ASVAB General Science Test 4

Answer: C

Correct answer: Earth’s rotation on its axis. Earth spins once about every 24 hours, carrying each location into sunlight and then into darkness, which produces day and night. Revolution, Earth's yearlong trip around the Sun, works with axial tilt to create seasons, not daily cycles. A handy way to keep them straight: rotation rhymes with spinning in place, while revolution is going around. Earth's distance from the Sun changes only slightly and slowly over a year, so it cannot explain a daily cycle.

• A: Revolution is involved in annual seasons but not the direct daily cycle.
• B: Lunar shadows cause limited solar eclipses, not each night.
• C (correct): As Earth rotates, locations face toward or away from the Sun.
• D: Distance changes do not make a location face away every day.

Answer: B

Correct answer: It is transferred mostly into thermal energy and other forms. Energy is conserved: it cannot be created or destroyed, only changed from one form to another. When brake pads rub against the wheel rims, friction converts the bicycle's kinetic energy mainly into heat, which is why brakes feel warm after a hard stop. A small share becomes sound, such as a squeal. The energy is not lost; it spreads into the surroundings in a less useful form.

• A: Energy conservation rules out destruction of energy during ordinary braking.
• B (correct): Energy transfers to heating of brakes, tires, air and surroundings, plus some sound.
• C: Braking on level ground does not require all kinetic energy to become height energy.
• D: No conservation principle requires a bicycle’s kinetic energy to become tire mass in this situation.

Answer: B

Correct answer: Small intestine. Absorption depends on surface area, and the small intestine is built for it: long length, circular folds, finger-like villi and microscopic microvilli together create an enormous inner surface. Sugars and amino acids enter blood capillaries in the villi, while most fats enter lymph vessels called lacteals. The large intestine is a tempting choice, but by the time food reaches it most nutrients are gone; it mainly reclaims water and electrolytes.

• A: It stores bile, not digested nutrients from the intestinal lumen.
• B (correct): Its large absorptive surface transfers many digested nutrients into blood or lymph.
• C: It mainly moves food toward the stomach.
• D: It primarily handles leftover water, electrolytes and stool formation.

Answer: D

Correct answer: Troposphere. The troposphere is the lowest layer, extending roughly 8 to 15 km up, and it holds most of the atmosphere's mass and nearly all its water vapor. Because it is heated mainly from the ground, warm air rises and cools there, forming clouds and storms. Above it, the stratosphere contains the ozone layer and is much drier and more stable, which is why jets often cruise near its base.

• A: The thermosphere is high above the troposphere.
• B: The stratosphere contains much of the ozone layer.
• C: The mesosphere is much higher than weather-cloud levels.
• D (correct): The troposphere is the lowest main atmospheric layer and contains most everyday weather.

Answer: B

Correct answer: 15 km/h. Total distance is 9 km + 6 km = 15 km. Total time is

or 1 hour. Average speed is 15 km / 1 h = 15 km/h.

• A: This uses only the first leg's distance over the full hour instead of the total 15 km.
• B (correct): Total distance 15 km divided by total time 60 min (1 h), including the rest, gives 15 km/h.
• C: This is 15 km divided by 60 minutes, which is 0.25 km per minute, mislabeled as km per hour.
• D: This leaves out the 15-minute rest; average speed counts every second that passes, including stops.

Answer: B

Correct answer: Increasing its frequency. Pitch is how the ear perceives the frequency of a sound wave: more vibrations per second sound higher. Amplitude is a separate property that sets loudness, so making a tone louder does not change its pitch. Distance from a stationary source mainly reduces intensity. A guitar string shows this clearly: tightening or shortening it makes it vibrate faster and sound higher, while plucking it harder only makes it louder.

• A: Decreasing frequency lowers a pure tone’s pitch instead of raising it.
• B (correct): A higher sound-wave frequency corresponds to higher pitch.
• C: Greater amplitude generally affects loudness/intensity, not the frequency that sets pitch.
• D: Greater distance usually reduces intensity; without relative motion it need not increase pitch.

Answer: C

Correct answer: A mutation can be neutral, harmful or advantageous depending on context. A mutation is any change in a DNA sequence. Many occur in regions that do not affect proteins or swap a codon for one that codes for the same amino acid, so they are neutral. Others disrupt a needed protein and cause harm, while a few help, such as the sickle-cell allele, which gives one-copy carriers resistance to malaria. The misconception is that mutations are always bad or appear because an organism needs them.

• A: Mutations are not necessarily beneficial.
• B: Some variants are harmless, neutral or context-dependent.
• C (correct): The effect of a DNA change varies by location and environment.
• D: Variants are not created by intention.

Answer: B

Correct answer: A–C–G–T. Base pairing is fixed by shape and hydrogen bonding: A always pairs with T, and G always pairs with C. To find the opposite strand, replace each base with its partner one position at a time, so T becomes A, G becomes C, C becomes G and A becomes T. Frequent mistakes are copying the original letters or slipping in uracil, which appears only in RNA. In a real double helix, the two strands also run in opposite directions.

• A: Those letters do not complement the stated positions.
• B (correct): T pairs with A, G with C, C with G and A with T.
• C: Uracil belongs to RNA, and several pairs are wrong.
• D: Copying the same bases does not apply complementarity.

Answer: D

Correct answer: 15 N. Perpendicular forces combine with the Pythagorean theorem.

• A: Subtracting works only for forces in opposite directions.
• B: Simply adding works only for forces in the same direction, not for forces at right angles.
• C: Averaging the two forces has no physical meaning for combining them.
• D (correct): For forces at right angles, use the Pythagorean theorem: the square root of 81 + 144 is the square root of 225, which is 15 N.

Answer: D

Correct answer: Primary succession involving pioneers and gradual soil formation. Primary succession starts on surfaces that have never had soil, such as cooled lava or bare rock. Pioneer species like lichens and mosses colonize first; they help break down rock and add organic matter when they die, slowly building soil. Over decades or centuries, grasses, shrubs and eventually trees can follow. Secondary succession is the tempting distractor, but it occurs only where soil already exists, as after a fire.

• A: Secondary succession requires existing soil and biological remnants, which new lava lacks.
• B: This is not a description of succession.
• C: Mature forest cannot generally form instantly on bare lava.
• D (correct): Bare substrate supports the concept of primary succession.

Answer: D

Correct answer: Tray Y, with 35% compared with 30%. Groups of different sizes should be compared as percents. Tray X:

or 30%. Tray Y:

or 35%. Tray X had more sprouts in total, but Tray Y germinated at a higher rate.

• A: This compares raw counts even though the trays held different numbers of seeds.
• B: Tray Y's rate is right, but 27 is Tray X's count of sprouts, not its percentage.
• C: This divides Tray X's 27 sprouts by 60, the size of the other tray, instead of by its own 90 seeds.
• D (correct): Tray Y's rate is 21 / 60 = 35%, while Tray X's rate is 27 / 90 = 30%.

Answer: B

Correct answer: Y has the higher hydrogen-ion level, even though hydrochloric acid is the stronger acid. The lower pH always has the higher hydrogen-ion level, so Y, at about pH 2, has roughly 10 times more than X, at pH 3. Hydrochloric acid is still the stronger acid because it ionizes almost completely; Y's acidity comes from a high concentration of a weak acid.

• A: Strength describes how completely an acid ionizes, but X is dilute, and its higher pH shows fewer hydrogen ions.
• B (correct): Y's lower pH shows more hydrogen ions, which a large amount of weak acid can supply; strength and concentration are separate ideas.
• C: Acetic acid is a weak acid that ionizes only partly; Y's low pH comes from its high concentration.
• D: Their pH values differ by 1 unit, which is a tenfold difference in hydrogen-ion level.

Answer: D

Correct answer: One ninth as bright. Light from a star spreads over the surface of an ever-larger sphere, and a sphere's area grows with the square of its radius. Tripling the distance spreads the same light over 3² = 9 times the area, so each square meter receives one ninth as much. The common mistake is assuming brightness drops in simple proportion to distance, which would give one third. The same inverse-square rule applies to gravity and to sound spreading in open air.

• A: This reverses the inverse-square relationship.
• B: This incorrectly uses a linear, not square, dependence.
• C: Farther distance reduces, rather than increases, received brightness.
• D (correct): Inverse-square spreading gives relative brightness $\frac{1}{3}$² = $\frac{1}{9}$.

Answer: D

Correct answer: 11.0 u. A weighted average multiplies each value by its fraction and adds the results, so the more common isotope pulls the average toward itself. Here 80% of 10 is 8 and 20% of 15 is 3, giving 11. A quick sanity check: the answer must lie between 10 and 15 and closer to 10, since most atoms have mass 10. A simple average of 12.5 would be right only if the two isotopes were equally common.

• A: 12.5 u is an equal-abundance average, not the weighted value.
• B: An average of ten would ignore the heavier 20% component.
• C: The masses must be averaged, not added.
• D (correct): 0.80 × 10 + 0.20 × 15 = 8 + 3 = 11 u.

Answer: C

Correct answer: X swells; Y shrinks. Compare solute outside with solute inside, then send water toward the side with more solute. Around X the solution is hypotonic, so water enters and the cell swells; an animal cell lacks a wall and may even burst. Around Y the solution is hypertonic, so water leaves and the cell shrinks. Hypo means under, as in less solute outside. A common mistake is reversing the direction, as if water followed the lower solute concentration.

• A: Different tonicity can change cell volume.
• B: This reverses the osmotic predictions.
• C (correct): Correct: Outside X is hypotonic so water tends to enter; outside Y is hypertonic so water tends to leave.
• D: Water follows osmotic conditions, not a fixed outward direction.