Topic Test.     Shape and Form in Molecules, Biological Activity and 
                      The Chemical Reactions Characteristic of Cells                [answers given below

True/False
1.  Configuration is the shape of a molecule, which may not be altered without breaking bonds?
2.  The absorption of light causes a change in the shape of the retinal isomer in human vision?
3.  Local changes in pH, temperature, and ionic strength can change the conformation of a molecule?
4. Chemical reactivity in cells is defined as bond breaking and reforming?

Multiple Choice
5.  A redox reaction?
   
             a) transfers a phosphate from ATP to glucose
       
         b) combines two molecules with the concomitant loss of  water
   
             c) removes electrons from a donor transferring them to an acceptor
                d) none of these is a correct choice

6.  The 3-dimensional outline, contour, or surface configuration of a molecule which is formed without the breaking of chemical bonds in the molecules is its?
    
a) conformation    b) configuration     c) biological reactivity     d) spatial isomerization

7.   The 'straighter' form of the human visual pigment chromophore, retinal, which has 
      absorbed light is? 

         
a) rhodopsin     b) 11-trans-retinal     c) 11-cis-retinal     d) cis-ribosome     e) photoisomer

8.   Which of the following macromolecules are made by a condensation reaction?
        
a) proteins     b) nucleic acids     c) polysaccharides     d) phospholipids


 

 

 

 

 

 

 

 

 

 

 

Topic Test :  Answers

1.  True.  To change a molecules configuration one must break and/or reform covalent bonds. 
2.  True.  The absorption of visible light causes retinal to change from 11-cis-retinal
               to 11-trans-retinal, a straighter shape of the retinal isomer in human visual pigment?
3.  True.  Local changes in pH, temperature, and ionic strength can influence the weak 
               electrostatic forces that help hold a molecule in a specific conformation.
4. True.   The breaking and reforming of bonds is chemical reactivity.

Multiple Choice

5.  c.  A redox reaction is the removal of electrons from a donor molecules transferring them to an acceptor molecule.

6.  a.  Conformation is the shape and surface contour of  a molecule that can be formed without
           the breaking of chemical bonds is the molecules?

7.  b.   11-trans-retinal is the 'straighter' form of the human visual pigment chromophore, 
           retinal, which is formed after it has absorbed light. 

8.  e.   All of these macromolecules are made by a condensation reaction, which eliminates water.  

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