GED Science Exam Flashcards

Q: How many questions are on the GED Science test?

The GED Science test has approximately 34-40 questions to complete in 90 minutes with no break. Question types are all technology-enhanced: multiple choice, drag-and-drop, fill-in-the-blank, hot spot (click an area), and drop-down. Short-answer items were removed from the test in 2018.

Q: What is the passing score for GED Science?

You need a score of 145 or higher on the 100-200 point scale to pass. Scoring 165-174 earns GED College Ready status, and 175 or above earns GED College Ready + Credit status, which can qualify for college credit at participating institutions.

Q: How many times can I retake the GED Science test, and is there a waiting period?

GED Testing Service allows two retests with no restrictions between attempts. If you fail a third or later attempt, you must wait 60 days before retaking that subject. Some states apply additional requirements on top of this baseline policy, so confirm your state's specific rules at ged.com before scheduling a retest.

Q: Can I use a calculator on the GED Science test?

Yes. A TI-30XS Multiview calculator is built into the on-screen testing interface for the Science test, and a calculator reference sheet is provided. Test-takers at in-person testing centers may also bring their own physical TI-30XS calculator.

Q: Is there a published pass rate specifically for GED Science?

No. GED Testing Service does not publish an official pass rate broken out by individual subject test. The commonly cited GED pass rate of roughly 58-60% describes candidates who complete and pass all four subjects to earn the full credential, not the Science subject alone.

Q: What topics make up the GED Science test?

Life Science (about 40%) covers cells, genetics, evolution, ecosystems, and human body systems. Physical Science (about 40%) covers atoms, chemical reactions, forces and motion, and energy and electricity. Earth and Space Science (about 20%) covers plate tectonics, the rock cycle, weather and climate, and the solar system. Two science practices - reading and reasoning through scientific text, and using numbers and graphics - are assessed throughout all three content areas rather than as a separately weighted section.

Question 1

What organelle produces the ATP energy a cell uses?

Accepted Answer

The mitochondria - often called the 'powerhouse of the cell' - breaks down glucose in cellular respiration to release usable energy (ATP). This differs from the nucleus, which stores and directs genetic information rather than producing energy.

Question 2

A cell has a rigid outer wall, a large central vacuole, and chloroplasts. What type of cell is it?

Accepted Answer

A plant cell. The cell wall gives rigid structural support (animal cells lack one), the large vacuole stores water for pressure support, and chloroplasts carry out photosynthesis - none of which appear in animal cells.

Question 3

Photosynthesis vs. cellular respiration: which one uses oxygen and produces carbon dioxide?

Accepted Answer

Cellular respiration (in mitochondria) consumes glucose and oxygen to release CO2, water, and ATP. Photosynthesis (in chloroplasts) does the reverse: it uses CO2 and water plus light energy to produce glucose and oxygen.

Question 4

What is the key difference between mitosis and meiosis?

Accepted Answer

Mitosis produces 2 genetically identical daughter cells for growth and repair in body cells. Meiosis produces 4 genetically unique daughter cells (sex cells) with half the chromosome number, enabling sexual reproduction.

Question 5

A pea plant is Tt (heterozygous) for tall height, where T is dominant. What is its phenotype?

Accepted Answer

Tall. Phenotype is the observable trait; since T (dominant) is present, it masks the recessive t allele, so genotype Tt shows the dominant phenotype even though the plant carries one recessive allele.

Question 6

Cross two heterozygous parents (Tt x Tt) in a Punnett square. What genotype and phenotype ratios result?

Accepted Answer

Genotype ratio 1 TT : 2 Tt : 1 tt. Phenotype ratio 3:1 (3 tall to 1 short) because both TT and Tt produce the dominant tall phenotype - only tt shows the recessive trait.

Question 7

What is the difference between genotype and phenotype?

Accepted Answer

Genotype is the genetic makeup written as allele letters (e.g., Bb). Phenotype is the physical, observable trait that genotype produces (e.g., brown eyes). Two different genotypes, like BB and Bb, can produce the same phenotype.

Question 8

What causes a mutation, and is it always harmful?

Accepted Answer

A mutation is a random change in a DNA sequence. It is not always harmful - mutations can be harmful, neutral, or beneficial, and beneficial mutations are the raw material for evolution by natural selection.

Question 9

According to natural selection, why do certain traits become more common in a population over generations?

Accepted Answer

Individuals with traits better suited to their environment survive and reproduce at higher rates, passing those traits to offspring. Over many generations this shifts the population's trait frequencies - it is differential reproductive success, not an individual changing during its lifetime.

Question 10

What two kinds of evidence support that species share a common ancestor?

Accepted Answer

The fossil record, which shows transitional forms across geologic time, and molecular or anatomical evidence such as homologous structures and shared DNA sequences among related species.

Question 11

Define adaptation in the context of evolution.

Accepted Answer

An inherited trait that increases an organism's chance of survival and reproduction in its specific environment, such as a thick coat in a cold climate. Adaptations arise from natural selection acting on random mutations over generations, not from an organism intentionally changing.

Question 12

In a food web, what is the key difference between a producer and a consumer?

Accepted Answer

A producer (a plant or algae) makes its own food through photosynthesis. A consumer must eat other organisms to obtain energy. A third group, decomposers, break down dead organic matter and recycle nutrients back into the ecosystem.

Question 13

Two species interact where one benefits and the other is unaffected. What type of symbiosis is this?

Accepted Answer

Commensalism. This differs from mutualism, where both species benefit, and parasitism, where one species benefits while the other is harmed - GED questions often ask you to tell these three relationships apart from a described scenario.

Question 14

If a predator population increases sharply, what typically happens next in a predator-prey cycle?

Accepted Answer

The prey population declines from increased predation, which then causes the predator population to decline due to reduced food supply - producing a cyclical, lagged rise-and-fall pattern between the two populations over time.

Question 15

What is a biome, and how does it differ from an ecosystem?

Accepted Answer

A biome is a large geographic region defined by its climate and dominant plant and animal life, such as desert, tundra, or rainforest. An ecosystem is smaller in scale: the community of organisms interacting with each other and their physical environment within a biome.

Question 16

Which body system's main job is exchanging oxygen and carbon dioxide with the blood?

Accepted Answer

The respiratory system (lungs and airways). It works closely with the circulatory system, which pumps the newly oxygenated blood out to body tissues - GED questions often ask you to connect systems that work together.

Question 17

What is the primary function of the endocrine system, and how does it differ from the nervous system?

Accepted Answer

The endocrine system releases hormones into the bloodstream for slower, longer-lasting chemical signaling, such as growth or metabolism. The nervous system sends fast electrical signals through neurons for immediate responses - both communicate, but they differ in speed and signal type.

Question 18

What does the excretory system remove from the body, and which organ is central to this?

Accepted Answer

It removes metabolic waste products, especially nitrogenous waste (urea) and excess water and salts, filtered from the blood mainly by the kidneys and eliminated as urine.

Question 19

How does the immune system's role differ from the circulatory system's role, despite both involving blood?

Accepted Answer

The circulatory system's job is pumping and transporting blood, oxygen, and nutrients throughout the body via the heart and vessels. The immune system uses cells that travel in the blood, such as white blood cells and antibodies, specifically to identify and fight pathogens - transport versus defense.

Question 20

What subatomic particle determines which element an atom is?

Accepted Answer

The number of protons, also called the atomic number. Changing the proton count changes the element entirely; changing the neutron count creates an isotope of the same element, and changing the electron count creates an ion.

Question 21

Two atoms of the same element have different numbers of neutrons. What are they called?

Accepted Answer

Isotopes. They share the same atomic number (protons) and chemical behavior but have different mass numbers (protons plus neutrons) - some isotopes are radioactive and decay over time, which is the basis of radiometric dating.

Question 22

What is the difference between an element and a compound?

Accepted Answer

An element is a pure substance made of only one type of atom, such as oxygen (O). A compound is two or more different elements chemically bonded together in a fixed ratio, such as water (H2O), and its properties differ from its component elements.

Question 23

In a balanced chemical equation, what does the law of conservation of mass require?

Accepted Answer

The total mass of the reactants must equal the total mass of the products. Atoms are rearranged into new substances during a reaction, but no atoms are created or destroyed.

Question 24

A reaction container feels warm to the touch as it proceeds. Is this reaction exothermic or endothermic?

Accepted Answer

Exothermic - it releases heat energy to its surroundings, which is why it feels warm. An endothermic reaction absorbs heat from its surroundings instead and would feel cool.

Question 25

What does a catalyst do in a chemical reaction, and is it used up?

Accepted Answer

A catalyst speeds up the reaction rate by lowering the activation energy required, but it is not consumed or permanently changed by the reaction - it can be reused.

Question 26

Name two factors, besides a catalyst, that increase a chemical reaction's rate.

Accepted Answer

Increasing temperature (more particle collisions with more energy) and increasing the concentration or surface area of reactants (more particles available to collide and react).

Question 27

Why does a gas have no fixed shape or volume, unlike a liquid?

Accepted Answer

Gas particles move quickly and spread apart with weak attractive forces, so they expand to fill any container. Liquid particles stay close together with moderate attraction, giving a fixed volume but a shape that flows to match its container.

Question 28

What happens to a substance's particles during melting?

Accepted Answer

Particles gain thermal energy, vibrate faster, and break free of the fixed positions holding them in a rigid solid structure, letting them move past one another as a liquid. Temperature stays constant at the melting point throughout the phase change.

Question 29

On the pH scale, what range of values indicates a base rather than an acid?

Accepted Answer

A pH above 7 indicates a base; below 7 indicates an acid; exactly 7 is neutral, like pure water. Lower pH numbers mean stronger acids, and higher pH numbers mean stronger bases.

Question 30

What two products form when an acid and a base react in a neutralization reaction?

Accepted Answer

Water and a salt. The acid's H+ ions combine with the base's OH- ions to form water, while the remaining ions combine to form a salt - this is why neutralization moves the pH toward 7.

Question 31

A book sits still on a table until pushed. Which of Newton's laws explains why it stays at rest?

Accepted Answer

Newton's First Law, the law of inertia: an object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted on by an unbalanced (net) force.

Question 32

How do you calculate the net force needed to accelerate an object, per Newton's Second Law?

Accepted Answer

Force equals mass times acceleration (F = ma). A larger mass requires more force to reach the same acceleration; rearranged, acceleration equals force divided by mass.

Question 33

You push against a wall. According to Newton's Third Law, what happens?

Accepted Answer

The wall pushes back on you with an equal and opposite force. For every action force there is a reaction force equal in size and opposite in direction, acting on the other object.

Question 34

What is the difference between speed and velocity?

Accepted Answer

Speed is only the rate of motion, a single number such as 60 mph. Velocity includes both rate and direction, such as 60 mph north - a car going around a curve at constant speed still has changing velocity because its direction changes.

Question 35

A ball held at the top of a hill has what type of energy? What about as it rolls down?

Accepted Answer

At the top it has potential energy, stored energy due to its height. As it rolls down, that potential energy converts into kinetic energy, the energy of motion - total mechanical energy stays constant if no energy is lost to friction.

Question 36

What does the law of conservation of energy state?

Accepted Answer

Energy cannot be created or destroyed, only converted from one form to another, such as chemical to kinetic, or transferred between objects. The total energy in a closed system stays constant.

Question 37

What is the difference between a conductor and an insulator in an electrical circuit?

Accepted Answer

A conductor, such as copper wire, allows electric current to flow through it easily. An insulator, such as rubber or plastic, resists and blocks the flow of electric current - insulators are used to coat wires safely.

Question 38

For a circuit to allow current to flow continuously, what must it be?

Accepted Answer

A closed, complete loop - current only flows when the circuit path is unbroken from the power source through the components and back. An open circuit, such as a break or a switched-off point, stops current flow entirely.

Question 39

At a convergent plate boundary where two continental plates collide, what land feature commonly forms?

Accepted Answer

Mountain ranges - the colliding plates crumple and push the crust upward, as with the Himalayas. This differs from a divergent boundary, where plates pull apart and new crust forms, often creating rift valleys or ocean ridges.

Question 40

Which type of plate boundary is most associated with earthquakes but not new crust formation, like California's San Andreas Fault?

Accepted Answer

A transform boundary, where two plates slide horizontally past each other. Friction along the fault builds up stress that releases suddenly as an earthquake.

Question 41

List Earth's layers from the outermost to the innermost.

Accepted Answer

Crust (thin, outer rocky layer), mantle (thick, mostly solid but capable of slow flow), outer core (liquid iron-nickel), and inner core (solid iron-nickel at the center) - density and temperature increase toward the center.

Question 42

A rock forms from cooled, hardened magma or lava. What type of rock is it?

Accepted Answer

Igneous rock. Sedimentary rock instead forms from compressed and cemented sediment layers, and metamorphic rock forms when existing rock is transformed by heat and pressure without melting.

Question 43

In undisturbed rock layers, what does the principle of superposition tell you about the layers' relative ages?

Accepted Answer

The oldest layers are on the bottom and the youngest layers are on top, since each layer was deposited on top of the one before it - this lets scientists determine relative age from a rock layer's position.

Question 44

What is the key difference between weather and climate?

Accepted Answer

Weather is the short-term, day-to-day condition of the atmosphere, such as temperature or precipitation, in a specific place. Climate is the long-term average weather pattern of a region measured over decades - a single cold day does not disprove a long-term warming trend.

Question 45

What causes the greenhouse effect, and is it naturally necessary for life on Earth?

Accepted Answer

Gases like carbon dioxide and methane trap heat radiating from Earth's surface, warming the atmosphere. A natural greenhouse effect is necessary to keep Earth warm enough for life; the concern is human activity intensifying it beyond natural levels, driving climate change.

Question 46

What powers the Sun and other stars, releasing enormous energy?

Accepted Answer

Nuclear fusion - hydrogen atoms fuse together under extreme heat and pressure in the star's core to form helium, releasing massive amounts of energy as light and heat.

Question 47

What causes Earth's seasons: distance from the Sun, or something else?

Accepted Answer

Earth's axial tilt of about 23.5 degrees, not distance from the Sun. As Earth orbits the Sun, the tilt causes different hemispheres to receive more direct sunlight at different times of year, producing seasons.

Question 48

In an experiment testing plant growth under different light colors, which variable is the independent variable?

Accepted Answer

The light color - it is the variable the researcher deliberately changes. The dependent variable, plant growth or height, is what the researcher measures in response; a control group with standard light provides a baseline for comparison.

Question 49

A data set is 2, 4, 4, 6, 9. What are the mean, median, and mode?

Accepted Answer

Mean equals the sum divided by the count: 25 divided by 5 = 5. Median is the middle value in the ordered list: 4. Mode is the most frequent value: 4. The GED tests reading these values from tables and graphs, not just applying formulas.

Question 50

On a line graph in a GED science passage, what does a steep upward trend generally indicate compared to a flat line?

Accepted Answer

A steep upward trend indicates the measured (dependent) variable is rapidly increasing as the independent variable increases; a flat line indicates little to no change in the dependent variable - reading trend direction and steepness is a core science-practice skill on the GED.

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