UNIT 6 AP BIO EXAM REVIEW | LATEST
ACTUAL QUESTIONS WITH VERIFIED
ANSWERS
TOPIC 6.1 DNA and RNA Structure - correct-answer-ENDURING UNDERSTANDING:
Heritable information provides for continuity of life.
LEARNING OBJECTIVE
IST-1.K Describe the structures involved in passing hereditary information from
one generation to the next.
ESSENTIAL KNOWLEDGE
IST-1.K.1 DNA, and in some cases RNA, is the primary source of heritable
information.
IST-1.K.2 Genetic information is transmitted from one generation to the next
through DNA or RNA—
a. Genetic information is stored in and passed to subsequent generations through
DNA molecules and, in some cases, RNA molecules.
b. Prokaryotic organisms typically have circular chromosomes, while eukaryotic
organisms typically have multiple linear chromosomes.
IST-1.K.3 Prokaryotes and eukaryotes can contain plasmids, which are small extra-
chromosomal, double-stranded, circular DNA molecules.
LEARNING OBJECTIVE
IST-1.L Describe the characteristics of DNA that allow it to be used as the
hereditary material.
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ESSENTIAL KNOWLEDGE
IST-1.L.1 DNA, and sometimes RNA, exhibits specific nucleotide base pairing that
is conserved through evolution: adenine pairs with thymine or uracil (A-T or A-U)
and cytosine pairs with guanine (C-G)—
a. Purines (G and A) have a double ring structure.
b. Pyrimidines (C, T, and U) have a single ring structure.
What is the significance of this famous experiment (what does it demonstrate)? -
correct-answer-the Hershey-Chase experiments were a series of experiments
conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm
that DNA is genetic material. While DNA had been known to biologists since 1869,
many scientists still assumed at the time that proteins carried the information for
inheritance because DNA appeared to be an inert molecule, and, since it is located
in the nucleus, its role was considered to be phosphorus storage. In their
experiments, Hershey and Chase showed that when bacteriophages, which are
composed of DNA and protein, infect bacteria, their DNA enters the host bacterial
cell, but most of their protein does not. Hershey and Chase and subsequent
discoveries all served to prove that DNA is the hereditary material.
How did Crick, Watson, Franklin and Wilkins contribute to our knowledge of DNA?
- correct-answer-Combined, they revealed the double helix structure of the DNA
molecule.
Draw a plasmid. Where are plasmids found in Prokaryotic cells? Where are they
found in Eukaryotic cells (HINT consider the evolution of some Eukaryotic
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organelles!)? - correct-answer-Plasmids are small rings of DNA free floating inside
Prokaryotes. They are also found in mitochondria and chloroplasts (consider the
Endosymbiotic Theory that these organelles were once free-living prokaryotes)
Come up with some way to remember (to link the facts together) that A and G are
Purines and have a double ring, while C, T, and U are Pyrimidines and have just
one ring. Then share your idea with someone and see what idea they came up
with! - correct-answer-A and G got married and have 2 wedding rings
C, T, and U build pyramids with one ring
Briefly explain in your own words how the base pairing rules of DNA lead to its
ability to be used as the hereditary material of life (aka, to be copied and passed
to a resulting daughter cell). - correct-answer-The base pairing rules for DNA are
governed by the complementary base pairs: adenine (A) with thymine (T) in an A-
T pairing and cytosine (C) with guanine (G) in a C-G pairing. Conversely, thymine
only binds with adenine in a T-A pairing and guanine only binds with cytosine in a
G-C pairing.
A always matches with T, and G always matches with C.....but why?
Proofreading enzymes run along the DNA molecule to be sure there are no mis-
pairings between bases, but how do they know when a mistake has happened? -
correct-answer-complementary bases