ASVAB General Science Practice Test 3 — Questions and Answers
Question 1: Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?
- Ribosome
- Nucleus
- Mitochondria (Correct answer)
- Golgi apparatus
Correct answer: Mitochondria
Mitochondria are the site of aerobic cellular respiration, producing the majority of ATP (adenosine triphosphate) used by the cell.
Mitochondria are double-membraned organelles found in eukaryotic cells. They carry out aerobic cellular respiration — a three-stage process: glycolysis (in cytoplasm), the Krebs cycle (in mitochondrial matrix), and oxidative phosphorylation/electron transport chain (on inner mitochondrial membrane). The net yield is approximately 36–38 ATP molecules per glucose molecule. Mitochondria have their own DNA (mtDNA), supporting the endosymbiotic theory that they were once free-living bacteria. Ribosomes synthesize proteins; the nucleus contains DNA; the Golgi apparatus packages and ships proteins. On the ASVAB GS section, cell organelle functions are frequently tested. Key memory aid: Mitochondria = energy; Ribosomes = protein synthesis; Nucleus = control center; Chloroplasts (in plants) = photosynthesis.
Question 2: What type of chemical bond involves the sharing of electrons between atoms?
- Ionic bond
- Hydrogen bond
- Covalent bond (Correct answer)
- Metallic bond
Correct answer: Covalent bond
Covalent bonds form when two atoms share one or more pairs of electrons, creating molecules such as H₂O and CO₂.
Chemical bonding determines the properties of all matter. Covalent bonds: electrons are shared between atoms — typically between nonmetals (e.g., H₂, O₂, H₂O, CO₂). Ionic bonds: electrons are transferred from one atom to another, creating oppositely charged ions that attract — typically between a metal and nonmetal (e.g., NaCl). Hydrogen bonds: weak attractions between a hydrogen atom bonded to N, O, or F and another electronegative atom — responsible for water's high boiling point and surface tension. Metallic bonds: electrons are delocalized in a 'sea' of electrons, giving metals conductivity and malleability. On the ASVAB, remember: sharing = covalent; transfer = ionic. Covalent compounds tend to have lower melting points and don't conduct electricity as liquids, while ionic compounds have high melting points and conduct when dissolved or melted.
Question 3: Which of Newton's laws states that for every action there is an equal and opposite reaction?
- First Law (Law of Inertia)
- Second Law (F = ma)
- Third Law (Action-Reaction) (Correct answer)
- Law of Universal Gravitation
Correct answer: Third Law (Action-Reaction)
Newton's Third Law states that when object A exerts a force on object B, object B exerts an equal and opposite force on object A simultaneously.
Newton's three laws of motion underpin classical mechanics. First Law (Inertia): an object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted upon by a net external force. Second Law: F = ma — force equals mass times acceleration; this law quantifies how forces change motion. Third Law (Action-Reaction): forces always come in equal and opposite pairs. Key point: the action and reaction forces act on DIFFERENT objects — they do not cancel each other out. Examples: a gun recoiling when fired, a swimmer pushing off a wall, rocket propulsion. Law of Universal Gravitation (not one of the three laws of motion): F = Gm₁m₂/r². On the ASVAB GS section, know all three Newton's laws and be able to apply F = ma for simple calculations.
Question 4: What is the process by which water vapor cools and transforms into liquid water droplets, forming clouds?
- Evaporation
- Condensation (Correct answer)
- Precipitation
- Sublimation
Correct answer: Condensation
Condensation is the phase change from gas (water vapor) to liquid. In the atmosphere, water vapor condenses around dust particles at the dew point to form cloud droplets.
The water cycle (hydrological cycle) involves several phase changes. Evaporation: liquid water → water vapor (requires energy input). Condensation: water vapor → liquid water (releases energy, occurs when air cools to dew point). Precipitation: water falls from clouds as rain, snow, sleet, or hail. Sublimation: solid → gas without passing through liquid (e.g., dry ice, frost disappearing in cold dry air). Transpiration: plants release water vapor. Cloud formation requires three things: water vapor, a cooling mechanism (usually air rising and expanding), and condensation nuclei (dust, pollen, sea salt particles). On the ASVAB GS section, earth science questions often cover the water cycle, weather systems, and atmospheric layers (troposphere, stratosphere, mesosphere, thermosphere, exosphere).
Question 5: What is the atomic number of an element?
- The number of neutrons in the nucleus
- The total number of protons and neutrons
- The number of protons in the nucleus (Correct answer)
- The number of electrons in the outermost shell
Correct answer: The number of protons in the nucleus
The atomic number equals the number of protons in an atom's nucleus. It uniquely identifies an element — carbon always has 6 protons, oxygen always has 8.
An atom's subatomic particles define its identity and properties. Protons (positive charge) are in the nucleus; their count = atomic number, which uniquely identifies the element. Neutrons (no charge) are also in the nucleus; protons + neutrons = mass number (atomic mass). Electrons (negative charge) orbit the nucleus in shells; in a neutral atom, electron count = proton count. Isotopes of an element have the same number of protons but different neutrons (e.g., Carbon-12 and Carbon-14 both have 6 protons but 6 and 8 neutrons respectively). On the periodic table, elements are arranged by increasing atomic number. On the ASVAB GS section, understand: atomic number = protons; mass number = protons + neutrons; isotopes differ by neutron count; ions differ from neutral atoms by electron count.
Question 6: Which type of rock forms from the cooling and solidification of magma or lava?
- Sedimentary
- Metamorphic
- Igneous (Correct answer)
- Fossil-bearing
Correct answer: Igneous
Igneous rocks form from the cooling of magma (underground) or lava (at the surface). Examples include granite (intrusive) and basalt (extrusive).
The rock cycle involves three main rock types formed by different processes. Igneous rocks: form from molten material. Intrusive (plutonic) igneous rocks cool slowly underground, forming large crystals (e.g., granite). Extrusive (volcanic) igneous rocks cool quickly at the surface, forming small crystals or glassy textures (e.g., basalt, obsidian). Sedimentary rocks: form from compressed layers of sediment (e.g., sandstone, limestone, shale) — most fossils are found here. Metamorphic rocks: form when existing rocks are transformed by heat, pressure, or chemical reactions (e.g., marble from limestone, schist from shale). 'Fossil-bearing' is not a rock type — it describes sedimentary rocks. On the ASVAB GS section, know the three rock types, their formation processes, and common examples of each.
ASVAB General Science Practice Test 3
Which organelle is responsible for producing ATP through cellular respiration in eukaryotic cells?