BIOD 151 FULL EXAM ANSWER KEY (MODULES 1–6) – 160
QUESTIONS WITH VERIFIED ANSWERS & DETAILED
EXPLANATIONS,2027-2027
1) Which of the following is considered the basic structural and functional unit
of all living organisms, capable of performing all life processes on its own?
A. Atom
B. Molecule
C. Cell
D. Tissue
E. Organ
Answer: C. Cell
Explanation: The cell is the smallest unit capable of carrying out all functions
necessary for life, including metabolism, growth, and reproduction.
2) Which organelle in eukaryotic cells is primarily responsible for producing
energy in the form of ATP, often referred to as the “powerhouse of the cell”?
A. Nucleus
B. Mitochondria
C. Ribosome
D. Golgi apparatus
E. Lysosome
Answer: B. Mitochondria
Explanation: Mitochondria perform cellular respiration, converting glucose and
oxygen into ATP, which powers cellular activities.
,3) Among the macromolecules essential to life, which one serves as the main
energy source for cells, especially during immediate energy needs?
A. Protein
B. Lipid
C. Carbohydrate
D. Nucleic acid
E. Vitamin
Answer: C. Carbohydrate
Explanation: Carbohydrates are metabolized into glucose, the primary fuel for
cellular respiration and energy production.
4) DNA consists of four nitrogenous bases. Which set correctly represents the
bases found in DNA and not RNA?
A. Adenine, Thymine, Guanine, Cytosine
B. Adenine, Uracil, Guanine, Cytosine
C. Adenine, Thymine, Guanine, Uracil
D. Adenine, Cytosine, Uracil, Guanine
E. Thymine, Cytosine, Uracil, Guanine
Answer: A. Adenine, Thymine, Guanine, Cytosine
Explanation: DNA contains A-T and G-C base pairs. RNA replaces thymine with
uracil.
5) During the process of transcription, which enzyme is responsible for reading
the DNA template strand and synthesizing a complementary RNA molecule?
A. DNA polymerase
B. RNA polymerase
C. Ligase
D. Helicase
E. Primase
Answer: B. RNA polymerase
Explanation: RNA polymerase binds to DNA and creates a complementary RNA
strand during transcription.
,6) The backbone of DNA is composed of repeating units of sugar molecules
linked to phosphate groups, forming the structural framework of the molecule.
Which combination is correct?
A. Sugar and phosphate
B. Amino acids
C. Nitrogenous bases only
D. Lipids
E. Proteins
Answer: A. Sugar and phosphate
Explanation: DNA’s structure consists of a sugar-phosphate backbone with
nitrogenous bases projecting inward, forming base pairs.
7) Which phase of the cell cycle involves replication of the DNA, ensuring that
each daughter cell receives an identical set of chromosomes?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
E. Cytokinesis
Answer: B. S phase
Explanation: During the S (synthesis) phase, DNA is duplicated, producing sister
chromatids for cell division.
8) Enzymes are biological catalysts that speed up chemical reactions without
being consumed. Which factor directly affects enzyme activity by altering its
three-dimensional structure?
A. Substrate concentration
B. pH and temperature
C. Presence of cofactors
D. Inhibitors only
E. All of the above
Answer: B. pH and temperature
, Explanation: Extreme pH or temperature can denature enzymes, preventing
proper substrate binding and activity.
9) Which type of bond holds the two strands of a DNA double helix together,
stabilizing the molecule through base pairing?
A. Covalent bonds
B. Hydrogen bonds
C. Ionic bonds
D. Peptide bonds
E. Disulfide bonds
Answer: B. Hydrogen bonds
Explanation: Hydrogen bonds form between complementary nitrogenous bases: A
pairs with T, and G pairs with C.
10) In human anatomy, which organ system is primarily responsible for
transporting oxygen, nutrients, and hormones to cells, while removing carbon
dioxide and metabolic wastes?
A. Digestive system
B. Circulatory system
C. Respiratory system
D. Lymphatic system
E. Nervous system
Answer: B. Circulatory system
Explanation: The circulatory system, including the heart, blood, and vessels,
delivers oxygen and nutrients to tissues and removes waste.
11) The human skeletal system provides structural support and protection. Which
type of tissue is rigid, mineralized, and forms the bulk of bones?
A. Cartilage
B. Bone
C. Muscle
D. Epithelial
QUESTIONS WITH VERIFIED ANSWERS & DETAILED
EXPLANATIONS,2027-2027
1) Which of the following is considered the basic structural and functional unit
of all living organisms, capable of performing all life processes on its own?
A. Atom
B. Molecule
C. Cell
D. Tissue
E. Organ
Answer: C. Cell
Explanation: The cell is the smallest unit capable of carrying out all functions
necessary for life, including metabolism, growth, and reproduction.
2) Which organelle in eukaryotic cells is primarily responsible for producing
energy in the form of ATP, often referred to as the “powerhouse of the cell”?
A. Nucleus
B. Mitochondria
C. Ribosome
D. Golgi apparatus
E. Lysosome
Answer: B. Mitochondria
Explanation: Mitochondria perform cellular respiration, converting glucose and
oxygen into ATP, which powers cellular activities.
,3) Among the macromolecules essential to life, which one serves as the main
energy source for cells, especially during immediate energy needs?
A. Protein
B. Lipid
C. Carbohydrate
D. Nucleic acid
E. Vitamin
Answer: C. Carbohydrate
Explanation: Carbohydrates are metabolized into glucose, the primary fuel for
cellular respiration and energy production.
4) DNA consists of four nitrogenous bases. Which set correctly represents the
bases found in DNA and not RNA?
A. Adenine, Thymine, Guanine, Cytosine
B. Adenine, Uracil, Guanine, Cytosine
C. Adenine, Thymine, Guanine, Uracil
D. Adenine, Cytosine, Uracil, Guanine
E. Thymine, Cytosine, Uracil, Guanine
Answer: A. Adenine, Thymine, Guanine, Cytosine
Explanation: DNA contains A-T and G-C base pairs. RNA replaces thymine with
uracil.
5) During the process of transcription, which enzyme is responsible for reading
the DNA template strand and synthesizing a complementary RNA molecule?
A. DNA polymerase
B. RNA polymerase
C. Ligase
D. Helicase
E. Primase
Answer: B. RNA polymerase
Explanation: RNA polymerase binds to DNA and creates a complementary RNA
strand during transcription.
,6) The backbone of DNA is composed of repeating units of sugar molecules
linked to phosphate groups, forming the structural framework of the molecule.
Which combination is correct?
A. Sugar and phosphate
B. Amino acids
C. Nitrogenous bases only
D. Lipids
E. Proteins
Answer: A. Sugar and phosphate
Explanation: DNA’s structure consists of a sugar-phosphate backbone with
nitrogenous bases projecting inward, forming base pairs.
7) Which phase of the cell cycle involves replication of the DNA, ensuring that
each daughter cell receives an identical set of chromosomes?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
E. Cytokinesis
Answer: B. S phase
Explanation: During the S (synthesis) phase, DNA is duplicated, producing sister
chromatids for cell division.
8) Enzymes are biological catalysts that speed up chemical reactions without
being consumed. Which factor directly affects enzyme activity by altering its
three-dimensional structure?
A. Substrate concentration
B. pH and temperature
C. Presence of cofactors
D. Inhibitors only
E. All of the above
Answer: B. pH and temperature
, Explanation: Extreme pH or temperature can denature enzymes, preventing
proper substrate binding and activity.
9) Which type of bond holds the two strands of a DNA double helix together,
stabilizing the molecule through base pairing?
A. Covalent bonds
B. Hydrogen bonds
C. Ionic bonds
D. Peptide bonds
E. Disulfide bonds
Answer: B. Hydrogen bonds
Explanation: Hydrogen bonds form between complementary nitrogenous bases: A
pairs with T, and G pairs with C.
10) In human anatomy, which organ system is primarily responsible for
transporting oxygen, nutrients, and hormones to cells, while removing carbon
dioxide and metabolic wastes?
A. Digestive system
B. Circulatory system
C. Respiratory system
D. Lymphatic system
E. Nervous system
Answer: B. Circulatory system
Explanation: The circulatory system, including the heart, blood, and vessels,
delivers oxygen and nutrients to tissues and removes waste.
11) The human skeletal system provides structural support and protection. Which
type of tissue is rigid, mineralized, and forms the bulk of bones?
A. Cartilage
B. Bone
C. Muscle
D. Epithelial
