1
Transport in plants
Grade 8 biologySlide2
Diffusion
A type of passive
transport(not requiring energy)
involving the movement
of particles
from an area
of higher concentration
to an area
of lower concentration.
Diffusion
is spontaneous and automatic.Slide3
Osmosis
passage of water from a region of
high
water
concentration,
through a
semi-permeable
membrane
,
to a region of
low
water concentration.Slide4
Endosmosis
inward
osmosis
inward
passage of liquid through a membrane of a cell or cavitySlide5
Exosmosis
outward
osmosis
outward
passage of liquid through a membrane of a cell or cavitySlide6
PlasmolysisSlide7
Hypertonic hypotonic and isotonic solutions
Videos on
Elodea in hypertonic solution
Elodea in hypotonic solution
Demonstration Slide8
Turgor pressure( video)
also
called turgidity
,
is the main pressure of the cell contents against the cell wall in plant cells.
Turgor
is a force exerted outward on a plant cell wall by the water contained in the cell.
This
force gives the plant rigidity, and may help to keep it erect.
Turgor
can result in the bursting of a cell.Slide9
Exercise
Write a letter from the cell membrane to cell wall of a plant cell, explaining how their closeness or interactions depend on the availability of water in their respective surroundings.
Make sure you use all the terms you have
learnt till now !!Slide10
Wall pressure
It is the pressure exerted by the cell wall on the contents of the cell, including the cell membrane.Slide11
Turgid and flaccid cells
Plant cells need to be
turgid
(
i.e
rigid) to support plant tissues
.
Plant cells become turgid when
water
moves into the cell by osmosis, and the
central vacuole
swells and pushes against the cell wall
.
When plant cells are placed in concentrated sugar solutions they lose water by osmosis and they become "
flaccid
"; this is the exact opposite of "turgid
"
Turgid
plant cells contain more water than flaccid cells and exert a greater osmotic pressure on its cell walls.