Constructed Response
The Chemistry of Life
The Chemistry of Life
Teacher Guide
Students will need about 30 minutes to complete this constructed response task.
Objectives assessed:
• Distinguish between inorganic and organic molecules.
• Identify four main groups of organic molecules: carbohydrates, lipids, proteins, and
nucleic acids.
1. A student was studying organic molecules and researching the characteristics of the four
main macromolecules of life. Compare and contrast each of the following:
• The structure and function of carbohydrates and proteins
• The structure and function of lipids and nucleic acids
Correct response(s):
Sample Correct Response:
The molecules of life are all made of carbon with other elements attached to them.
Carbohydrates can be single carbohydrate molecules, like glucose or consist of multiple
units. Some, such as starch and cellulose are large polymers. Proteins are polymers of
amino acids. Protein molecules are generally very large consisting of hundreds of amino
acids. Carbohydrates are found in chains or rings, while proteins are always found in chains.
Both these molecules of life contain carbon, hydrogen, and oxygen, but proteins also have
nitrogen linked to the carbon skeleton. This nitrogen is what distinguishes a protein from a
carbohydrate.Some proteins also contain sulfur. Peptide bonds hold proteins together
whereas carbohydrate polymers have glycosidic bonds.. Carbohydrates can have a
structural function (such as cellulose) or are involved in storing energy (such as starch) and
supplying energy to cells in the form of simple sugars. Many proteins serve as enzymes that
speed life’s chemical reactions. Other proteins, such as keratin, serve as structural parts of a
living thing.
Lipids and nucleic acids are also made of carbon, hydrogen, and oxygen, but in varying
amounts. Nucleic acids also have nitrogen as part of their molecules. Lipid molecules are
usually long carbon chains and have hydrogen attached to them. Attached to this chain is a
chemical group that varies in structure, but always contains oxygen. If a lipid has more
places for hydrogen to attach to it, it is called unsaturated. If all of the places are taken by
hydrogen, it is called saturated. Nucleic acids are large polymers made of building blocks
called nucleotides. Each nucleotide is composed of a sugar backbone (the sugars are
carbohydrates), a phosphate group, and a nitrogen base. Lipids are a large part of every
cell’s membranes. They can also serve as signaling molecules such as hormones. They are
important for storing energy in the form of fat in animals and oils in plants. Nucleic acids are
found within cells and are involved as DNA in storing the genetic code for an organism’s
traits and as RNA in the synthesis of proteins.
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The Chemistry of Life
Response scoring tool:
Score
Content
5
A score of 5 accurately describes the structures of each of the four
biomolecules and compares them with its assigned match. Details are
given about carbon skeletons and what makes the skeleton into the
designated biomolecule.
4
A score of 4 accurately describes the biomolecules in terms of structure
of carbon skeletons, but does not discuss additional elements.
Comparisons are not complete.
3
A score of 3 indicates moderate understanding of the biomolecules, but
does not discuss carbon skeletons or other attached elements.
Comparisons are weak.
2
A score of 2 shows minimal knowledge of biomolecules and does not
discuss carbon or other elements at all. There is minimal connection
between the designated biomolecules.
1
A score of 1 indicates minimal knowledge of biomolecules and does not
discuss any connections between them at all.
0
No response, or response not appropriate to the question.
Objectives assessed:
• Discuss the nature of enzymes
2. Catalase is an enzyme found in the living tissues of many animals, including beef liver.
Catalase is involved in reactions that break down hydrogen peroxide, a toxic substance,
into harmless water and oxygen. A scientist studying the characteristics of catalase
places a piece of beef liver in a test tube containing a solution of hydrogen peroxide.
• How will the presence of the beef liver affect the hydrogen peroxide solution in the
test tube?
• Suppose an individual did not have enough of the catalase enzyme in her body.
Identify the role of this enzyme in maintaining this person’s health.
Correct response(s):
Sample Correct Response: Since the beef liver contains catalase, the catalase will
efficiently break down the hydrogen peroxide into water and oxygen. A sign that this
chemical reaction is occurring would be the production of bubbles (or a gas) as the oxygen
is produced. If someone did not have enough catalase in the body toxic hydrogen peroxide, t
would not be broken down efficiently. Concentrations would build up in the body. The person
would fall ill and, if they did not receive treatment, would die.
Response scoring tool:
Score
Content
3
Accurately predicts that the beef will effectively break down the hydrogen
peroxide into water and oxygen. Also predicts that a lack of catalase in a
human body would likely cause severe illness and provides an accurate
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The Chemistry of Life
2
1
0
explanation.
Meets two of the three criteria.
Meets one of the three criteria.
No response, or response not appropriate to the question.
Objectives assessed:
• Describe the role of adenosine triphosphate in cells
3. The diagram below shows a molecule of adenosine triphosphate, or ATP.
• Use the following labels to show the structural components of ATP: A (for
Adenosine), Ribose (for sugar), and P (for phosphate groups).
• Draw an arrow to indicate where the release of the highest amount of energy
would occur.
• Explain how this energy is released.
Correct response(s):
Sample Correct Response:
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The Chemistry of Life
Response scoring tool:
Score
Content
3
Accurately labels the ATP molecule with Adenosine, Ribose, and three
“P”s. Also draws an arrow pointing to the third phosphate bond and
explains that a release of high energy occurs when this bond is broken.
2
Meets two of the three criteria.
1
Meets one of the three criteria.
0
No response, or response not appropriate to the question.
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