3.E: Biological Macromolecules (Exercises)
3.1: Synthesis of Biological Molecules
Multiple Choice
Dehydration synthesis leads to formation of
A. monomers
B. polymers
C. water and polymers
D. none of the above
- Answer
-
B
During the breakdown of polymers, which of the following reactions takes place?
A. hydrolysis
B. dehydration
C. condensation
D. covalent bond
- Answer
-
A
Free Response
Why are biological macromolecules considered organic?
- Answer
-
Biological macromolecules are considered organic because they are built on a carbon framework primarily composed of carbon atoms bonded to hydrogen, oxygen, nitrogen, and other elements. Organic molecules by definition are carbon-based compounds.
3.2: Carbohydrates
Multiple Choice
An example of a monosaccharide is ________.
A. fructose
B. glucose
C. galactose
D. all of the above
- Answer
-
D
Cellulose and starch are examples of:
A. monosaccharides
B. disaccharides
C. lipids
D. polysaccharides
- Answer
-
D
Plant cell walls contain which of the following in abundance?
A. starch
B. cellulose
C. glycogen
D. lactose
- Answer
-
B
Free Response
Describe the similarities and differences between glycogen and starch.
- Answer
-
Glycogen and starch are both polysaccharides composed of glucose monomers that function in energy storage. However, they differ in that glycogen is used for energy storage in animals while starch is used for energy storage in plants. Additionally, the polysaccharide chains in starch can be branched or unbranched, where as the polysaccharide chains in glycogen and typically highly branched.
Why is it impossible for humans to digest food that contains cellulose?
- Answer
-
Human cannot digest cellulose because we lack the digestive enzymes necessary to break the β 1-4 glycosidic bonds between the glucose monomers of cellulose strands.
3.3: Lipids
Multiple Choice
Phospholipids are important components of __________.
A. the plasma membrane of cells
B. the ring structure of steroids
C. the waxy covering on leaves
D. the double bond in hydrocarbon chains
- Answer
-
A
Saturated fats have all of the following characteristics except:
A. they are solid at room temperature
B. they have single bonds within the carbon chain
C. they are usually obtained from animal sources
D. they tend to dissolve in water easily
- Answer
-
D
Free Response
Explain at least three functions that lipids serve in plants and/or animals.
- Answer
-
Fat serves as a valuable way for animals to store energy. It can also provide insulation. Phospholipids and steroids are important components of cell membranes.
3.4: Proteins
Multiple Choice
The monomers that make up proteins are called _________.
A. nucleotides
B. disaccharides
C. amino acids
D. chaperones
- Answer
-
C
The α -helix and the β -pleated sheet are part of which protein structure?
A. primary
B. secondary
C. tertiary
D. quaternary
- Answer
-
B
Mad cow disease is an infectious disease where one misfolded protein causes all other copies of the protein to begin misfolding. This is an example of a disease impacting ____ structure.
A. primary
B. secondary
C. tertiary
D. quaternary
- Answer
-
C
Free Response
Explain what happens if even one amino acid is substituted for another in a polypeptide chain. Provide a specific example.
- Answer
-
A change in gene sequence can lead to a different amino acid being added to a polypeptide chain instead of the normal one. This causes a change in protein structure and function. For example, in sickle cell anemia, the hemoglobin β chain has a single amino acid substitution. Because of this change, the disc-shaped red blood cells assume a crescent shape, which can result in serious health problems.
Describe the differences in the four protein structures.
- Answer
-
Each level of protein structure builds upon the previous one. Primary structure is the linear sequence of amino acids in a polypeptide chain. Secondary structure is the local folding of the polypeptide in some regions held predominantly by hydrogen bonding forces. Tertiary structure gives the polypeptide it's unique three-dimensional structure and the interactions among R groups create this complex three-dimensional shape. Lastly, the quaternary structures is the arrangement of multiple polypeptide chains (subunits) into a single functional protein.
3.5: Nucleic Acids
Multiple Choice
The building blocks of nucleic acids are ________.
A. sugars
B. nitrogenous bases
C. peptides
D. nucleotides
- Answer
-
D
A nucleotide of DNA may contain ________.
A. ribose, uracil, and a phosphate group
B. deoxyribose, uracil, and a phosphate group
C. deoxyribose, thymine, and a phosphate group
D. ribose, thymine, and a phosphate group
- Answer
-
C
How does the double helix structure of DNA support its role in encoding the genome?
A. The sugar-phosphate backbone provides a template for DNA replication.
B. tRNA pairing with the template strand creates proteins encoded by the genome.
C. Complementary base pairing creates a very stable structure.
D. Complementary base pairing allows for easy editing of both strands of DNA.
- Answer
-
C
Free Response
What are the structural differences between RNA and DNA?
- Answer
-
The structural differences include the following:
- Distinct sugars - RNA uses riboses whereas DNA uses deoxyribose.
- Unique pyrimidines bases - RNA uses uracil and cytosine whereas DNA uses thymine and cytosine.
- Typical number of strands - RNA is usually single stranded whereas DNA is double-stranded
What are the four types of RNA and how do they function?
- Answer
-
The four types of RNA are messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA). Their unique functions are listed below.
- mRNA - Carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are synthesized. It serves as a template for making proteins based on the copied complementary sequence of nucleotides.
- rRNA - Ensures the proper alignment of the mRNA and the Ribosomes and catalyzes peptide bond formation between two aligned amino acids
- tRNA - Carries the correct amino acid to the protein synthesis site.
- miRNA - Regulate gene expression by interfering with the expression of certain mRNA messages.
Contributors and Attributions
Remixed and/or curated from the following works:
Clark, M. A., Douglas, M., & Choi, J. (2018). 1.3.10 Review Questions and 1.3.11 Critical Thinking Questions . In Biology 2e . OpenStax (CC BY 4.0; Access for free at https://openstax.org/books/biology-2e/pages/1-introduction ).