TLS Online TPP Program

#Question id: 10906


The pressure-flow model explains phloem translocation as a flow of solution (bulk flow) driven by an osmotically generated pressure gradient between source and sink.

a) Phloem translocation, both active and passive mechanisms were considered. All theories, both active and passive, assume an energy requirement in both sources and sinks.

b) In sources, energy is necessary to move photosynthate from producing cells into the sieve elements. This movement of photosynthate is called phloem loading.

c) In sinks, energy is essential for some aspects of movement from sieve elements to sink cells, which store or metabolize the sugar. This movement of photosynthate from sieve elements to sink cells is called phloem unloading.

d) The Active mechanisms of phloem transport further assume that energy is required in the sieve elements of the path between sources and sinks simply to maintain structures.

From the given statements find out the correct for pressure-flow model.

#SCPH05 I Biotechnology
  1. A, B, C and D       
  2. A, B, and C
  3. B and C only         
  4. A and D only

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TLS Online TPP Program

#Question id: 2150

#SCPH28 | Zoology

Which of the following increase(s) membrane fluidity?

TLS Online TPP Program

#Question id: 2151

#SCPH28 | Zoology

Which of the following statement(s) is (are) true of transmembrane proteins?

a. All contain a hydrophobic α helix.

b. Some serve as membrane attachment sites for peripheral membrane proteins.

c. Some contain more than one membrane-spanning domain.

d. All are asymmetrically oriented in the lipid bilayer.

TLS Online TPP Program

#Question id: 2152

#SCPH28 | Zoology

Precursors of membrane phospholipids are

a. soluble in the cytosol.                    

b. incorporated into biosynthetic intermediates.

c. sometimes complexed with fatty-acid-binding proteins.

d. stored in glycerolosomes.

e. sometimes activated by conjugation with CDP.

TLS Online TPP Program

#Question id: 2153

#SCPH28 | Zoology

Membrane phospholipids include

a. cholesterol.            

b. plasmologens.        

c. sphingolipids.         

d. triglycerides.                      

e. bile acids.

TLS Online TPP Program

#Question id: 2154

#SCPH28 | Zoology

Membrane lipids are distributed appropriately between the two leaflets of a given membrane by

a. dockases.    

b. trumpases.              

c. fatty acid desaturases.        

d. flippases.    

e. transmembrane tunnelases.

TLS Online TPP Program

#Question id: 2155

#SCPH28 | Zoology

Cholesterol is

a. unrelated to any plant lipids.                     

b. not found in chloroplast membranes.

c. encoded by an intron-containing gene on chromosome 23.

d. relatively abundant in the plasma membrane and endocytic membranes.

e. synthesized in the ER.