OAT Biology Practice Test 2024 [With Explanation] Untimed

OAT Biology Practice Test 2024 [With Explanation] Untimed: Try our free Optometry Admission Test (OAT) Biology online quiz for better OAT test prep. Biology is integral to mastering the OAT’s Survey of Natural Sciences portion.

The biology review in this Practice Test begins with a chapter on a strategy that tests your knowledge of that content and reviews the quiz to find any missing knowledge gaps. The biology knowledge you need for the DAT encompasses various topics in cell and molecular biology, diversity of life, vertebrate anatomy and physiology, developmental biology, genetics and evolution, and ecology and behavior.

Mastering biology on the OAT means memorizing biology vocabulary and facts and learning to integrate your knowledge, make connections, and otherwise approach the multiple-choice questions in the Biology subtest and the entire Survey of Natural Sciences section in the best way possible.

OAT Biology Practice Test 2024

Biology content appears in the Survey of Natural Sciences section, which contains the Biology, General Chemistry, and Organic Chemistry subtests. In the real test, the Survey of Natural Sciences has 100 questions that must be completed in 90 minutes. Questions 1–40 are always related to biology.

Test Name OAT Practice Test 2024
Test Purpose Admission into optometry schools
Subject Survey of Natural Sciences
Sub Test Biology
Sample Questions 40
Time Limit Untimed

 Cell and Molecular Biology 

Which organelle is primarily responsible for energy production in the cell?

  • (A) Nucleus
  • (B) Mitochondria
  • (C) Lysosome
  • (D) Ribosome
  • (E) Endoplasmic Reticulum
View Answer
Answer: (B) Mitochondria Explanation: The mitochondria are known as the powerhouse of the cell because they generate most of the cell’s supply of adenosine triphosphate (ATP), which is used as a source of chemical energy.

During which phase of the cell cycle does DNA replication occur?

  • (A) G1 phase
  • (B) S phase
  • (C) G2 phase
  • (D) M phase
  • (E) Cytokinesis
View Answer
Answer: (B) S phase Explanation: DNA replication occurs during the S (synthesis) phase of the cell cycle, ensuring that each daughter cell receives an identical set of chromosomes.

What is the main function of ribosomes?

  • (A) DNA replication
  • (B) Protein synthesis
  • (C) Lipid metabolism
  • (D) Cell division
  • (E) Photosynthesis
View Answer
Answer: (B) Protein synthesis Explanation: Ribosomes are the molecular machines in the cell that synthesize proteins by translating messenger RNA (mRNA) into polypeptide chains.

Which of the following is a component of the plasma membrane?

  • (A) Nucleic acids
  • (B) Phospholipids
  • (C) Ribosomes
  • (D) Golgi apparatus
  • (E) Mitochondria
View Answer
Answer: (B) Phospholipids Explanation: The plasma membrane is primarily composed of a bilayer of phospholipids, which form a barrier that separates the cell from its environment.

What process describes the movement of water across a selectively permeable membrane?

  • (A) Diffusion
  • (B) Osmosis
  • (C) Active transport
  • (D) Facilitated diffusion
  • (E) Endocytosis
View Answer
Answer: (B) Osmosis Explanation: Osmosis is the movement of water molecules through a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Which phase of mitosis is characterized by the alignment of chromosomes along the metaphase plate?

  • (A) Prophase
  • (B) Metaphase
  • (C) Anaphase
  • (D) Telophase
  • (E) Cytokinesis
View Answer
Answer: (B) Metaphase Explanation: During metaphase, chromosomes line up along the metaphase plate, an imaginary line equidistant from the two spindle poles.

What is the end product of glycolysis?

  • (A) Glucose
  • (B) Pyruvate
  • (C) ATP
  • (D) Carbon dioxide
  • (E) Water
View Answer
Answer: (B) Pyruvate Explanation: Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing a net gain of two ATP molecules.

In which part of the chloroplast does the Calvin cycle take place?

  • (A) Thylakoid membrane
  • (B) Stroma
  • (C) Granum
  • (D) Inner membrane
  • (E) Outer membrane
View Answer
Answer: (B) Stroma Explanation: The Calvin cycle, which fixes carbon dioxide into organic molecules, occurs in the stroma of the chloroplast.

What is the primary function of enzymes in biological reactions?

  • (A) Increase the equilibrium constant
  • (B) Decrease the activation energy
  • (C) Increase the temperature
  • (D) Change the free energy of the reaction
  • (E) Increase the reaction time
View Answer
Answer: (B) Decrease the activation energy Explanation: Enzymes function as catalysts by lowering the activation energy required for a reaction to proceed, thereby increasing the reaction rate.

Which type of bond forms between the hydrogen and oxygen atoms within a single water molecule?

  • (A) Ionic bond
  • (B) Covalent bond
  • (C) Hydrogen bond
  • (D) Peptide bond
  • (E) Metallic bond
View Answer
Answer: (B) Covalent bond Explanation: Within a single water molecule, the hydrogen and oxygen atoms are bonded together by covalent bonds, where electrons are shared between atoms.

 Diversity of Life 

Which kingdom includes multicellular organisms that are primarily autotrophic?

  • (A) Fungi
  • (B) Protista
  • (C) Plantae
  • (D) Animalia
  • (E) Archaebacteria
View Answer
Answer: (C) Plantae Explanation: The Plantae kingdom includes multicellular organisms, such as plants, that are primarily autotrophic, meaning they produce their own food through photosynthesis.

Which group of microorganisms includes those that can survive extreme environments, such as high temperatures or high salinity?

  • (A) Eubacteria
  • (B) Fungi
  • (C) Protista
  • (D) Archaebacteria
  • (E) Viruses
View Answer
Answer: (D) Archaebacteria Explanation: Archaebacteria are a group of microorganisms that can survive in extreme environments, such as hot springs, salt lakes, and anaerobic conditions.

What type of symmetry is exhibited by organisms in the phylum Cnidaria?

  • (A) Bilateral symmetry
  • (B) Radial symmetry
  • (C) Asymmetry
  • (D) Spherical symmetry
  • (E) None of the above
View Answer
Answer: (B) Radial symmetry Explanation: Organisms in the phylum Cnidaria, such as jellyfish and corals, exhibit radial symmetry, where body parts are arranged around a central axis.

Which of the following is not a characteristic of viruses?

  • (A) Can reproduce independently
  • (B) Contains genetic material
  • (C) Requires a host cell to replicate
  • (D) Can cause disease
  • (E) Is composed of proteins and nucleic acids
View Answer
Answer: (A) Can reproduce independently Explanation: Viruses cannot reproduce independently; they require a host cell to replicate their genetic material and produce new virus particles.

Which structure is found in plant cells but not in animal cells?

  • (A) Nucleus
  • (B) Mitochondria
  • (C) Chloroplast
  • (D) Ribosome
  • (E) Endoplasmic reticulum
View Answer
Answer: (C) Chloroplast Explanation: Chloroplasts, which are the sites of photosynthesis, are found in plant cells but not in animal cells.

Which of the following methods do fungi obtain their nutrients?

  • (A) Photosynthesis
  • (B) Chemosynthesis
  • (C) Absorption
  • (D) Ingestion
  • (E) Nitrogen fixation
View Answer
Answer: (C) Absorption Explanation: Fungi obtain nutrients through absorption, where they secrete digestive enzymes to break down organic matter and then absorb the resulting small molecules.

Which phylum includes organisms with jointed appendages and an exoskeleton made of chitin?

  • (A) Annelida
  • (B) Mollusca
  • (C) Arthropoda
  • (D) Echinodermata
  • (E) Cnidaria
View Answer
Answer: (C) Arthropoda Explanation: Arthropods, such as insects, arachnids, and crustaceans, have jointed appendages and an exoskeleton made of chitin.

In the classification hierarchy, which level is immediately higher than genus?

  • (A) Species
  • (B) Family
  • (C) Order
  • (D) Class
  • (E) Phylum
View Answer
Answer: (B) Family Explanation: In the taxonomic hierarchy, the family level is immediately higher than the genus level.

 Structure and Function of Systems 

Which system is primarily responsible for transporting oxygen and nutrients throughout the body?

  • (A) Digestive system
  • (B) Circulatory system
  • (C) Nervous system
  • (D) Respiratory system
  • (E) Endocrine system
View Answer
Answer: (B) Circulatory system Explanation: The circulatory system, including the heart and blood vessels, is responsible for transporting oxygen, nutrients, and other substances throughout the body.

Which part of the brain coordinates voluntary muscle movements and maintains posture and balance?

  • (A) Cerebrum
  • (B) Cerebellum
  • (C) Medulla oblongata
  • (D) Hypothalamus
  • (E) Thalamus
View Answer
Answer: (B) Cerebellum Explanation: The cerebellum is responsible for coordinating voluntary muscle movements, maintaining posture, and ensuring balance.

Which type of blood vessel carries blood away from the heart?

  • (A) Veins
  • (B) Capillaries
  • (C) Arteries
  • (D) Venules
  • (E) Lymphatic vessels
View Answer
Answer: (C) Arteries Explanation: Arteries are blood vessels that carry blood away from the heart to various parts of the body.

What is the main function of the nephron in the kidney?

  • (A) Production of insulin
  • (B) Filtration of blood to form urine
  • (C) Storage of bile
  • (D) Regulation of blood pressure
  • (E) Absorption of nutrients
View Answer
Answer: (B) Filtration of blood to form urine Explanation: The nephron is the functional unit of the kidney that filters blood to form urine, removing waste products and excess substances from the bloodstream.

The skin, hair, and nails are included in which system and function as a barrier to protect the body from the outside environment?

  • (A) Skeletal system
  • (B) Muscular system
  • (C) Integumentary system
  • (D) Endocrine system
  • (E) Respiratory system
View Answer
Answer: (C) Integumentary system Explanation: The integumentary system, which includes the skin, hair, and nails, protects the body from external factors such as pathogens, chemicals, and physical injuries.

Which hormone is responsible for regulating blood sugar levels by promoting the uptake of glucose into cells?

  • (A) Glucagon
  • (B) Insulin
  • (C) Adrenaline
  • (D) Thyroxine
  • (E) Cortisol
View Answer
Answer: (B) Insulin Explanation: Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels by promoting the uptake of glucose into cells, lowering blood glucose levels.

Which part of the digestive system is primarily responsible for nutrient absorption?

  • (A) Stomach
  • (B) Small intestine
  • (C) Large intestine
  • (D) Esophagus
  • (E) Rectum
View Answer
Answer: (B) Small intestine Explanation: The small intestine is the primary site for nutrient absorption, where digested food is absorbed into the bloodstream.

What is the role of the lymphatic system in the body?

  • (A) Transporting oxygen and nutrients
  • (B) Producing hormones
  • (C) Defending against infections
  • (D) Digesting food
  • (E) Controlling body temperature
View Answer
Answer: (C) Defending against infections Explanation: The lymphatic system helps defend the body against infections by producing and transporting lymphocytes, removing waste, and filtering lymph fluid through lymph nodes.

Which system controls and coordinates body activities through electrical impulses and chemical signals?

  • (A) Endocrine system
  • (B) Muscular system
  • (C) Nervous system
  • (D) Circulatory system
  • (E) Digestive system
View Answer
Answer: (C) Nervous system Explanation: The nervous system controls and coordinates body activities through electrical impulses transmitted by neurons and chemical signals called neurotransmitters.

Which structure in the respiratory system is the site of gas exchange?

  • (A) Trachea
  • (B) Bronchi
  • (C) Alveoli
  • (D) Larynx
  • (E) Pharynx
View Answer
Answer: (C) Alveoli Explanation: The alveoli are small air sacs in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be expelled.


What is the term for a segment of DNA that codes for a specific protein?

  • (A) Chromosome
  • (B) Gene
  • (C) Allele
  • (D) Codon
  • (E) Genome
View Answer
Answer: (B) Gene Explanation: A gene is a segment of DNA that contains the instructions for making a specific protein, which contributes to an organism’s traits.

Which process results in the formation of gametes with half the number of chromosomes as the parent cell?

  • (A) Mitosis
  • (B) Meiosis
  • (C) Binary fission
  • (D) Budding
  • (E) Regeneration
View Answer
Answer: (B) Meiosis Explanation: Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically unique gametes, such as sperm and eggs.

What is the term for a gene variation that can exist at a particular locus?

  • (A) Chromosome
  • (B) Allele
  • (C) Genotype
  • (D) Phenotype
  • (E) Karyotype
View Answer
Answer: (B) Allele Explanation: An allele is a variation of a gene that can exist at a specific locus on a chromosome, contributing to the diversity of traits within a population.

Which genetic disorder is caused by an extra copy of chromosome 21?

  • (A) Turner syndrome
  • (B) Klinefelter syndrome
  • (C) Down syndrome
  • (D) Cystic fibrosis
  • (E) Huntington’s disease
View Answer
Answer: (C) Down syndrome Explanation: Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, leading to developmental and intellectual delays.

What is the process by which a DNA sequence is copied into mRNA?

  • (A) Replication
  • (B) Transcription
  • (C) Translation
  • (D) Mutation
  • (E) Splicing
View Answer
Answer: (B) Transcription Explanation: Transcription is the process by which the DNA sequence of a gene is copied into messenger RNA (mRNA), which carries the genetic information to the ribosome for protein synthesis.

Which technique is used to amplify a specific segment of DNA?

  • (A) Gel electrophoresis
  • (B) Polymerase chain reaction (PCR)
  • (C) DNA sequencing
  • (D) Cloning
  • (E) Hybridization
View Answer
Answer: (B) Polymerase chain reaction (PCR) Explanation: PCR is a technique used to amplify a specific segment of DNA, allowing for the creation of millions of copies of a particular DNA sequence.

 Evolution and Ecology 

What is the mechanism by which populations evolve over generations due to changes in allele frequencies?

  • (A) Genetic drift
  • (B) Gene flow
  • (C) Natural selection
  • (D) Mutation
  • (E) Non-random mating
View Answer
Answer: (C) Natural selection Explanation: Natural selection is the mechanism by which populations evolve over generations as individuals with advantageous traits are more likely to survive and reproduce, leading to changes in allele frequencies.

What term describes a relationship between two species in which both benefit?

  • (A) Predation
  • (B) Parasitism
  • (C) Mutualism
  • (D) Commensalism
  • (E) Competition
View Answer
Answer: (C) Mutualism Explanation: Mutualism describes a relationship between two species in which both benefit, such as bees pollinating flowers while obtaining nectar for food.

Which process describes the movement of individuals into a population, increasing genetic diversity?

  • (A) Genetic drift
  • (B) Gene flow
  • (C) Natural selection
  • (D) Mutation
  • (E) Speciation
View Answer
Answer: (B) Gene flow Explanation: Gene flow refers to the movement of individuals or their genetic material into a population, increasing genetic diversity and potentially introducing new alleles.

What is the term for a random change in allele frequencies within a population, often having a greater effect in small populations?

  • (A) Genetic drift
  • (B) Gene flow
  • (C) Natural selection
  • (D) Mutation
  • (E) Non-random mating
View Answer
Answer: (A) Genetic drift Explanation: Genetic drift is a random change in allele frequencies within a population, which can have a significant effect, especially in small populations.

Which type of selection favors individuals with extreme trait values over those with intermediate values?

  • (A) Stabilizing selection
  • (B) Directional selection
  • (C) Disruptive selection
  • (D) Sexual selection
  • (E) Artificial selection
View Answer
Answer: (C) Disruptive selection Explanation: Disruptive selection favors individuals with extreme values of a trait over those with intermediate values, leading to a bimodal distribution of traits.

What is the term for the process by which new species arise from existing species?

  • (A) Adaptation
  • (B) Speciation
  • (C) Extinction
  • (D) Evolution
  • (E) Hybridization
View Answer
Answer: (B) Speciation Explanation: Speciation is the process by which new species arise from existing species, typically through mechanisms such as geographic isolation or reproductive isolation.

See also:

 Untimed Tests with Explanation