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AEPA Earth Science AZ045 study materials
AEPA Earth Science AZ045 study resources

AEPA Earth Science AZ045 practice questions

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Question 1Scientific Inquiry and the Nature of Science

A scientist proposes that a certain rock layer formed from volcanic ash because it contains glass shards. This proposal is best described as

  1. an unreplicated observation
  2. a testable hypothesis Correct answer.
  3. an established theory
  4. a scientific law

Explanation

A hypothesis is a tentative, testable explanation for an observation. A scientific law states a consistent relationship, and a theory is a broad explanation supported by extensive evidence. Because the ash-layer idea can be tested against rock evidence, it is a hypothesis.

Question 2Scientific Inquiry and the Nature of Science

A student notices that a cliff face contains rounded pebbles. Concluding that the pebbles were once transported by flowing water is primarily

  1. an inference Correct answer.
  2. a measurement
  3. an observation
  4. a controlled experiment

Explanation

An observation is a direct record of what can be sensed or measured. An inference is a conclusion drawn from observations using prior knowledge. Rounded pebbles are observed; the transport history is inferred.

Question 3Scientific Inquiry and the Nature of Science

In an experiment testing how temperature affects the rate of evaporation, the temperature is the

  1. the responding variable
  2. the independent variable Correct answer.
  3. a held-constant factor
  4. the control condition

Explanation

The independent variable is the factor the experimenter deliberately changes. The dependent variable is the measured response, and controlled variables are held constant. Temperature is manipulated, so it is independent.

Question 4Scientific Inquiry and the Nature of Science

Researchers test a new soil treatment on 10 plots, applying it to 5 plots and no treatment to 5 otherwise identical plots. The untreated plots serve as

  1. the independent variable
  2. a random sample
  3. a repeated trial
  4. the control group Correct answer.

Explanation

A control group receives no treatment or a standard treatment and is otherwise identical to the experimental group. It provides a baseline for judging the treatment's effect. The untreated plots serve that role.

Question 5Scientific Inquiry and the Nature of Science

Two independent research teams perform the same experiment with different samples and obtain similar results. This best illustrates

  1. calibration
  2. replication Correct answer.
  3. repetition
  4. extrapolation

Explanation

Replication is repetition of a study by independent researchers, often with new samples. Repetition is performing the same procedure multiple times within one study. Independent teams obtaining similar results illustrate replication.

Question 6Scientific Inquiry and the Nature of Science

A thermometer reads 20.0 °C three times in a row for a sample whose true temperature is 25.0 °C. These readings are

  1. neither precise nor accurate
  2. accurate and precise
  3. precise but not accurate Correct answer.
  4. accurate but not precise

Explanation

Precision describes how closely repeated measurements agree with one another. Accuracy describes how close a measurement is to the true value. Readings clustered at 20.0 °C are precise but far from 25.0 °C.

Question 7Scientific Inquiry and the Nature of Science

Which measurement is written with the greatest precision?

  1. 12.0 m
  2. 12 m
  3. 12.00 m Correct answer.
  4. 1.2 × 10^1 m

Explanation

Precision of a reported measurement is indicated by the smallest place value stated. Writing 12.00 m records hundredths of a meter, finer than tenths or whole meters. More decimal places indicate greater precision, not necessarily greater accuracy.

Question 8Scientific Inquiry and the Nature of Science

Which of these is an SI base unit?

  1. newton
  2. liter
  3. kilogram Correct answer.
  4. degree Celsius

Explanation

The SI base unit of mass is the kilogram. The newton is a derived unit of force, the liter is a non-SI unit of volume, and the degree Celsius is a derived unit of temperature.

Question 9Scientific Inquiry and the Nature of Science

A rock sample has a mass of 2.5 kg. What is its mass in grams?

  1. 2,500 g Correct answer.
  2. 25,000 g
  3. 0.025 g
  4. 250 g

Explanation

One kilogram equals 1,000 grams, so multiply 2.5 kg by 1,000. This gives 2,500 g. Moving the decimal three places right converts kilograms to grams.

Question 10Scientific Inquiry and the Nature of Science

A mineral sample has a mass of 45 g and a volume of 15 cm³. Its density is

  1. 0.33 g/cm³
  2. 675 g/cm³
  3. 30 g/cm³
  4. 3.0 g/cm³ Correct answer.

Explanation

Density equals mass divided by volume. Dividing 45 g by 15 cm³ gives 3.0 g/cm³. The units are grams per cubic centimeter.

Question 11Scientific Inquiry and the Nature of Science

A student measures a mineral's density as 2.8 g/cm³; the accepted value is 3.0 g/cm³. What is the percent error?

  1. 0.67%
  2. 20%
  3. 6.7% Correct answer.
  4. 7.1%

Explanation

Percent error equals the absolute difference between measured and accepted values, divided by the accepted value, times 100. Here |2.8 - 3.0| / 3.0 × 100 = 6.7%. The denominator must be the accepted value, not the measured value.

Question 12Scientific Inquiry and the Nature of Science

Which graph is most appropriate for showing how temperature changed continuously over 24 hours?

  1. scatter plot with no connecting line
  2. bar graph
  3. line graph Correct answer.
  4. pie chart

Explanation

A line graph is used when the independent variable is continuous, such as time. It shows trends and rates of change between points. Pie charts and bar graphs compare categories, and unconnected scatter points do not emphasize continuity.

Question 13Scientific Inquiry and the Nature of Science

On a graph of distance versus time for a moving object, the slope of the line represents

  1. force
  2. speed Correct answer.
  3. acceleration
  4. mass

Explanation

Slope equals change in the vertical variable divided by change in the horizontal variable. For distance versus time, that is change in distance over change in time, which is speed. Acceleration would require a velocity-versus-time graph.

Question 14Scientific Inquiry and the Nature of Science

A graph shows stream discharge measured at flows of 10, 20, 30, and 40 m³/s. Estimating discharge at 25 m³/s by reading between plotted points is

  1. calibration
  2. interpolation Correct answer.
  3. extrapolation
  4. systematic error

Explanation

Interpolation estimates a value between known data points. Extrapolation estimates beyond the measured range. Reading 25 m³/s between the plotted 20 and 30 m³/s values is interpolation.

Question 15Scientific Inquiry and the Nature of Science

A geologist samples rocks only along a road cut because access is easy. The main problem with this sampling method is that it

  1. produces only qualitative data
  2. may not represent the area Correct answer.
  3. uses too many samples
  4. requires expensive equipment

Explanation

A sample should represent the population or area being studied. Sampling only along an accessible road cut can overrepresent rocks exposed there and miss others. This is a sampling bias, not merely a small-sample issue.

Question 16Scientific Inquiry and the Nature of Science

Which change would most improve the reliability of a conclusion based on field measurements?

  1. using a single experienced observer
  2. increasing the number of measurements Correct answer.
  3. measuring only the most accessible site
  4. recording values to more decimal places

Explanation

Reliability improves when results are based on many independent measurements, which reduces the influence of random error. More decimal places do not correct a biased or sparse sample. A single observer or one site increases the chance of systematic bias.

Question 17Scientific Inquiry and the Nature of Science

A study finds that years with more earthquakes also tend to have more reported landslide deaths. The safest conclusion is that

  1. landslide deaths cause earthquakes
  2. the correlation proves a common cause
  3. they are correlated, not proven causal Correct answer.
  4. earthquakes cause all landslide deaths

Explanation

A correlation means two variables vary together; it does not by itself show that one causes the other. A third factor, such as population growth in hazardous regions, could influence both. Causation requires additional evidence and mechanism.

Question 18Scientific Inquiry and the Nature of Science

The main purpose of peer review before publication is to

  1. make research easier to read
  2. guarantee that the reported results are correct
  3. experts evaluate methods and evidence Correct answer.
  4. replicate the experiment elsewhere

Explanation

Peer review asks independent experts to judge whether the methods, evidence, and conclusions meet disciplinary standards. It improves quality but does not guarantee correctness or replicate the study. Replication happens after publication.

Question 19Scientific Inquiry and the Nature of Science

Which statement best distinguishes a scientific law from a scientific theory?

  1. a law is always mathematical; a theory never is
  2. a law is proven, while a theory is a guess
  3. a law describes patterns; a theory explains them Correct answer.
  4. a law explains why; a theory describes what happens

Explanation

A scientific law describes a consistent, observed relationship, often mathematically. A theory explains why that relationship occurs and is supported by extensive evidence. Neither is a guess, and theories do not become laws.

Question 20Scientific Inquiry and the Nature of Science

A computer model of groundwater flow is useful mainly because it

  1. proves that the model's predictions are exact
  2. replaces the need for field data
  3. simplifies complex systems to test scenarios Correct answer.
  4. cannot be revised once built

Explanation

Models simplify real systems so scientists can examine interactions and test scenarios that would be impractical in the field. They depend on assumptions and data and must be revised as evidence improves. A model supplements, rather than replaces, field observations.

Question 21Scientific Inquiry and the Nature of Science

The principle that the same geologic processes observed today operated in the past is called

  1. the principle of catastrophism
  2. the concept of isostasy
  3. the law of superposition
  4. uniformitarianism Correct answer.

Explanation

Uniformitarianism holds that the same physical and chemical processes observed today have operated throughout Earth history. It does not require that rates always be constant. Catastrophism emphasizes sudden events, superposition is a stratigraphic principle, and isostasy concerns crustal balance.

Question 22Scientific Inquiry and the Nature of Science

A sedimentary layer accumulates 0.5 mm per year. How long would 2 m of sediment take to accumulate, assuming a constant rate?

  1. 400 years
  2. 40,000 years
  3. 4,000 years Correct answer.
  4. 40 years

Explanation

Convert 2 m to 2,000 mm, then divide by the rate: 2,000 mm ÷ 0.5 mm/year = 4,000 years. The calculation assumes the rate stays constant, which is a simplifying assumption.

Question 23Scientific Inquiry and the Nature of Science

A geologist studying a puzzling landform develops several possible explanations and tests each against evidence. This approach mainly helps to

  1. guarantee the correct answer
  2. reduce attachment to one explanation Correct answer.
  3. speed up data collection
  4. avoid the need for any field observations

Explanation

Multiple working hypotheses encourage testing several explanations against evidence rather than committing early to one. This reduces confirmation bias and strengthens reasoning. It cannot guarantee a correct answer or replace field data.

Question 24Scientific Inquiry and the Nature of Science

A length is reported as 12.4 cm ± 0.2 cm. This means the measurement

  1. has an error of 0.2%
  2. is exactly 12.4 cm
  3. likely between 12.2 cm and 12.6 cm Correct answer.
  4. cannot be used in further calculations

Explanation

The ± value expresses the estimated uncertainty of the measurement. A reading of 12.4 cm ± 0.2 cm is consistent with a true value from 12.2 cm to 12.6 cm. It does not mean the measurement is exact or unusable.

Question 25Scientific Inquiry and the Nature of Science

Which action is the most serious violation of scientific integrity?

  1. publishing a small pilot study
  2. fabricating data to support a hypothesis Correct answer.
  3. revising a hypothesis after seeing results
  4. reporting an unexpected result

Explanation

Fabricating data violates the core requirement that scientific claims rest on honest evidence. Revising hypotheses, reporting unexpected results, and publishing pilot studies are legitimate practices when reported transparently. Fabrication misrepresents the evidence itself.

Question 26Scientific Inquiry and the Nature of Science

A student measures how the growth of bean plants changes when the amount of light each plant receives is varied. In this experiment, the amount of light is the

  1. dependent variable
  2. variable held constant
  3. measured response variable
  4. independent variable Correct answer.

Explanation

The independent variable is the factor the experimenter deliberately changes in order to observe its effect. Here the light level is manipulated, while plant growth is the response that is measured, making growth the dependent variable. All other conditions, such as soil type and water volume, must be held constant.

Question 27Scientific Inquiry and the Nature of Science

A geologist notes that a cliff contains rounded, smooth pebbles. Which statement is an inference rather than an observation?

  1. The cliff is about 8 meters tall.
  2. The pebbles in the cliff face are rounded and smooth.
  3. The pebbles are mostly gray and tan.
  4. The pebbles were carried by a fast-flowing river. Correct answer.

Explanation

An observation is a direct record of what can be seen or measured, whereas an inference is an interpretation built from observations plus prior knowledge. The rounded shape is observed, but the transport history is a conclusion drawn from that shape, so it is an inference. Inferences can be reasonable yet still require further evidence.

Question 28Scientific Inquiry and the Nature of Science

Which of these is a qualitative observation?

  1. The water sample has a temperature of 18 °C.
  2. The water sample is cloudy. Correct answer.
  3. The water sample has a volume of 200 mL.
  4. The water sample has a mass of 250 grams.

Explanation

Qualitative observations describe qualities such as appearance, odor, or texture and do not involve numerical measurements. Cloudiness describes appearance, so it is qualitative, whereas a temperature, mass, or volume reading is quantitative because each includes a number and a unit.

Question 29Scientific Inquiry and the Nature of Science

In a controlled experiment testing a new fertilizer, the group of plants that receives no fertilizer is the

  1. control group Correct answer.
  2. dependent group
  3. sample group
  4. experimental group

Explanation

A control group is handled exactly like the experimental group except that it does not receive the treatment under study. Comparing the two groups shows whether the fertilizer itself caused the observed difference. Without such a comparison, other factors could account for the results.

Question 30Scientific Inquiry and the Nature of Science

A scientist wants to estimate the average grain size in a thick sandstone layer. Which sampling plan is most likely to give a representative result?

  1. collecting samples from many randomly chosen spots in the layer Correct answer.
  2. collecting samples only from the thickest part of the layer
  3. collecting a single large sample from the most easily reached outcrop
  4. collecting samples only where the rock looks most typical

Explanation

A representative sample must reflect the full range of variation in the material, and random sampling from many locations provides that coverage. Samples chosen for convenience, thickness, or typical appearance can systematically miss parts of the layer and bias the estimate. Random selection also allows the uncertainty of the estimate to be evaluated.

Question 31Scientific Inquiry and the Nature of Science

A result is published, and three independent research teams repeat the experiment and obtain the same outcome. This mainly increases confidence that the result is

  1. reproducible Correct answer.
  2. precisely measured
  3. widely accepted
  4. free of bias

Explanation

Reproducibility means that independent investigators using the same procedures obtain the same result, which is a core test of a scientific claim. Agreement across separate teams reduces the chance that the original finding was caused by local error, equipment problems, or coincidence. Reproducibility is therefore a stronger test than a single successful study.

Question 32Scientific Inquiry and the Nature of Science

Two lakes are compared to see whether a new wastewater plant lowered nitrate levels. The plant began operating on Lake A in the same year that a severe drought lowered water levels in both lakes. In this study, the drought is best described as

  1. a confounding factor Correct answer.
  2. a replicated control group
  3. the dependent variable
  4. a random measurement error

Explanation

A confounding factor is an additional variable that changes at the same time as the tested factor and can also affect the outcome. Because the drought occurred along with the plant's opening, any nitrate change cannot be attributed to the plant alone. A stronger design would compare lakes affected and unaffected by the plant over a period when other conditions were similar.

Question 33Scientific Inquiry and the Nature of Science

During a stream-flow study, one discharge reading is about ten times larger than every other reading. The most appropriate first step is to

  1. change the unusual reading so that it matches the others
  2. discard the unusual reading because it does not fit the pattern
  3. check the field notes and instrument for a recording error Correct answer.
  4. average the unusual reading with all the others without comment

Explanation

An anomalous value should be investigated before any decision is made about keeping or excluding it. Checking notes, units, and instrument records can reveal whether the value is a recording mistake or a real event such as a flood. Only after that check can the scientist justify keeping, flagging, or excluding the value.

Question 34Scientific Inquiry and the Nature of Science

A computer model predicts that a coastline will erode 2 m per year, but ten years of surveys show about 0.5 m per year. The best response is to

  1. keep the model unchanged and collect no more data
  2. revise the model to include the slower erosion processes Correct answer.
  3. discard the shoreline surveys because computer models are more reliable
  4. report only the years that match the prediction

Explanation

Models are tools that must be revised when their predictions conflict with observations. Ten years of field surveys are direct evidence, so the model's assumptions or parameters need adjustment to account for the slower erosion. Revising and retesting the model is how scientific understanding improves.

Question 35Scientific Inquiry and the Nature of Science

A student records soil temperature every 5 minutes while a sample is heated under a lamp. The data show a steady rise for 30 minutes, then no change for 20 minutes, then another rise. The best description of the data is that the temperature

  1. rose at a completely constant rate for the entire period
  2. plateaued for a time and then resumed rising Correct answer.
  3. showed no clear pattern at any point
  4. fell steadily after the first half hour

Explanation

The record shows a rise, a period with no change, and then a further rise, which is a plateau followed by renewed warming. Reading the data in the order collected, rather than assuming a single overall trend, is what supports this description. The plateau may reflect a phase change such as evaporation of soil moisture.

Question 36Scientific Inquiry and the Nature of Science

A well-tested explanation for a broad set of observations, supported by many independent lines of evidence, is best called

  1. a scientific theory Correct answer.
  2. a single confirmed prediction
  3. a scientific law
  4. a preliminary hypothesis

Explanation

In science, a theory is a broad explanation supported by extensive and independent evidence, not a guess. A law instead describes a consistent relationship, often in mathematical form, without necessarily explaining why it occurs. The two serve different purposes and one does not become the other as evidence accumulates.

Question 37Scientific Inquiry and the Nature of Science

A geologist must classify the color of many rock samples. Which practice would best reduce observer bias?

  1. classifying only the samples that look most familiar
  2. comparing each sample with a standard color chart Correct answer.
  3. classifying each sample quickly before opinions change
  4. asking one experienced geologist to classify all samples

Explanation

Observer bias is reduced by using objective, standardized criteria that any trained person would apply in the same way. A reference color chart replaces personal judgment with a consistent scale, so different observers are more likely to agree. Agreement between independent observers is itself a form of evidence that the classification is reliable.

Question 38Scientific Inquiry and the Nature of Science

Which statement describes a claim that is not scientifically testable?

  1. Radon levels in basements can be lowered by improved ventilation.
  2. Earthquake waves travel faster through dense rock than through loose sediment.
  3. A force invisible to all instruments controls all earthquakes. Correct answer.
  4. Some earthquakes occur along faults that were previously unknown.

Explanation

A scientifically testable claim must make a prediction that could, in principle, be shown to be false by evidence. A force that no instrument can detect and that yields no distinguishing prediction cannot be tested, so the claim falls outside scientific investigation. Testability does not guarantee that a claim is true; it only makes the claim open to evaluation.

Question 39Scientific Inquiry and the Nature of Science

Two rock layers at different sites contain the same fossil species. Which conclusion is best supported?

  1. The two layers are likely similar in age. Correct answer.
  2. The layers formed from identical sediments.
  3. The fossils migrated between the sites in historical times.
  4. The two layers must be exactly the same age to the year.

Explanation

A shared fossil species indicates that the two layers fall within the same limited span of geologic time, so a similar age is a reasonable inference. The match does not require identical ages or identical sediment, because a species persists over a range of time and can be preserved in different materials. This is why fossils are useful for correlating rocks across wide areas.

Question 40Scientific Inquiry and the Nature of Science

Which sequence best describes how a new scientific explanation becomes widely accepted?

  1. It is supported by one careful experiment performed in a single laboratory.
  2. It is announced at a major conference and then quickly taught in textbooks.
  3. It survives repeated testing, peer review, and independent replication. Correct answer.
  4. It is approved by a majority vote of scientists at an annual meeting.

Explanation

Acceptance in science depends on evidence that withstands scrutiny, including peer review, repeated testing, and replication by independent researchers. A single study, a public announcement, or a vote cannot substitute for that accumulated body of evidence. Acceptance is always provisional, because later evidence can require the explanation to be revised.

Question 41Earth Materials, Structure, and Plate Tectonics

Which rock type forms from the cooling and solidification of molten material?

  1. Metamorphic rock
  2. Clastic rock
  3. Igneous rock Correct answer.
  4. Sedimentary rock

Explanation

Igneous rocks crystallize from magma or lava, and the cooling rate controls their texture. Sedimentary rocks form from deposited material, while metamorphic rocks form by altering existing rock.

Question 42Earth Materials, Structure, and Plate Tectonics

A mineral scratches fluorite but cannot scratch orthoclase. Which Mohs hardness is most consistent with this observation?

  1. 7
  2. 5 Correct answer.
  3. 9
  4. 3

Explanation

On the Mohs scale, fluorite is 4 and orthoclase is 6. A mineral that scratches fluorite must be harder than 4, and one that cannot scratch orthoclase must be softer than 6. Only a hardness of 5 satisfies both conditions.

Question 43Earth Materials, Structure, and Plate Tectonics

At a convergent boundary between two oceanic plates, which feature is most likely to form?

  1. Transform fault
  2. Mid-ocean ridge
  3. Volcanic island arc Correct answer.
  4. Rift valley

Explanation

When two oceanic plates converge, the older, denser plate subducts. Water released from the slab promotes melting in the mantle, and rising magma forms a volcanic island arc.

Question 44Earth Materials, Structure, and Plate Tectonics

Which layer of Earth is liquid and generates the magnetic field through convection?

  1. Crust
  2. Outer core Correct answer.
  3. Mesosphere
  4. Lithosphere

Explanation

Earth's outer core is liquid iron-nickel, and its convection together with rotation generates the magnetic field. The crust and lithosphere are solid, and the mesosphere is solid mantle rock.

Question 45Earth Materials, Structure, and Plate Tectonics

Magnetic striping on the seafloor is symmetrical around mid-ocean ridges because new crust records magnetic reversals as it forms and spreads. Which statement best explains this pattern?

  1. Seawater permanently magnetizes the crust
  2. New crust records reversals as it forms and spreads Correct answer.
  3. Sediment accumulates evenly on both sides
  4. Ridges move laterally away from the stripes

Explanation

At mid-ocean ridges, magma cools and records the current magnetic polarity. As new crust spreads symmetrically, reversals produce matching stripes on both sides of the ridge.

Question 46Earth Materials, Structure, and Plate Tectonics

A fault with mostly horizontal movement where blocks slide past each other is called a:

  1. Reverse fault
  2. Normal fault
  3. Strike-slip fault Correct answer.
  4. Thrust fault

Explanation

Strike-slip faults have mainly horizontal displacement parallel to the fault strike. Normal and reverse faults have dip-slip motion, and a thrust fault is a low-angle reverse fault.

Question 47Earth Materials, Structure, and Plate Tectonics

Which seismic wave travels fastest and is first detected at a seismograph?

  1. S wave
  2. Surface wave
  3. Love wave
  4. P wave Correct answer.

Explanation

P waves are compressional and travel fastest through solids and liquids, so they arrive first. S waves are slower shear waves, and surface waves are slowest.

Question 48Earth Materials, Structure, and Plate Tectonics

A volcano erupting low-viscosity basaltic lava with gentle slopes is most likely a:

  1. Lava dome
  2. Caldera
  3. Shield volcano Correct answer.
  4. Stratovolcano

Explanation

Low-viscosity basaltic lava flows long distances before solidifying, building broad, gently sloping shield volcanoes. Stratovolcanoes and lava domes form from more viscous magma.

Question 49Earth Materials, Structure, and Plate Tectonics

Frost wedging is most effective in which environment?

  1. Deep ocean floor
  2. Tropical rainforest with constant warmth
  3. Mountain regions with repeated freeze-thaw cycles Correct answer.
  4. Hot deserts with little moisture

Explanation

Water in cracks expands when it freezes, prying rock apart. Repeated freeze-thaw cycles are most common in cold mountain environments.

Question 50Earth Materials, Structure, and Plate Tectonics

Which process turns loose sediment into sedimentary rock?

  1. Volcanism
  2. Melting
  3. Lithification Correct answer.
  4. Metamorphism

Explanation

Lithification includes compaction and cementation of sediment into rock. Melting produces magma, metamorphism alters existing rock, and volcanism produces igneous materials.