Biology Questions and Answers
- What is the wall resistance
of plant cells? Does this
resistance facilitate or make
difficult the entrance of water
into the cell?
Wall resistance,is the pressure made by the distension or turgor pressure (TP),
of the plant cell wall in opposition to the
increase oresistance works against thf the cell volume. Te entrance ohe wall (^) f
water in the cell, i.e., it acts forcing the
exiting oentrance f water of the solvent band compensating ty osmosis.he
- What does the formula
DPD = SF – TP mean?
DPD is the abbreviation opressure deficit, SF (suction fof diffusionrce) is th (^) e
vacuolar turgor pressure.osmotic pressure and TP is the
The difference between SF andetermines whether water tends or notd TP (^)
to enter the cell. Iand water tends to ef SF > nter the cell byTP, DPD > 0
osmosis. If TP > SF, DPD < 0 and water
cannot enter the cell by osmosis.
- What are the values of
DPD for plant cells under
hypertonic, isotonic and
hypotonic media?
In plant cells under hypertonic medium
there is loss of water > 0 (the vacuolar pressure is highfor the exterior, SF
because it is concentrated) and TP = 0
(there is no distension since the cellular volumof the cell walle is reduced) so (^)
DPD = SF. These cells are called
plasmolysed cells, situationcharacterized by the retraction (^) of the
cell membrane that detach from the cell
wall.
In plant cells under isotonic medium
there is no increase owater volume, SF > 0 f the internaland TP = 0 (since (^)
the cell wall is not distended). The cell
membrane sligand in this situation the htly touches thcell is called ae cell wall
flaccid cell.
In plant cells under hypotonic medium
there is tendency of water to enter, SF= TP (since the osmotic pressure is
totally compensated by the distension of
the cell wall) ahas expanded itself to this pond DPD = 0. The cell thatint is
called a turgid cell.
- What is the formula of the
DPD for withered (shrunken)
plant cells? How is that
situation possible?
Withered plant cellsshrunk due to loss of water are those tby hat have
evaporation replacement. In this situation twithout enough (^) he cell
membrane retracts and detaches from
the cell wall. Texpands in length to stimulate thhe cell wall moreovere
entrance of water making TP < 0. Since
DPD = SF – TP its formula becomes DPD and TP is ne= SF + |gative (TP|.< 0)
- What is deplasmolysis of
plant cells?
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