Levels of Organization and Chemistry Practice Questions

74 multiple-choice questions on Levels of organization and chemistry for paramedic and EMT students, from Chapter 8 (Anatomy and Physiology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

74 practice questions

1. What is the correct order of structural organization, from smallest to largest?

   1. A. Chemical, tissue, cell, organ, organ system, organism
   2. B. Cell, chemical, tissue, organ, organ system, organism
   3. C. Chemical, cell, tissue, organ, organ system, organism
   4. D. Tissue, cell, chemical, organ, organism, organ system
   Show answer

   Answer: C. Chemical, cell, tissue, organ, organ system, organism

   Atoms and molecules form cells, cells form tissues, tissues form organs, organs form systems, and systems form the organism.

2. Which is a characteristic shared by all living things?

   1. A. Metabolism
   2. B. Voluntary movement
   3. C. Consciousness
   4. D. Photosynthesis
   Show answer

   Answer: A. Metabolism

   Living things metabolize, grow, respond to stimuli, reproduce, and maintain homeostasis.

3. Which subatomic particle carries a positive charge?

   1. A. Photon
   2. B. Neutron
   3. C. Proton
   4. D. Electron
   Show answer

   Answer: C. Proton

   Protons are positive, electrons are negative, and neutrons have no charge.

4. A chemical bond formed when atoms share electrons is a(n):

   1. A. Metallic bond
   2. B. Covalent bond
   3. C. Hydrogen bond
   4. D. Ionic bond
   Show answer

   Answer: B. Covalent bond

   Covalent bonds share electrons. Ionic bonds form when electrons are transferred from one atom to another.

5. Reactions that build larger molecules from smaller ones and require energy are called:

   1. A. Oxidation
   2. B. Hydrolysis
   3. C. Catabolism
   4. D. Anabolism
   Show answer

   Answer: D. Anabolism

   Anabolism builds up and uses energy. Catabolism breaks down and releases energy. Together they make up metabolism.

6. An ion with a positive charge is called a(n):

   1. A. Neutron
   2. B. Anion
   3. C. Isotope
   4. D. Cation
   Show answer

   Answer: D. Cation

   Cations are positive (Na+, K+, Ca++, Mg++). Anions are negative (Cl-, HCO3-).

7. What is the primary extracellular cation?

   1. A. Phosphate
   2. B. Magnesium
   3. C. Potassium
   4. D. Sodium
   Show answer

   Answer: D. Sodium

   Sodium dominates outside the cell and is the major factor in water distribution. Water follows sodium.

8. What is the primary intracellular cation?

   1. A. Sodium (Na+)
   2. B. Potassium
   3. C. Chloride (Cl-)
   4. D. Calcium (Ca++)
   Show answer

   Answer: B. Potassium

   Potassium dominates inside the cell. Small changes in serum potassium can cause dangerous dysrhythmias.

9. Calcium plays a key role in:

   1. A. Oxygen transport by hemoglobin
   2. B. Fluid balance and water distribution
   3. C. Fat digestion and bile production
   4. D. Muscle contraction and blood clotting
   Show answer

   Answer: D. Muscle contraction and blood clotting

   Calcium is needed for muscle contraction (including the heart), nerve transmission, bone strength, and clotting.

10. What is the most abundant extracellular anion?

    1. A. Phosphate
    2. B. Bicarbonate
    3. C. Sulfate
    4. D. Chloride
    Show answer

    Answer: D. Chloride

    Chloride is the main negative ion outside the cell and tends to follow sodium.

11. What is the normal pH range of arterial blood?

    1. A. 7.45-7.55
    2. B. 6.95-7.05
    3. C. 7.25-7.35
    4. D. 7.35-7.45
    Show answer

    Answer: D. 7.35-7.45

    Below 7.35 is acidosis; above 7.45 is alkalosis. Even small shifts disrupt enzymes and cell function.

12. A substance that releases hydrogen ions (H+) in solution is a(n):

    1. A. Base
    2. B. Acid
    3. C. Buffer
    4. D. Salt
    Show answer

    Answer: B. Acid

    Acids release H+ and lower pH. Bases accept H+ and raise pH.

13. The most important buffer system in the blood is the:

    1. A. Phosphate buffer
    2. B. Bicarbonate buffer
    3. C. Ammonia buffer
    4. D. Protein buffer
    Show answer

    Answer: B. Bicarbonate buffer

    The carbonic acid-bicarbonate system works in seconds. The lungs (blowing off CO2) and the kidneys (excreting H+) back it up.

14. Excess glucose is stored in the liver and muscle as:

    1. A. Glycogen
    2. B. Glucagon
    3. C. Triglycerides
    4. D. Albumin
    Show answer

    Answer: A. Glycogen

    Glycogen is stored glucose. Glucagon is the hormone that tells the liver to break glycogen down.

15. Which level of organization is directly above the cell?

    1. A. Atom
    2. B. Tissue
    3. C. Organ
    4. D. Organ system
    Show answer

    Answer: B. Tissue

    Groups of similar cells form tissues.

16. The smallest unit of matter that retains the properties of an element is the:

    1. A. Cell
    2. B. Compound
    3. C. Atom
    4. D. Molecule
    Show answer

    Answer: C. Atom

    Atoms combine to form molecules.

17. Two or more atoms bonded together form a:

    1. A. Molecule
    2. B. Organelle
    3. C. Tissue
    4. D. Cell
    Show answer

    Answer: A. Molecule

    Water is a molecule of hydrogen and oxygen.

18. The smallest living unit of the body is the:

    1. A. Cell
    2. B. Molecule
    3. C. Atom
    4. D. Tissue
    Show answer

    Answer: A. Cell

    All life processes occur at the cellular level.

19. Anatomy is the study of:

    1. A. Disease
    2. B. Structure
    3. C. Chemistry
    4. D. Function
    Show answer

    Answer: B. Structure

    Physiology is the study of function.

20. Physiology is the study of:

    1. A. How the body is built
    2. B. How diseases develop
    3. C. How body parts function
    4. D. How cells divide and grow
    Show answer

    Answer: C. How body parts function

    Structure and function are always related.

21. Hypoxia damages mitochondria, which injures myocytes, which impairs cardiac muscle, which weakens the heart. At which level of organization is 'cardiac muscle'?

    1. A. Cell
    2. B. Organ
    3. C. Tissue
    4. D. Organ system
    Show answer

    Answer: C. Tissue

    Cardiac muscle is a tissue: a group of similar cells working together. Myocytes are cells, mitochondria are organelles inside cells, the heart is an organ, and the heart with its vessels forms the cardiovascular organ system.

22. Metabolism refers to:

    1. A. The rate at which cells divide
    2. B. Only the breakdown of food for energy
    3. C. Only reactions that build new tissue
    4. D. All chemical reactions in the body
    Show answer

    Answer: D. All chemical reactions in the body

    It includes both building up and breaking down.

23. Catabolism refers to reactions that:

    1. A. Store energy as glycogen and fat
    2. B. Break down molecules, releasing energy
    3. C. Copy DNA before cell division
    4. D. Build larger molecules and use energy
    Show answer

    Answer: B. Break down molecules, releasing energy

    Digestion is a catabolic process.

24. The electrons of an atom carry what charge?

    1. A. Negative
    2. B. Variable
    3. C. Positive
    4. D. Neutral
    Show answer

    Answer: A. Negative

    They orbit the positively charged nucleus.

25. Neutrons carry what charge?

    1. A. Variable charge
    2. B. No charge
    3. C. Positive charge
    4. D. Negative charge
    Show answer

    Answer: B. No charge

    They add mass without charge.

26. The atomic nucleus contains:

    1. A. Electrons and neutrons
    2. B. Protons, neutrons, and electrons
    3. C. Protons and neutrons
    4. D. Protons and electrons
    Show answer

    Answer: C. Protons and neutrons

    Electrons orbit outside the nucleus.

27. An ionic bond forms when atoms:

    1. A. Share a pair of electrons equally
    2. B. Attract via hydrogen atoms
    3. C. Share electrons unequally
    4. D. Transfer electrons between them
    Show answer

    Answer: D. Transfer electrons between them

    Sodium chloride is held together by ionic bonds.

28. Which type of bond holds water molecules to one another?

    1. A. Covalent
    2. B. Hydrogen
    3. C. Metallic
    4. D. Ionic
    Show answer

    Answer: B. Hydrogen

    Hydrogen bonds give water many of its properties.

29. An electrolyte is a substance that:

    1. A. Raises osmolarity but carries no charge
    2. B. Forms ions in solution that conduct current
    3. C. Dissolves in water without forming ions
    4. D. Stays electrically neutral when dissolved
    Show answer

    Answer: B. Forms ions in solution that conduct current

    Sodium, potassium, and chloride are electrolytes. An electrolyte separates into charged particles (ions) in solution and conducts electricity.

30. An anion carries what charge?

    1. A. Neutral
    2. B. Negative
    3. C. Variable
    4. D. Positive
    Show answer

    Answer: B. Negative

    Chloride and bicarbonate are anions.

31. Which is a cation?

    1. A. Potassium
    2. B. Phosphate
    3. C. Chloride
    4. D. Bicarbonate
    Show answer

    Answer: A. Potassium

    Cations are positively charged.

32. A crush victim's limb is freed after hours of entrapment. Which electrolyte is most likely to surge into the circulation from damaged muscle cells?

    1. A. Sodium
    2. B. Chloride
    3. C. Bicarbonate
    4. D. Potassium
    Show answer

    Answer: D. Potassium

    Potassium is the main intracellular cation, so when crushed muscle cells break down and the limb is reperfused, potassium floods the circulation. This can cause peaked T waves and cardiac arrest. Sodium and chloride are mainly extracellular. Bicarbonate falls as acid is released.

33. The main determinant of water distribution in the body is:

    1. A. Potassium
    2. B. Sodium
    3. C. Calcium
    4. D. Chloride
    Show answer

    Answer: B. Sodium

    Water follows sodium.

34. Magnesium is important for:

    1. A. Carrying fat in the bloodstream
    2. B. Enzyme function and cardiac rhythm
    3. C. Thyroid hormone production
    4. D. Oxygen binding in hemoglobin
    Show answer

    Answer: B. Enzyme function and cardiac rhythm

    Low magnesium contributes to torsades de pointes. Magnesium also supports muscle contraction.

35. After a large transfusion of citrated blood, a trauma patient develops hypocalcemia. Which finding is most consistent with it?

    1. A. Muscle flaccidity and faster clotting
    2. B. Polyuria and intense thirst
    3. C. Muscle twitching and worsening bleeding
    4. D. Bradypnea with pinpoint pupils
    Show answer

    Answer: C. Muscle twitching and worsening bleeding

    Calcium is needed for clotting and muscle contraction. Citrate in stored blood binds calcium, so low calcium causes neuromuscular irritability (twitching, tetany), weaker cardiac contraction, and coagulopathy. Faster clotting is the opposite effect. Polyuria with thirst suggests hyperglycemia or hypercalcemia, and pinpoint pupils with slow breathing suggest opioids.

36. A solution with a pH of 8.5 is:

    1. A. Neutral
    2. B. Alkaline
    3. C. Acidic
    4. D. Isotonic
    Show answer

    Answer: B. Alkaline

    Values above 7 are alkaline.

37. A pH of 7.0 is considered:

    1. A. Alkaline
    2. B. Acidic
    3. C. Physiologic (normal blood pH)
    4. D. Neutral
    Show answer

    Answer: D. Neutral

    Pure water is neutral. Normal arterial blood is slightly alkaline at 7.35 to 7.45, so a pH of 7.0 is below the physiologic range rather than equal to it.

38. A pH change of one unit represents a change in hydrogen ion concentration of:

    1. A. 2 times
    2. B. 10 times
    3. C. 100 times
    4. D. 1,000 times
    Show answer

    Answer: B. 10 times

    The pH scale is logarithmic.

39. Arterial blood pH below 7.35 is called:

    1. A. Alkalosis
    2. B. Hypoxemia
    3. C. Hypercapnia
    4. D. Acidosis
    Show answer

    Answer: D. Acidosis

    Above 7.45 is alkalosis.

40. Which organ system provides the fastest compensation for an acid-base disturbance?

    1. A. Endocrine system
    2. B. Respiratory
    3. C. Digestive system
    4. D. Renal system
    Show answer

    Answer: B. Respiratory

    The lungs adjust CO2 within minutes.

41. The kidneys compensate for acid-base disturbances over:

    1. A. Seconds to minutes
    2. B. Minutes to an hour
    3. C. Hours to days
    4. D. Several weeks or more
    Show answer

    Answer: C. Hours to days

    Renal compensation is slower but powerful.

42. A buffer functions to:

    1. A. Resist changes in pH
    2. B. Raise pH toward alkalosis
    3. C. Eliminate acid from the body
    4. D. Lower pH by adding hydrogen ions
    Show answer

    Answer: A. Resist changes in pH

    Bicarbonate is the main blood buffer. It does this by accepting or donating hydrogen ions.

43. Carbon dioxide combines with water to form:

    1. A. Bicarbonate only
    2. B. Hydrochloric acid
    3. C. Carbonic acid
    4. D. Lactic acid
    Show answer

    Answer: C. Carbonic acid

    This is why retained CO2 produces acidosis.

44. Hyperventilation lowers carbon dioxide and causes:

    1. A. Respiratory alkalosis
    2. B. Respiratory acidosis
    3. C. Metabolic alkalosis
    4. D. Metabolic acidosis
    Show answer

    Answer: A. Respiratory alkalosis

    Blowing off CO2 raises pH.

45. An organic compound is one that contains:

    1. A. Water
    2. B. Sodium
    3. C. Oxygen only
    4. D. Carbon
    Show answer

    Answer: D. Carbon

    Carbohydrates, proteins, lipids, and nucleic acids are organic.

46. Carbohydrates function primarily as:

    1. A. Building blocks for enzymes
    2. B. Main quick energy source
    3. C. Storage of genetic information
    4. D. Structural support for cells
    Show answer

    Answer: B. Main quick energy source

    Glucose is the fundamental carbohydrate fuel. Carbohydrates are the body's main quick energy source.

47. Proteins are constructed from:

    1. A. Nucleotides
    2. B. Amino acids
    3. C. Fatty acids
    4. D. Simple sugars
    Show answer

    Answer: B. Amino acids

    Sequence determines a protein's shape and function.

48. Lipids are important because they:

    1. A. Provide the fastest energy source
    2. B. Carry oxygen in the blood
    3. C. Store energy and form membranes
    4. D. Catalyze most cell reactions
    Show answer

    Answer: C. Store energy and form membranes

    Cholesterol is a lipid used to make steroid hormones. They also serve as precursors for steroid hormones.

49. Nucleic acids such as DNA function to:

    1. A. Store genetic information
    2. B. Speed chemical reactions
    3. C. Buffer pH in the blood
    4. D. Transport oxygen to tissues
    Show answer

    Answer: A. Store genetic information

    RNA carries instructions from DNA to ribosomes. DNA stores and transmits genetic information.

50. Enzymes act as:

    1. A. Structural fibers in tissue
    2. B. Hormones carried by blood
    3. C. Energy sources for cells
    4. D. Catalysts that speed reactions
    Show answer

    Answer: D. Catalysts that speed reactions

    They are not consumed in the reaction.

51. Enzyme function is impaired by:

    1. A. Binding of cofactors such as magnesium
    2. B. Normal blood pH of 7.4
    3. C. A rising substrate concentration
    4. D. Extreme pH or temperature
    Show answer

    Answer: D. Extreme pH or temperature

    This is one reason acidosis is so damaging. Enzymes are proteins whose shape depends on pH and temperature, so extremes denature them. Cofactors such as magnesium are needed for many enzymes to work, and more substrate raises the reaction rate until the enzyme is saturated; neither impairs it.

52. The normal blood glucose range for a fasting adult is approximately:

    1. A. 150 to 200 mg/dL
    2. B. 70 to 100 mg/dL
    3. C. 30 to 50 mg/dL
    4. D. 200 to 300 mg/dL
    Show answer

    Answer: B. 70 to 100 mg/dL

    Values vary slightly by reference source.

53. A hypoglycemic patient with chronic alcohol use and poor food intake responds poorly to IM glucagon. The most likely reason is:

    1. A. Excess insulin from the pancreas
    2. B. Too much glycogen stored in muscle
    3. C. Glucagon cannot be absorbed from muscle
    4. D. Depleted liver glycogen stores
    Show answer

    Answer: D. Depleted liver glycogen stores

    Glucagon raises glucose by breaking down liver glycogen (glycogenolysis). Malnourished and alcoholic patients have little glycogen in reserve, so glucagon works poorly and IV dextrose is preferred. Muscle glycogen cannot be released into the blood. IM glucagon is absorbed well.

54. When glycogen stores are depleted, the body next uses:

    1. A. Creatine phosphate in muscle
    2. B. Glucagon stored in the pancreas
    3. C. Fat, producing ketones
    4. D. Cholesterol, producing bile acids
    Show answer

    Answer: C. Fat, producing ketones

    Prolonged fasting leads to ketone production. After glycogen runs low, the body shifts to fat, and the liver turns fatty acids into ketones. Creatine phosphate is a seconds-long backup for ATP during exertion, not a reserve fuel. Glucagon is a hormone that signals the liver to release glucose; it is not a fuel itself. Cholesterol is used for membranes, steroids, and bile acids, not burned for energy.

55. Gluconeogenesis refers to:

    1. A. Making new glucose from protein
    2. B. Breaking glycogen into glucose
    3. C. Storing glucose as glycogen
    4. D. Converting glucose into fat
    Show answer

    Answer: A. Making new glucose from protein

    The liver performs most of it. Noncarbohydrate sources include amino acids, lactate, and glycerol.

56. Adenosine triphosphate functions as:

    1. A. The cell's energy currency
    2. B. An enzyme that digests sugar
    3. C. A structural protein in cells
    4. D. A hormone that regulates growth
    Show answer

    Answer: A. The cell's energy currency

    Energy is released when a phosphate bond is broken.

57. Which element is essential to hemoglobin's ability to carry oxygen?

    1. A. Potassium
    2. B. Zinc
    3. C. Calcium
    4. D. Iron
    Show answer

    Answer: D. Iron

    Iron deficiency causes anemia.

58. Osmolarity refers to:

    1. A. Hydrogen ion concentration
    2. B. Concentration of dissolved particles
    3. C. Total circulating blood volume
    4. D. Pressure exerted by blood on vessels
    Show answer

    Answer: B. Concentration of dissolved particles

    It determines how water moves between compartments.

59. A hypertonic solution has:

    1. A. Fewer solutes than plasma
    2. B. Only water and no solutes
    3. C. More solutes than plasma
    4. D. The same osmolarity as plasma
    Show answer

    Answer: C. More solutes than plasma

    It draws water out of cells.

60. A hypotonic solution has:

    1. A. More solutes than plasma
    2. B. Large proteins like albumin
    3. C. Fewer solutes than plasma
    4. D. Equal solutes to plasma
    Show answer

    Answer: C. Fewer solutes than plasma

    It causes cells to swell.

61. Dehydration in the body primarily reflects:

    1. A. Excess sodium intake only
    2. B. Loss of plasma proteins
    3. C. Loss of red blood cells
    4. D. Loss of water and electrolytes
    Show answer

    Answer: D. Loss of water and electrolytes

    Vomiting, diarrhea, and sweating are common causes.

62. Which is true about water's role in the body?

    1. A. It is lost mainly through the skin
    2. B. It is a major source of energy
    3. C. It is mostly stored in the plasma
    4. D. It is the body's main solvent
    Show answer

    Answer: D. It is the body's main solvent

    It also transports nutrients and helps regulate temperature. Water is the solvent for nearly all body chemistry.

63. The pH of the stomach is normally:

    1. A. Slightly alkaline like blood
    2. B. Strongly alkaline
    3. C. Strongly acidic
    4. D. Roughly neutral
    Show answer

    Answer: C. Strongly acidic

    Gastric acid aids digestion and kills organisms.

64. Which of the following would raise blood pH?

    1. A. Producing lactic acid
    2. B. Ketone accumulation
    3. C. Retaining carbon dioxide
    4. D. Hyperventilating
    Show answer

    Answer: D. Hyperventilating

    Removing CO2 makes blood more alkaline.

65. The measurable effect of acidosis on potassium is generally to:

    1. A. Drive potassium into cells
    2. B. Raise serum potassium
    3. C. Have no effect on potassium
    4. D. Lower serum potassium
    Show answer

    Answer: B. Raise serum potassium

    This is important in crush injury and renal failure. Potassium shifts out of cells as hydrogen ions move in.

66. Isotonic saline has a sodium chloride concentration of about:

    1. A. 5 percent
    2. B. 3 percent
    3. C. 0.45 percent
    4. D. 0.9 percent
    Show answer

    Answer: D. 0.9 percent

    It approximates plasma osmolarity.

67. The chemical level of organization includes:

    1. A. Atoms and molecules
    2. B. Organs and systems
    3. C. Tissues and organs
    4. D. Cells and tissues
    Show answer

    Answer: A. Atoms and molecules

    It is the foundation of all the others.

68. Homeostasis at the chemical level depends most on:

    1. A. Muscle mass and tone
    2. B. An intact skin barrier
    3. C. Electrolyte and pH balance
    4. D. Bone density and strength
    Show answer

    Answer: C. Electrolyte and pH balance

    Small shifts disrupt enzyme and cell function.

69. A trace element is one that:

    1. A. Makes up most of body mass
    2. B. Is found only in the blood
    3. C. Is essential in tiny amounts
    4. D. Is toxic at any level
    Show answer

    Answer: C. Is essential in tiny amounts

    Iron, zinc, and iodine are examples.

70. A solution's solute is:

    1. A. The substance dissolved
    2. B. The mixture as a whole
    3. C. The liquid that dissolves it
    4. D. The particles that settle out
    Show answer

    Answer: A. The substance dissolved

    Water is the body's universal solvent.

71. Which best describes a compound?

    1. A. Atoms of one element bonded
    2. B. Different elements bonded together
    3. C. Any physical mixture of substances
    4. D. A single atom with a charge
    Show answer

    Answer: B. Different elements bonded together

    Water and sodium chloride are compounds. A compound forms when two or more different elements bond chemically.

72. Free radicals are harmful because they:

    1. A. Raise blood pH sharply
    2. B. Bind hemoglobin tightly
    3. C. Block glucose uptake
    4. D. Damage cell structures
    Show answer

    Answer: D. Damage cell structures

    Antioxidants help neutralize them. They are unstable molecules that react with membranes, proteins, and DNA.

73. Carbon monoxide is dangerous chemically because it:

    1. A. Directly acidifies the blood
    2. B. Paralyzes the respiratory muscles
    3. C. Outcompetes oxygen for hemoglobin
    4. D. Blocks carbon dioxide removal
    Show answer

    Answer: C. Outcompetes oxygen for hemoglobin

    It prevents oxygen transport and use. CO binds hemoglobin more than 200 times more strongly than oxygen does.

74. Which pairing is correct?

    1. A. Sodium, primary intracellular cation
    2. B. Potassium, primary extracellular cation
    3. C. Calcium, essential for muscle contraction
    4. D. Chloride, primary cation
    Show answer

    Answer: C. Calcium, essential for muscle contraction

    Calcium is required for actin-myosin interaction.