Biochemistry Multiple-Choice Test (With Answers)
1. What defines matter?
A) Anything that has mass and takes up space (Answer: A)
B) Anything that moves
C) A substance that contains oxygen
D) Only solid objects
2. The basic structural unit of all living things is the:
A) Cell (Answer: A)
B) Atom
C) Molecule
D) Organ
3. The three main states of matter are:
A) Solid, liquid, and gas (Answer: A)
B) Ice, water, and vapor
C) Mass, energy, and force
D) Elements, compounds, and mixtures
4. Atoms are composed of:
A) Protons, neutrons, and electrons (Answer: A)
B) Molecules and ions
C) Only electrons
D) Compounds and elements
5. The periodic table organizes elements based on:
A) Atomic number (Answer: A)
B) Mass number
C) Electron configuration
D) Density
6. The atomic symbol for oxygen is:
A) O (Answer: A)
B) Ox
C) Oy
D) Om
7. The nucleus of an atom contains:
A) Protons and neutrons (Answer: A)
B) Electrons and protons
C) Only electrons
D) Neutrons and electrons
8. Science operates based on:
A) Observation, experimentation, and evidence (Answer: A)
B) Random guessing
C) Popular beliefs
D) Personal opinions
9. Isotopes of an element have:
A) The same number of protons but different numbers of neutrons (Answer: A)
B) Different atomic numbers
C) Different chemical properties
D) No relevance in chemistry
10. Radioactivity results from:
A) Unstable atomic nuclei (Answer: A)
B) Chemical reactions
C) Ionic bonding
D) Physical changes
11. Electrons occupy:
A) Energy levels or shells (Answer: A)
B) The nucleus of the atom
C) Only one fixed orbit
D) Random positions inside the nucleus
12. Nuclear medicine uses:
A) Radioactive isotopes for diagnosis and treatment (Answer: A)
B) Ionic compounds
C) Covalent bonding
D) Chemical buffers
13. A chemical change results in:
A) The formation of a new substance (Answer: A)
B) A phase change
C) Mixing of substances without reaction
D) Only a color change
14. Ionic compounds are formed by:
A) Transfer of electrons (Answer: A)
B) Sharing of electrons
C) Hydrogen bonding
D) Covalent forces
15. The correct formula for sodium chloride is:
A) NaCl (Answer: A)
B) NaC
C) ClNa
D) Na2Cl
16. A polyatomic ion consists of:
A) Two or more atoms with a charge (Answer: A)
B) A single element
C) Only one type of ion
D) Neutral molecules
17. Covalent bonds involve:
A) Sharing of electrons (Answer: A)
B) Transfer of electrons
C) Loss of protons
D) Hydrogen ions
18. Water molecules exhibit:
A) Hydrogen bonding (Answer: A)
B) Ionic bonding
C) Metallic bonding
D) Radioactivity
19. A chemical reaction must be:
A) Balanced (Answer: A)
B) Irreversible
C) Spontaneous
D) Endothermic
20. An anabolic reaction:
A) Builds larger molecules from smaller ones (Answer: A)
B) Breaks molecules down
C) Involves oxidation
D) Releases energy
21. A catabolic reaction:
A) Breaks down molecules (Answer: A)
B) Forms larger molecules
C) Requires no enzymes
D) Does not occur in living organisms
22. Oxidation involves:
A) Loss of electrons (Answer: A)
B) Gain of electrons
C) No electron transfer
D) Formation of new protons
23. Acids are substances that:
A) Donate protons (H⁺ ions) (Answer: A)
B) Accept protons
C) Contain hydroxide ions
D) Are always neutral
24. Buffers help:
A) Maintain pH balance (Answer: A)
B) Increase acidity
C) Remove all ions
D) Make solutions more basic
25. Acid reflux is caused by:
A) Stomach acid moving into the esophagus (Answer: A)
B) Insufficient stomach acid
C) Lack of digestion
D) Absence of enzymes
26. Electrolytes are essential for:
A) Nerve and muscle function (Answer: A)
B) Making energy
C) DNA replication
D) Breaking down fats
27. Water is essential to life because it:
A) Supports biochemical reactions (Answer: A)
B) Provides energy
C) Contains carbon
D) Is an ionic compound
28. The polarity of water molecules allows for:
A) Cohesion and adhesion (Answer: A)
B) Radioactive decay
C) Metallic bonding
D) No chemical interactions
29. The chemical formula of water is:
A) H₂O (Answer: A)
B) HO₂
C) H₂O₂
D) OH
30. The pH of pure water is:
A) 7 (Answer: A)
B) 5
C) 10
D) 3
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