DAT Exam Prep 2026 Updated Practice Questions
Comprehensive Dental Admission Test Review Science
Reasoning Preparation, Detailed Explanations,
Complete Success Workbook
DOMAIN 1: BIOLOGY (Questions 1-20)
QUESTION 1
Which of the following does NOT occur during telophase of mitosis?
A) Reassembly of the nuclear envelope
B) Reappearance of the nucleoli
C) Condensation of chromosomes
D) Cytokinesis begins
ANSWER: C) Condensation of chromosomes
RATIONALE: During telophase, the chromosomes decondense (uncoil), the
nuclear envelope reassembles, nucleoli reappear, and cytokinesis begins.
Chromosome condensation occurs during prophase, not telophase. Therefore,
condensation of chromosomes is the process that does NOT occur during
telophase.
QUESTION 2
Enzymes that catalyze the transfer of phosphate groups from ATP to organic
molecules are called:
A) Phosphatases
B) Kinases
C) Dehydrogenases
D) Isomerases
ANSWER: B) Kinases
RATIONALE: Kinases are enzymes that catalyze the phosphorylation of organic
molecules by transferring phosphate groups from ATP to substrates. Phosphatases
,(A) remove phosphate groups. Dehydrogenases (C) catalyze oxidation-reduction
reactions. Isomerases (D) catalyze structural rearrangements within molecules.
QUESTION 3
During cellular respiration, NAD⁺ is reduced to NADH in which of the following
processes?
A) Glycolysis only
B) The Krebs cycle only
C) Both glycolysis and the Krebs cycle
D) The electron transport chain
ANSWER: C) Both glycolysis and the Krebs cycle
RATIONALE: NAD⁺ is reduced to NADH during both glycolysis (when
glyceraldehyde-3-phosphate is oxidized) and the Krebs cycle (during isocitrate
dehydrogenase, alpha-ketoglutarate dehydrogenase, and malate dehydrogenase
reactions). The electron transport chain (D) oxidizes NADH back to NAD⁺, rather
than reducing it.
QUESTION 4
A cell has 46 chromosomes at the beginning of meiosis I. How many
chromosomes will each daughter cell have after meiosis II is complete?
A) 23
B) 46
C) 92
D) 12
ANSWER: A) 23
RATIONALE: Meiosis reduces the chromosome number by half. A diploid cell
(2n = 46) undergoes meiosis I to produce two haploid cells (n = 23), and meiosis II
separates sister chromatids without changing the chromosome number. Thus, each
of the four daughter cells produced at the end of meiosis II contains 23
chromosomes.
,QUESTION 5
Which of the following is NOT a characteristic of the Kingdom Animalia?
A) Multicellular
B) Eukaryotic
C) Cell walls composed of chitin
D) Heterotrophic
ANSWER: C) Cell walls composed of chitin
RATIONALE: Animal cells lack cell walls. Chitin is found in the cell walls of
fungi (Kingdom Fungi) and in the exoskeletons of arthropods. Animals are
multicellular (A), eukaryotic (B), and heterotrophic (D), but they do not have cell
walls.
QUESTION 6
What is the function of the enzyme helicase in DNA replication?
A) Synthesizes new DNA strands
B) Unwinds the double helix by breaking hydrogen bonds
C) Joins Okazaki fragments
D) Prevents supercoiling ahead of the replication fork
ANSWER: B) Unwinds the double helix by breaking hydrogen bonds
RATIONALE: Helicase unwinds the DNA double helix by breaking the hydrogen
bonds between complementary base pairs, creating the replication fork. DNA
polymerase (A) synthesizes new strands. DNA ligase (C) joins Okazaki fragments.
Topoisomerase (D) prevents supercoiling.
QUESTION 7
In the Hardy-Weinberg equilibrium equation, p² + 2pq + q² = 1, what does 2pq
represent?
A) Frequency of the dominant genotype
B) Frequency of the recessive genotype
C) Frequency of the heterozygous genotype
D) Frequency of the dominant allele
, ANSWER: C) Frequency of the heterozygous genotype
RATIONALE: In the Hardy-Weinberg equation, p² represents the frequency of
the homozygous dominant genotype, q² represents the frequency of the
homozygous recessive genotype, and 2pq represents the frequency of the
heterozygous genotype. p and q represent allele frequencies.
QUESTION 8
Which of the following organelles is responsible for the synthesis of ATP through
oxidative phosphorylation?
A) Nucleus
B) Ribosome
C) Mitochondrion
D) Golgi apparatus
ANSWER: C) Mitochondrion
RATIONALE: The mitochondrion is the site of oxidative phosphorylation, where
ATP is synthesized through the electron transport chain and chemiosmosis. The
nucleus (A) contains genetic material. Ribosomes (B) synthesize proteins. The
Golgi apparatus (D) modifies and packages proteins.
QUESTION 9
A mutation that results in the substitution of one amino acid for another in a
protein is called a:
A) Nonsense mutation
B) Missense mutation
C) Silent mutation
D) Frameshift mutation
ANSWER: B) Missense mutation
RATIONALE: A missense mutation is a point mutation that results in a change in
a single nucleotide, leading to the substitution of one amino acid for another in the
protein. Nonsense mutations (A) create a premature stop codon. Silent mutations
(C) do not change the amino acid. Frameshift mutations (D) result from insertions
or deletions.
Comprehensive Dental Admission Test Review Science
Reasoning Preparation, Detailed Explanations,
Complete Success Workbook
DOMAIN 1: BIOLOGY (Questions 1-20)
QUESTION 1
Which of the following does NOT occur during telophase of mitosis?
A) Reassembly of the nuclear envelope
B) Reappearance of the nucleoli
C) Condensation of chromosomes
D) Cytokinesis begins
ANSWER: C) Condensation of chromosomes
RATIONALE: During telophase, the chromosomes decondense (uncoil), the
nuclear envelope reassembles, nucleoli reappear, and cytokinesis begins.
Chromosome condensation occurs during prophase, not telophase. Therefore,
condensation of chromosomes is the process that does NOT occur during
telophase.
QUESTION 2
Enzymes that catalyze the transfer of phosphate groups from ATP to organic
molecules are called:
A) Phosphatases
B) Kinases
C) Dehydrogenases
D) Isomerases
ANSWER: B) Kinases
RATIONALE: Kinases are enzymes that catalyze the phosphorylation of organic
molecules by transferring phosphate groups from ATP to substrates. Phosphatases
,(A) remove phosphate groups. Dehydrogenases (C) catalyze oxidation-reduction
reactions. Isomerases (D) catalyze structural rearrangements within molecules.
QUESTION 3
During cellular respiration, NAD⁺ is reduced to NADH in which of the following
processes?
A) Glycolysis only
B) The Krebs cycle only
C) Both glycolysis and the Krebs cycle
D) The electron transport chain
ANSWER: C) Both glycolysis and the Krebs cycle
RATIONALE: NAD⁺ is reduced to NADH during both glycolysis (when
glyceraldehyde-3-phosphate is oxidized) and the Krebs cycle (during isocitrate
dehydrogenase, alpha-ketoglutarate dehydrogenase, and malate dehydrogenase
reactions). The electron transport chain (D) oxidizes NADH back to NAD⁺, rather
than reducing it.
QUESTION 4
A cell has 46 chromosomes at the beginning of meiosis I. How many
chromosomes will each daughter cell have after meiosis II is complete?
A) 23
B) 46
C) 92
D) 12
ANSWER: A) 23
RATIONALE: Meiosis reduces the chromosome number by half. A diploid cell
(2n = 46) undergoes meiosis I to produce two haploid cells (n = 23), and meiosis II
separates sister chromatids without changing the chromosome number. Thus, each
of the four daughter cells produced at the end of meiosis II contains 23
chromosomes.
,QUESTION 5
Which of the following is NOT a characteristic of the Kingdom Animalia?
A) Multicellular
B) Eukaryotic
C) Cell walls composed of chitin
D) Heterotrophic
ANSWER: C) Cell walls composed of chitin
RATIONALE: Animal cells lack cell walls. Chitin is found in the cell walls of
fungi (Kingdom Fungi) and in the exoskeletons of arthropods. Animals are
multicellular (A), eukaryotic (B), and heterotrophic (D), but they do not have cell
walls.
QUESTION 6
What is the function of the enzyme helicase in DNA replication?
A) Synthesizes new DNA strands
B) Unwinds the double helix by breaking hydrogen bonds
C) Joins Okazaki fragments
D) Prevents supercoiling ahead of the replication fork
ANSWER: B) Unwinds the double helix by breaking hydrogen bonds
RATIONALE: Helicase unwinds the DNA double helix by breaking the hydrogen
bonds between complementary base pairs, creating the replication fork. DNA
polymerase (A) synthesizes new strands. DNA ligase (C) joins Okazaki fragments.
Topoisomerase (D) prevents supercoiling.
QUESTION 7
In the Hardy-Weinberg equilibrium equation, p² + 2pq + q² = 1, what does 2pq
represent?
A) Frequency of the dominant genotype
B) Frequency of the recessive genotype
C) Frequency of the heterozygous genotype
D) Frequency of the dominant allele
, ANSWER: C) Frequency of the heterozygous genotype
RATIONALE: In the Hardy-Weinberg equation, p² represents the frequency of
the homozygous dominant genotype, q² represents the frequency of the
homozygous recessive genotype, and 2pq represents the frequency of the
heterozygous genotype. p and q represent allele frequencies.
QUESTION 8
Which of the following organelles is responsible for the synthesis of ATP through
oxidative phosphorylation?
A) Nucleus
B) Ribosome
C) Mitochondrion
D) Golgi apparatus
ANSWER: C) Mitochondrion
RATIONALE: The mitochondrion is the site of oxidative phosphorylation, where
ATP is synthesized through the electron transport chain and chemiosmosis. The
nucleus (A) contains genetic material. Ribosomes (B) synthesize proteins. The
Golgi apparatus (D) modifies and packages proteins.
QUESTION 9
A mutation that results in the substitution of one amino acid for another in a
protein is called a:
A) Nonsense mutation
B) Missense mutation
C) Silent mutation
D) Frameshift mutation
ANSWER: B) Missense mutation
RATIONALE: A missense mutation is a point mutation that results in a change in
a single nucleotide, leading to the substitution of one amino acid for another in the
protein. Nonsense mutations (A) create a premature stop codon. Silent mutations
(C) do not change the amino acid. Frameshift mutations (D) result from insertions
or deletions.
