WGU C190 Objective Assessment (2026/2027)
Introduction to Biology | 100 Practice Questions
with Answers & Detailed Explanations | Instant
Pdf Download
1. A researcher observes that a cell maintains stable internal temperature
and pH despite significant external environmental fluctuations. Which
biological concept best explains this ability?
A. Evolution
B. Homeostasis
C. Metabolism
D. Adaptation
✅ Answer: B
Explanation: Homeostasis is the ability of a cell or organism to maintain stable
internal conditions despite external changes. This includes regulation of
temperature, pH, and ion balance through feedback mechanisms. It is essential
for enzyme function and survival, making it a core principle in biology.
2. During aerobic cellular respiration in eukaryotic cells, which organelle is
primarily responsible for producing the majority of ATP through oxidative
phosphorylation?
A. Nucleus
B. Mitochondrion
C. Ribosome
D. Golgi apparatus
,✅ Answer: B
Explanation: The mitochondrion is the site of oxidative phosphorylation, where
electrons are transferred through the electron transport chain to generate a
proton gradient used to synthesize ATP. This process produces most of the
cell’s ATP, far more than glycolysis.
3. A mutation alters a DNA nucleotide sequence but does not change the
amino acid coded due to redundancy in the genetic code. What type of
mutation is this?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
✅ Answer: C
Explanation: A silent mutation occurs when a codon change still codes for the
same amino acid because multiple codons can encode the same amino acid.
Although the DNA sequence changes, the protein remains unchanged, so
function is typically unaffected.
4. In a population of organisms, individuals with traits that improve
survival are more likely to reproduce successfully. Which biological
process is being demonstrated in this scenario?
A. Genetic drift
B. Gene flow
C. Natural selection
D. Mutation
✅ Answer: C
Explanation: Natural selection occurs when advantageous traits increase an
,organism’s likelihood of survival and reproduction. Over time, these traits
become more common in the population, driving evolution.
5. Enzymes accelerate chemical reactions in biological systems without
being consumed in the process. What is their primary function in
metabolism?
A. Increase temperature of reactions
B. Lower activation energy of reactions
C. Provide energy directly to reactions
D. Store genetic information
✅ Answer: B
Explanation: Enzymes function as biological catalysts by lowering the activation
energy required for a reaction to occur. This allows reactions to proceed faster
at normal biological temperatures, making life-sustaining processes possible.
6. Which class of biological macromolecules is primarily responsible for
storing genetic information and transmitting it from one generation to the
next?
A. Proteins
B. Lipids
C. Nucleic acids
D. Carbohydrates
✅ Answer: C
Explanation: Nucleic acids, such as DNA and RNA, store and transmit genetic
information. DNA contains the instructions for building proteins, while RNA helps
carry out those instructions during protein synthesis.
, 7. A cell membrane allows certain molecules to pass while restricting
others, helping maintain internal balance. What property best describes
this selective control?
A. Diffusion
B. Osmosis
C. Selective permeability
D. Active transport
✅ Answer: C
Explanation: Selective permeability means the membrane allows some
substances (like small or nonpolar molecules) to pass while blocking others.
This is critical for maintaining homeostasis within the cell.
8. During photosynthesis, plants convert light energy into chemical energy
stored in organic molecules. Which molecule primarily stores this energy
for later use?
A. Oxygen
B. Carbon dioxide
C. Glucose
D. ATP only
✅ Answer: C
Explanation: Glucose is the primary long-term energy storage molecule
produced during photosynthesis. While ATP is also produced, it is used
immediately, whereas glucose stores energy for later cellular processes.
9. Water moves across a semipermeable membrane from an area of lower
solute concentration to higher solute concentration. Which transport
process is responsible?
Introduction to Biology | 100 Practice Questions
with Answers & Detailed Explanations | Instant
Pdf Download
1. A researcher observes that a cell maintains stable internal temperature
and pH despite significant external environmental fluctuations. Which
biological concept best explains this ability?
A. Evolution
B. Homeostasis
C. Metabolism
D. Adaptation
✅ Answer: B
Explanation: Homeostasis is the ability of a cell or organism to maintain stable
internal conditions despite external changes. This includes regulation of
temperature, pH, and ion balance through feedback mechanisms. It is essential
for enzyme function and survival, making it a core principle in biology.
2. During aerobic cellular respiration in eukaryotic cells, which organelle is
primarily responsible for producing the majority of ATP through oxidative
phosphorylation?
A. Nucleus
B. Mitochondrion
C. Ribosome
D. Golgi apparatus
,✅ Answer: B
Explanation: The mitochondrion is the site of oxidative phosphorylation, where
electrons are transferred through the electron transport chain to generate a
proton gradient used to synthesize ATP. This process produces most of the
cell’s ATP, far more than glycolysis.
3. A mutation alters a DNA nucleotide sequence but does not change the
amino acid coded due to redundancy in the genetic code. What type of
mutation is this?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
✅ Answer: C
Explanation: A silent mutation occurs when a codon change still codes for the
same amino acid because multiple codons can encode the same amino acid.
Although the DNA sequence changes, the protein remains unchanged, so
function is typically unaffected.
4. In a population of organisms, individuals with traits that improve
survival are more likely to reproduce successfully. Which biological
process is being demonstrated in this scenario?
A. Genetic drift
B. Gene flow
C. Natural selection
D. Mutation
✅ Answer: C
Explanation: Natural selection occurs when advantageous traits increase an
,organism’s likelihood of survival and reproduction. Over time, these traits
become more common in the population, driving evolution.
5. Enzymes accelerate chemical reactions in biological systems without
being consumed in the process. What is their primary function in
metabolism?
A. Increase temperature of reactions
B. Lower activation energy of reactions
C. Provide energy directly to reactions
D. Store genetic information
✅ Answer: B
Explanation: Enzymes function as biological catalysts by lowering the activation
energy required for a reaction to occur. This allows reactions to proceed faster
at normal biological temperatures, making life-sustaining processes possible.
6. Which class of biological macromolecules is primarily responsible for
storing genetic information and transmitting it from one generation to the
next?
A. Proteins
B. Lipids
C. Nucleic acids
D. Carbohydrates
✅ Answer: C
Explanation: Nucleic acids, such as DNA and RNA, store and transmit genetic
information. DNA contains the instructions for building proteins, while RNA helps
carry out those instructions during protein synthesis.
, 7. A cell membrane allows certain molecules to pass while restricting
others, helping maintain internal balance. What property best describes
this selective control?
A. Diffusion
B. Osmosis
C. Selective permeability
D. Active transport
✅ Answer: C
Explanation: Selective permeability means the membrane allows some
substances (like small or nonpolar molecules) to pass while blocking others.
This is critical for maintaining homeostasis within the cell.
8. During photosynthesis, plants convert light energy into chemical energy
stored in organic molecules. Which molecule primarily stores this energy
for later use?
A. Oxygen
B. Carbon dioxide
C. Glucose
D. ATP only
✅ Answer: C
Explanation: Glucose is the primary long-term energy storage molecule
produced during photosynthesis. While ATP is also produced, it is used
immediately, whereas glucose stores energy for later cellular processes.
9. Water moves across a semipermeable membrane from an area of lower
solute concentration to higher solute concentration. Which transport
process is responsible?
