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Section 2: Free-Response Questions 2. The chemical structure shown below is cellulose. It is

Write your answer to each part clearly. Support your answers made up of repeating glucose molecules.
with relevant information and examples. Where calculations H OH CH OH
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are required, show your work. 2
C C H H C O O

1. Metformin (Met) is a diabetes treatment drug that, in OH H H
some cases, can reduce the rate of cancer development C H C C OH H C
and mortality. In people with diabetes, blood-glucose H C O O C C H
levels are elevated. Researchers studied the effects that CH 2 OH H OH
metformin has on groups of mice that were fed two (a) Identify the type of bond joining the glucose
different diets, a standard chow diet (STD) and a high- molecules together.
fat–sucrose diet (HFS). The STD mice represented

normal and healthy individuals, while the HFS mice (b) Cellulose is rigid and gives structure to plant stems
represented people with diabetes. Four-week-old mice and cell walls. Starch is also made of repeating
were injected with tumor cells and then divided into glucose molecules, but its function is for energy
four treatment categories: a standard chow diet (STD), storage. Describe how the chemical structures of
a standard chow diet plus metformin (STD + Met), a these molecules are a major factor in their func-
high-fat–sucrose diet (HFS), and a high-fat–sucrose tional difference within living systems.
diet plus metformin. Tumor growth was monitored (c) Describe the sequence of chemical events which
over a period of 25 days and the results are shown in leads to building the polymer cellulose from glucose
the graph. monomers.
(d) Explain the difference between the sequence of
2000 chemical events to build cellulose with the chemical
STD events necessary to break down cellulose. Use
Tumor volume (mm 3 ) 1000 Met HFS + Met p = 0.025 within the cellulose molecule.
STD + Met
1500
arrows to represent where bonds would be broken
HFS

500

0
0 7 10 15 20 25
Days after tumor injection
Data from https://www.nature.com/articles/s41598-020-71946-32

(a) Diabetes is tightly linked to diet; however,

certain cases can also be attributed to genetics.
Name the class of macromolecule and a specific
macromolecule that would be most helpful in
determining a genetic predisposition to diabetes.
(b) Determine if there is a statistically significant
difference between the HFS and HFS + Met
treatments after 25 days of tumor growth. Justify
your answer.
(c) Describe the trends we would see for each
treatment if the experiment were extended for
another 10 days.
(d) Describe a possible hypothesis for this experiment.

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UNIT 1 AP PRAcTice QuesTiONs 91
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