BIO 1050 EXAM 3 CELLULAR RESPIRATION, PHOTOSYNTHESIS, CELL
CYCLE, MITOSIS, MEIOSIS, MENDELIAN GENETICS, INHERITANCE
PATTERNS, MOLECULAR GENETICS – DNA REPLICATION,
TRANSCRIPTION, TRANSLATION COMPLETE QUESTIONS WITH 100%
VERIFIED ANSWERS
1. During which phase of the cell cycle does DNA replication occur?
A) G1 phase
B) G2 phase
C) M phase
D) S phase (Correct)
Rationale: DNA synthesis occurs in S (synthesis) phase, ensuring each
daughter cell gets a complete copy of the genome.
2. A cell has 12 chromosomes at G1. After mitosis, each daughter cell
will have:
A) 6 chromosomes
B) 12 chromosomes (Correct)
C) 24 chromosomes
D) 48 chromosomes
Rationale: Mitosis produces genetically identical daughter cells with the
same chromosome number as the parent.
3. Which process reduces the chromosome number by half?
A) Mitosis
B) Meiosis (Correct)
C) Binary fission
D) Cytokinesis
,Rationale: Meiosis includes two divisions, reducing diploid (2n) to
haploid (n) gametes.
4. Crossing over occurs during:
A) Prophase I (Correct)
B) Metaphase II
C) Anaphase I
D) Telophase II
Rationale: Homologous chromosomes pair and exchange segments in
prophase I, increasing genetic variation.
5. In a monohybrid cross between two heterozygotes (Aa × Aa), what
fraction of offspring is expected to be homozygous dominant?
A) 1/4 (Correct)
B) 1/2
C) 3/4
D) All
Rationale: Punnett square yields 1 AA : 2 Aa : 1 aa → 25% AA.
6. A man with type AB blood and a woman with type O blood can have
a child with which blood type?
A) A only
B) B only
C) A or B (Correct)
D) AB or O
Rationale: AB genotype IAIB × O genotype ii → offspring IAi (type A) or
IBi (type B).
7. Which molecule directly donates electrons to the electron transport
chain in cellular respiration?
A) Glucose
,B) ATP
C) NADH (Correct)
D) Acetyl-CoA
Rationale: NADH donates electrons at Complex I; FADH2 donates at
Complex II.
8. Where in the mitochondrion does the Krebs cycle occur?
A) Outer membrane
B) Inner membrane
C) Matrix (Correct)
D) Intermembrane space
Rationale: Pyruvate is converted to acetyl-CoA and enters the Krebs
cycle in the mitochondrial matrix.
9. The final electron acceptor in the electron transport chain of aerobic
respiration is:
A) Water
B) Oxygen (Correct)
C) Carbon dioxide
D) NAD+
Rationale: O2 combines with electrons and protons to form H2O,
allowing the chain to continue.
10. In photosynthesis, the light-independent reactions (Calvin cycle)
occur in the:
A) Thylakoid membrane
B) Stroma (Correct)
C) Grana
D) Lumen
, Rationale: CO2 fixation and sugar synthesis happen in the stroma, using
ATP and NADPH from light reactions.
11. The pigment that directly converts light energy to chemical energy
in photosystem II is:
A) Chlorophyll b
B) Carotenoids
C) Chlorophyll a (P680) (Correct)
D) Xanthophyll
Rationale: P680 is the reaction center chlorophyll a in PSII; it donates
excited electrons.
12. A woman is a carrier for hemophilia (X-linked recessive). If she has a
child with a normal man, what is the chance a son will have
hemophilia?
A) 0%
B) 25%
C) 50% (Correct)
D) 100%
Rationale: Mother XHXh × father XHY → sons: 50% XHY (normal), 50%
XhY (hemophilia).
13. Which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5′→3′ direction?
A) Helicase
B) DNA polymerase (Correct)
C) Ligase
D) Primase
Rationale: DNA polymerase III (prokaryotes) or δ/ε (eukaryotes)
catalyzes phosphodiester bond formation.
CYCLE, MITOSIS, MEIOSIS, MENDELIAN GENETICS, INHERITANCE
PATTERNS, MOLECULAR GENETICS – DNA REPLICATION,
TRANSCRIPTION, TRANSLATION COMPLETE QUESTIONS WITH 100%
VERIFIED ANSWERS
1. During which phase of the cell cycle does DNA replication occur?
A) G1 phase
B) G2 phase
C) M phase
D) S phase (Correct)
Rationale: DNA synthesis occurs in S (synthesis) phase, ensuring each
daughter cell gets a complete copy of the genome.
2. A cell has 12 chromosomes at G1. After mitosis, each daughter cell
will have:
A) 6 chromosomes
B) 12 chromosomes (Correct)
C) 24 chromosomes
D) 48 chromosomes
Rationale: Mitosis produces genetically identical daughter cells with the
same chromosome number as the parent.
3. Which process reduces the chromosome number by half?
A) Mitosis
B) Meiosis (Correct)
C) Binary fission
D) Cytokinesis
,Rationale: Meiosis includes two divisions, reducing diploid (2n) to
haploid (n) gametes.
4. Crossing over occurs during:
A) Prophase I (Correct)
B) Metaphase II
C) Anaphase I
D) Telophase II
Rationale: Homologous chromosomes pair and exchange segments in
prophase I, increasing genetic variation.
5. In a monohybrid cross between two heterozygotes (Aa × Aa), what
fraction of offspring is expected to be homozygous dominant?
A) 1/4 (Correct)
B) 1/2
C) 3/4
D) All
Rationale: Punnett square yields 1 AA : 2 Aa : 1 aa → 25% AA.
6. A man with type AB blood and a woman with type O blood can have
a child with which blood type?
A) A only
B) B only
C) A or B (Correct)
D) AB or O
Rationale: AB genotype IAIB × O genotype ii → offspring IAi (type A) or
IBi (type B).
7. Which molecule directly donates electrons to the electron transport
chain in cellular respiration?
A) Glucose
,B) ATP
C) NADH (Correct)
D) Acetyl-CoA
Rationale: NADH donates electrons at Complex I; FADH2 donates at
Complex II.
8. Where in the mitochondrion does the Krebs cycle occur?
A) Outer membrane
B) Inner membrane
C) Matrix (Correct)
D) Intermembrane space
Rationale: Pyruvate is converted to acetyl-CoA and enters the Krebs
cycle in the mitochondrial matrix.
9. The final electron acceptor in the electron transport chain of aerobic
respiration is:
A) Water
B) Oxygen (Correct)
C) Carbon dioxide
D) NAD+
Rationale: O2 combines with electrons and protons to form H2O,
allowing the chain to continue.
10. In photosynthesis, the light-independent reactions (Calvin cycle)
occur in the:
A) Thylakoid membrane
B) Stroma (Correct)
C) Grana
D) Lumen
, Rationale: CO2 fixation and sugar synthesis happen in the stroma, using
ATP and NADPH from light reactions.
11. The pigment that directly converts light energy to chemical energy
in photosystem II is:
A) Chlorophyll b
B) Carotenoids
C) Chlorophyll a (P680) (Correct)
D) Xanthophyll
Rationale: P680 is the reaction center chlorophyll a in PSII; it donates
excited electrons.
12. A woman is a carrier for hemophilia (X-linked recessive). If she has a
child with a normal man, what is the chance a son will have
hemophilia?
A) 0%
B) 25%
C) 50% (Correct)
D) 100%
Rationale: Mother XHXh × father XHY → sons: 50% XHY (normal), 50%
XhY (hemophilia).
13. Which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5′→3′ direction?
A) Helicase
B) DNA polymerase (Correct)
C) Ligase
D) Primase
Rationale: DNA polymerase III (prokaryotes) or δ/ε (eukaryotes)
catalyzes phosphodiester bond formation.
