21.      Which of the followingterms refers to RNA only?
a.        Doublehelix
b.        Thymine
c.        Uracil
d.        Cytosine
e.        Guanine
22.      Codons are locatedon:
a.        Ribosomes                 d.        rRNA
b.        tRNA                          e.        DNA
c.        mRNA
23.      EcoR1 and HindIII are twodifferent restriction enzymes. If the DNAs of different organismsare cut as described below, which DNAs could NOT join together andbe permanently sealed?
a.     Human DNA cut with EcoR1/ chimpDNA cut with EcoR1
b.     Prokaryotic DNA cut withHindIII/ eukaryotic DNA cut with HindIII
c.     Mouse liver DNA cut with EcoR1/mouse kidney DNA cut with EcoR1
d.     Mouse DNA cut with HindIII/chimp DNA cut with HindIII
e.     Bacterial DNA cut with EcoR1/mouse DNA cut with HindIII
24.                  Organism                   Diploid Chromosome number
Crab                                       236
Human                                  46
SpiderLily                             46
Pea                                         14
Yeast  (fungus)                      12
The chromosome counts above support the idea that:
a.                    the more chromosomes a species has, the more complex it is.
b.                  the fewer chromosomes a species has, the more ancient itsevolutionary history.
c.                    all species have a unique chromosome number common only tothem.
d.                   species may differ from each other in chromosome number.
                     ÂÂ
27. Roundup-Ready â„¢ Soybeans are:
      a.   easierto harvest than other varieties.
      b.   resistant to insect attack.
      c.   higherin nutrition than other varieties.
      d.   resistant to a specific herbicide.
                                 e.        not usable infood products
28       Which of thefollowing organisms has the most chromosomes (DNA?)
           a.        a fruit fly
           b.        a human
           c.        a dog
           d.        a grassplant
           e.        you cannot tellwithout looking at cells.
                      29.      One species’ DNA differsfrom others in its _____.
           a         sugars
           b         phosphates
           c         basesequences
           d         all of theabove
                      30.      What are the base-pairingrules for DNA?
           a         A-G,T-C
           b         A-C,T-G
           c         A-U,C-G
           d         A-T,G-C
           e         either c ord