BIOD 102/ BIOD102 Essential Biology II W/Lab Actual
Exam 2026/2027 | Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
Q1: During which phase of mitosis do sister chromatids separate and move to opposite poles?
A. Prophase
B. Metaphase
C. Anaphase [CORRECT]
D. Telophase
Correct Answer: C
Rationale: Correct because anaphase is defined by the separation of sister chromatids at the
centromere and their migration to opposite spindle poles.
---
Q2: Which checkpoint ensures that DNA replication is complete before the cell enters mitosis?
A. G1 checkpoint
B. G2 checkpoint [CORRECT]
C. M checkpoint
D. S checkpoint
Correct Answer: B
Rationale: Correct because the G2 checkpoint verifies completion of DNA replication and
checks for DNA damage before allowing entry into mitosis.
---
Q3: A cell with 24 chromosomes undergoes meiosis. How many chromosomes will each
daughter cell contain?
A. 24
B. 48
C. 12 [CORRECT]
D. 6
Correct Answer: C
Rationale: Correct because meiosis is a reduction division that halves the chromosome number,
producing haploid cells with 12 chromosomes each.
---
,Q4: Which event occurs during prophase I of meiosis but not during mitosis?
A. Chromosome condensation
B. Crossing over between homologous chromosomes [CORRECT]
C. Spindle fiber formation
D. Nuclear envelope breakdown
Correct Answer: B
Rationale: Correct because crossing over occurs only in prophase I of meiosis, where
homologous chromosomes exchange genetic material at chiasmata.
---
Q5: A cross between two heterozygous tall pea plants (Tt × Tt) produces what phenotypic ratio?
A. 1:1
B. 3:1 [CORRECT]
C. 9:3:3:1
D. 1:2:1
Correct Answer: B
Rationale: Correct because a monohybrid cross of two heterozygotes yields a 3:1 phenotypic
ratio of dominant to recessive traits.
---
Q6: Which inheritance pattern is demonstrated when a red flower crossed with a white flower
produces pink offspring?
A. Complete dominance
B. Codominance
C. Incomplete dominance [CORRECT]
D. Epistasis
Correct Answer: C
Rationale: Correct because incomplete dominance produces an intermediate phenotype (pink)
from two homozygous parents (red and white).
---
Q7: A human male with Klinefelter syndrome has which karyotype?
A. 45, X
B. 47, XXY [CORRECT]
C. 47, XYY
D. 46, XY
Correct Answer: B
, Rationale: Correct because Klinefelter syndrome results from an extra X chromosome,
producing a 47, XXY karyotype with male phenotype.
---
Q8: Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase [CORRECT]
C. Ligase
D. Primase
Correct Answer: B
Rationale: Correct because helicase breaks hydrogen bonds between complementary base
pairs to separate the DNA strands at the replication fork.
---
Q9: During transcription, which strand of DNA is used as the template?
A. Leading strand
B. Lagging strand
C. Template strand [CORRECT]
D. Coding strand
Correct Answer: C
Rationale: Correct because RNA polymerase reads the template strand (3' to 5') to synthesize
mRNA in the 5' to 3' direction.
---
Q10: Which process converts mRNA into a polypeptide chain?
A. Replication
B. Transcription
C. Translation [CORRECT]
D. Transformation
Correct Answer: C
Rationale: Correct because translation occurs at the ribosome, where mRNA codons are
matched with tRNA anticodons to assemble amino acids.
---
Q11: A mutation that changes a single nucleotide but does not alter the amino acid sequence is
called:
A. Missense mutation
Exam 2026/2027 | Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
Q1: During which phase of mitosis do sister chromatids separate and move to opposite poles?
A. Prophase
B. Metaphase
C. Anaphase [CORRECT]
D. Telophase
Correct Answer: C
Rationale: Correct because anaphase is defined by the separation of sister chromatids at the
centromere and their migration to opposite spindle poles.
---
Q2: Which checkpoint ensures that DNA replication is complete before the cell enters mitosis?
A. G1 checkpoint
B. G2 checkpoint [CORRECT]
C. M checkpoint
D. S checkpoint
Correct Answer: B
Rationale: Correct because the G2 checkpoint verifies completion of DNA replication and
checks for DNA damage before allowing entry into mitosis.
---
Q3: A cell with 24 chromosomes undergoes meiosis. How many chromosomes will each
daughter cell contain?
A. 24
B. 48
C. 12 [CORRECT]
D. 6
Correct Answer: C
Rationale: Correct because meiosis is a reduction division that halves the chromosome number,
producing haploid cells with 12 chromosomes each.
---
,Q4: Which event occurs during prophase I of meiosis but not during mitosis?
A. Chromosome condensation
B. Crossing over between homologous chromosomes [CORRECT]
C. Spindle fiber formation
D. Nuclear envelope breakdown
Correct Answer: B
Rationale: Correct because crossing over occurs only in prophase I of meiosis, where
homologous chromosomes exchange genetic material at chiasmata.
---
Q5: A cross between two heterozygous tall pea plants (Tt × Tt) produces what phenotypic ratio?
A. 1:1
B. 3:1 [CORRECT]
C. 9:3:3:1
D. 1:2:1
Correct Answer: B
Rationale: Correct because a monohybrid cross of two heterozygotes yields a 3:1 phenotypic
ratio of dominant to recessive traits.
---
Q6: Which inheritance pattern is demonstrated when a red flower crossed with a white flower
produces pink offspring?
A. Complete dominance
B. Codominance
C. Incomplete dominance [CORRECT]
D. Epistasis
Correct Answer: C
Rationale: Correct because incomplete dominance produces an intermediate phenotype (pink)
from two homozygous parents (red and white).
---
Q7: A human male with Klinefelter syndrome has which karyotype?
A. 45, X
B. 47, XXY [CORRECT]
C. 47, XYY
D. 46, XY
Correct Answer: B
, Rationale: Correct because Klinefelter syndrome results from an extra X chromosome,
producing a 47, XXY karyotype with male phenotype.
---
Q8: Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase [CORRECT]
C. Ligase
D. Primase
Correct Answer: B
Rationale: Correct because helicase breaks hydrogen bonds between complementary base
pairs to separate the DNA strands at the replication fork.
---
Q9: During transcription, which strand of DNA is used as the template?
A. Leading strand
B. Lagging strand
C. Template strand [CORRECT]
D. Coding strand
Correct Answer: C
Rationale: Correct because RNA polymerase reads the template strand (3' to 5') to synthesize
mRNA in the 5' to 3' direction.
---
Q10: Which process converts mRNA into a polypeptide chain?
A. Replication
B. Transcription
C. Translation [CORRECT]
D. Transformation
Correct Answer: C
Rationale: Correct because translation occurs at the ribosome, where mRNA codons are
matched with tRNA anticodons to assemble amino acids.
---
Q11: A mutation that changes a single nucleotide but does not alter the amino acid sequence is
called:
A. Missense mutation
