HESI A2 BIOLOGY COMPREHENSIVE
EXAM QUESTIONS & ANSWERS
(VERIFIED ANSWERS) WITH EXPERT
EXPLANATIONS | 2026 – 2027 UPDATE
(PDF)
1. Which organelle is responsible for the detoxification of metabolic byproducts and the
synthesis of lipids and steroids?
A. Rough Endoplasmic Reticulum
B. Lysosome
C. Golgi Apparatus
D. Smooth Endoplasmic Reticulum
Answer: D
Conceptual Explanation: The Smooth ER lacks ribosomes and is involved in lipid
synthesis, carbohydrate metabolism, and the detoxification of drugs and poisons.
2. During which phase of the cell cycle does DNA replication specifically occur?
A. S Phase
B. G2 Phase
C. G1 Phase
,D. M Phase
Answer: A
Conceptual Explanation: The S (Synthesis) phase of interphase is when the cell replicates
its DNA to ensure daughter cells have a complete set of chromosomes.
3. In a dihybrid cross between two individuals heterozygous for two traits (AaBb x AaBb),
what is the expected phenotypic ratio assuming independent assortment?
A. 3:1
B. 1:2:1
C. 1:1:1:1
D. 9:3:3:1
Answer: D
Conceptual Explanation: A dihybrid cross involving two heterozygous parents follows
Mendel’s Law of Independent Assortment, resulting in a 9:3:3:1 phenotypic ratio.
4. Which molecule acts as the final electron acceptor in the electron transport chain during
aerobic cellular respiration?
A. Water
B. Carbon Dioxide
C. Oxygen
D. NAD+
, Answer: C
Conceptual Explanation: Oxygen is the final electron acceptor at the end of the electron
transport chain, where it combines with electrons and hydrogen ions to form water.
5. What is the primary function of tRNA during the process of translation?
A. Transporting specific amino acids to the ribosome
B. Translating the DNA sequence into mRNA
C. Carrying the genetic code from the nucleus to the ribosome
D. Forming the structural backbone of the ribosome
Answer: A
Conceptual Explanation: tRNA (transfer RNA) molecules match their anticodons to mRNA
codons to deliver the correct amino acids for protein synthesis.
6. Which process results in the production of four non-identical haploid daughter cells?
A. Meiosis
B. Binary Fission
C. Mitosis
D. Budding
Answer: A
EXAM QUESTIONS & ANSWERS
(VERIFIED ANSWERS) WITH EXPERT
EXPLANATIONS | 2026 – 2027 UPDATE
(PDF)
1. Which organelle is responsible for the detoxification of metabolic byproducts and the
synthesis of lipids and steroids?
A. Rough Endoplasmic Reticulum
B. Lysosome
C. Golgi Apparatus
D. Smooth Endoplasmic Reticulum
Answer: D
Conceptual Explanation: The Smooth ER lacks ribosomes and is involved in lipid
synthesis, carbohydrate metabolism, and the detoxification of drugs and poisons.
2. During which phase of the cell cycle does DNA replication specifically occur?
A. S Phase
B. G2 Phase
C. G1 Phase
,D. M Phase
Answer: A
Conceptual Explanation: The S (Synthesis) phase of interphase is when the cell replicates
its DNA to ensure daughter cells have a complete set of chromosomes.
3. In a dihybrid cross between two individuals heterozygous for two traits (AaBb x AaBb),
what is the expected phenotypic ratio assuming independent assortment?
A. 3:1
B. 1:2:1
C. 1:1:1:1
D. 9:3:3:1
Answer: D
Conceptual Explanation: A dihybrid cross involving two heterozygous parents follows
Mendel’s Law of Independent Assortment, resulting in a 9:3:3:1 phenotypic ratio.
4. Which molecule acts as the final electron acceptor in the electron transport chain during
aerobic cellular respiration?
A. Water
B. Carbon Dioxide
C. Oxygen
D. NAD+
, Answer: C
Conceptual Explanation: Oxygen is the final electron acceptor at the end of the electron
transport chain, where it combines with electrons and hydrogen ions to form water.
5. What is the primary function of tRNA during the process of translation?
A. Transporting specific amino acids to the ribosome
B. Translating the DNA sequence into mRNA
C. Carrying the genetic code from the nucleus to the ribosome
D. Forming the structural backbone of the ribosome
Answer: A
Conceptual Explanation: tRNA (transfer RNA) molecules match their anticodons to mRNA
codons to deliver the correct amino acids for protein synthesis.
6. Which process results in the production of four non-identical haploid daughter cells?
A. Meiosis
B. Binary Fission
C. Mitosis
D. Budding
Answer: A
