HESI A2 Science Practice Test 2026 – Complete Exam Prep – All Questions

Browse all practice questions for the HESI A2 SCIENCE Practice Test. Search by topic, open any question and review its full explanation, then test yourself in the practice quiz.

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Aerobic vs Anaerobic Respiration: What's the Real Difference?What is the difference between aerobic and anaerobic respiration?Did You Know Skin is the Largest Organ in Your Body?What is the largest organ in the human body?Discovering the Role of Plasma Cells in the Immune SystemWhat do plasma cells produce?How Hemoglobin and Red Blood Cells Work Together to Keep You AliveIn which type of cells is hemoglobin primarily found?How Hemoglobin Functions in Your BodyHow does hemoglobin function in the body?Let’s Break Down The Structure of Amino Acids TogetherWhat is the basic structure of an amino acid?Let's Explore the Kidney's Essential Role in Filtering BloodWhich organ is primarily responsible for filtering blood and producing urine?The Consequences of Impaired Placental Function During PregnancyWhat can be a consequence of impaired placental function during pregnancy?The Endocrine System: The Unsung Hero of Hormone RegulationWhich body system is primarily responsible for hormone regulation?The Essential Role of Thyroid Hormones in Our MetabolismWhat is the primary function of thyroid hormone?The Key Role of the Lymphatic System in Our BodyWhat role does the lymphatic system play in the body?The Role of the Pancreas: Your Body’s Insulin FactoryWhich organ produces insulin?The Science Behind Photosynthesis: The Key to Life on EarthWhat is the formula for photosynthesis?Understanding Antigens: The Key Players in Our Immune ResponseWhat is an antigen?Understanding Biodiversity: Why It Matters in ScienceWhich of the following best defines biodiversity?Understanding Biomes: The Big Picture of Our PlanetWhat is a biome?Understanding Cellular Respiration: The Path to Energy ProductionWhich of the following lists the correct stages of cellular respiration?Understanding Chloroplasts: The Powerhouses of Photosynthesis in PlantsWhat structure in plant cells allows for photosynthesis to occur?Understanding DNA Mutations and Their ImplicationsWhat is defined as a change in the DNA sequence of a gene?Understanding Dominant Alleles in GeneticsWhat is a dominant allele?Understanding Dominant Inheritance: The Key to GeneticsWhich type of genetic inheritance is characterized by a trait expressed with just one allele copy?Understanding Enzymes: The Unsung Heroes of Biochemical ReactionsWhat do enzymes primarily function as in biochemical reactions?Understanding Glucose as the Body's Energy PowerhouseWhat is the primary source of energy for the human body?Understanding Homeostasis in Biological SystemsWhat is homeostasis in biological systems?Understanding How Dehydration Synthesis Forms PolymersWhat type of reaction is responsible for forming a polymer from monomers?Understanding Mitosis: The Key to Cellular ReproductionWhat is the primary purpose of mitosis?Understanding Neurotransmitters: The Chemical Messengers of Your Nervous SystemWhat role do neurotransmitters play in the nervous system?Understanding Osmosis: The Key to Biological BalanceDefine osmosis.Understanding Ovulation: The Key to Pregnancy and FertilityThe point in a female's menstrual cycle that is most associated with pregnancy/fertility is?Understanding Peptide Bonds: The Essential Connection in Protein SynthesisWhich type of bond forms between amino acids during protein synthesis?Understanding Prokaryotic Cells: What Makes Them UniqueWhich of the following accurately describes prokaryotic cells?Understanding Reflex Arcs: The Quick Response MechanismWhat is a reflex arc?Understanding the Building Blocks: Amino Acids and ProteinsWhat is the main structural unit of protein?Understanding the Central Dogma of Molecular BiologyWhat does the central dogma in molecular biology describe?Understanding the Core of Your Nervous SystemWhat are the primary components of the nervous system?Understanding the Crucial Role of Hemoglobin in Our Respiratory FunctionWhat role does hemoglobin play in respiratory function?Understanding the Difference Between Ions and Neutral AtomsWhat distinguishes an ion from a neutral atom?Understanding the Four Major Types of Macromolecules Essential for LifeWhat are the four major types of macromolecules essential for life?Understanding the Golgi Apparatus: The Cell's Packaging CenterWhat is the purpose of the Golgi apparatus?Understanding the Heart: It’s More than Just a PumpWhat is the main function of the heart?Understanding the Hormone That Powers Your MetabolismWhich hormone is primarily linked to metabolism regulation?Understanding the Importance of pH in Human Body FluidsWhat is the typical pH range of most human body fluids?Understanding the Powerhouse of Protein Synthesis: The RibosomeWhat organelle is responsible for protein synthesis?Understanding the Primary Function of the KidneysWhat is the primary function of the kidneys?Understanding the Process of Transcription in Molecular BiologyWhat is the name of the process by which DNA is transcribed to mRNA?Understanding the Role of Bile in Fat DigestionWhat is the primary function of bile in digestion?Understanding the Role of Chlorophyll in PhotosynthesisWhat role does chlorophyll play in photosynthesis?Understanding the Role of Enzymes in Biological ReactionsWhat is the role of enzymes in biological reactions?Understanding the Role of Peptide Bonds in Amino Acid ConnectionsWhat type of bond forms between two amino acids?Understanding the Role of Red Blood Cells: The Oxygen Transporters of Our BodyWhat is the primary function of red blood cells?Understanding the Role of Ribosomes in Cellular FunctionWhat is the primary function of ribosomes in cells?Understanding the Role of the Cerebellum in Balance and CoordinationWhich part of the brain is responsible for regulating balance and coordination?Understanding the Role of the Circulatory System in Nutrient and Oxygen TransportWhich organ system is responsible for transporting nutrients and oxygen throughout the body?Understanding the Role of the Large Intestine in DigestionWhat is the role of the large intestine in the digestive system?Understanding the Role of the Placenta in PregnancyWhich statement accurately describes the role of the placenta during pregnancy?Understanding the Role of the Placenta: A Deep Dive into Pregnancy BiologyWhat is a key component of the placenta during pregnancy?Understanding the Role of Thyroid Hormones in MetabolismWhat physiological changes does thyroid hormone induce?Understanding the Role of Your Endocrine SystemWhat is the primary function of the endocrine system?Understanding the Smooth Endoplasmic Reticulum and Its FunctionsWhat is the function of the smooth endoplasmic reticulum?Understanding the Two Main Types of Nucleic Acids: DNA and RNAWhat are the two main types of nucleic acids?Understanding the Two Types of Cells in the Nervous SystemWhat are the two types of cells in the nervous system?Understanding Viruses: The Biological Basics You Need to KnowWhat is the definition of a virus?Understanding What Happens During Anaphase of MitosisWhat happens during the anaphase of mitosis?Understanding What HESI A2 Stands For and Its ImportanceWhat do the letters in the HESI A2 stand for?Understanding White Blood Cells and Their Role in Immune ResponseWhich type of blood cells are primarily involved in the immune response?Understanding Why Oxygen is Crucial for Cellular RespirationIn what cellular process is oxygen primarily utilized?Unlocking the Power of Mitochondria in Your CellsWhat is the primary function of mitochondria within a cell?What Do Plasmids Do in Bacteria?What is the main function of plasmids in bacteria?What Does DNA Stand For? Unpacking the Essentials of Deoxyribonucleic AcidWhat does DNA stand for?What does the symbol for Titanium represent on the periodic table?What is the symbol for Titanium on the periodic table?What Exactly Are Carbohydrates? A Simple BreakdownHow can a carbohydrate be defined?What Happens During the S Phase of the Cell Cycle?What occurs during the S phase of the cell cycle?What Happens When Glucose Breaks Down During Cellular Respiration?What is formed when glucose is broken down during cellular respiration?What Is Biotechnology and Why It MattersDefine biotechnology.What Joint Type Offers the Most Movement?What type of joint allows for the greatest range of motion?What You Need to Know About Cellulose and the Plant Cell WallWhich substance is the primary component of the plant cell wall?What You Need to Know About Thyroid Hormones and Their Role in MetabolismWhat process is primarily regulated by thyroid hormones?What You Should Know About Cell Membrane FunctionsWhat is the primary function of the cell membrane?What’s Behind the Immune System’s Shield?What is the primary role of the immune system?Why Amino Acids Are Vital: The Building Blocks of ProteinsWhat are the building blocks of proteins?Why Biodiversity Matters for Ecosystem Resilience and StabilityWhat is a significant benefit of biodiversity in ecosystems?Why Cells Are the Basic Units of Life You Need to UnderstandWhat is the basic unit of life?Why Decreased Biodiversity is a Bigger Threat Than You ThinkWhat is the primary risk of decreased biodiversity?Why Hemoglobin is Essential for Your Body's Oxygen NeedsWhat is hemoglobin primarily responsible for?Why Knowing the Respiratory System Matters for Your HESI A2 Science TestWhat is the primary function of the respiratory system?Why Mitochondria are the Cell's PowerhouseWhich organelle is primarily involved in energy production?Why Red Blood Cells are the Body’s Oxygen Delivery HeroesWhich cells in the body help to transport oxygen?Why Understanding the Cytoplasm is Key to Your HESI A2 Science SuccessWhat is the function of the cytoplasm?

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The atomic number of an element is determined by the number of which particle in the nucleus?
Which type of cells are capable of engulfing bacterial cells?
Which process do plants primarily use to absorb water and nutrients from the soil?
How many electrons can the second shell of an atom hold if filled to capacity?
On the periodic table, what element is represented by the symbol Sn?
What product is released during the process of photosynthesis that is essential for human life?
Skin, sweat glands, and nails are considered part of which organ system?
The thyroid gland requires what element to function properly?
Is glycogen considered a steroid?
On the periodic table, what element is represented by the symbol Cr?
What pH level indicates that a solution is alkaline?
What is the role of capillaries in the circulatory system?
Is the pancreas part of the urinary structure?
Which of the following is not a major class of biological units?
In what form do plants primarily store energy?
What is the primary function of capillaries?
Elements are made of small particles known as what?
Different tissues combine to form what structural unit?
What are the "sensory fingers" of a nerve called?
What is the process of cytoplasm division during plant cell replication called?
The majority of the periodic table is comprised of elements that are classified as what?
What are arterioles, venules, and capillaries collectively known as?
Which tissue cannot be considered a major tissue type?
How many chromosomes are present in the human body?
In body weight calculations, what has the highest concentration in the body?
What muscle type is characterized by intercalated disks?
What type of chemical reaction is represented by the equation AB + CD = AD + CB?
What term describes the photosynthesis process involving plants?
What is the term for the rhythmical changes in the body that occur over a 24-hour period?
What is the term for the breakdown of organic molecules?
Atoms that gain or lose electrons are known as what?
How many particles are in one mole of a substance?
Lactose is considered which type of sugar?
What type of bond is formed when electrons are shared between atoms?
Homeostasis in the body is primarily regulated through which type of process?
What is the main role of the cerebellum in the brain?
What term describes the process of changing substances into a different form that entered the body?
Which type of RNA carries the genetic information from DNA to the ribosome for protein synthesis?
Which subatomic particle has no charge?
What is the correct sequence of Mitosis?
What is the thin layer of tissue that lines the back of the eyeball where the image of an object is projected?
Which element has the atomic number 1?
What type of skeleton do starfish possess?
Which organ system contains the brain?
What cell structure is responsible for conducting nerve signals from the cell body to target cells in neural tissue?
What are the end products of photosynthesis?
Which element is the most numerous in the human body?
What role do amino acids play in the body?
Which of the following bases is not associated with RNA?
One calorie is the amount of heat required to raise how many grams of water by one degree Celsius?
Insulin is produced in which part of the pancreas?
What is the main component of the cell membrane?
What two structures compose the central nervous system?
What is the charge of an electron?
Which cell organelle is known for producing the most ATP?
What describes the process of a WBC engulfing a bacterial cell?
The specific scientific name of an organism is identified by what two classifications?
What is the primary function of phagocytosis?
Blood entering the right ventricle in the heart during normal circulation goes to which structure next?
Is the tibia part of the axial skeleton?
What is the primary role of ribosomes in the cell?
How are household ammonia and human blood classified in terms of pH?
What is the three-dimensional shape of a molecule known as?
Which arteries carry low oxygenated blood to the lungs?
What are compounds that have the same mass and elements but different structural alignments called?
What type of chemical reaction is indicated by the equation AB = A + B?
Which of the following cartilage is considered the firmest type of connective tissue?
What is the characteristic number of covalent bonds that carbon forms?
What term is used to describe the movement of substances out of a cell?
Which organelle is responsible for detoxifying harmful substances in the cell?
When two or more elements are combined, what is formed?
Is the kidney part of the gastrointestinal structure?
Which cranial nerve is designated as cranial nerve #1?
Which area of the brain is primarily responsible for balance and processing visual input?
What is the sugar found in each nucleotide of RNA called?
What is the heat required to increase the temperature of 1 gram of water by 1 degree Celsius called?
An atom with only one electron in its outer orbit is referred to as what?
What is the primary function of dendrites in a neuron?
At what point during mitosis do the chromosomes (chromatids) separate?
What process describes the movement of molecules across a membrane?
Which of the following structures is primarily involved in filtering blood in the kidneys?
What type of ions have a negative charge?
Which group of cells in the immune system is directly involved in fighting infections?
Blood entering the left ventricle in the heart during normal circulation goes to which structure next?
What is not a characteristic of smooth muscle?
Which organelle is primarily responsible for protein synthesis?
During the breakdown of glucose, which stage produces the most energy?
What is the primary molecule involved in energy transfer in cells?
What is the process called that converts DNA to RNA?
Which function is not performed by the plasma membrane in cells?
Gas exchange occurs in which type of tissue?
Under which conditions is glucose converted to the most ATP?
What kind of molecule is formed when glucose is combined with different monosaccharides?
Which structures provide information about the body's position in space with movement from the ear?
Which animal is considered an invertebrate?
How many chains of nucleotides are coiled together in DNA?
What is the common state of matter found at room temperature for most metals?
Which type of animal has a backbone?
Which molecule is a product of photosynthesis?
Which type of tissue is primarily responsible for contraction and movement?
Can proteins break down fats?
What type of reaction achieves a state of chemical equilibrium where the products have used almost all the reactants?
What type of sugar is glucose classified as?
The principle of natural selection is key to what process that allows for the survival of the fittest?
What is the chemical formula for Ammonia?
The atomic weight of an atom is the ratio of an atom's mass compared to which reference atom?
What type of transport requires energy to move substances across a membrane?
Which of the following bases is not associated with deoxyribonucleic acid (DNA)?
What mechanism is applied when skeletal muscle contracts?
Which of the following elements is considered a noble gas?
What are the building blocks of proteins?
What is the primary function of red blood cells?
Which particles can be found in the nucleus of an atom?
Gregor Mendel's pioneering genetic research primarily utilized which type of plants?
Solutes dissolve in what substance to form a solution?
Which of the following correctly describes cytokinesis?
Which element is not considered a major element in the human body?
What is the process by which plants convert sunlight into energy?
Which of the following is not a function of the kidneys?
Which of the following statements best describes enzymes?
What is the chemical name for the compound NaCl?
Which compound is essential for the process of photosynthesis?
Which structure is absent in invertebrates?
The ability of unspecialized cells to develop into specialized cells is known as what?
Which of the following is NOT a product of photosynthesis?
What percentage of human blood consists of water?

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