MMSC491 EXAM WITH CORRECT ANSWERS 2026./GRADED A+ /JUST RELEASED !!!

MMSC 491/691 Exam WITH CORRECT
ANSWERS 2026

1. guanine and uracil - ANSWER-In a DNA double helix each type
of base forms a stable base pair with only one type of base.
When bases on an RNA strand are involved in base pairing,
which bases can form stable base pairs with more than one
type of base?



a. adenine and uracil
b. cytosine and uracil
c. guanine and uracil
d. uracil



2. Purines carry an amino group, unlike pyrimidines - ANSWER-
Regarding the structure of bases in nucleic acids, which, if
any, of the following statements is incorrect?



a. Pyrimidines have a single heterocylic ring consisting of
four carbon atoms plus two nitrogen atoms that are
linked to the same carbonyl (-C=O) group
b. Purines have two heterocyclic rings, each with two
nitrogen atoms
c. Thymine = 5-methyluracil
d. Purines carry an amino group, unlike pyrimidines



3. The internal sugar residues in a DNA strand normally have
free hydroxyl groups, unlike those in an RNA strand. -
ANSWER-Regarding the sugar residues in nucleic acids, which,
if any, of the following statements is incorrect?

, a. The sugar is always based on a heterocyclic ring that
consists of one oxygen atom and four carbon atoms, one
of which is connected to a fifth carbon atom, the 5?
carbon atom.
b. The internal sugar residues in a DNA strand normally
have free hydroxyl groups, unlike those in an RNA
strand.
c. Bases are covalently linked to the carbon 1? atoms of the
sugars.
d. Neighboring sugar residues are linked to each other by a
phosphodiester bond that connects the 3' carbon atom
on one sugar to the 5' carbon atom of its neighbor.



4. DNA replication is said to be semi-conservative because for
each DNA helix only one strand serves as a template for new
DNA synthesis. - ANSWER-Regarding DNA replication, which, if
any, of the following statements is incorrect?



a. DNA replication is said to be semi-conservative because
for each DNA helix only one strand serves as a template
for new DNA synthesis.
b. The two DNA strands of the parental DNA helix are
unwound using a DNA helicase.
c. The replication fork marks the point at which DNA is
actively being replicated from a single DNA duplex to
form new DNA strands.
d. The synthesis of new DNA strands always proceeds in the
5' --> 3' direction.



5. A DNA polymerase always requires a DNA template to
synthesize a complementary DNA. - ANSWER-Regarding DNA
replication and DNA synthesis, which, if any, of the following
statements is incorrect?



a. The leading strand is replicated continuously.

, b. The lagging strand is replicated discontinuously: the new
DNA is synthesized as short pieces of DNA that must be
ligated together.
c. A DNA polymerase always requires a DNA template to
synthesize a complementary DNA.
d. A DNA polymerase requires a short RNA primer when
synthesizing new DNA strands using a DNA template.



6. A functional RNA that is not translated to make a protein. -
ANSWER-Which is the best definition of noncoding RNA?



a. A mutant mRNA that is not capable of making a protein.
b. Any RNA sequence that is not translated to make a
protein
c. Any RNA sequence in an mRNA, or in the primary
transcript used to make the mRNA, that is not translated
to make a protein.
d. A functional RNA that is not translated to make a
protein.



7. 2n chromosomes, DNA content of 2C in G1; 2n chromosomes,
DNA content of 4C in G2. - ANSWER-If we take the number of
chromosomes in a haploid sperm cell or egg cell to be n and
the total content of genomic DNA to be C, what is the number
of chromosomes and the total genomic DNA content of a
diploid G1 phase cell and in a diploid G2 phase cell from the
same organism.



a. n chromosomes, DNA content of 2C in G1; 2n
chromosomes, DNA content of 4C in G2.
b. 2n chromosomes, DNA content of 2C in G1; 4n
chromosomes, DNA content of 4C in G2.
c. 2n chromosomes, DNA content of 2C in G1; 4n
chromosomes, DNA content of 2C in G2.
d. 2n chromosomes, DNA content of 2C in G1; 2n
chromosomes, DNA content of 4C in G2.