ASVAB General Science Practice Test

25 practice questions

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1. Question 1 of 25Medium

   What is the primary difference in composition between comets and asteroids?

   1. AA. Comets are composed entirely of pure iron, while asteroids consist mostly of frozen gases.
   2. BB. Comets contain substantial amounts of volatile ices, while asteroids are mostly rock and metal.
   3. CC. Comets follow nearly circular orbits, while asteroids travel along highly eccentric paths.
   4. DD. Comets originate inside the asteroid belt, while asteroids originate inside the Oort cloud.
   Show answer to question 1

   Answer: B. Comets contain substantial amounts of volatile ices, while asteroids are mostly rock and metal.

   Comets are composed largely of dust and volatile ices like water, carbon dioxide, and methane, which vaporize to create a visible coma and tail when nearing the Sun. Asteroids consist primarily of rocky silicates and metals that withstand solar heat without producing a coma.

2. Question 2 of 25Easy

   What is the main result of mitosis in a typical body cell?

   1. AA. Two daughter cells with the same chromosome number as the parent
   2. BB. Four daughter cells with half the chromosome number of the parent
   3. CC. Two daughter cells with half the chromosome number of the parent
   4. DD. Four daughter cells with twice the chromosome number of the parent
   Show answer to question 2

   Answer: A. Two daughter cells with the same chromosome number as the parent

   Mitosis is a single nuclear division that produces two daughter cells with the same chromosome number as the parent cell. The four haploid cells described in another option are the product of meiosis, not mitosis.

3. Question 3 of 25Hard

   A radioactive carbon-14 nucleus containing 6 protons and 8 neutrons undergoes beta decay, converting one neutron into a proton. What element is produced by this transformation?

   1. AA. Boron
   2. BB. Oxygen
   3. CC. Nitrogen
   4. DD. Carbon
   Show answer to question 3

   Answer: C. Nitrogen

   Converting a neutron into a proton raises the atomic number from 6 to 7 while the total mass number remains 14. Nitrogen is the chemical element defined by an atomic number of 7. Boron has an atomic number of 5, which would require the loss of a proton.

4. Question 4 of 25Medium

   What is the primary function of the selectively permeable plasma membrane surrounding a cell?

   1. AA. Regulating the movement of substances into and out of the cell
   2. BB. Providing rigid structural support to prevent cell burst
   3. CC. Storing genetic information required for cell division
   4. DD. Producing adenosine triphosphate through cellular respiration
   Show answer to question 4

   Answer: A. Regulating the movement of substances into and out of the cell

   The plasma membrane is a phospholipid bilayer that controls which ions and organic molecules can enter or leave the cell. The cell wall provides rigid structural support in plants and fungi, but the plasma membrane itself is flexible and focuses on selective transport.

5. Question 5 of 25Medium

   Which laboratory technique separates the components of a liquid mixture using differences in their boiling points?

   1. AA. Electrolysis
   2. BB. Combustion
   3. CC. Neutralization
   4. DD. Distillation
   Show answer to question 5

   Answer: D. Distillation

   Distillation is a physical separation technique that vaporizes a liquid and condenses it back to separate components based on boiling points. Electrolysis and neutralization are chemical processes that change the chemical identity of substances rather than physically separating a mixture.

6. Question 6 of 25Medium

   What happens to the temperature of a pure substance during a phase change from liquid to gas at its boiling point?

   1. AA. It drops briefly because boiling carries away heat.
   2. BB. It fluctuates rapidly between two fixed temperatures.
   3. CC. It rises steadily as thermal energy is continuously added.
   4. DD. It remains constant until the phase change is complete.
   Show answer to question 6

   Answer: D. It remains constant until the phase change is complete.

   During a phase change, added heat is used to break intermolecular bonds rather than increase kinetic energy, keeping the temperature constant until the entire liquid vaporizes. A steady temperature rise occurs only before boiling begins and after all liquid has turned to gas.

7. Question 7 of 25Easy

   Why does a beam of light bend when it passes from air into water at an angle?

   1. AA. Its wave amplitude doubles immediately upon entering the liquid.
   2. BB. Its radiant energy is fully absorbed by surface particles.
   3. CC. Its propagation speed changes as it enters the new medium.
   4. DD. Its wave frequency increases significantly in water.
   Show answer to question 7

   Answer: C. Its propagation speed changes as it enters the new medium.

   Refraction is the bending of a wave caused by a change in its speed as it transitions from one medium into another of different optical density. While light slows down when entering water, its frequency remains constant because wave frequency is determined exclusively by the source emitting the light.

8. Question 8 of 25Hard

   Which landform is produced mainly by deposition rather than by erosion?

   1. AA. A sea arch
   2. BB. A glacial valley
   3. CC. A river canyon
   4. DD. A sand dune
   Show answer to question 8

   Answer: D. A sand dune

   A sand dune is built up from sand dropped by wind when the wind slows, so it is a depositional landform. Canyons, sea arches, and glacial valleys are formed mainly by removal of material through erosion.

9. Question 9 of 25Easy

   The slow movement of tectonic plates is mainly driven by which process?

   1. AA. the pull of the Moon's gravity on Earth's crust
   2. BB. strong prevailing winds pushing against the land
   3. CC. convection currents in the hot rock of the mantle
   4. DD. the rotation of Earth dragging the plates westward
   Show answer to question 9

   Answer: C. convection currents in the hot rock of the mantle

   Heat from Earth's interior makes mantle rock flow very slowly, and this convection carries the rigid plates riding on top of it. The Moon's gravity raises ocean tides but does not supply the force that moves tectonic plates.

10. Question 10 of 25Easy

    Which observation provides the strongest evidence that a chemical change has taken place?

    1. AA. A solid substance breaks into smaller pieces
    2. BB. A clear liquid turns into a gas when heated to its boiling point
    3. CC. Two room-temperature liquids mix and spontaneously release heat and gas
    4. DD. A warm wax liquid solidifies into a block as it cools
    Show answer to question 10

    Answer: C. Two room-temperature liquids mix and spontaneously release heat and gas

    The spontaneous generation of heat and gas upon mixing two room-temperature substances indicates the formation of new chemical bonds through a chemical reaction. A liquid turning into a gas upon heating is merely a phase change, which is a physical process that preserves the original molecular identity.

11. Question 11 of 25Medium

    Which scenario provides an example of primary ecological succession?

    1. AA. Ferns sprouting after a moderate forest fire
    2. BB. Pioneer weeds emerging after clear-cut logging
    3. CC. Grasses regrowing in an abandoned farm field
    4. DD. Lichens colonizing newly cooled volcanic rock
    Show answer to question 11

    Answer: D. Lichens colonizing newly cooled volcanic rock

    Primary succession begins in essentially lifeless environments where no previous soil exists, such as bare, newly formed volcanic rock. Abandoned farm fields, burned forests, and logged areas already contain intact soil, meaning they undergo secondary succession instead.

12. Question 12 of 25Medium

    Which cellular component typically occupies the majority of volume in a mature plant cell and helps maintain internal hydrostatic pressure?

    1. AA. Lysosome
    2. BB. Peroxisome
    3. CC. Central vacuole
    4. DD. Contractile vacuole
    Show answer to question 12

    Answer: C. Central vacuole

    A mature plant cell contains a large central vacuole filled with cell sap that maintains turgor pressure against the cell wall. Animal cells may contain multiple small, temporary vacuoles, but they lack this large, permanent central storage structure.

13. Question 13 of 25Easy

    An organism has the genotype Bb for a particular trait. Which term describes this genotype?

    1. AA. Homozygous recessive
    2. BB. Haploid
    3. CC. Heterozygous
    4. DD. Homozygous dominant
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    Answer: C. Heterozygous

    A genotype with two different alleles, such as Bb, is heterozygous. Homozygous dominant would be BB, homozygous recessive would be bb, and haploid refers to having one set of chromosomes.

14. Question 14 of 25Medium

    When energy flows from herbivores to carnivores, in what form is most of the non-transferred energy released into the environment?

    1. AA. Chemical bonds inside water molecules
    2. BB. Heat generated through cellular respiration
    3. CC. Kinetic energy stored permanently in topsoil
    4. DD. Electromagnetic waves stored in plant stems
    Show answer to question 14

    Answer: B. Heat generated through cellular respiration

    Organisms use the majority of ingested chemical energy to fuel metabolic activities like movement and maintenance, releasing that energy into the surroundings as low-grade heat. It is not stored in soil or converted into electromagnetic radiation within plant tissues.

15. Question 15 of 25Easy

    Most of the world's active volcanoes and major earthquakes occur along a belt surrounding which body of water?

    1. AA. Pacific Ocean
    2. BB. Atlantic Ocean
    3. CC. Arctic Ocean
    4. DD. Indian Ocean
    Show answer to question 15

    Answer: A. Pacific Ocean

    The Ring of Fire is a major horseshoe-shaped zone encircling the Pacific Ocean basin where tectonic plate collisions and subduction zones generate frequent seismic and volcanic activity. The Atlantic Ocean contains a divergent boundary called the Mid-Atlantic Ridge, which produces far fewer destructive surface earthquakes.

16. Question 16 of 25Medium

    The chemical process represented by the equation Zn + 2HCl -> ZnCl2 + H2 is an example of which type of reaction?

    1. AA. Double replacement
    2. BB. Single replacement
    3. CC. Decomposition
    4. DD. Synthesis
    Show answer to question 16

    Answer: B. Single replacement

    A single replacement reaction occurs when an uncombined element trades places with another element in a compound, as zinc displaces hydrogen from hydrochloric acid. A synthesis reaction combines simpler substances into a single product, while a double replacement reaction involves two compounds exchanging ions.

17. Question 17 of 25Easy

    Which of the following is an example of a statement describing climate rather than weather?

    1. AA. Phoenix typically experiences hot, dry summers with little rainfall.
    2. BB. A cold front is expected to drop temperatures by fifteen degrees tomorrow.
    3. CC. A severe thunderstorm caused flash flooding downtown this afternoon.
    4. DD. Dense fog reduced visibility along the coastline early this morning.
    Show answer to question 17

    Answer: A. Phoenix typically experiences hot, dry summers with little rainfall.

    Describing typical summer conditions over extended time periods reflects climate normals for a region. Referring to a drop in temperatures from an incoming cold front represents a short-term weather forecast rather than a climate description.

18. Question 18 of 25Medium

    A paleontologist finds a dinosaur footprint preserved in ancient mudstone but no bones of the animal. This footprint is classified as which type of fossil?

    1. AA. A replacement fossil
    2. BB. A trace fossil
    3. CC. A mold fossil
    4. DD. A cast fossil
    Show answer to question 18

    Answer: B. A trace fossil

    A trace fossil preserves evidence of an organism's activity, such as a footprint, burrow or trail, rather than the body itself. A mold is an impression of a body part, and a cast is material filling such an impression; a replacement fossil forms when minerals substitute for hard parts like bone or shell. The footprint records behavior, not anatomy, so it is a trace fossil.

19. Question 19 of 25Medium

    Which method is standard for determining the volume of an irregularly shaped solid rock in a laboratory?

    1. AA. Submerging the rock in a graduated cylinder and measuring displaced water
    2. BB. Measuring the exterior dimensions with calipers and applying a formula
    3. CC. Weighing the rock on a balance and multiplying by gravity
    4. DD. Wrapping the rock in foil to measure the total surface area
    Show answer to question 19

    Answer: A. Submerging the rock in a graduated cylinder and measuring displaced water

    The water displacement method works because a completely submerged object displaces an amount of liquid equal to its own volume. Measuring mass on a balance gives the object's mass rather than its volume.

20. Question 20 of 25Medium

    After precipitation falls on the ground, what is the process called when water first soaks into the surface soil layer?

    1. AA. Evaporation
    2. BB. Condensation
    3. CC. Surface runoff
    4. DD. Infiltration
    Show answer to question 20

    Answer: D. Infiltration

    Infiltration is the physical transition of water from the land surface downward into the upper soil zone. Surface runoff occurs when water flows over the ground surface without soaking in, typically because the ground is saturated or impermeable. Evaporation returns water back to the atmosphere rather than absorbing it into the earth.

21. Question 21 of 25Hard

    When regional metamorphism subjects shale to progressively increasing heat and directed pressure, which sequence reflects the correct progression of metamorphic rocks formed?

    1. AA. Schist to slate to gneiss to phyllite
    2. BB. Phyllite to gneiss to slate to schist
    3. CC. Gneiss to schist to slate to phyllite
    4. DD. Slate to phyllite to schist to gneiss
    Show answer to question 21

    Answer: D. Slate to phyllite to schist to gneiss

    Under increasing metamorphic grade, fine-grained shale transforms first into low-grade slate, then phyllite, followed by medium-grade schist, and ultimately high-grade banded gneiss. Beginning with gneiss or schist reflects high-grade metamorphic conditions rather than the early stages of shale transformation.

22. Question 22 of 25Hard

    A small group of seeds from a mainland plant colonizes a remote volcanic island with rocky, arid soil. Over many generations, the island descendants develop much deeper taproots than the ancestral mainland population. Which process best explains this divergence?

    1. AA. Acquired characteristics accumulated during the lifetimes of individual plants were transmitted to their seeds.
    2. BB. The island plants crossbred with unrelated native shrubs to immediately absorb their root structures.
    3. CC. Volcanic soil chemicals directly induced identical genetic mutations across the entire plant community.
    4. DD. Selective pressure from limited groundwater favored plants with alleles that promoted deeper root growth.
    Show answer to question 22

    Answer: D. Selective pressure from limited groundwater favored plants with alleles that promoted deeper root growth.

    The arid conditions created a selective pressure favoring plants whose root systems reached deeper moisture reserves, enabling those individuals to survive and reproduce more successfully. Traits acquired through use or disuse during an individual's lifetime are not encoded in the DNA and therefore cannot be inherited by offspring.

23. Question 23 of 25Hard

    Gram for gram, which of these nutrients supplies the most energy to the body?

    1. AA. Protein
    2. BB. Fat
    3. CC. Carbohydrate
    4. DD. Water
    Show answer to question 23

    Answer: B. Fat

    Fat yields about 9 Calories per gram, while carbohydrate and protein each yield about 4 Calories per gram, making fat the most energy-dense nutrient. Water provides no energy at all, so it cannot be the answer even though it is essential to digestion.

24. Question 24 of 25Hard

    The Gulf Stream is best classified as which type of ocean current?

    1. AA. A cold and broad eastern boundary current
    2. BB. A warm and fast western boundary current
    3. CC. A deep and stagnant equatorial countercurrent
    4. DD. A seasonal wind-driven polar bottom current
    Show answer to question 24

    Answer: B. A warm and fast western boundary current

    The Gulf Stream is a warm, swift western boundary current formed along the western edge of the North Atlantic gyre that carries heat from the tropics toward Europe. Eastern boundary currents are typically broad, shallow, and transport colder water toward the equator.

25. Question 25 of 25Hard

    Why does temperature increase with increasing altitude within the stratosphere?

    1. AA. Ozone molecules absorb solar ultraviolet radiation and release heat
    2. BB. Strong convection currents carry warm air upward from the mesosphere
    3. CC. Dense greenhouse gases near the top trap rising thermal energy
    4. DD. Solar wind particles directly collide with free oxygen atoms
    Show answer to question 25

    Answer: A. Ozone molecules absorb solar ultraviolet radiation and release heat

    Temperatures increase with altitude in the stratosphere because ozone molecules concentrated in this layer absorb solar ultraviolet radiation and convert that energy into heat. The mesosphere above is actually the coldest layer of the atmosphere, so convection cannot carry warmth down from it, nor does the mesosphere drive upward heating.

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