General Science Practice Test 3 for the ASVAB

Answer: D

Correct answer: Homologous structures. Features with the same underlying bone plan that now serve different purposes are homologous. They point to a common ancestor, which is why they count as evidence for evolution.

• A: Analogous structures do similar jobs but evolved separately, such as bird and butterfly wings; these limbs do different jobs and share ancestry.
• B: Acquired traits develop during one organism's life and are not inherited, unlike these inherited bone patterns.
• C: Codominance describes two alleles both showing in a heterozygote, not shared body structures among species.
• D (correct): These share an underlying design inherited from a common ancestor, even though their jobs now differ.

Answer: A

Correct answer: They land at the same time. Gravity pulls harder on the heavier ball, but that ball also has proportionally more inertia, so the two effects cancel. With air resistance negligible, both accelerate at g and hit the ground together.

• A (correct): Both fall with the same acceleration g because the heavier ball's larger weight is matched by its larger inertia.
• B: Lighter objects do not fall faster; without air resistance every object falls with the same acceleration.
• C: Fall time does not depend on mass at all, so it cannot shrink in proportion to mass.
• D: This is the common misconception that heavier objects fall faster; extra weight is offset by extra inertia.

Answer: C

Correct answer: Pluto. In 2006 the International Astronomical Union defined a planet as a body that orbits the Sun, is massive enough to be nearly round, and has cleared its orbital neighborhood of other objects. Pluto meets the first two criteria but shares its region with many Kuiper Belt objects, so it is classified as a dwarf planet. Neptune, though farthest, is a major planet.

• A: Saturn is a gas-giant major planet.
• B: Uranus is an ice-giant major planet.
• C (correct): Pluto is officially classified as a dwarf planet.
• D: Neptune is the eighth recognized major planet.

Answer: B

Correct answer: Integumentary system. The word integument means a covering. Skin is the body's largest organ, and together with hair, nails and skin glands it forms a barrier against microbes, injury and water loss. Sweat glands and changes in blood flow near the surface help control body temperature, and skin also senses touch and produces vitamin D with sunlight. Hair and nails are made of keratin produced by skin cells, which is why they belong to this system.

• A: It includes lungs and conducting airways.
• B (correct): It covers the body surface and helps protect and regulate temperature.
• C: It includes kidneys, ureters, bladder and urethra.
• D: It includes organs that make gametes and support reproduction.

Answer: B

Correct answer: 68 °F. A Fahrenheit degree is smaller than a Celsius degree: 100 Celsius degrees span the same range as 180 Fahrenheit degrees, a ratio of 9/5. The scales also start at different points, since water freezes at 0 °C but 32 °F. So multiply by 9/5 first, then add 32. Skipping either step gives a wrong value: 36 °F without the offset, or 52 °F without the scaling. A useful check: 20 °C is a mild room, and 68 °F matches that.

• A: About 293 corresponds to 20 °C in kelvins, not Fahrenheit.
• B (correct): 20 × $\frac{9}{5}$ + 32 = 68 °F, the correct Fahrenheit value.
• C: Thirty-six is 20 × 9/5 without adding the 32-degree offset.
• D: Fifty-two adds 32 to 20 but skips multiplying by 9/5.

Answer: A

Correct answer: 20 rabbits per km². Population density is the number of individuals per unit of area, so the count always goes on top of the fraction and the area goes on the bottom. Checking units helps: rabbits divided by square kilometers gives rabbits per square kilometer. Flipping the fraction gives area per rabbit, and multiplying the numbers produces units that make no sense. Density lets ecologists compare populations living in areas of different sizes.

• A (correct): Divide individuals by area: $\frac{240}{12}$ = 20 rabbits/km².
• B: This is not individuals per area.
• C: This repeats area rather than calculating density.
• D: Multiplication gives wrong units/quantity.

Answer: C

Correct answer: 50%. Set up a Punnett square: the Aa parent can pass on A or a, each half the time, while the aa parent can pass on only a. The four boxes give Aa, Aa, aa, aa, so half of the offspring are expected to be aa. This cross is called a test cross, because crossing an unknown individual with a recessive one reveals its hidden alleles. The familiar 25% figure applies only when both parents are Aa.

• A: Some offspring can inherit the dominant A allele.
• B: An aa combination is possible from $\frac{A}{a}$ and a parents.
• C (correct): Half the gametes from Aa contain a, and aa contributes a: $\frac{1}{2}$ aa.
• D: 25% would match Aa × Aa, not this cross.

Answer: A

Correct answer: 19.9 mL, 20.0 mL, 20.1 mL. Accuracy means being close to the true value, and precision means repeated readings are close to each other. Readings of 19.9, 20.0 and 20.1 mL are tightly grouped and centered on 20.0 mL, so they are both.

• A (correct): These readings cluster tightly together and sit right at the true value of 20.0 mL.
• B: These readings are widely scattered and their average is not at 20.0 mL, so they are neither precise nor accurate.
• C: These readings agree closely with each other, but they are all about 2.4 mL too high, so they are precise but not accurate.
• D: These readings average 20.0 mL, but they are spread far apart, so they are not precise.

Answer: D

Correct answer: The twenty plants given plain water. A control group is a set of subjects that does not receive the treatment. The plants given plain water show how beans grow without the plant food, so they are the control group. The matching soil, pot size and light are controlled variables.

• A: These plants receive the treatment being tested, so they are the treatment group.
• B: These are controlled variables held constant across all groups, not a group of subjects.
• C: Plant height is the measured outcome, which is the dependent variable.
• D (correct): These plants do not receive the plant food, so they serve as the baseline for comparison.

Answer: D

Correct answer: 0 m/s. Velocity is a vector: it depends on displacement, the straight-line change in position from start to finish, including direction. Walking 30 m east and then 30 m west returns the student to the starting point, so the displacement is zero and the average velocity is zero. Average speed is different; it uses total distance, here 60 m over 30 s, or 2 m/s. Confusing speed with velocity is the main trap in problems like this.

• A: The route ends at its starting position.
• B: 2 $\frac{\mathrm{m}}{\mathrm{s}}$ is average speed, not net displacement divided by time.
• C: 60 m is a distance, not a velocity.
• D (correct): Net displacement is zero, so average velocity is zero.

Answer: B

Correct answer: Double displacement. Barium trades its chloride partner for sulfate, and sodium trades sulfate for chloride. Two compounds exchanging partners is a double displacement reaction, and the white solid barium sulfate is the precipitate.

• A: Decomposition breaks one compound apart, but this reaction starts with two compounds.
• B (correct): Two compounds swap partners, AB plus CD giving AD plus CB, and one new product is a solid precipitate.
• C: Single displacement needs a free element replacing another, but both reactants here are compounds.
• D: Synthesis forms one product from several reactants, but this reaction makes two products.

Answer: D

Correct answer: 3 m. Frequency is fixed by the source, so it does not change when a wave crosses into a new material. Only speed and wavelength change, and they stay proportional through v = fλ. In material B, dividing 150 m/s by 50 Hz gives 3 m. The information about material A is a distractor: 6 m there implies 300 m/s, so cutting the speed in half also halves the wavelength, confirming 3 m.

• A: Two meters would imply 100 $\frac{\mathrm{m}}{\mathrm{s}}$, below the stated speed in material B.
• B: Six meters is the wavelength in A and does not reflect the changed speed.
• C: One meter would imply a propagation speed of only 50 $\frac{\mathrm{m}}{\mathrm{s}}$ at 50 Hz.
• D (correct): λB = $\frac{150}{50}$ = 3 m; the frequency stays constant across the boundary.

Answer: B

Correct answer: Similar sediment alone does not prove identical ages; further dating or correlation is needed. The same kind of sediment, such as beach sand, can be deposited in many places at many different times, so appearance alone shows similar environments, not equal ages. Geologists match ages using index fossils, distinctive ash layers, magnetic reversals, or radiometric dating of volcanic beds. Claiming identical timing from composition is a classic error of mistaking similarity for correlation.

• A: No evidence suggests a different planetary source.
• B (correct): Similar material can form at different times; correlation or numerical dating requires further evidence.
• C: Matching composition is not sufficient to guarantee age identity.
• D: Relative and radiometric methods can help date geologic sequences under suitable conditions.

Answer: B

Correct answer: Cell grows and copies DNA in interphase -> mitosis separates chromosomes -> cytokinesis divides the cell. DNA is copied before mitosis during interphase; nuclear segregation occurs in mitosis; cytokinesis usually follows or overlaps.

• A: Ribosome assembly and osmosis are different processes.
• B (correct): DNA is copied during interphase before mitosis, mitosis separates the chromosomes, and cytokinesis then splits the cell.
• C: Replication must come before mitosis so that each daughter cell receives a full copy of the chromosomes.
• D: Photosynthesis does not separate chromosomes and DNA synthesis precedes mitosis.

Answer: B

Correct answer: Neon is a group-18 noble gas with a stable outer-electron arrangement. Reactivity is driven by how strongly an atom tends to gain, lose or share outer electrons. Neon's outer shell is already full, so it has little to gain by reacting. Chlorine, in group 17, is one electron short of a full shell and grabs electrons readily, making it one of the most reactive nonmetals. Avoid absolute claims, though: heavier noble gases such as xenon can form compounds.

• A: Neon’s Z = 10 is smaller than that of many elements.
• B (correct): Neon’s filled valence shell underlies its low reactivity in common conditions.
• C: Noble gases are relatively unreactive; the absolute claim is false for some heavier members.
• D: Chlorine is a group-17 halogen, not a transition metal.