Download 2002 AP Biology Free-Response Questions Form B

2002 AP® BIOLOGY FREE-RESPONSE QUESTIONS (Form B)
BIOLOGY
SECTION II
Time—1 hour and 30 minutes
Directions: Answer all questions.
Answers must be in essay form. Outline form is not acceptable. Labeled diagrams may be used to supplement
discussion, but in no case will a diagram alone suffice. It is important that you read each question completely before
you begin to write. Write all your answers on the pages following the questions in this booklet.
1. Bacteria were cultured in a system that allowed for the continual addition of fresh nutrients and the removal
of waste products. Bacteriophage (virus) were added at the time shown and the following population changes
were observed.
(a) Describe and explain the observed results.
(b) Discuss the infection cycle of a DNA virus from attachment to lysis.
(c) Describe how the genome of a retrovirus like HIV (Human Immunodeficiency Virus) becomes
incorporated into the genome of the host cell.
Copyright © 2002 by College Entrance Examination Board. All rights reserved.
Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board.
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AP® BIOLOGY
2002 SCORING GUIDELINES (Form B)
Question 1
1. (a)
Describe and explain the observed results. (1 point for each bullet, 4 points maximum)
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1. (b)
Discuss the infection cycle of a DNA virus from attachment to lysis (4 points maximum)
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1. (c)
description only of relative numbers of bacteria and viruses over time; must include initial bacterial
growth phase
bacterial growth dynamics (exponential phase, carrying capacity)
infection phase (virus “attacks” bacteria, bacteria decline while virus multiplies)
recovery phase (resistant mutant/immune bacteria survive to reproduce, virus number drops)
co-existence phase (viruses multiply only in non-resistant/“sensitive” cells or lysogenic situation
develops)
exceptional description of a particular phase
population reaches an equilibrium
attachment to host cell (cell wall, membrane, etc., attachment to something)
penetration/injection of DNA/nucleic acid
synthesis of viral components (nucleic acids and/or proteins)
assembly/packaging of viruses
lysis (release, budding); needs details beyond simply cells burst/lysed
Describe how the genome of a retrovirus like HIV (Human Immunodeficiency Virus) becomes
incorporated into the genome of the host cell. (4 points maximum)
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retrovirus = RNA virus
use of reverse transcriptase (enzyme) to create DNA “version”
single strand to double strand conversion
enzymatic incorporation into human genome, give at least one enzyme
exceptional description of mechanism
Copyright © 2002 by College Entrance Examination Board. All rights reserved.
Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board.
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AP® BIOLOGY
2002 SCORING COMMENTARY (Form B)
Question 1
Sample B (Score 9)
In part (a), a point was earned for the infection phase. A point was also earned for the interpretation
of the populations reaching equilibrium, with an elaboration point for the description of a mutation preventing
viral attachment.
Part (b) earned a point for the virus “anchoring to the bacterium,” a point for the insertion of the viral genome
into the host cell, a point for the idea that viruses assemble inside the host, and a point for the elaborate
description of lysis.
In part (c), a point was earned for the statement that retroviruses have an RNA genome and a point for the
function of reverse transcriptase.
Sample C (Score 10)
In part (a), a point was earned for the description of the infection phase, a point for the dynamics of the bacterial
growth, a point for the survival of resistant bacteria, and a point for dynamic equilibrium.
Part (b) earned a point for attachment and another for injection of DNA. A point is earned for the synthesis of
the viral proteins, and a point for the break down of the cell membrane.
In part (c), a point was earned for stating that the genetic material of a retro virus is RNA and another for the
function of reverse transcriptase.
Sample D (Score 6)
In part (a), a point was earned for exponential growth. In part (b), a point was earned for attachment to the host
and another for injection of DNA. A point is also earned for the description of lysis.
Part (c) earned a point for RNA being the genetic material of the retrovirus and another for the function of
reverse transcriptase.
Copyright © 2002 by College Entrance Examination Board. All rights reserved.
Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board.
2