Which one of the following is correct for the transmembrane proteins in lipid bilayer of plasma membrane?
They are absent in animal cells
They act as channel proteins
They are absent in plant cells
They are only externally located
B.
They act as channel proteins
The tunnel proteins or transmembrane proteins run throughout the lipid bilayer and individually or in group form channels for the passage of water and water soluble substances. The channels however, possess selective properties for passage of different ions and other polar substances.
Assertion: Translocation of sugar from source (leaf) to sink is defined as pressure flow hypothesis.
Reason: Translocation of the solute is facilitated through living phloem sieve tube cells.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Potometer works on the principle of
amount of water absorbed equals the maount transpired
osmotic pressure
root pressure
potential difference between the tip of the tube and that of the plant
A plasmolysed cell can be deplasmolysed by placing it in
isotonic solution
saturated solution
pure water or hypotonic solution
hypertonic solution
The real forces responsible for the movement of water from one cell to another cell is mainly
Osmotic Pressure (OP)
Turgor Pressure (TP)
Diffusion Pressure Deficit (DPD)
imbibition
Which one of the following does'nt help in molecule transport?
Diffusion
Osmosis
Surface tension
Active transport
What is correct about the movement of substance across the membrane in facilitated diffusion?
It is an active transport
It doesn't cause transport of molecules from low concentration to high concentration
It is insensitive to inhibitors
It is a very specific transport
