BI 121 EXAM 1 REVIEW (2026/2027) | KEY CONCEPTS AND VERIFIED ANSWERS |
GRADED A+
BI 121: General Biology I - Exam 1 Comprehensive Review | Core Domains: Scientific Method & Inquiry,
Basic Chemistry for Biology (Atoms, Bonds, Water), Biological Macromolecules (Carbohydrates, Lipids,
Proteins, Nucleic Acids), Cell Structure & Function, Membrane Transport & Homeostasis, Cellular
Energy & Metabolism (Enzymes, ATP, Photosynthesis, Cellular Respiration), and Introduction to
Genetics & DNA | Introductory Biology Focus | Foundational Course Exam Review Format
Exam Structure
The BI 121 Exam 1 for the 2026/2027 academic cycle is a 75-question, multiple-choice question (MCQ)
examination.
Introduction
This BI 121 Exam 1 Review for the 2026/2027 cycle prepares students for the first comprehensive
assessment in introductory biology. The content establishes the foundational chemical and cellular
principles essential for understanding life processes, emphasizing the structure and function of biological
molecules, cellular organization, energy transformations, and the basic mechanisms that maintain
homeostasis.
Answer Format
All correct answers and biological principles must be presented in bold and green, followed by detailed
rationales that explain chemical bonding in biological contexts, differentiate macromolecule structures
and functions, describe cellular organelle roles, compare mechanisms of membrane transport, and
illustrate energy flow through metabolic pathways.
Questions (75 Total)
1. Which property of water allows it to moderate temperature in living organisms?
A. Low heat capacity
B. High specific heat capacity
C. High density as a solid
D. Nonpolar nature
Rationale: Water has a high specific heat capacity, meaning it absorbs or releases large amounts of
heat with minimal temperature change. This stabilizes internal temperatures in cells and organisms. Ice
being less dense than liquid water (C) allows aquatic life to survive winters, but it does not regulate
temperature directly.
2. A scientist tests the effect of fertilizer on plant growth. The group receiving no fertilizer is the:
A. Experimental group
B. Control group
,C. Dependent variable
D. Independent variable
Rationale: The control group serves as a baseline and does not receive the experimental treatment
(fertilizer). The experimental group receives the treatment. The independent variable is the fertilizer
(manipulated); the dependent variable is plant growth (measured).
3. Which type of bond holds together the two strands of a DNA double helix?
A. Covalent bonds
B. Hydrogen bonds
C. Ionic bonds
D. Peptide bonds
Rationale: Hydrogen bonds form between complementary nitrogenous bases (A-T and G-C) in DNA.
These weak bonds allow the strands to separate during replication and transcription. Covalent bonds
hold nucleotides together within each strand; peptide bonds link amino acids.
4. Which macromolecule is primarily used for long-term energy storage in animals?
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic acids
Rationale: Lipids (e.g., triglycerides) store more energy per gram than carbohydrates and are
hydrophobic, making them ideal for compact, long-term storage in adipose tissue. Carbohydrates (e.g.,
glycogen) provide short-term energy. Proteins are structural/enzymatic; nucleic acids store genetic
information.
5. The organelle responsible for protein synthesis and modification is the:
A. Mitochondria
B. Endoplasmic reticulum (rough and smooth)
C. Lysosome
D. Golgi apparatus
Rationale: The rough ER (with ribosomes) synthesizes proteins; the smooth ER synthesizes lipids and
detoxifies. The Golgi modifies, sorts, and packages proteins from the ER. Mitochondria produce ATP;
, lysosomes digest waste. Both rough ER and Golgi are involved, but the ER is the primary site of
synthesis.
6. In osmosis, water moves across a semipermeable membrane from an area of:
A. Higher solute concentration to lower solute concentration
B. Lower solute concentration to higher solute concentration
C. Equal solute concentrations
D. Higher water pressure to lower water pressure
Rationale: Osmosis is the diffusion of water toward higher solute concentration (or lower water
concentration) to equalize concentrations. Water moves to dilute the solute. This passive process is
critical for cell volume regulation.
7. Enzymes speed up chemical reactions by:
A. Increasing activation energy
B. Lowering activation energy
C. Being consumed in the reaction
D. Changing the reaction’s equilibrium
Rationale: Enzymes are catalysts that lower the activation energy required for a reaction to proceed,
speeding up the rate without being consumed or altering equilibrium. Each enzyme is specific to its
substrate due to its unique active site shape.
8. Where does glycolysis occur in eukaryotic cells?
A. Mitochondrial matrix
B. Cytoplasm
C. Inner mitochondrial membrane
D. Nucleus
Rationale: Glycolysis—the breakdown of glucose into pyruvate—occurs in the cytoplasm and does not
require oxygen. The Krebs cycle and electron transport chain occur in mitochondria. This allows
anaerobic ATP production even without organelles (as in prokaryotes).
9. Which molecule carries genetic information in most living organisms?
A. Protein
B. DNA
GRADED A+
BI 121: General Biology I - Exam 1 Comprehensive Review | Core Domains: Scientific Method & Inquiry,
Basic Chemistry for Biology (Atoms, Bonds, Water), Biological Macromolecules (Carbohydrates, Lipids,
Proteins, Nucleic Acids), Cell Structure & Function, Membrane Transport & Homeostasis, Cellular
Energy & Metabolism (Enzymes, ATP, Photosynthesis, Cellular Respiration), and Introduction to
Genetics & DNA | Introductory Biology Focus | Foundational Course Exam Review Format
Exam Structure
The BI 121 Exam 1 for the 2026/2027 academic cycle is a 75-question, multiple-choice question (MCQ)
examination.
Introduction
This BI 121 Exam 1 Review for the 2026/2027 cycle prepares students for the first comprehensive
assessment in introductory biology. The content establishes the foundational chemical and cellular
principles essential for understanding life processes, emphasizing the structure and function of biological
molecules, cellular organization, energy transformations, and the basic mechanisms that maintain
homeostasis.
Answer Format
All correct answers and biological principles must be presented in bold and green, followed by detailed
rationales that explain chemical bonding in biological contexts, differentiate macromolecule structures
and functions, describe cellular organelle roles, compare mechanisms of membrane transport, and
illustrate energy flow through metabolic pathways.
Questions (75 Total)
1. Which property of water allows it to moderate temperature in living organisms?
A. Low heat capacity
B. High specific heat capacity
C. High density as a solid
D. Nonpolar nature
Rationale: Water has a high specific heat capacity, meaning it absorbs or releases large amounts of
heat with minimal temperature change. This stabilizes internal temperatures in cells and organisms. Ice
being less dense than liquid water (C) allows aquatic life to survive winters, but it does not regulate
temperature directly.
2. A scientist tests the effect of fertilizer on plant growth. The group receiving no fertilizer is the:
A. Experimental group
B. Control group
,C. Dependent variable
D. Independent variable
Rationale: The control group serves as a baseline and does not receive the experimental treatment
(fertilizer). The experimental group receives the treatment. The independent variable is the fertilizer
(manipulated); the dependent variable is plant growth (measured).
3. Which type of bond holds together the two strands of a DNA double helix?
A. Covalent bonds
B. Hydrogen bonds
C. Ionic bonds
D. Peptide bonds
Rationale: Hydrogen bonds form between complementary nitrogenous bases (A-T and G-C) in DNA.
These weak bonds allow the strands to separate during replication and transcription. Covalent bonds
hold nucleotides together within each strand; peptide bonds link amino acids.
4. Which macromolecule is primarily used for long-term energy storage in animals?
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic acids
Rationale: Lipids (e.g., triglycerides) store more energy per gram than carbohydrates and are
hydrophobic, making them ideal for compact, long-term storage in adipose tissue. Carbohydrates (e.g.,
glycogen) provide short-term energy. Proteins are structural/enzymatic; nucleic acids store genetic
information.
5. The organelle responsible for protein synthesis and modification is the:
A. Mitochondria
B. Endoplasmic reticulum (rough and smooth)
C. Lysosome
D. Golgi apparatus
Rationale: The rough ER (with ribosomes) synthesizes proteins; the smooth ER synthesizes lipids and
detoxifies. The Golgi modifies, sorts, and packages proteins from the ER. Mitochondria produce ATP;
, lysosomes digest waste. Both rough ER and Golgi are involved, but the ER is the primary site of
synthesis.
6. In osmosis, water moves across a semipermeable membrane from an area of:
A. Higher solute concentration to lower solute concentration
B. Lower solute concentration to higher solute concentration
C. Equal solute concentrations
D. Higher water pressure to lower water pressure
Rationale: Osmosis is the diffusion of water toward higher solute concentration (or lower water
concentration) to equalize concentrations. Water moves to dilute the solute. This passive process is
critical for cell volume regulation.
7. Enzymes speed up chemical reactions by:
A. Increasing activation energy
B. Lowering activation energy
C. Being consumed in the reaction
D. Changing the reaction’s equilibrium
Rationale: Enzymes are catalysts that lower the activation energy required for a reaction to proceed,
speeding up the rate without being consumed or altering equilibrium. Each enzyme is specific to its
substrate due to its unique active site shape.
8. Where does glycolysis occur in eukaryotic cells?
A. Mitochondrial matrix
B. Cytoplasm
C. Inner mitochondrial membrane
D. Nucleus
Rationale: Glycolysis—the breakdown of glucose into pyruvate—occurs in the cytoplasm and does not
require oxygen. The Krebs cycle and electron transport chain occur in mitochondria. This allows
anaerobic ATP production even without organelles (as in prokaryotes).
9. Which molecule carries genetic information in most living organisms?
A. Protein
B. DNA
