SAT BIOLOGY (ECOLOGICAL + MOLECULAR) EXAM
QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES GRADED A+ LATEST
1. Which organelle is primarily responsible for ATP production in eukaryotic
cells?
A) Nucleus
B) Ribosome
C) Mitochondrion
D) Golgi apparatus
E) Lysosome
Answer: C
Rationale: The mitochondrion produces ATP via oxidative phosphorylation.
2. During which phase of the cell cycle does DNA replication occur?
A) G1
B) S
C) G2
D) M
E) Cytokinesis
Answer: B
Rationale: DNA replication occurs during the S (Synthesis) phase.
3. Which macromolecule is the main component of the cell membrane?
A) Carbohydrate
B) Protein
C) Lipid
D) Nucleic acid
E) Polysaccharide
Answer: C
Rationale: Phospholipids form the bilayer of the cell membrane.
,4. Which process allows bacteria to exchange genetic material through direct
contact?
A) Transformation
B) Transduction
C) Conjugation
D) Binary fission
E) Transcription
Answer: C
Rationale: Conjugation involves transfer of plasmids via a pilus.
5. Which enzyme unwinds DNA during replication?
A) Ligase
B) Helicase
C) DNA polymerase
D) RNA polymerase
E) Topoisomerase
Answer: B
Rationale: Helicase separates DNA strands for replication.
6. In which organelle does photosynthesis occur?
A) Mitochondrion
B) Chloroplast
C) Endoplasmic reticulum
D) Nucleus
E) Peroxisome
Answer: B
Rationale: Chloroplasts contain chlorophyll and conduct photosynthesis.
7. Which type of RNA carries amino acids to the ribosome during translation?
A) mRNA
B) rRNA
C) tRNA
D) snRNA
E) miRNA
Answer: C
Rationale: tRNA delivers amino acids to the ribosome in translation.
,8. Which process produces gametes with half the chromosome number of the
parent cell?
A) Mitosis
B) Meiosis
C) Binary fission
D) Budding
E) Fertilization
Answer: B
Rationale: Meiosis reduces the chromosome number by half for gametes.
9. Which molecule is the primary carrier of genetic information in cells?
A) RNA
B) DNA
C) Protein
D) ATP
E) Lipid
Answer: B
Rationale: DNA stores hereditary information in all living organisms.
10. Which component of a nucleotide differentiates DNA from RNA?
A) Phosphate
B) Nitrogenous base
C) Sugar
D) Hydrogen bonds
E) Ribose
Answer: C
Rationale: DNA has deoxyribose; RNA has ribose.
11. Which phase of mitosis is characterized by the separation of sister chromatids?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
E) Interphase
Answer: C
Rationale: Anaphase is when sister chromatids are pulled apart.
, 12. Which type of enzyme joins Okazaki fragments during DNA replication?
A) DNA polymerase
B) Ligase
C) Helicase
D) Primase
E) Topoisomerase
Answer: B
Rationale: Ligase seals the sugar-phosphate backbone between fragments.
13. Which type of bond holds complementary base pairs together in DNA?
A) Covalent
B) Ionic
C) Hydrogen
D) Peptide
E) Phosphodiester
Answer: C
Rationale: Hydrogen bonds hold A–T (2 bonds) and G–C (3 bonds) together.
14. Which organelle modifies, sorts, and packages proteins for transport?
A) Endoplasmic reticulum
B) Golgi apparatus
C) Lysosome
D) Ribosome
E) Peroxisome
Answer: B
Rationale: The Golgi apparatus processes and packages proteins.
15. During transcription, which strand of DNA serves as the template?
A) Coding strand
B) Template strand
C) Both strands
D) None
E) Exon only
Answer: B
Rationale: RNA polymerase reads the template strand to synthesize RNA.
QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES GRADED A+ LATEST
1. Which organelle is primarily responsible for ATP production in eukaryotic
cells?
A) Nucleus
B) Ribosome
C) Mitochondrion
D) Golgi apparatus
E) Lysosome
Answer: C
Rationale: The mitochondrion produces ATP via oxidative phosphorylation.
2. During which phase of the cell cycle does DNA replication occur?
A) G1
B) S
C) G2
D) M
E) Cytokinesis
Answer: B
Rationale: DNA replication occurs during the S (Synthesis) phase.
3. Which macromolecule is the main component of the cell membrane?
A) Carbohydrate
B) Protein
C) Lipid
D) Nucleic acid
E) Polysaccharide
Answer: C
Rationale: Phospholipids form the bilayer of the cell membrane.
,4. Which process allows bacteria to exchange genetic material through direct
contact?
A) Transformation
B) Transduction
C) Conjugation
D) Binary fission
E) Transcription
Answer: C
Rationale: Conjugation involves transfer of plasmids via a pilus.
5. Which enzyme unwinds DNA during replication?
A) Ligase
B) Helicase
C) DNA polymerase
D) RNA polymerase
E) Topoisomerase
Answer: B
Rationale: Helicase separates DNA strands for replication.
6. In which organelle does photosynthesis occur?
A) Mitochondrion
B) Chloroplast
C) Endoplasmic reticulum
D) Nucleus
E) Peroxisome
Answer: B
Rationale: Chloroplasts contain chlorophyll and conduct photosynthesis.
7. Which type of RNA carries amino acids to the ribosome during translation?
A) mRNA
B) rRNA
C) tRNA
D) snRNA
E) miRNA
Answer: C
Rationale: tRNA delivers amino acids to the ribosome in translation.
,8. Which process produces gametes with half the chromosome number of the
parent cell?
A) Mitosis
B) Meiosis
C) Binary fission
D) Budding
E) Fertilization
Answer: B
Rationale: Meiosis reduces the chromosome number by half for gametes.
9. Which molecule is the primary carrier of genetic information in cells?
A) RNA
B) DNA
C) Protein
D) ATP
E) Lipid
Answer: B
Rationale: DNA stores hereditary information in all living organisms.
10. Which component of a nucleotide differentiates DNA from RNA?
A) Phosphate
B) Nitrogenous base
C) Sugar
D) Hydrogen bonds
E) Ribose
Answer: C
Rationale: DNA has deoxyribose; RNA has ribose.
11. Which phase of mitosis is characterized by the separation of sister chromatids?
A) Prophase
B) Metaphase
C) Anaphase
D) Telophase
E) Interphase
Answer: C
Rationale: Anaphase is when sister chromatids are pulled apart.
, 12. Which type of enzyme joins Okazaki fragments during DNA replication?
A) DNA polymerase
B) Ligase
C) Helicase
D) Primase
E) Topoisomerase
Answer: B
Rationale: Ligase seals the sugar-phosphate backbone between fragments.
13. Which type of bond holds complementary base pairs together in DNA?
A) Covalent
B) Ionic
C) Hydrogen
D) Peptide
E) Phosphodiester
Answer: C
Rationale: Hydrogen bonds hold A–T (2 bonds) and G–C (3 bonds) together.
14. Which organelle modifies, sorts, and packages proteins for transport?
A) Endoplasmic reticulum
B) Golgi apparatus
C) Lysosome
D) Ribosome
E) Peroxisome
Answer: B
Rationale: The Golgi apparatus processes and packages proteins.
15. During transcription, which strand of DNA serves as the template?
A) Coding strand
B) Template strand
C) Both strands
D) None
E) Exon only
Answer: B
Rationale: RNA polymerase reads the template strand to synthesize RNA.
