WGU C190 Objective Assessment | Introduction to Biology | 2026/2027 Page 1
WGU C190 OBJECTIVE ASSESSMENT
Introduction to Biology | Q/A | 100% Correct Verified Answers | LATEST
2026/2027 Update - Aligned with WGU C190 Course Competencies
Section 1: Basic Chemistry and Biological Molecules (Q1-Q15)
Q1: A biology student is analyzing an unknown atom and determines it has 6 protons, 6 neutrons, and 6 electrons. She then
examines a second atom of the same element that has 6 protons, 7 neutrons, and 6 electrons. What is the relationship
between these two atoms?
A. They are ions with different charges
B. They are isotopes of the same element [CORRECT]
C. They are different elements
D. They are isotones with the same neutron count
Correct Answer: B
Rationale: Both atoms have 6 protons, identifying them as carbon. They differ in neutron number (6 vs 7), making them isotopes — specifically
carbon-12 and carbon-13. Isotopes have the same atomic number but different mass numbers.
Q2: Sodium chloride (NaCl) dissolves readily in water, producing Na and Cl ions. What type of chemical bond was
broken when NaCl dissolved, and what property of water enabled this process?
A. Covalent bond; water's ability to form hydrogen bonds with Na and Cl
B. Ionic bond; water's polarity allows it to surround and separate the ions [CORRECT]
C. Hydrogen bond; water's high specific heat destabilizes the crystal lattice
D. Metallic bond; water's cohesive forces pull the metal ions apart
Correct Answer: B
Rationale: NaCl is held together by ionic bonds formed through electron transfer from Na to Cl. Water's polarity — with its partial negative
oxygen and partial positive hydrogens — allows it to hydrate and separate the ions, dissolving the crystal.
Q3: Which type of chemical bond involves the sharing of electron pairs between atoms and is the strongest bond found in
biological molecules?
A. Hydrogen bond
B. Ionic bond
C. Covalent bond [CORRECT]
D. Van der Waals interaction
Correct Answer: C
Rationale: Covalent bonds involve the sharing of one or more electron pairs between atoms and are the strongest bonds commonly found in
biological molecules. They form the backbone of organic compounds such as proteins, carbohydrates, and nucleic acids.
Q4: During a laboratory exercise, a student notices that water forms droplets that bead up on a freshly waxed car surface
but spreads out and soaks into a cotton shirt. Which properties of water best explain these observations?
A. High specific heat and high heat of vaporization
B. Cohesion and adhesion [CORRECT]
C. Solvent properties and evaporative cooling
D. Low density as a solid and high surface tension
Correct Answer: B
Rationale: Water beading on the waxed surface demonstrates cohesion — water molecules attracting each other due to hydrogen bonding.
Water spreading into cotton demonstrates adhesion — water molecules attracting to the polar cellulose fibers in the fabric.
Q5: A researcher is studying why coastal climates tend to have milder temperature fluctuations compared to inland areas
at the same latitude. Which property of water is most responsible for this phenomenon?
WGU C190 Introduction to Biology Practice Examination
,WGU C190 Objective Assessment | Introduction to Biology | 2026/2027 Page 2
A. Water is an excellent solvent for ionic and polar substances
B. Water has a high specific heat capacity [CORRECT]
C. Water exhibits strong cohesive forces at its surface
D. Water expands when it freezes, becoming less dense
Correct Answer: B
Rationale: Water's high specific heat means it absorbs or releases large amounts of energy with relatively little temperature change. This
property allows oceans and large bodies of water to moderate nearby coastal temperatures, reducing extreme fluctuations.
Q6: When an athlete sweats during intense exercise, the evaporation of water from the skin surface helps cool the body.
What property of water is primarily responsible for this cooling effect?
A. High specific heat
B. Evaporative cooling [CORRECT]
C. Cohesion among water molecules
D. Water's role as a universal solvent
Correct Answer: B
Rationale: Evaporative cooling occurs because the molecules with the highest kinetic energy (the hottest ones) escape from the liquid surface as
gas, lowering the average kinetic energy and thus the temperature of the remaining liquid. This is why sweating effectively cools the body.
Q7: A clinical lab technician measures a patient's blood sample and finds a hydrogen ion concentration [H ] of 1 × 10 ⁸
M. What is the pH of this sample, and how does it compare to a neutral pH of 7?
A. pH 8; 10 times more basic than neutral [CORRECT]
B. pH 8; 10 times more acidic than neutral
C. pH 6; 10 times more acidic than neutral
D. pH 8; 100 times more basic than neutral
Correct Answer: A
Rationale: pH is calculated as −log[H ]. For [H ] = 1 × 10 ⁸ M, pH = 8. The pH scale is logarithmic, so each unit change represents a
tenfold change in H concentration. A pH of 8 is 10 times more basic (lower H ) than a neutral pH of 7.
Q8: A patient with diabetic ketoacidosis has blood pH dropping from 7.4 to 7.1. The body responds by using the
bicarbonate buffer system. Which of the following best describes how this buffer system minimizes the pH change?
A. The buffer donates H ions to neutralize the excess OH in the blood
B. The buffer accepts H ions, converting HCO₃ to H₂CO₃ and reducing acidity [CORRECT]
C. The buffer releases OH ions to directly neutralize all free H ions
D. The buffer raises blood temperature to accelerate acid breakdown
Correct Answer: B
Rationale: The bicarbonate buffer system resists pH changes by accepting excess H ions: H + HCO₃ → H₂CO₃. This removes free
hydrogen ions from solution, preventing the blood from becoming too acidic and helping maintain homeostasis.
Q9: A nutrition scientist is comparing the structural carbohydrates found in different organisms: starch in potatoes,
glycogen in human muscle, cellulose in plant cell walls, and chitin in insect exoskeletons. What do all four of these molecules
have in common?
A. They are all composed of glucose monomers linked by the same type of glycosidic bonds
B. They are all polysaccharides that serve as structural or energy-storage molecules [CORRECT]
C. They are all digestible by human enzymes and provide equal caloric value
D. They are all branched polymers containing both α and β glycosidic linkages
Correct Answer: B
Rationale: All four are polysaccharides — long polymers of monosaccharide units. Starch and glycogen store energy, while cellulose and chitin
serve structural roles. However, they differ in their glycosidic bond types (α vs β), branching patterns, and digestibility by humans.
Q10: A food scientist is comparing butter (solid at room temperature) with olive oil (liquid at room temperature). Which
structural difference between their fatty acid components best explains this difference in physical state?
A. Butter contains phospholipids while olive oil contains triglycerides
B. Butter has a higher proportion of saturated fatty acids with straight chains that pack tightly [CORRECT]
WGU C190 Introduction to Biology Practice Examination
, WGU C190 Objective Assessment | Introduction to Biology | 2026/2027 Page 3
C. Olive oil contains primarily trans fats that prevent solidification
D. Butter contains more double bonds creating kinks that increase melting point
Correct Answer: B
Rationale: Saturated fatty acids have no double bonds, allowing their hydrocarbon chains to pack tightly together, resulting in a solid state at
room temperature. Unsaturated fatty acids (abundant in olive oil) have cis double bonds that create kinks, preventing tight packing and keeping
them liquid.
Q11: A biochemist synthesizes a short polypeptide by linking three amino acids together in a dehydration reaction. Which
bond is formed between the amino acids, and what is released as a byproduct?
A. A hydrogen bond; water is released
B. A peptide bond; a molecule of water is released [CORRECT]
C. A peptide bond; carbon dioxide is released
D. A glycosidic bond; a molecule of water is released
Correct Answer: B
Rationale: Peptide bonds form through dehydration synthesis (condensation) between the carboxyl group of one amino acid and the amino
group of another, releasing H₂O. This covalent bond is the defining feature linking amino acids into polypeptide chains.
Q12: Which level of protein structure involves the coiling or folding of the polypeptide chain into patterns such as alpha
helices and beta sheets, stabilized primarily by hydrogen bonds?
A. Primary structure
B. Secondary structure [CORRECT]
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Secondary structure refers to local folding patterns — most commonly alpha helices and beta pleated sheets — stabilized by
hydrogen bonds between backbone amide and carbonyl groups. Primary structure is the amino acid sequence; tertiary structure is the overall
3D shape; quaternary involves multiple subunits.
Q13: A researcher is studying how the enzyme lactase breaks down the sugar lactose into glucose and galactose. When she
adds a molecule that closely resembles lactose to the reaction mixture, the rate of lactose breakdown decreases. What type
of inhibition is occurring, and how does the inhibitor work?
A. Non-competitive inhibition; the inhibitor binds to an allosteric site
B. Allosteric inhibition; the inhibitor changes the enzyme's overall shape
C. Competitive inhibition; the inhibitor competes with lactose for the active site [CORRECT]
D. Irreversible inhibition; the inhibitor permanently destroys the enzyme
Correct Answer: C
Rationale: A molecule resembling the substrate that binds to the active site and reduces reaction rate describes competitive inhibition. The
inhibitor and substrate compete for the same active site. Increasing substrate concentration can overcome this type of inhibition.
Q14: A molecular biologist isolates a nucleic acid sample from a virus and finds that it contains the sugar ribose, the base
uracil, and is single-stranded. Which type of nucleic acid does this sample contain, and how does it differ structurally from
the other major type?
A. DNA; it differs from RNA by having deoxyribose sugar and thymine instead of uracil
B. RNA; it differs from DNA by having ribose sugar, uracil instead of thymine, and being single-stranded [CORRECT]
C. DNA; it differs from RNA by being double-stranded and containing thymine
D. RNA; it differs from DNA by having deoxyribose and forming a double helix
Correct Answer: B
Rationale: The presence of ribose (not deoxyribose) and uracil (not thymine), along with being single-stranded, identifies this as RNA. DNA
differs by having deoxyribose sugar, thymine instead of uracil, and typically exists as a double-stranded helix with A-T and G-C base pairing.
Q15: A student measures the activity of the enzyme pepsin at different pH values and finds it works optimally around pH 2.
When the pH is raised to 7, enzyme activity drops dramatically. What is the most likely explanation for this observation?
WGU C190 Introduction to Biology Practice Examination
WGU C190 OBJECTIVE ASSESSMENT
Introduction to Biology | Q/A | 100% Correct Verified Answers | LATEST
2026/2027 Update - Aligned with WGU C190 Course Competencies
Section 1: Basic Chemistry and Biological Molecules (Q1-Q15)
Q1: A biology student is analyzing an unknown atom and determines it has 6 protons, 6 neutrons, and 6 electrons. She then
examines a second atom of the same element that has 6 protons, 7 neutrons, and 6 electrons. What is the relationship
between these two atoms?
A. They are ions with different charges
B. They are isotopes of the same element [CORRECT]
C. They are different elements
D. They are isotones with the same neutron count
Correct Answer: B
Rationale: Both atoms have 6 protons, identifying them as carbon. They differ in neutron number (6 vs 7), making them isotopes — specifically
carbon-12 and carbon-13. Isotopes have the same atomic number but different mass numbers.
Q2: Sodium chloride (NaCl) dissolves readily in water, producing Na and Cl ions. What type of chemical bond was
broken when NaCl dissolved, and what property of water enabled this process?
A. Covalent bond; water's ability to form hydrogen bonds with Na and Cl
B. Ionic bond; water's polarity allows it to surround and separate the ions [CORRECT]
C. Hydrogen bond; water's high specific heat destabilizes the crystal lattice
D. Metallic bond; water's cohesive forces pull the metal ions apart
Correct Answer: B
Rationale: NaCl is held together by ionic bonds formed through electron transfer from Na to Cl. Water's polarity — with its partial negative
oxygen and partial positive hydrogens — allows it to hydrate and separate the ions, dissolving the crystal.
Q3: Which type of chemical bond involves the sharing of electron pairs between atoms and is the strongest bond found in
biological molecules?
A. Hydrogen bond
B. Ionic bond
C. Covalent bond [CORRECT]
D. Van der Waals interaction
Correct Answer: C
Rationale: Covalent bonds involve the sharing of one or more electron pairs between atoms and are the strongest bonds commonly found in
biological molecules. They form the backbone of organic compounds such as proteins, carbohydrates, and nucleic acids.
Q4: During a laboratory exercise, a student notices that water forms droplets that bead up on a freshly waxed car surface
but spreads out and soaks into a cotton shirt. Which properties of water best explain these observations?
A. High specific heat and high heat of vaporization
B. Cohesion and adhesion [CORRECT]
C. Solvent properties and evaporative cooling
D. Low density as a solid and high surface tension
Correct Answer: B
Rationale: Water beading on the waxed surface demonstrates cohesion — water molecules attracting each other due to hydrogen bonding.
Water spreading into cotton demonstrates adhesion — water molecules attracting to the polar cellulose fibers in the fabric.
Q5: A researcher is studying why coastal climates tend to have milder temperature fluctuations compared to inland areas
at the same latitude. Which property of water is most responsible for this phenomenon?
WGU C190 Introduction to Biology Practice Examination
,WGU C190 Objective Assessment | Introduction to Biology | 2026/2027 Page 2
A. Water is an excellent solvent for ionic and polar substances
B. Water has a high specific heat capacity [CORRECT]
C. Water exhibits strong cohesive forces at its surface
D. Water expands when it freezes, becoming less dense
Correct Answer: B
Rationale: Water's high specific heat means it absorbs or releases large amounts of energy with relatively little temperature change. This
property allows oceans and large bodies of water to moderate nearby coastal temperatures, reducing extreme fluctuations.
Q6: When an athlete sweats during intense exercise, the evaporation of water from the skin surface helps cool the body.
What property of water is primarily responsible for this cooling effect?
A. High specific heat
B. Evaporative cooling [CORRECT]
C. Cohesion among water molecules
D. Water's role as a universal solvent
Correct Answer: B
Rationale: Evaporative cooling occurs because the molecules with the highest kinetic energy (the hottest ones) escape from the liquid surface as
gas, lowering the average kinetic energy and thus the temperature of the remaining liquid. This is why sweating effectively cools the body.
Q7: A clinical lab technician measures a patient's blood sample and finds a hydrogen ion concentration [H ] of 1 × 10 ⁸
M. What is the pH of this sample, and how does it compare to a neutral pH of 7?
A. pH 8; 10 times more basic than neutral [CORRECT]
B. pH 8; 10 times more acidic than neutral
C. pH 6; 10 times more acidic than neutral
D. pH 8; 100 times more basic than neutral
Correct Answer: A
Rationale: pH is calculated as −log[H ]. For [H ] = 1 × 10 ⁸ M, pH = 8. The pH scale is logarithmic, so each unit change represents a
tenfold change in H concentration. A pH of 8 is 10 times more basic (lower H ) than a neutral pH of 7.
Q8: A patient with diabetic ketoacidosis has blood pH dropping from 7.4 to 7.1. The body responds by using the
bicarbonate buffer system. Which of the following best describes how this buffer system minimizes the pH change?
A. The buffer donates H ions to neutralize the excess OH in the blood
B. The buffer accepts H ions, converting HCO₃ to H₂CO₃ and reducing acidity [CORRECT]
C. The buffer releases OH ions to directly neutralize all free H ions
D. The buffer raises blood temperature to accelerate acid breakdown
Correct Answer: B
Rationale: The bicarbonate buffer system resists pH changes by accepting excess H ions: H + HCO₃ → H₂CO₃. This removes free
hydrogen ions from solution, preventing the blood from becoming too acidic and helping maintain homeostasis.
Q9: A nutrition scientist is comparing the structural carbohydrates found in different organisms: starch in potatoes,
glycogen in human muscle, cellulose in plant cell walls, and chitin in insect exoskeletons. What do all four of these molecules
have in common?
A. They are all composed of glucose monomers linked by the same type of glycosidic bonds
B. They are all polysaccharides that serve as structural or energy-storage molecules [CORRECT]
C. They are all digestible by human enzymes and provide equal caloric value
D. They are all branched polymers containing both α and β glycosidic linkages
Correct Answer: B
Rationale: All four are polysaccharides — long polymers of monosaccharide units. Starch and glycogen store energy, while cellulose and chitin
serve structural roles. However, they differ in their glycosidic bond types (α vs β), branching patterns, and digestibility by humans.
Q10: A food scientist is comparing butter (solid at room temperature) with olive oil (liquid at room temperature). Which
structural difference between their fatty acid components best explains this difference in physical state?
A. Butter contains phospholipids while olive oil contains triglycerides
B. Butter has a higher proportion of saturated fatty acids with straight chains that pack tightly [CORRECT]
WGU C190 Introduction to Biology Practice Examination
, WGU C190 Objective Assessment | Introduction to Biology | 2026/2027 Page 3
C. Olive oil contains primarily trans fats that prevent solidification
D. Butter contains more double bonds creating kinks that increase melting point
Correct Answer: B
Rationale: Saturated fatty acids have no double bonds, allowing their hydrocarbon chains to pack tightly together, resulting in a solid state at
room temperature. Unsaturated fatty acids (abundant in olive oil) have cis double bonds that create kinks, preventing tight packing and keeping
them liquid.
Q11: A biochemist synthesizes a short polypeptide by linking three amino acids together in a dehydration reaction. Which
bond is formed between the amino acids, and what is released as a byproduct?
A. A hydrogen bond; water is released
B. A peptide bond; a molecule of water is released [CORRECT]
C. A peptide bond; carbon dioxide is released
D. A glycosidic bond; a molecule of water is released
Correct Answer: B
Rationale: Peptide bonds form through dehydration synthesis (condensation) between the carboxyl group of one amino acid and the amino
group of another, releasing H₂O. This covalent bond is the defining feature linking amino acids into polypeptide chains.
Q12: Which level of protein structure involves the coiling or folding of the polypeptide chain into patterns such as alpha
helices and beta sheets, stabilized primarily by hydrogen bonds?
A. Primary structure
B. Secondary structure [CORRECT]
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Secondary structure refers to local folding patterns — most commonly alpha helices and beta pleated sheets — stabilized by
hydrogen bonds between backbone amide and carbonyl groups. Primary structure is the amino acid sequence; tertiary structure is the overall
3D shape; quaternary involves multiple subunits.
Q13: A researcher is studying how the enzyme lactase breaks down the sugar lactose into glucose and galactose. When she
adds a molecule that closely resembles lactose to the reaction mixture, the rate of lactose breakdown decreases. What type
of inhibition is occurring, and how does the inhibitor work?
A. Non-competitive inhibition; the inhibitor binds to an allosteric site
B. Allosteric inhibition; the inhibitor changes the enzyme's overall shape
C. Competitive inhibition; the inhibitor competes with lactose for the active site [CORRECT]
D. Irreversible inhibition; the inhibitor permanently destroys the enzyme
Correct Answer: C
Rationale: A molecule resembling the substrate that binds to the active site and reduces reaction rate describes competitive inhibition. The
inhibitor and substrate compete for the same active site. Increasing substrate concentration can overcome this type of inhibition.
Q14: A molecular biologist isolates a nucleic acid sample from a virus and finds that it contains the sugar ribose, the base
uracil, and is single-stranded. Which type of nucleic acid does this sample contain, and how does it differ structurally from
the other major type?
A. DNA; it differs from RNA by having deoxyribose sugar and thymine instead of uracil
B. RNA; it differs from DNA by having ribose sugar, uracil instead of thymine, and being single-stranded [CORRECT]
C. DNA; it differs from RNA by being double-stranded and containing thymine
D. RNA; it differs from DNA by having deoxyribose and forming a double helix
Correct Answer: B
Rationale: The presence of ribose (not deoxyribose) and uracil (not thymine), along with being single-stranded, identifies this as RNA. DNA
differs by having deoxyribose sugar, thymine instead of uracil, and typically exists as a double-stranded helix with A-T and G-C base pairing.
Q15: A student measures the activity of the enzyme pepsin at different pH values and finds it works optimally around pH 2.
When the pH is raised to 7, enzyme activity drops dramatically. What is the most likely explanation for this observation?
WGU C190 Introduction to Biology Practice Examination
