About this practice test

15 free GED science questions in the style of the real test, covering life science, physical science and earth and space science. Most are built around a short experiment, data table or passage, just like the GED. Every question has the answer, a full explanation and the most common mistake. Allow about 20 minutes. Your answers are checked on this page, and nothing is sent anywhere.

How This Practice Test Works

The real GED Science test takes 90 minutes. It's less about memorizing facts and more about reading: most questions give you an experiment, a chart or a short passage and ask what it shows. You'll also need a few basic ideas, such as variables in an experiment, energy, and simple formulas like speed and density.

This set follows the same mix as the real test: about 40% life science, 40% physical science and 20% earth and space science. Answer every question, then select Check my answers at the bottom to see your score and the skills to work on.

Part 1: Life Science (Questions 1–6)

About 40% of the real GED Science test.

Question 1Experiment design: variables

A student wants to know whether fertilizer affects how tall bean plants grow. She sets up three groups of 10 plants. Each group gets the same pot size, soil, water and sunlight. Group 1 gets no fertilizer, Group 2 gets 5 grams a week and Group 3 gets 10 grams a week. After 3 weeks she measures the height of every plant.

What is the independent variable in this experiment?

Show answer and explanation

Answer: A. The amount of fertilizer

The independent variable is the one thing the scientist changes on purpose. Here she gives each group a different amount of fertilizer, so fertilizer is the independent variable. Plant height is what she measures, which makes it the dependent variable.

Common mistake: Choosing plant height. That's the dependent variable: it's the result, not the thing being changed.

Question 2Experiment design: control group

Use the information from question 1.

Which group is the control group?

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Answer: A. Group 1, which gets no fertilizer

The control group doesn't get the treatment being tested. Group 1 gets no fertilizer, so the student can compare the other groups against it to see what fertilizer changes.

Common mistake: Picking "all three groups". Keeping water, soil and sunlight the same makes them controlled variables, which is different from a control group.

Question 3Genetics: Punnett squares

In pea plants, purple flowers (P) are dominant over white flowers (p). Two plants that are both Pp are crossed. What is the chance that an offspring has white flowers?

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Answer: B. 25%

Draw the Punnett square for Pp × Pp: the four boxes are PP, Pp, Pp and pp. Only pp has white flowers, because white is recessive and needs two copies. That's 1 box out of 4, or 25%.

Common mistake: Answering 50% because half the letters are p. A plant needs two recessive copies to show the recessive trait.

Question 4Ecology: food chains

In the food chain grass → grasshopper → frog → hawk, which organism is the primary consumer?

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Answer: B. Grasshopper

A primary consumer is the first animal in the chain: it eats the producer. Grass is the producer because it makes its own food from sunlight. The grasshopper eats the grass, so it's the primary consumer. The frog is the secondary consumer and the hawk is the tertiary consumer.

Common mistake: Choosing grass. Grass is the producer, not a consumer.

Question 5Reading data tables

A lab measured how fast an enzyme worked at different temperatures.

Temperature (°C)Reactions per minute
2012
3025
4038
5015
602

Based on the table, at which temperature was the enzyme most active?

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Answer: B. 40°C

Look for the highest number in the "Reactions per minute" column. It's 38, at 40°C. Above 40°C the rate drops quickly.

Common mistake: Choosing 60°C because it's the highest temperature. The question asks about activity, which is the other column.

Question 6Drawing conclusions from data

Use the information from question 5.

Which statement is best supported by the data?

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Answer: D. The enzyme's activity rises up to about 40°C and then falls.

From 20°C to 40°C the rate climbs from 12 to 38, then it falls to 15 at 50°C and 2 at 60°C. So activity rises up to about 40°C and then drops. That's the only statement that matches every row.

Common mistake: Picking "stops working completely above 40°C". The enzyme still does 15 reactions per minute at 50°C, so that goes further than the data shows.

Part 2: Physical Science (Questions 7–12)

About 40% of the real test: chemistry and physics.

Question 7Speed

A car travels 150 miles in 2.5 hours. What is its average speed?

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Answer: B. 60 miles per hour

Average speed = distance ÷ time = 150 ÷ 2.5 = 60 miles per hour.

Common mistake: Multiplying instead of dividing (150 × 2.5 = 375). Speed is always distance divided by time.

Question 8Density

A block has a mass of 240 grams and a volume of 80 cubic centimeters. What is its density?

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Answer: B. 3 g/cm³

Density = mass ÷ volume = 240 ÷ 80 = 3 grams per cubic centimeter. Water's density is 1 g/cm³, so this block would sink.

Common mistake: Dividing the wrong way round (80 ÷ 240 = 0.33). Mass goes on top.

Question 9Energy transformations

A flashlight runs on batteries. When it's switched on, which energy change takes place?

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Answer: A. Chemical energy → electrical energy → light energy

A battery stores chemical energy. When the circuit is closed, that becomes electrical energy, and the bulb turns the electrical energy into light (plus some heat).

Common mistake: Reversing the order. Energy flows from where it's stored (the battery's chemicals) to where it's used (the bulb).

Question 10Force and motion

Using the formula F = m × a, what force is needed to accelerate a 1,200 kg car at 2 m/s²?

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Answer: C. 2,400 N

Force = mass × acceleration = 1,200 kg × 2 m/s² = 2,400 newtons (N).

Common mistake: Dividing (1,200 ÷ 2 = 600). The formula multiplies mass by acceleration.

Question 11Chemical equations

Look at this balanced equation: 2H2 + O2 → 2H2O. How many hydrogen atoms are on each side?

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Answer: C. 4

On the left, 2H2 means 2 molecules with 2 hydrogen atoms each: 2 × 2 = 4. On the right, 2H2O also has 2 × 2 = 4. A balanced equation has the same number of each kind of atom on both sides.

Common mistake: Counting only the small number (2) and forgetting the big number in front, which multiplies the whole molecule.

Question 12Physical and chemical changes

Which of these is a chemical change?

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Answer: D. Iron rusting

In a chemical change a new substance forms. When iron rusts, it reacts with oxygen and water to form iron oxide, which is a different substance. Melting, dissolving and cutting only change the form or size; the substance stays the same.

Common mistake: Choosing sugar dissolving. The sugar is still sugar. You could get it back by letting the water evaporate.

Part 3: Earth and Space Science (Questions 13–15)

About 20% of the real test.

Question 13Earth's seasons

What causes Earth to have seasons?

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Answer: C. The tilt of Earth's axis as it orbits the Sun

Earth's axis is tilted about 23.5°. As Earth orbits the Sun, first one hemisphere and then the other leans toward the Sun, getting more direct sunlight and longer days. That's summer for that hemisphere.

Common mistake: Choosing distance from the Sun. Earth is actually closest to the Sun in early January, which is winter in the Northern Hemisphere.

Question 14Rock layers and relative age

A canyon wall shows four layers of sedimentary rock that have not been folded or overturned. From top to bottom they are: Layer A (sandstone), Layer B (shale), Layer C (limestone) and Layer D (sandstone).

Which layer is most likely the oldest?

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Answer: D. Layer D

Sediment settles in layers, with new layers on top of older ones. In layers that haven't been disturbed, the bottom layer formed first, so Layer D is the oldest. This is called the law of superposition.

Common mistake: Picking Layer A because it's listed first. The top layer is the youngest.

Question 15Calculating change from data

Average carbon dioxide (CO2) level in the air, measured at Mauna Loa Observatory, Hawaii (rounded, in parts per million, ppm).

YearCO2 (ppm)
1980339
1990354
2000370
2010390
2020414

By about how much did the CO2 level rise from 1980 to 2020?

Show answer and explanation

Answer: C. 75 ppm

Subtract the starting value from the ending value: 414 − 339 = 75 parts per million.

Common mistake: Choosing 414, the 2020 level. The question asks for the change, not the final amount.

What to Practice Next

GED Science rewards a few skills that come up in almost every question. Work on whichever of these you missed:

  • Reading tables and graphs. Before you look at the answers, say in one sentence what the data shows: what goes up, what goes down, and where it peaks.

  • Experiment vocabulary. Know the independent variable (what's changed), the dependent variable (what's measured), the control group and a hypothesis. They appear on almost every GED Science test.

  • Simple science math. Speed = distance ÷ time, density = mass ÷ volume, force = mass × acceleration, and finding the mean or the change between two values.

  • Not going past the data. Many wrong answers say more than the data shows ("always", "completely", "never"). Pick the answer the evidence actually supports.

For a fuller picture of where you stand, take the free GED science diagnostic on LearnerOS. For a fast study plan, see how to prepare for GED science quickly. If you'd like help, our GED science tutoring classes focus on reading data and experiments. You can also try the free GED math practice test or check your scores on the GED practice tests page.

Common Questions

What's on the GED Science test?

Three areas: life science (about 40%), physical science, meaning chemistry and physics (about 40%), and earth and space science (about 20%). Most questions ask you to read an experiment, chart or passage rather than recall facts.

How long is the GED Science test?

The GED Science test takes 90 minutes. You can take it on its own day, separately from the other three subjects.

What score do I need to pass GED Science?

You need at least 145 out of 200, the same as every other GED subject.

Is GED Science hard?

Most people find it easier than they expect, because it's mostly a reading and reasoning test. If you can read a chart, follow an experiment and do basic math, you have the core skills. The questions above show the most common traps.

Is this the official GED practice test?

No. These are original practice questions written in the style of the GED. The official practice test is GED Ready, sold on GED.com, and it gives a score that predicts your real result.