BIO 101 EXAM 3 FINAL PAPER 2026
COMPREHENSIVE QUESTIONS AND
ACCURATE SOLUTIONS
◉ 1. What region on the DNA strand must an RNA polymerase bind
to first?
Answer: RNA polymerase binds to the promoter, which is at the
beginning of the gene.
RNA polymerase also unwinds (unzips) the two strands of DNA.
◉ 1. mRNA must be processed and modified before it can leave the
nucleus. What are the three modifications that must take place?
Answer: A "cap" structure is added to the 5' end of mRNA(short
sequence of modified nucleotides).
A poly-A tail structure is added to the 3' end of mRNA (100 to
200adenines).
The cap and tail protect mRNA from degradation and help
ribosomes attach to 5' end of the mRNA molecule.
,Introns are sequences in genes that are not used for producing a
protein. Introns are removed from the mRNA.
Exons are the sequences that specify amino acids
.Tip to Remember : Exons exit the nucleus, or Exons are expressed as
a protein.
◉ 1. What is the difference between an intron and an exon? Which
one exits the nucleus?
Answer: Introns are sequences in genes that are not used for
producing a protein. Introns are removed from the mRNA.
Exons are the sequences that specify amino acids
.Tip to Remember : Exons exit the nucleus, or Exons are expressed as
a protein.
◉ 1. What is a silent mutation?
Answer: mutations in DNA that do not have an observable effect on
the organism's phenotype.
◉ 1. What is a substitution mutation?
, Answer: replacement of one DNA base pair with another.• This can
be silent if the mutated gene encodes the same protein as the
original version
◉ 1. What are insertion and deletion mutations?
Answer: An insertion mutation - adds one or more nucleotides to a
gene.
A deletion mutation - removes nucleotides.
◉ 1. Which of the following DNA strands is complementary to the
DNA sequence below.
5'-ATCGTACG-3'
a. 5'-TACCATCC-5'
b. 3'-TAGCATGC-5'
c. 5'-TAGCATGC-3'
Answer: b. 3'-TAGCATGC-5'
Because it flipped the 5' and 3' with the complimentary base pairing.
◉ What is a start codon?
COMPREHENSIVE QUESTIONS AND
ACCURATE SOLUTIONS
◉ 1. What region on the DNA strand must an RNA polymerase bind
to first?
Answer: RNA polymerase binds to the promoter, which is at the
beginning of the gene.
RNA polymerase also unwinds (unzips) the two strands of DNA.
◉ 1. mRNA must be processed and modified before it can leave the
nucleus. What are the three modifications that must take place?
Answer: A "cap" structure is added to the 5' end of mRNA(short
sequence of modified nucleotides).
A poly-A tail structure is added to the 3' end of mRNA (100 to
200adenines).
The cap and tail protect mRNA from degradation and help
ribosomes attach to 5' end of the mRNA molecule.
,Introns are sequences in genes that are not used for producing a
protein. Introns are removed from the mRNA.
Exons are the sequences that specify amino acids
.Tip to Remember : Exons exit the nucleus, or Exons are expressed as
a protein.
◉ 1. What is the difference between an intron and an exon? Which
one exits the nucleus?
Answer: Introns are sequences in genes that are not used for
producing a protein. Introns are removed from the mRNA.
Exons are the sequences that specify amino acids
.Tip to Remember : Exons exit the nucleus, or Exons are expressed as
a protein.
◉ 1. What is a silent mutation?
Answer: mutations in DNA that do not have an observable effect on
the organism's phenotype.
◉ 1. What is a substitution mutation?
, Answer: replacement of one DNA base pair with another.• This can
be silent if the mutated gene encodes the same protein as the
original version
◉ 1. What are insertion and deletion mutations?
Answer: An insertion mutation - adds one or more nucleotides to a
gene.
A deletion mutation - removes nucleotides.
◉ 1. Which of the following DNA strands is complementary to the
DNA sequence below.
5'-ATCGTACG-3'
a. 5'-TACCATCC-5'
b. 3'-TAGCATGC-5'
c. 5'-TAGCATGC-3'
Answer: b. 3'-TAGCATGC-5'
Because it flipped the 5' and 3' with the complimentary base pairing.
◉ What is a start codon?
