Bio 1500 Exam 5 Questions And Answers
|Latest 2025 | Guaranteed Pass
In his work with pneumonia-causing bacteria and mice, Griffith found that __________. -
Answer✔some substance from pathogenic cells was transferred to nonpathogenic cells, making
them pathogenic
What is the basis for the difference in how the leading and lagging strands of DNA molecules
are synthesized? - Answer✔dna polymerase can join new nucleotides only to the 3' end of a
growing strand
In analyzing the number of different bases in a DNA sample, which result would be consistent
with the base-pairing rules? - Answer✔A + G = C + T
The elongation of the leading strand during DNA synthesis __________. - Answer✔depends on
the action of DNA polymerase
In a nucleosome, the DNA is wrapped around __________. - Answer✔histones
Which of the following sequences in double-stranded DNA is most likely to be recognized as a
cutting site for a restriction enzyme?
1. acca and tggt
2. aaaa and tttt
3. ggcc and ccgg
4. aagg and ttcc
5. agtc and tcag - Answer✔ggcc
ccgg
(restriction sites are typically palindromic)
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two
more generations (two rounds of DNA replication). DNA extracted from these cells is
centrifuged. What density distribution of DNA would you expect in this experiment? -
Answer✔one low-density and one intermediate-density band
1|Page
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 1:27PM. A+
A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for
DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA
molecule consists of a normal strand paired with numerous segments of DNA a few hundred
nucleotides long. What has she probably left out of the mixture? - Answer✔DNA ligase
The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an
uncommon base, opposite thymine. What combination of proteins could repair such damage? -
Answer✔nuclease, DNA polymerase, DNA ligase
During Griffith's experiments with Streptococcus pneumoniae in mice, material from _____
bacteria transformed _____ bacteria. - Answer✔heat-killed virulent ... living nonvirulent
Avery and his colleagues' 1944 experiment showed that DNA _____. - Answer✔was the
substance that transformed the bacteria in Griffith's experiment
A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage
T4. If this composite phage were allowed to infect a bacterium, the phages produced in the
host cell would have _____. - Answer✔the protein and DNA of T4
In an important experiment, a radioactively labeled bacteriophage was allowed to infect
bacteria. In a first trial, the phage contained radioactive DNA, and radioactivity was detected
inside the bacteria. Next, phage containing radioactive protein was used, and the radioactivity
was not detected inside the bacteria. These experiments led to the conclusion that _____. -
Answer✔the genetic material of the phage is DNA
Monomers for the synthesis of DNA are called _____. - Answer✔nucleotides
Chargaff found that for DNA _____. - Answer✔the ratio of A to T is close to 1:1 and the ratio of
G to C is close to 1:1
What technique was most helpful to Watson and Crick in developing their model for the
structure of DNA? - Answer✔X-ray crystallography
In DNA, the two purines are _____, and the two pyrimidines are _____. - Answer✔adenine and
guanine ... cytosine and thymine
Which of the following is correct?
1. Adenine forms two hydrogen bonds with guanine; thymine forms three hydrogen bonds with
cytosine.
2. Adenine forms three hydrogen bonds with thymine; guanine forms two hydrogen bonds with
cytosine.
3. Adenine forms two covalent bonds with thymine; guanine forms three covalent bonds with
cytosine.
4. Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with
cytosine.
2|Page