22 Science Practice Questions & Answers

1. 1. A student investigates whether the distance of a lamp changes how fast a water plant releases oxygen bubbles. She puts identical sprigs of the same plant into five beakers of water kept at 22 °C, places the lamp 10, 20, 30, 40, and 50 cm from the beakers in turn, and counts the bubbles released in five minutes at each distance. Which quantity in this investigation is the dependent variable?

   • A.The species of water plant used in every beaker
   • B.The number of bubbles counted in five minutes✓ Answer
   • C.The temperature of the water, kept at 22 °C
   • D.The distance from the lamp to each of the beakers

   The dependent variable is the outcome the researcher measures to see whether it responds; here that is the bubble count. The lamp distance is the independent variable she deliberately changes, while water temperature and plant species are held constant so they cannot explain any difference.

   Source: GED Assessment Guide for Educators: Science, Science Practice SP.2.e — identify and interpret independent and dependent variablesReport a problem with this question

2. 2. In a certain trait, allele A is completely dominant over allele a. Two parents are each heterozygous (Aa). Their first three children all show the dominant phenotype. What is the probability that a fourth child will show the recessive phenotype?

   • A.25%, because each fertilization is an independent event✓ Answer
   • B.0%, because all three older children showed the dominant trait
   • C.75%, because three of every four offspring show the dominant type
   • D.100%, because the recessive phenotype is due to appear next

   An Aa x Aa Punnett square gives AA, Aa, Aa, aa, so one box in four is recessive. Each fertilization is independent of the ones before it, so earlier children do not change the 25% chance for the next child.

   Source: GED Science content topic L.e.2 (monohybrid Punnett squares) with Science Practice SP.8.c (probability of independent events)Report a problem with this question

3. 3. In a meadow food web, grass is eaten by grasshoppers and by mice. Grasshoppers are eaten by frogs, frogs are eaten by snakes, and hawks eat both snakes and mice. A disease removes nearly all of the frogs from the meadow. Which change does this food web most directly predict?

   • A.The mouse population will drop at once, because mice depend on the frogs
   • B.The hawk population will rise, because snakes will suddenly have more food
   • C.The grass will spread quickly, because fewer animals remain to feed on it
   • D.The grasshopper population will rise, because one of its predators is gone✓ Answer

   Removing a predator releases the population it fed on, so grasshoppers increase first. Grass is eaten by grasshoppers and mice, so it should decline rather than spread; mice never fed on frogs; and snakes lose their prey, so hawks gain no extra food.

   Source: GED Science content topic L.c.2 — food chains and webs, and the effect of removing one linkReport a problem with this question

4. 4. In an ecosystem the producers capture 20,000 kcal of energy. About 10% of the energy at each trophic level is stored by the level above it, and most of the rest is lost as heat. About how much energy is stored by the secondary consumers, the level that feeds on the primary consumers?

   • A.About 20 kcal of energy
   • B.About 2,000 kcal of energy
   • C.About 200 kcal of energy✓ Answer
   • D.About 18,000 kcal of energy

   Energy is transferred twice: 10% of 20,000 kcal gives 2,000 kcal in the primary consumers, and 10% of that gives 200 kcal in the secondary consumers. Because roughly 90% is lost as heat at each step, an energy pyramid narrows sharply toward the top.

   Source: GED Science content topic L.c.1 — energy pyramids and the roughly 10% transfer between trophic levelsReport a problem with this question

5. 5. After a meal, the concentration of glucose in the blood rises. The pancreas then releases insulin, body cells take up more glucose, blood glucose falls back toward its usual level, and insulin release slows down. Which statement best describes this pattern of regulation?

   • A.It is negative feedback, because the response reverses the change and restores the set point✓ Answer
   • B.It is positive feedback, because the response makes the original change even larger
   • C.It is an immune response, because the body is reacting to a foreign substance
   • D.It is a failure of regulation, because blood glucose changes after every meal

   In negative feedback the body's response acts in the opposite direction to the change that triggered it, which is why rising glucose triggers insulin and insulin brings glucose back down. Positive feedback would push glucose still higher instead of restoring the set point.

   Source: GED Science content topic L.a.2 — homeostasis and negative-feedback mechanismsReport a problem with this question

6. 6. Two equations are given. Photosynthesis: 6CO2 + 6H2O + light energy -> C6H12O6 + 6O2. Aerobic cellular respiration: C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP. Which statement is supported by comparing these two equations?

   • A.Both processes release oxygen gas as one of their final products
   • B.Cellular respiration stores light energy in the bonds of glucose
   • C.The products of photosynthesis are the reactants of aerobic respiration✓ Answer
   • D.Only plants respire, while only animals carry out photosynthesis

   Glucose and oxygen appear on the product side of photosynthesis and on the reactant side of respiration, while carbon dioxide and water do the reverse, which makes the two reactions complements of each other. Respiration consumes oxygen rather than releasing it, and plant cells respire as well.

   Source: GED Science content topic L.b.1 — photosynthesis and aerobic cellular respiration as reciprocal reactionsReport a problem with this question

7. 7. Soot from nearby factories darkened the tree bark in a forest. Over twenty years the share of dark-colored beetles living on those trees rose from about 10% to about 85%. Observers also recorded that birds hunting on the darkened bark caught light-colored beetles far more often than dark ones. Which explanation is best supported by this information?

   • A.The birds caused mutations in the beetles that made their shells darker
   • B.Dark beetles survived and reproduced more often, so the dark allele spread✓ Answer
   • C.Beetles inherited dark color because their parents were exposed to soot
   • D.Each beetle darkened its own color to blend into the sooty bark of the trees

   Natural selection acts on variation that already exists in a population: birds removed more light beetles, so dark beetles left more offspring and their allele became common. Individual beetles cannot change their inherited color, and traits acquired during a parent's lifetime are not passed on.

   Source: GED Science content topic L.f.2 — natural selection requires heritable variation and differential survival and reproductionReport a problem with this question

8. 8. A school nurse compares two classrooms for eight weeks. Students in Classroom A use hand sanitizer after lunch each day and students in Classroom B do not. Classroom A also received a new air purifier on the first day of the study. Classroom A recorded 6 illness-related absences and Classroom B recorded 14. Which is the most serious weakness in the design of this investigation?

   • A.Absences were counted as whole students, so the two totals cannot be compared
   • B.The study ran for eight weeks, a span too short for absences to differ at all
   • C.Classroom B should have used sanitizer as well, so that both groups matched
   • D.Two conditions differed between the rooms, so the sanitizer alone cannot be credited✓ Answer

   A fair comparison changes one variable at a time; here the sanitizer and the air purifier were both introduced in Classroom A, so the two effects are confounded and neither can be isolated. Giving both rooms sanitizer would remove the comparison altogether rather than fix it.

   Source: GED Assessment Guide for Educators: Science, Science Practice SP.2.c — strengths and weaknesses of an experimental designReport a problem with this question

9. 9. A school nurse compares two classrooms for eight weeks. Students in Classroom A use hand sanitizer after lunch each day and students in Classroom B do not. Classroom A also received a new air purifier on the first day of the study. Classroom A recorded 6 illness-related absences and Classroom B recorded 14. Which statement is supported by the results exactly as they are reported?

   • A.Students in Classroom B washed their hands less often than those in Classroom A
   • B.Hand sanitizer prevents illness among schoolchildren in every kind of classroom
   • C.Air purifiers reduce absences more effectively than hand sanitizer does in a classroom
   • D.Classroom A had fewer illness-related absences than Classroom B over the eight weeks✓ Answer

   A supported conclusion says no more than the data show: the study counted absences in two rooms over eight weeks, so only that comparison can be stated. The other choices generalize to all schools, credit the purifier, or add a hand-washing measurement that was never taken.

   Source: GED Assessment Guide for Educators: Science, Science Practices SP.3.a and SP.4.a — cite evidence that supports a conclusionReport a problem with this question

10. 10. Density is calculated as density = mass divided by volume, and liquid water has a density of 1.0 g/cm3. A solid block has a mass of 48 g and a volume of 60 cm3. What is the block's density, and what will the block do when it is placed in water?

    • A.1.25 g/cm3, so the block floats
    • B.0.8 g/cm3, so the block floats✓ Answer
    • C.1.25 g/cm3, so the block sinks
    • D.0.8 g/cm3, so the block sinks

    Dividing 48 g by 60 cm3 gives 0.8 g/cm3. An object floats when its density is lower than the density of the fluid around it, and 0.8 g/cm3 is less than the 1.0 g/cm3 of water.

    Source: GED Science content topic P.c.2 — density = mass/volume and predicting whether an object floats or sinksReport a problem with this question

11. 11. A cart at the top of a track has 500 J of gravitational potential energy. At the bottom of the track, measurements show that the cart has 470 J of kinetic energy. What best accounts for the 30 J that does not appear as kinetic energy?

    • A.The cart used up 30 J, so the total energy of the system became smaller
    • B.Friction transferred 30 J into the track and the air as heat and sound✓ Answer
    • C.The cart destroyed 30 J of energy as it rolled down the length of the track
    • D.30 J of energy turned into new matter inside the body of the moving cart

    Energy is conserved: it can change form but cannot be created or destroyed, so the missing 30 J must have left the cart in another form. Friction between the cart and the track, and drag through the air, convert mechanical energy into thermal energy and sound.

    Source: GED Science content topic P.a.3 — law of conservation of energy and transformations with loss to thermal energyReport a problem with this question

12. 12. A reaction is carried out in a sealed flask. The reactants together contain 250 kJ of chemical energy and the products together contain 180 kJ. During the reaction the outside of the flask becomes noticeably warm. How should this reaction be classified, and why?

    • A.Endothermic, because the outside of the sealed flask became warm to the touch
    • B.Exothermic, because the products hold less energy and the difference was released✓ Answer
    • C.Endothermic, because the products hold less energy than the reactants do
    • D.Exothermic, because the reaction pulled energy in from the warm air of the room

    When the products store less chemical energy than the reactants, the 70 kJ difference has to go somewhere, and it leaves the reaction as heat warming the flask and the surroundings. An endothermic reaction would absorb energy and leave the flask feeling cooler instead.

    Source: GED Science content topic P.a.2 — endothermic and exothermic reactions read from reactant and product energiesReport a problem with this question

13. 13. Use the relationship net force = mass multiplied by acceleration. A car with a mass of 1,200 kg accelerates at 2.5 m/s2 along a straight road. What is the net force acting on the car?

    • A.480 N
    • B.1,202.5 N
    • C.30,000 N
    • D.3,000 N✓ Answer

    Newton's second law multiplies mass by acceleration, so 1,200 kg x 2.5 m/s2 = 3,000 N. Dividing the mass by the acceleration or adding the two quantities gives the other choices, but neither operation follows from the relationship supplied.

    Source: GED Science content topic P.b.2 — Newton's second law, net force = mass x accelerationReport a problem with this question

14. 14. In science, work = force multiplied by the distance the object moves in the direction of the force. A person pushes on a parked car with a steady force of 300 N for 30 seconds, and the car does not move at all. How much work is done on the car?

    • A.300 J, because a steady force of 300 N was applied to the parked car
    • B.10 J, because 300 N divided by 30 s gives 10 as the answer
    • C.9,000 J, because a force of 300 N acted for a full 30 seconds
    • D.0 J, because the car never moved in the direction of the force✓ Answer

    Work requires displacement: force multiplied by a distance of zero is zero, no matter how large the force or how long it lasts. Time appears in power rather than in work, so multiplying or dividing by 30 s does not apply here.

    Source: GED Science content topic P.b.3 — work = force x distance; no work is done if the object does not moveReport a problem with this question

15. 15. A student records the position of a toy car along a straight track: at 0 s it is at 0 m, at 2 s at 10 m, at 4 s at 20 m, at 6 s at 20 m, and at 8 s at 30 m. Which statement about the car's motion is supported by these data?

    • A.The car moved fastest between 4 s and 6 s, covering the most ground
    • B.The car moved backward between 6 s and 8 s, returning toward the start
    • C.The car stayed at rest between 4 s and 6 s, since its position held✓ Answer
    • D.The car traveled at the same speed during each 2-second interval

    On a position record, speed is the change in position divided by the change in time, so an unchanged position from 4 s to 6 s means the speed was zero. The position never decreases, so the car never moved backward, and the 4 s to 6 s gap of 0 m breaks the constant-speed pattern.

    Source: GED Science content topic P.b.1 — interpreting position-time data, where the slope of the graph is speedReport a problem with this question

16. 16. A table gives how much potassium nitrate dissolves in 100 g of water: 32 g at 20 °C, 64 g at 40 °C, and 110 g at 60 °C. A student stirs 64 g of potassium nitrate into 100 g of water held at 60 °C, and all of the solid dissolves. How should the resulting solution be described?

    • A.Unsaturated, because at 60 °C as much as 110 g could dissolve✓ Answer
    • B.Supersaturated, because more solute dissolved than the table permits
    • C.Impossible, because potassium nitrate stops dissolving above 40 °C
    • D.Saturated, because 64 g is the largest amount that the table lists

    A solution is unsaturated when it holds less solute than it could hold at that temperature. At 60 °C the water can dissolve 110 g, so 64 g leaves room for more; the 64 g figure belongs to 40 °C, and hotter water generally dissolves more solid solute rather than less.

    Source: GED Science content topic P.c.4 — reading a solubility table and classifying saturated, unsaturated and supersaturated solutionsReport a problem with this question

17. 17. In a sealed container, 10.0 g of a metal reacts completely with 6.4 g of oxygen to form a metal oxide, and no gas escapes from the container. What is the mass of the metal oxide that is produced?

    • A.16.4 g✓ Answer
    • B.10.0 g
    • C.6.4 g
    • D.3.6 g

    Mass is conserved in a chemical reaction because atoms are rearranged rather than created or destroyed, so the mass of the product equals the total mass of the reactants: 10.0 g + 6.4 g = 16.4 g. Subtracting the masses would treat the oxygen as if it had disappeared.

    Source: GED Science content topic P.c.3 — conservation of mass in chemical reactionsReport a problem with this question

18. 18. A text states that in the electromagnetic spectrum the order from longest to shortest wavelength is radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma, and that the energy carried by each wave increases as the wavelength gets shorter. Which statement is supported by this information?

    • A.Infrared waves carry more energy per wave than the ultraviolet waves do
    • B.Radio waves carry more energy per wave than X-rays and gamma rays
    • C.Visible light has the shortest wavelength of any wave in the list
    • D.Ultraviolet waves carry more energy per wave than infrared waves do✓ Answer

    Ultraviolet sits closer to the short-wavelength end of the list than infrared does, and the passage states that shorter wavelength means higher energy per wave. That higher energy is why ultraviolet light can damage skin cells while infrared is felt mainly as warmth.

    Source: GED Science content topic P.a.5 — the electromagnetic spectrum and the inverse wavelength-energy relationshipReport a problem with this question

19. 19. Earth is actually closest to the Sun in early January, and yet January is the middle of winter in the Northern Hemisphere while it is summer in the Southern Hemisphere. Which explanation of the seasons is consistent with these facts?

    • A.Distance from the Sun drives the seasons, but the oceans delay it by months
    • B.Earth turns more slowly in January, so less sunlight reaches the ground
    • C.Earth's tilted axis gives the north weaker, shorter sunlight in January✓ Answer
    • D.The Sun gives off less energy in January than it gives off in July

    Seasons come from the tilt of Earth's axis, which changes the angle and the daily duration of sunlight for each hemisphere as Earth orbits. Distance cannot be the cause, since both hemispheres are the same distance from the Sun yet have opposite seasons at the same time.

    Source: GED Science content topic ES.c.2 — Earth's revolution and axial tilt as the cause of the seasonsReport a problem with this question

20. 20. Rock samples taken from the ocean floor show that the rock closest to a long undersea mountain ridge is the youngest and that the rock grows steadily older with distance from the ridge, following the same pattern on both sides of it. What does this pattern best support?

    • A.The whole ocean floor formed at one time and has not changed since
    • B.New crust forms at the ridge and then spreads outward on both sides✓ Answer
    • C.Old crust is being pushed down into the mantle along the ridge itself
    • D.The two plates slide past each other at the ridge without making crust

    A symmetrical age pattern means rock is being added at the ridge and carried away in both directions, which is the signature of a divergent boundary where plates separate. Rock of many different ages rules out a single formation event, and sliding plates would not create new sea floor.

    Source: GED Science content topic ES.b.4 — plate tectonics and divergent boundaries at mid-ocean ridgesReport a problem with this question

21. 21. A science text explains that sunlight passes through the atmosphere and warms Earth's surface, and that the warmed surface then radiates energy back outward as infrared radiation. Which statement best describes how greenhouse gases such as carbon dioxide and methane warm the lower atmosphere?

    • A.They absorb infrared energy from the surface and send part of it back down✓ Answer
    • B.They make the Sun release more energy in the direction of the Earth
    • C.They form a solid barrier that keeps warm air trapped near the ground
    • D.They block most of the incoming sunlight before it can reach the ground

    Greenhouse gases are transparent to incoming visible sunlight but absorb the longer-wavelength infrared the surface radiates, then re-emit some of it downward, which slows the escape of energy to space. They are gases, not a physical lid, and they have no effect on how much energy the Sun produces.

    Source: GED Science content topic ES.b.1 — the greenhouse effect and the role of carbon dioxide and methaneReport a problem with this question

22. 22. A table lists four electricity sources with their carbon dioxide emissions per kilowatt-hour during operation: wind, renewable, about 0 g; solar, renewable, about 0 g; natural gas, non-renewable, about 450 g; coal, non-renewable, about 900 g. Which conclusion is supported by this table?

    • A.Coal counts as renewable because new coal is forming underground today
    • B.Coal could be replaced entirely by wind power within a few short years
    • C.The two renewable sources listed emit less carbon dioxide per kilowatt-hour✓ Answer
    • D.Electricity from wind and solar costs less per kilowatt-hour than coal power does

    The table reports only emissions and renewability, so the supported conclusion is the emissions comparison it actually contains: about 0 g for wind and solar against 450 g and 900 g. Cost and replacement timelines are not in the table, and coal forms far too slowly to be renewable.

    Source: GED Science content topic ES.a.3 — renewable versus non-renewable resources with Science Practice SP.1.c (interpreting a data table)Report a problem with this question

Practice questions based on the GED Testing Service Assessment Guide for Educators and standard high-school-equivalency curriculum. GED is a registered trademark of the American Council on Education; this site is not affiliated with or endorsed by ACE or GED Testing Service. Passing scores, fees, retake limits, and age and residency eligibility are set by GED Testing Service and by individual states and change over time — confirm current requirements for your state before testing. Note that the Reasoning Through Language Arts test also includes an extended-response essay, which multiple-choice practice cannot cover. About the GED test →