This is the answer key for the 3rd marking period´s partial exam.

1. CENTRO ESCOLAR SOLALTO
10th Biology
Teacher Javier Aguirre, B.A.
3rd Term 2010
NAME_________________________ Date: _____________
Biology Partial Exam No. 1
Multiple Choice: Please, circle the letter of the best answer. (7 points; 1 point
each)
1. Heterotrophs are also called _______________.
a. producers
b. autotrophs
c. consumers
d. "self-feeders"
2. What are the waste products of cellular respiration?
a. Carbon dioxide and water
b. ATP and ADP
c. Carbon dioxide and oxygen
d. Energy and glucose
3. What metabolic stage is part of both
cellular respiration and fermentation?
a. Electron transport
b. Glycolysis
c. Krebs cycle
d. ATP Synthase action
4. What is the net gain of ATP molecules produced directly by glycolysis?
a. 2
b. 4
c. 34
d. 38
5. Electron transport occurs in the _______________.
a. cytoplasm
b. matrix of the mitochondria
c. outer membrane of the mitochondria
d. inner membrane of the mitochondria

2. 6. Which molecule accepts electrons from the final carrier in the electron
transport chain?
a. NAD
b. Pyruvic acid
c. Oxygen
d. Carbon
7. Which of the following molecules is not involved in fermentation?
a. Glucose
b. Pyruvic acid
c. NADH
d. Oxygen
Short Answer: Please answer the following question with a brief but accurate
statement. (16 points; 2 points each)
1. Explain why it can be said that most of life on Earth is solar-powered.
Producers (autotrophs) depend on light energy from the sun to
execute photosynthesis. Producers and consumers depend on the
products of photosynthesis for energy to perform cellular functions.
2. Describe what happens to the chemical energy in food that is not converted
to useful cellular work.
It is released in the form of thermal energy (heat).
3. How could you measure the calorie content of a peanut in the laboratory?
Burn a peanut under an insulated container of water to convert its
stored chemical energy into thermal energy (heat). Measure the
increase in water temperature to calculate the number of calories in a
peanut.
4. Describe how energy is stored in an ATP molecule.
Energy is stored in the bonds that
connect the phosphate groups in
ATP. Each phosphate group in ATP
is negatively charged, and since
like charges repel, the crowding of
the phosphate groups in the ATP
tail contributes to the potential
energy stored in ATP.
5. What are the three main types of cellular work? Give an example of each.
Chemical work  Building a large molecule, such as a protein
Mechanical work  Contracting muscle cells
Transport work  Pumping ions across a membrane

3. 6. Summarize the steps of glycolysis.
Two (2) ATP molecules are used to split glucose into two three-carbon
molecules, which transfer electrons and H+ ions to NAD+ creating
NADH. In the next step, two (2) pyruvic acid molecules and 4 ATP
molecules are created.
7. Which stage of cellular respiration uses oxygen directly to extract chemical
energy from organic compounds? Explain the steps in this stage.
The Electron Transport Chain uses oxygen directly to extract
chemical energy from organic compounds. NADH transfers electrons
and these move from carrier to carrier, until they are pulled to oxygen
at the end of the chain. Oxygen and the electrons combine with
hydrogen ions to form water.
8. Compare and contrast fermentation that occurs in human muscle cells and
in yeast cells.
Both break down glucose without oxygen. The waste product of
fermentation in muscle cells is lactic acid. The waste product in yeast
fermentation is ethyl alcohol.
Visualizing Concepts: (6 points; 1 point each)
1. Fill in the blank spaces with the information that correctly completes this
fermentation concept map.
a. Bacterial fungi d. CO2
b. Yeast cells e. Sour taste / decomposition
c. Lactic acid f. Bubbles / it to rise

4. 2. Use the diagram below to answer the questions. (6 points; 2 points each)
a. What are the chemical reactants in photosynthesis? What are the
chemical products?
Reactants: Carbon dioxide and water
Products: Oxygen and glucose
b. What do the double arrows in each reaction indicate?
They indicate the direction in which the reaction occurs.
c. How are photosynthesis and cellular respiration related? How are
they different?
They are related because each produces chemicals used by the
other reaction. They are different because photosynthesis stores
energy in chemical compounds, while cellular respiration transfers
that energy to ATP.

5. 3. The data table below lists the kilocalories (kcal) needed for various
activities. Refer to the table to answer the questions that follow.
(6 points; 2 points each)
a. How many hours would a 67.5-kg person have to walk to use up
the energy contained in a cheeseburger containing 430 kcal?
About 2.72 hours
b. How far would this person have walked if he were walking 3 km per
hour?
About 8.16 km
c. What form of exercise would use up the cheeseburger's calories in
the shortest amount of time? Explain your answer.
The best form of exercise is running because it burns the most
calories per hour.
Applying Concepts - Analyzing Information (12 points; 4 points each)
1. Red blood cells do not contain mitochondria. Which stage or stages of sugar
breakdown can take place in these cells? Explain your answer.
Glycolysis is the only stage that does not take place in the
mitochondria. (Cytoplasm)
2. How is the process by which your body extracts energy from food similar to
how a car's engine extracts energy from fuel? How is it different?
Both use oxygen while burning organic molecules (aerobic). Both
produce water and CO2 as waste products and convert some energy
into thermal energy (heat). Our cells, however, are more efficient and
lose less energy as heat. Cars use gasoline; cells use glucose.

6. 3. Explain the following statement: Heterotrophs depend on autotrophs for
energy.
Heterotrophs cannot make their own food. They need the organic
molecules created by autotrophs for the chemical energy to support
life processes.
What's Wrong With These Statements? (6 points; 2 points each)
Briefly explain why each statement is inaccurate or misleading.
1. Plants carry out photosynthesis plus cellular respiration and animals
carry out cellular respiration.
2. NADH and FADH trap most of the energy released from food during the
Krebs cycle.
Or
Most ATP is produced from food during the Electron Transport Chain.
3. While sprinting, your muscle cells decrease cellular respiration and
increase fermentation to produce ATP.
Integration (15 points; 5 points each)
Briefly explain through a drawing the three stages of cellular respiration,
including where each one takes place and the amount of ATP that is invested
and produced with each one.