ASVAB — All Questions

Which part of an animal cell controls which substances enter and leave the cell?

• a.the Golgi apparatus
• b.the nuclear envelope
• c.the cell membrane✓
• d.the cell's cytoplasm

The cell membrane is a lipid bilayer that lets some molecules cross and blocks others, so it decides what a cell takes in and what it expels. The nuclear envelope tempts because it is also a membrane with pores, but it guards the DNA inside the cell rather than the cell's outer boundary.

Which cell structures link amino acids together to build proteins?

• a.the ribosomes✓
• b.the chloroplasts
• c.the chromosomes
• d.the lysosomes

Ribosomes read the messenger RNA copy of a gene and link amino acids into a chain in that order, which is why cells that export a lot of protein are packed with them. Chromosomes tempt because they store the instructions, but storing a recipe is not the same as cooking from it.

Which organ filters urea and other wastes out of the blood to form urine?

• a.the bladder
• b.the spleen
• c.the kidney✓
• d.the liver

Each kidney holds about a million nephrons that filter blood under pressure, reabsorb water and useful salts, and pass the rest out as urine. The liver tempts because it is where urea is actually made from broken-down protein, but it hands that waste to the blood for the kidneys to clear.

Two parents each carry one dominant and one recessive copy of the same gene. What fraction of their children are expected to show the recessive trait?

• a.1 in 2
• b.1 in 4✓
• c.3 in 4
• d.1 in 3

Cross Aa with Aa and the four equally likely results are AA, Aa, aA and aa; only aa has no dominant copy left to mask it, so 1 in 4 shows the recessive trait. 1 in 2 is the share that end up carriers like the parents, and 3 in 4 is the share showing the dominant trait.

In an ecosystem, bacteria and fungi that break down dead plants and animals are called

• a.producers
• b.decomposers✓
• c.scavengers
• d.herbivores

Decomposers digest dead tissue chemically and release nitrogen, phosphorus and carbon back into soil and air, closing the loop so producers can build new tissue. Scavengers tempt because they also feed on the dead, but they are animals that eat chunks and leave remains behind.

In a scientific name such as Ursus americanus, the two words give the organism's

• a.family and genus
• b.class and order
• c.order and family
• d.genus and species✓

Linnaean naming uses the two narrowest ranks, a capitalized genus followed by a lowercase species, so each organism gets one name worldwide. The ranks run kingdom, phylum, class, order, family, genus, species; family and genus tempt as the next pair up but are too broad to name one kind.

A tendon in the human body attaches

• a.a bone to cartilage
• b.a muscle to a bone✓
• c.a muscle to a muscle
• d.a bone to a bone

A tendon is the tough cord that carries a muscle's pull through to the skeleton, which is how a contraction swings a bone at a joint. Ligaments are the tempting reverse: they tie bone to bone and limit travel, so a torn ligament loosens a joint while a torn tendon costs movement.

When a person inhales, the diaphragm

• a.contracts and moves downward✓
• b.relaxes and moves upward
• c.contracts and moves upward
• d.relaxes and moves downward

The diaphragm is a domed sheet of muscle, and contracting flattens it downward so the chest cavity enlarges, pressure inside drops below outside air pressure, and air flows in. Exhaling is the passive reverse, the muscle relaxing and doming upward. Air moves on pressure, not on pulling.

Metamorphic rock such as marble or slate is formed by

• a.slow cooling of molten magma
• b.evaporation of trapped sea water
• c.heat and pressure on buried rock✓
• d.compaction of layered sediment

Metamorphism recrystallizes a rock that stays solid, so heat and pressure turn limestone into marble and shale into slate without either one melting. Melting and cooling would make it igneous instead, and compacted sediment is how the original limestone formed, which is why that answer tempts.

New ocean floor is created at a mid-ocean ridge where two tectonic plates

• a.grind past each other sideways
• b.press together and fold upward
• c.move apart and magma rises✓
• d.collide and one plate sinks under

Where plates separate, pressure on the mantle beneath them drops, magma rises into the gap and freezes as fresh crust, which is why the seafloor is youngest at the ridge and older toward the continents. One plate sinking beneath another is the tempting reverse: subduction destroys crust.

Clouds form when

• a.sinking air warms and water vapor condenses
• b.rising air warms and water droplets evaporate
• c.rising air cools and water vapor condenses✓
• d.sinking air cools and water droplets freeze

Air expands and cools as it rises, and cooler air holds less water vapor, so once it reaches the dew point the vapor condenses onto dust to make droplets. Sinking air does the opposite, warming and drying out, which is why high pressure brings clear skies instead of cloud.

The ozone layer, which absorbs most of the sun's ultraviolet radiation, lies in which layer of the atmosphere?

• a.the stratosphere✓
• b.the ionosphere
• c.the troposphere
• d.the thermosphere

Ozone sits roughly 15 to 35 km up, and the heat released as it absorbs ultraviolet light is why the stratosphere grows warmer with height instead of colder. The troposphere tempts because it is the layer we live in and where weather happens, but it lies below the ozone shield.

Earth has seasons mainly because

• a.its orbit speeds up and slows down
• b.its distance from the sun varies
• c.the sun's output rises and falls
• d.its axis is tilted as it orbits✓

Earth's axis is tilted about 23.5 degrees and keeps pointing the same direction all year, so each hemisphere leans toward the sun for half the orbit and gets steeper rays and longer days. Distance is the classic misconception: Earth is nearest the sun in early January, northern midwinter.

Ocean tides on Earth are caused mainly by

• a.prevailing winds over the ocean
• b.the moon's gravitational pull✓
• c.the earth's magnetic field
• d.the spin of the moon on its axis

The moon's gravity pulls the ocean toward it and leaves a matching bulge on the opposite side of the planet, so a rotating Earth carries most coasts through two high tides a day. The sun raises tides too, but under half as strongly, because tidal pull falls off with distance cubed.

Dry ice changes directly from a solid to a gas without ever becoming liquid. This change is called

• a.evaporation
• b.condensation
• c.deposition
• d.sublimation✓

Sublimation is solid straight to gas with no liquid stage, which happens when the pressure is too low for the liquid form to be stable at that temperature. Deposition is the tempting reverse, gas straight to solid, which is how frost grows on a cold window without dew forming first.

An element's atomic number tells you the number of

• a.electron shells in its atoms
• b.protons inside its nucleus✓
• c.neutrons in its nucleus
• d.particles in its nucleus

The proton count defines the element, so changing it makes the atom a different element altogether. Neutron count varies between isotopes of one element, and protons plus neutrons give the mass number, which is why counting every nuclear particle is the tempting near miss here.

Elements in the same column, or group, of the periodic table react in similar ways because they have the same number of

• a.electrons in the outermost shell✓
• b.neutrons inside the nucleus
• c.protons inside the nucleus
• d.electron shells around the atom

Chemical behaviour is set by the outermost electrons, so every element in a column gains, loses or shares the same number of them and the whole group reacts alike. The number of shells is what changes going down a column, and it is what a row across the table has in common instead.

A solution with a pH of 4 is how much more acidic than a solution with a pH of 6?

• a.10 times as acidic
• b.100 times as acidic✓
• c.1,000 times as acidic
• d.2 times as acidic

The pH scale is base ten, so each whole unit is a tenfold change in hydrogen ion concentration. From 6 down to 4 is two steps, and 10 x 10 gives 100 times more acidic. Answering 2 comes from subtracting 6 - 4 and treating the scale as if it added rather than multiplied.

A log burns away and leaves a small pile of ash that weighs far less than the log did. The missing mass

• a.turned entirely into heat and light
• b.was destroyed in the reaction
• c.stayed in the ash as carbon
• d.escaped as gases and water vapor✓

Mass is conserved: burning rearranges atoms rather than destroying them, so the wood's carbon and hydrogen leave as carbon dioxide and water vapor while minerals remain as ash. Weigh a sealed fire and nothing is lost. Heat and light come from bond changes, not from matter vanishing.

Which of the following is a compound rather than a mixture?

• a.ocean seawater
• b.carbon dioxide✓
• c.ordinary air
• d.stainless steel

A compound has its elements chemically bonded in a fixed ratio and can be split only by a chemical reaction, so carbon dioxide is always one carbon to two oxygens. Mixtures keep the properties of their parts and come apart physically, air by cooling and distilling, seawater by evaporation.

A ball is dropped from a rooftop. As it falls toward the ground,

• a.kinetic energy becomes potential energy
• b.potential energy becomes kinetic energy✓
• c.potential energy becomes chemical energy
• d.kinetic energy becomes thermal energy

Gravity does work on the falling ball, so the store that depends on height shrinks while its speed and kinetic energy grow, and the total stays nearly constant until air drag bleeds some off as heat. The reverse conversion is what happens on the way up, as a thrown ball slows while climbing.

Heat from the sun crosses the near-vacuum of space and reaches Earth by

• a.conduction
• b.radiation✓
• c.convection
• d.insulation

Radiation carries energy as electromagnetic waves and needs no matter at all, which is why sunlight can cross empty space. Conduction needs particles touching so vibrations pass along, and convection needs a fluid free to circulate, so neither works where there is nothing to carry the heat.

Which property of a sound wave determines how loud the sound is?

• a.its frequency
• b.its wave speed
• c.its amplitude✓
• d.its wavelength

Amplitude is how far the air particles swing from rest, and a bigger swing delivers more energy to the eardrum, so the sound is louder. Frequency tempts, but it sets pitch, how high or low the note is; wave speed is fixed by the medium, so shouting does not make sound arrive any sooner.

A glass prism splits white light into a band of colors because

• a.each color bends by a different amount✓
• b.all colors bend by the same amount
• c.the glass creates colors as light passes
• d.the prism reflects colors off its faces

White light is a mixture of wavelengths, and glass slows violet more than red, so each color refracts through a slightly different angle and the beam fans out into a spectrum. The prism adds nothing of its own: a second prism can bend the colors back together into plain white light.

A car brakes hard and an unbelted passenger is thrown toward the windshield. This is best explained by

• a.friction dragging the body along
• b.gravity pulling the body forward
• c.the body's inertia keeping it moving✓
• d.the seat pushing the body forward

Newton's first law says a body keeps its speed and direction unless an outside force acts, so the passenger keeps travelling at the car's old speed while the brakes slow the car. Nothing throws the passenger forward; a belt supplies the backward force that would stop them with the car.

A wheelbarrow is a second-class lever. The load sits 1 foot from the wheel axle, and the handles are gripped 4 feet from that same axle. Ignoring the weight of the barrow itself, how much lift at the handles is needed to raise a 160-pound load?

• a.160 pounds
• b.640 pounds
• c.40 pounds✓
• d.64 pounds

A lever balances when effort x effort arm equals load x load arm. Here effort x 4 = 160 x 1, so the effort is 40 pounds. Inverting the arms and multiplying 160 by 4 gives 640 pounds; using the 4-foot arm on both sides hands back the load itself, 160 pounds.

A worker lifts a shovel by holding the very end of the handle still with one hand, which acts as the fulcrum, and pushing up with the other hand 1 foot along the shaft. The dirt on the blade weighs 10 pounds and sits 4 feet from the fulcrum hand. The push at the second hand must be about:

• a.14 pounds
• b.10 pounds
• c.30 pounds
• d.40 pounds✓

In a third-class lever the effort acts between the fulcrum and the load, so the effort arm is always shorter and the push must exceed the load. Effort x 1 = 10 x 4 gives 40 pounds. Measuring the load's 3-foot distance from the pushing hand rather than from the fulcrum gives 30 pounds.

A block and tackle is rigged so that three sections of rope support the movable block carrying the load. Ignoring friction, how much rope must be hauled in to raise the load 2 feet?

• a.6 feet✓
• b.3 feet
• c.2 feet
• d.4 feet

A machine cannot create energy, so effort x rope pulled equals load x height raised. Three supporting ropes cut the force to a third, so the rope has to move three times as far: 3 x 2 = 6 feet. Counting only the two ropes tied to the movable block gives 4 feet and understates the haul.

Three external spur gears are meshed in a straight row: gear A drives gear B, and gear B drives gear C. If gear A turns clockwise, gear C turns:

• a.clockwise, at a speed set by gear B's teeth
• b.counterclockwise, at a speed set by B
• c.clockwise, at a speed set by gears A and C✓
• d.counterclockwise, at a speed set by A and C

Every external mesh reverses rotation, so two meshes restore the original direction and gear C turns clockwise like gear A. The middle gear is an idler: it cancels out of the ratio, which depends only on the first and last tooth counts. Counting one reversal instead of two is the usual error.

A motor shaft carries a 15-tooth gear that drives a 45-tooth gear. Fixed to the same shaft as that 45-tooth gear is a 20-tooth gear, which drives a 60-tooth output gear. If the motor turns at 900 rpm, the output gear turns at:

• a.900 rpm
• b.300 rpm
• c.100 rpm✓
• d.150 rpm

In a compound train the stage ratios multiply: 45/15 = 3 drops 900 rpm to 300 rpm, and 60/20 = 3 drops that to 100 rpm, a 9 to 1 reduction. Stopping after one stage leaves 300 rpm, adding the ratios rather than multiplying gives 150 rpm, and inverting one stage hands back 900 rpm.

A motor delivering 20 pound-feet of torque turns a 16-tooth gear that drives a meshed 64-tooth gear. Ignoring friction, the torque available at the larger gear is:

• a.5 pound-feet
• b.20 pound-feet
• c.80 pound-feet✓
• d.320 pound-feet

Torque multiplies by the same ratio that speed divides by. The driven gear has 64/16 = 4 times the teeth, so it turns a quarter as fast and carries 4 x 20 = 80 pound-feet. Inverting the ratio gives 5 pound-feet; assuming a gear pair passes torque through unchanged gives 20.

Two pulleys of equal diameter are joined by a belt given a half twist, so the two strands cross between them. Compared with the same pulleys joined by an ordinary open belt, the crossed belt does what?

• a.It halves the driven pulley's rim speed
• b.It doubles the speed of the driven pulley's rim
• c.It reverses the driven pulley's rotation✓
• d.It cuts the torque the belt can carry

A belt drives whichever side of the rim it wraps. An open belt touches both pulleys on the same side, so they turn together; crossing it puts the belt on opposite sides and the driven pulley runs backward. Speed still depends only on the pulley diameters, so equal pulleys still turn at equal speed.

A bicycle's front chainring has 48 teeth and the rear sprocket it drives has 16 teeth. For each complete turn of the pedals, the rear wheel turns:

• a.32 turns
• b.4 turns
• c.1/3 turn
• d.3 turns✓

A chain passes the same number of teeth at each sprocket, so turns are inversely proportional to tooth count: 48/16 = 3 wheel turns per pedal turn. Inverting the ratio gives 1/3 turn, which would make the wheel slower than the pedals; subtracting the counts gives 32 and is not a ratio at all.

A worker rolls a 300-pound drum 24 feet up a ramp to a dock 6 feet above the ground. Ignoring friction, how much work is done on the drum?

• a.1,800 foot-pounds✓
• b.3,600 foot-pounds
• c.7,200 foot-pounds
• d.450 foot-pounds

Work against gravity is weight x vertical rise, not weight x distance traveled: 300 x 6 = 1,800 foot-pounds. Multiplying by the 24-foot ramp gives 7,200. The ramp cuts the push to 75 pounds over 24 feet, still 1,800; pairing that reduced push with the 6-foot rise gives 450.

An axe head measures 8 inches from its cutting edge back to its blunt end and is 2 inches thick at that blunt end. Ignoring friction, its mechanical advantage is about:

• a.4 to 1✓
• b.6 to 1
• c.2 to 1
• d.8 to 1

A wedge is an inclined plane that moves: its mechanical advantage is slope length divided by thickness, 8/2 = 4 to 1. A longer, thinner wedge splits with less force but must be driven farther. Reading the 8-inch length alone as the advantage gives 8 to 1, and subtracting the two gives 6.

A screw jack has threads with a pitch of 1/4 inch and is turned by a handle 14 inches long. Taking pi as 3.14 and ignoring friction, its mechanical advantage is about:

• a.about 14
• b.about 56
• c.about 88
• d.about 350✓

One turn moves the effort around a circle of 2 x 3.14 x 14 = about 88 inches while the load rises one pitch, 1/4 inch. Mechanical advantage is effort distance over load distance: 88 / 0.25 = about 350. Using the 14-inch handle instead of the circle it sweeps gives only about 56.

In a hydraulic jack the small piston has an area of 1 square inch and the large piston an area of 25 square inches. One stroke pushes the small piston down 5 inches. How far does the large piston rise on that stroke?

• a.0.20 inch✓
• b.125 inches
• c.5.0 inches
• d.1.25 inches

Liquid is nearly incompressible, so the volume leaving one cylinder arrives in the other: 1 x 5 = 25 x d, giving d = 0.2 inch. The 25-fold gain in force is paid for with 25 times less travel. Multiplying rather than dividing gives 125 inches and would create energy out of nothing.

In a hydraulic press the small piston is 2 inches in diameter and the large piston is 6 inches in diameter. A 100-pound force on the small piston produces what force at the large piston?

• a.100 pounds
• b.300 pounds
• c.600 pounds
• d.900 pounds✓

Pressure is the same throughout a closed fluid and force = pressure x area, so force scales with AREA, and area goes as the square of diameter. (6/2)^2 = 9, so 9 x 100 = 900 pounds. Using the diameter ratio of 3 directly gives 300; reading equal pressure as equal force gives 100.

A steel bar weighs 60 pounds hanging from a scale in air. Lowered until it is completely underwater, the same scale reads 52 pounds. The water the bar displaces weighs:

• a.60 pounds
• b.68 pounds
• c.52 pounds
• d.8 pounds✓

Archimedes' principle: the buoyant force equals the weight of fluid displaced, and it shows up as lost apparent weight. 60 - 52 = 8 pounds of water displaced. The submerged reading, 52, is what the scale still holds, and adding the loss back to the dry weight gives 68.

Standing water exerts about 0.43 pound per square inch of pressure for every foot of depth. A storage tank is filled with water to a depth of 30 feet. The water pressure on the tank floor is about:

• a.6.45 pounds per square inch
• b.12.9 pounds per square inch✓
• c.30.4 pounds per square inch
• d.69.8 pounds per square inch

Pressure in standing liquid is proportional to depth alone, so multiply the per-foot figure by the depth: 0.43 x 30 = 12.9 pounds per square inch. Dividing the depth by 0.43 gives about 69.8 and inverts the relation; adding the two numbers gives 30.4. The tank width never enters it.

A spring stretches 3 inches when a 12-pound weight hangs from it. Two identical springs are then joined end to end in a single line, and the same 12-pound weight is hung from the lower one. The total stretch is:

• a.3 inches
• b.1.5 inches
• c.6 inches✓
• d.12 inches

Springs joined end to end each carry the FULL load, so each stretches its own 3 inches and the stretches add: 3 + 3 = 6 inches. Springs side by side are the opposite case, splitting the load so each stretches 1.5 inches. Treating a series pair like a parallel pair produces that 1.5.

A spring stretches 2 inches under a 10-pound load. Still within its elastic limit, how far will the same spring stretch under a 25-pound load?

• a.12.5 inches
• b.4 inches
• c.2.5 inches
• d.5 inches✓

Within its elastic limit a spring's stretch is proportional to the load, so stretch per pound stays fixed: 2/10 = 0.2 inch per pound, and 25 x 0.2 = 5 inches. Taking the load ratio 25/10 = 2.5 as the answer reports the multiplier instead of multiplying the 2-inch stretch by it.

A seesaw 12 feet long pivots at its midpoint. A 90-pound child sits at one end. How far from the pivot must a 120-pound child sit on the other side to balance it?

• a.6.0 feet
• b.8.0 feet
• c.4.5 feet✓
• d.3.0 feet

Balance means matching moments: weight x distance on one side equals weight x distance on the other. 90 x 6 = 540, and 540 / 120 = 4.5 feet. The heavier child always sits closer to the pivot. Multiplying by the weight ratio instead of dividing pushes that child out to 8 feet.

A uniform beam 12 feet long weighs 200 pounds and rests on a support at each end. A 600-pound crate sits 3 feet from the left support. How much weight does the left support carry?

• a.450 pounds
• b.600 pounds
• c.550 pounds✓
• d.400 pounds

Take moments about the far support: a load 9 feet from it on a 12-foot span puts 600 x 9/12 = 450 pounds on the near support, and the beam's own 200 pounds acts at midspan, 100 to each end. 450 + 100 = 550. Splitting the crate evenly gives 400; ignoring the beam's weight leaves 450.

A loaded forklift is most likely to tip over when:

• a.its total weight exceeds the rated capacity
• b.its center of gravity moves outside the wheels✓
• c.the load weighs more than the counterweight
• d.its center of gravity is over the front axle

A body tips when a vertical line through its center of gravity falls outside the area enclosed by its supports. Raising a load raises that center, so a small tilt swings the line past the wheels. Weight by itself does not decide it: a heavy low load is steadier than a light high one.

A 250-pound crate rests on a floor where the coefficient of sliding friction is 0.4. Once it is moving, how much horizontal force keeps it sliding at a steady speed?

• a.150 pounds
• b.250 pounds
• c.100 pounds✓
• d.625 pounds

Sliding friction equals the coefficient times the force pressing the surfaces together: 0.4 x 250 = 100 pounds, and at steady speed the push only has to match friction. Dividing 250 by 0.4 gives 625; taking 250 minus 40 percent gives 150, which is what is left over, not what is needed.

Two identical steel blocks of equal weight are dragged across the same concrete floor, one resting on its wide face and the other standing on its narrow edge. The force needed to drag the block on its narrow edge is:

• a.about half that for the wide one
• b.about a quarter of the wide one
• c.about twice that for the wide one
• d.about the same as for the wide one✓

Sliding friction depends on the force pressing the surfaces together and on the two materials, not on how much area they share. Standing the block on edge raises the pressure but shrinks the contact area by the same factor, leaving the friction force unchanged. Weight, not footprint, sets it.

A hoist raises a 400-pound load 20 feet in 10 seconds. The power it delivers is:

• a.40 foot-pounds per second
• b.800 foot-pounds per second✓
• c.8,000 foot-pounds per second
• d.80 foot-pounds per second

Power is work divided by time, and work is force x distance: 400 x 20 = 8,000 foot-pounds, delivered in 10 seconds, is 800 foot-pounds per second. Quoting 8,000 reports the work and ignores the time, dividing by the 10 seconds a second time gives 80, and 40 never uses the 20-foot lift.

A pendulum bob is pulled to one side until it hangs 9 inches higher than its resting point, then released. Ignoring friction and air resistance, on the far side of its swing the bob rises:

• a.18 inches, twice as high
• b.6 inches, two thirds as high
• c.9 inches, the same height✓
• d.4.5 inches, half as high

With friction ignored, energy only trades between height and motion: the potential energy at release becomes kinetic energy at the bottom, then becomes height again. The bob returns to its starting height, 9 inches, no more and no less. Real pendulums fall short only because friction removes energy.

A windshield wiper is driven by a four-bar linkage whose motor crank turns steadily in complete circles. The wiper arm:

• a.rotates in full circles at the same speed
• b.turns in full circles at half that speed
• c.swings back and forth through a limited arc✓
• d.moves in a straight line at a steady pace

A linkage's output is set by the lengths of its bars. When the crank is short enough to rotate fully but the output bar cannot swing past its own pivot, steady rotation at the motor becomes a limited back-and-forth arc. That is how one motor turning one way sweeps a wiper both ways.