Carbohydrates
Which carbohydrate is correctly matched with its function?
A) Starch – long-term energy storage in animals
B) Glycogen – short-term glucose storage in muscle and liver cells
C) Cellulose – storage polysaccharide in plants
D) Chitin – carbohydrate used for photosynthesis in plants
B) Glycogen – short-term glucose storage in muscle and liver cells
Which type of linkage is typically found in lipids, such as triglycerides, connecting glycerol to fatty acids?
A) Glycosidic linkage
B) Peptide linkage
C) Phosphodiester linkage
D) Ester linkage
D) Ester linkage
What type of bond would you expect to find between the carboxyl group of one amino acid and the amino group of another in a polypeptide chain?
A) Glycosidic linkage
B) Phosphodiester linkage
C) Peptide bond
D) Ester linkage
C) Peptide bond
Which of the following is a purine base found in both DNA and RNA?
A) Thymine
B) Cytosine
C) Adenine
D) Uracil
C) Adenine
Amino acids are the building blocks of proteins, but what gives each of the 20 types its unique personality?
A) The number of carbon atoms in their backbone.
B) The differing side chains.
C) The presence of a sugar molecule in their structure.
D) The type of peptide bond they form.
B) The differing side chains.
In forming a disaccharide, what happens to the hydroxyl groups of the two monosaccharides?
A) They combine with oxygen to form ATP
B) One hydroxyl is replaced by a carbonyl group
C) They react to release a water molecule and form a covalent bond
D) They are removed completely with no byproduct
C) They react to release a water molecule and form a covalent bond
Fatty acids come in two flavors: saturated and unsaturated. What’s the key difference that makes unsaturated fatty acids bend and twist?
A) Saturated fatty acids have double bonds, causing bending.
B) Unsaturated fatty acids have one or more double bonds.
C) Saturated fatty acids have fewer hydrogen atoms.
D) Unsaturated fatty acids are always shorter in length.
B) Unsaturated fatty acids have one or more double bonds.
What environmental factor is least likely to directly cause denaturation by disrupting the weak interactions in tertiary and quaternary structures?
A) Extreme changes in pH, altering ionic bonds between R groups.
B) High temperatures, breaking hydrogen bonds and hydrophobic interactions.
C) Increased salt concentration, disrupting ionic and hydrogen bonds.
D) A single amino acid substitution in the primary structure.
D) A single amino acid substitution in the primary structure.
Imagine that adenine could pair with cytosine instead of thymine. What would most likely happen during DNA replication?
A) The base-pairing rules would still work, and replication would remain error-free
B) The double helix would have irregular shapes and errors in genetic information
C) The sugar-phosphate backbone would be unable to hold the strands together
D) Proteins would not require RNA to be made
B) The double helix would have irregular shapes and errors in genetic information
Which type of linkage is formed between monosaccharides to create disaccharides or polysaccharides in carbohydrates?
A) Peptide linkage
B) Glycosidic linkage
C) Phosphodiester linkage
D) Hydrogen linkage
B) Glycosidic linkage
When glucose exists in its ring form, the hydroxyl group on carbon-1 can be positioned either below or above the plane of the ring. This difference leads to:
A) Different disaccharide combinations
B) The distinction between α and β glucose
C) The loss of ability to form polymers
D) The conversion of glucose to fructose
B) The distinction between α and β glucose
Phospholipids are the ultimate multitaskers in cell membranes. What makes them amphipathic and perfect for forming bilayers?
A) They have a hydrophilic tail and a hydrophobic head.
B) They have a hydrophobic phosphate group and hydrophilic fatty acids.
C) They have a hydrophilic head and hydrophobic fatty acid tails.
D) They are entirely hydrophobic and repel water completely.
C) They have a hydrophilic head and hydrophobic fatty acid tails.
How does the precise folding of a protein’s polypeptide chain enable its specific function?
A) The linear amino acid sequence alone determines its role without folding.
B) The polypeptide’s precise twists, folds, and coils form a unique shape critical for its role.
C) The protein’s shape prevents interactions with other molecules.
D) The unfolded polypeptide chain provides flexibility for all functions.
B) The polypeptide’s precise twists, folds, and coils form a unique shape critical for its role.
Nucleotides are the monomers of nucleic acids, but what three components come together to form this essential unit?
A) Nitrogenous base, hexose sugar, and phosphate group
B) Nitrogenous base, pentose sugar, and phosphate group
C) Nucleoside, phosphate group, and glycosidic bond
D) Nitrogenous base, pentose sugar, and sulfate group
B) Nitrogenous base, pentose sugar, and phosphate group
Sickle-cell disease shows how a tiny change can wreak havoc. What causes this disorder at the molecular level?
A) A complete rearrangement of the protein’s quaternary structure.
B) A single amino acid substitution in hemoglobin’s primary structure.
C) The loss of an amino acid in the primary structure
D) The addition of an extra polypeptide chain to hemoglobin.
B) A single amino acid substitution in hemoglobin’s primary structure.
Plants and animals both store energy as polysaccharides, but they do it differently. What’s the key difference between starch in plants and glycogen in animals?
A) Starch is stored in liver cells, while glycogen is in chloroplasts.
B) Starch is a linear chain, while glycogen is highly branched.
C) Starch is made of glucose monomers, while glycogen is not.
D) Starch is a plant polysaccharide, while glycogen is an animal polysaccharide.
D) Starch is a plant polysaccharide, while glycogen is an animal polysaccharide.
A fat molecule, or triacylglycerol, is like a molecular trio. What are the key components that come together to form this energy-packed structure?
A) Three glucose molecules and a phosphate group.
B) Glycerol and three fatty acids joined by ester linkages.
C) Two amino acids and a glycerol backbone.
D) A steroid ring and a hydroxyl group.
B) Glycerol and three fatty acids joined by ester linkages.
Proteins are the workhorses of the cell, making up over half its dry weight. What diverse role do they not typically play, according to their many functions?
A) Acting as enzymes to speed up chemical reactions.
B) Serving as the primary energy storage molecule.
C) Providing structural support like keratin in hair.
D) Transporting substances like hemoglobin in blood.
B) Serving as the primary energy storage molecule.
DNA and RNA have distinct structural personalities. What key feature differentiates DNA from RNA?
A) DNA uses ribose sugar, while RNA uses deoxyribose sugar.
B) DNA’s two polynucleotide strands run antiparallel, while RNA is a single chain.
C) DNA contains uracil, while RNA contains thymine.
D) DNA forms a single polypeptide chain, while RNA forms a double helix.
B) DNA’s two polynucleotide strands run antiparallel, while RNA is a single chain.
Which of the following correctly identifies the primary structural components of phospholipids found in eukaryotic cell membranes?
A) Glycerol backbone, three fatty acids, and a phosphate polar head group
B) Glycerol backbone, two fatty acids, and a phosphate group with a polar head group
C) Sphingosine backbone, one fatty acid, and a phosphate group with a polar head group
D) Cholesterol core, one fatty acid, and a polar head group
B) Glycerol backbone, two fatty acids, and a phosphate group with a polar head group
Cellulose is the tough guy of plant cell walls, but what makes its structure different from starch, even though both are glucose polymers?
A) Cellulose uses α-glucose monomers, while starch uses β-glucose.
B) Cellulose has 1–4 β-glucose linkages, while starch has 1–4 α-glucose linkages.
C) Cellulose is a disaccharide, while starch is a monosaccharide.
D) Cellulose forms ring structures, while starch remains linear.
B) Cellulose has 1–4 β-glucose linkages, while starch has 1–4 α-glucose linkages.
Phospholipids are the master builders of cell membranes, creating a barrier that’s both selective and dynamic. What unique behavior do phospholipids exhibit when added to water, making them essential for life?
A) They dissolve completely, forming a uniform solution.
B) They self-assemble into a bilayer with hydrophobic tails facing inward.
C) They form rigid, crystalline structures that exclude water.
D) They break apart into individual glycerol and fatty acid components.
B) They self-assemble into a bilayer with hydrophobic tails facing inward.
A protein loses its normal shape after being exposed to high heat, but the peptide bonds between amino acids remain intact. Which levels of structure are most directly affected?
A) Only primary
B) Secondary, tertiary, and quaternary
C) Only tertiary
D) Primary and secondary
B) Secondary, tertiary, and quaternary
In DNA, if a strand has the sequence 5′-ATCG-3′, what is the complementary strand?
A) 5′-TAGC-3′
B) 3′-TAGC-5′
C) 5′-GCTA-3′
D) 3′-GCTA-5′
B) 3′-TAGC-5′
If the DNA template strand has the sequence 5′-GATCGT-3′, what is the sequence of the complementary RNA strand produced?
A) 5′-CUAGCA-3′
B) 3′-CUAGCA-5′
C) 5′-GAUCGU-3′
D) 3′-GAUCGU-5′
A) 5′-CUAGCA-3′