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MTTC Integrated Science (Elementary) (093) study materials
MTTC Integrated Science (Elementary) (093) study resources

MTTC Integrated Science (Elementary) (093) practice questions

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Question 1Scientific Inquiry, Investigation, and Processes of Science

A student records several statements during a plant investigation. Which statement is an inference rather than an observation?

  1. The plant stem is 12 cm tall
  2. The rock has a mass of 15 g
  3. Sunlight caused the plant to grow faster Correct answer.
  4. The beaker holds 50 mL of clear liquid

Explanation

An observation is information gathered directly through the senses or with a measuring tool. An inference is a conclusion or explanation drawn from observations, such as assigning a cause. Claiming that sunlight caused faster growth goes beyond what was directly measured.

Question 2Scientific Inquiry, Investigation, and Processes of Science

Which statement is a testable hypothesis for an investigation of seed germination?

  1. Seeds should be planted in spring
  2. Seeds at 25°C germinate faster than at 10°C Correct answer.
  3. Germination is the most important stage of plant growth
  4. Seeds germinate best when handled gently

Explanation

A testable hypothesis must make a specific prediction that can be supported or contradicted by evidence. Comparing germination at two controlled temperatures provides measurable outcomes. The other statements are opinions, recommendations, or too vague to test.

Question 3Scientific Inquiry, Investigation, and Processes of Science

Which SI base unit is used to express the thermodynamic temperature of a sample?

  1. liter
  2. kelvin Correct answer.
  3. newton
  4. kilogram

Explanation

The kelvin is the SI base unit for thermodynamic temperature. The kilogram is the base unit for mass, the newton is a derived unit of force, and the liter is a unit of volume.

Question 4Scientific Inquiry, Investigation, and Processes of Science

A student tests whether a new fertilizer increases tomato yield by applying it to 20 plants and comparing them with 20 untreated plants. Which group is the control group?

  1. the 20 plants receiving no fertilizer Correct answer.
  2. the 20 plants receiving fertilizer
  3. the total group of 40 plants
  4. the tomato variety used

Explanation

The control group provides a baseline by receiving the same conditions except for the factor being tested. Here the untreated plants show what yield would be without the fertilizer, so any difference can be attributed more confidently to the fertilizer.

Question 5Scientific Inquiry, Investigation, and Processes of Science

In an experiment measuring how water temperature affects the rate at which sugar dissolves, which is the dependent variable?

  1. container size
  2. dissolving time Correct answer.
  3. water temperature
  4. sugar amount

Explanation

The dependent variable is the outcome measured in response to the changed factor. Water temperature is manipulated, so dissolving time is the response that is measured. Sugar amount and container size must be held constant as controlled variables.

Question 6Scientific Inquiry, Investigation, and Processes of Science

A balance gives readings of 10.02 g, 10.01 g, and 10.03 g for the same object, whose true mass is 10.50 g. How should these measurements be described?

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

Explanation

Precision describes how close repeated measurements are to each other, while accuracy describes closeness to the true value. These readings cluster tightly, so they are precise, but they are all far from 10.50 g, so they are not accurate.

Question 7Scientific Inquiry, Investigation, and Processes of Science

Which type of graph is most appropriate for showing how a plant's height changes each day for four weeks?

  1. scatter plot
  2. bar graph
  3. line graph Correct answer.
  4. pie chart

Explanation

A line graph is used when data show a continuous change over time, with time on the horizontal axis and height on the vertical axis. It makes trends and rates of growth easy to compare. Pie charts, bar graphs, and scatter plots serve different purposes.

Question 8Scientific Inquiry, Investigation, and Processes of Science

Why is it important to repeat an experiment several times or use a large sample?

  1. to eliminate the need for a control group
  2. to guarantee that the hypothesis is correct
  3. to make each measurement more precise
  4. to reduce the influence of random variation Correct answer.

Explanation

Repeating trials or using a larger sample reduces the chance that random variation will produce misleading results. It improves the reliability of conclusions but cannot guarantee a hypothesis or remove the need for a control.

Question 9Scientific Inquiry, Investigation, and Processes of Science

A thermometer consistently reads 2°C too high every time it is used. Which type of measurement error does this represent?

  1. systematic error Correct answer.
  2. sampling error
  3. rounding error
  4. random error

Explanation

Systematic error is a consistent offset in the same direction, often caused by a miscalibrated instrument or faulty procedure. Because the thermometer is always 2°C high, the error does not average out with repeated trials.

Question 10Scientific Inquiry, Investigation, and Processes of Science

Which statement best describes a scientific theory?

  1. A summary statement that predicts events without explaining why
  2. A guess that has not yet been tested
  3. A well-supported explanation for a broad set of observations Correct answer.
  4. A law that has been proven beyond any possibility of change

Explanation

A scientific theory is a broad, well-supported explanation that organizes many observations and can be modified when new evidence appears. It is not an untested guess, and it does not become a law or become permanently fixed.

Question 11Scientific Inquiry, Investigation, and Processes of Science

During a stream study, a student records four notes about the water. Which note is a quantitative observation?

  1. The water smells like decaying leaves.
  2. The water has a faint green color.
  3. The water temperature is 14 °C. Correct answer.
  4. The water feels colder than the air.

Explanation

A quantitative observation records a measurable amount as a number with a unit, so a temperature reading of 14 °C qualifies. The other notes describe qualities detected by the senses and would need an instrument to become numerical data.

Question 12Scientific Inquiry, Investigation, and Processes of Science

A student pushes a wooden block across a table and records the force needed to start it moving. Which SI unit should the student attach to this measurement?

  1. kilogram
  2. newton Correct answer.
  3. joule
  4. pascal

Explanation

Force is expressed in newtons, a derived SI unit defined as kg·m/s². The joule measures energy, the kilogram is the base unit of mass, and the pascal measures pressure.

Question 13Scientific Inquiry, Investigation, and Processes of Science

In a fair test of how colored light affects bean seedling growth, which practice best reflects the principle of controlling variables?

  1. Holding soil, water, and temperature constant across groups Correct answer.
  2. Measuring only the tallest seedling in each group
  3. Growing the groups in separate rooms to save space
  4. Watering the red-light seedlings more often so they catch up

Explanation

Controlling variables means keeping every factor except the independent variable identical, so that only light color differs between groups. If soil, water, or temperature also varied, a growth difference could not be attributed to light color.

Question 14Scientific Inquiry, Investigation, and Processes of Science

A student claims that playing music makes bean plants grow faster. The music group sits on a sunny windowsill; the silent group sits in a dark closet. Both groups receive the same soil and water. Which statement best describes the main flaw in this design?

  1. Adding water to both groups introduces an unnecessary second independent variable.
  2. Measuring plant height in centimeters is not a valid way to record growth.
  3. Bean plants grow too quickly for a study of this length to show any effect.
  4. Light and music both differ between the groups, so the cause is unclear. Correct answer.

Explanation

A valid experiment changes only the independent variable, but here light exposure differs along with music, making light a confounding variable. Any growth difference could be caused by either factor, so the claim about music is unsupported.

Question 15Scientific Inquiry, Investigation, and Processes of Science

A 100 mL graduated cylinder is marked in 1 mL increments. A student fills it to a level between the 42 mL and 43 mL marks and judges it to be about halfway. How should the volume be recorded to reflect the instrument's precision?

  1. 40 mL
  2. 42.50 mL
  3. 42.5 mL Correct answer.
  4. 42 mL

Explanation

When reading an analog scale, the observer estimates one digit beyond the smallest marked division, so with 1 mL markings the volume is reported to 0.1 mL as 42.5 mL. Writing 42.50 mL would imply precision to 0.01 mL, which this cylinder cannot support.

Question 16Scientific Inquiry, Investigation, and Processes of Science

Students dissolve equal masses of sugar in stirred water held at four temperatures. Sugar dissolved in 210 s at 10 °C, 150 s at 20 °C, 100 s at 30 °C, and 65 s at 40 °C. Which conclusion is best supported by these data?

  1. Dissolving time causes the water temperature to rise.
  2. Sugar dissolves faster as water temperature increases. Correct answer.
  3. Water temperature has no measurable effect on dissolving time.
  4. Sugar dissolves faster as water temperature decreases.

Explanation

Dissolving time falls steadily from 210 s at 10 °C to 65 s at 40 °C, so warmer water shortens the time required. The trend is consistent across all four trials and directly contradicts the reverse and no-effect claims.

Question 17Scientific Inquiry, Investigation, and Processes of Science

A student wants to estimate the number of pill bugs in a school garden. She counts pill bugs only under the three boards nearest the gate. Why is this count unlikely to represent the garden's pill bug population?

  1. The gate area may not be typical of the whole garden. Correct answer.
  2. Counting individuals is less reliable than estimating by eye.
  3. The student should have counted only the largest pill bugs under each board.
  4. Pill bugs move too quickly to be counted accurately in daylight.

Explanation

A representative sample must reflect the range of conditions across the entire area of interest. Boards near a gate may differ in moisture, shade, or foot traffic, so a count taken only there produces a biased estimate that cannot be generalized to the garden.

Question 18Scientific Inquiry, Investigation, and Processes of Science

A research team publishes a detailed description of its apparatus, materials, and step-by-step procedure along with its results. What is the main scientific purpose of including these details?

  1. It allows other investigators to repeat the study and check the findings. Correct answer.
  2. It proves that the hypothesis was correct before the data were collected.
  3. It guarantees that the results will be accepted without criticism.
  4. It removes the need for a control group in future studies.

Explanation

Scientific knowledge depends on replication, so a procedure detailed enough for others to repeat lets the community test whether the results are reliable. Reporting methods does not protect a claim from criticism, replace controls, or establish a hypothesis in advance.

Question 19Scientific Inquiry, Investigation, and Processes of Science

A student explains that a plant grew taller because an invisible life force pushed it upward. Which feature of this explanation makes it least useful for scientific inquiry?

  1. It explains growth without using a mathematical equation.
  2. It relies on a force that cannot be measured or tested. Correct answer.
  3. It disagrees with the measured height of the plant.
  4. It was proposed by a student rather than a professional scientist.

Explanation

Scientific explanations must be testable, meaning evidence could support or contradict them. An unmeasurable life force cannot be observed, quantified, or falsified, so no result could ever count against the claim, which places it outside empirical investigation.

Question 20Scientific Inquiry, Investigation, and Processes of Science

A district reports that schools with more library books have higher average science scores. Which additional evidence would most strengthen the claim that library books cause higher scores?

  1. A second survey showing the same correlation in another district.
  2. A controlled trial where schools given extra books gain more. Correct answer.
  3. A graph showing book counts and science scores both rose over ten years.
  4. A statement from a librarian saying that books help students learn.

Explanation

Only an intervention that manipulates book access while holding other factors constant can separate causation from mere association. Repeating the correlation, citing testimony, or showing parallel trends over time all leave open alternative explanations such as funding or parent education.

Question 21Scientific Inquiry, Investigation, and Processes of Science

A student needs to measure 25 mL of water for an investigation. Which piece of laboratory equipment is most appropriate for this task?

  1. A triple-beam balance
  2. A metric ruler
  3. A Celsius thermometer
  4. A graduated cylinder Correct answer.

Explanation

A graduated cylinder is designed to measure the volume of liquids, so it is the appropriate tool for measuring 25 mL of water. A balance measures mass, a thermometer measures temperature, and a ruler measures length.

Question 22Scientific Inquiry, Investigation, and Processes of Science

In a controlled experiment testing a new plant food, one group of plants receives the plant food and another identical group receives only water. What is the main purpose of the group that receives only water?

  1. It increases the total sample size
  2. It guarantees the results will be precise
  3. It measures the independent variable
  4. It serves as a baseline for comparison Correct answer.

Explanation

The group receiving only water is the control group. It provides a standard against which the effect of the plant food can be compared, helping the student judge whether the treatment caused any change.

Question 23Scientific Inquiry, Investigation, and Processes of Science

Which SI unit is used to express the mass of a rock sample?

  1. Liter
  2. Kilogram Correct answer.
  3. Second
  4. Newton

Explanation

The kilogram is the SI base unit for mass. The newton measures force, the liter measures volume, and the second measures time.

Question 24Scientific Inquiry, Investigation, and Processes of Science

Which type of graph is best for displaying the percentage of students in a class who prefer each of five colors?

  1. Histogram
  2. Bar graph Correct answer.
  3. Scatterplot
  4. Line graph

Explanation

A bar graph is used to compare counts or percentages in separate categories, such as preferred colors. A line graph is better for change over time, a scatterplot shows relationships between two numerical variables, and a histogram displays the distribution of numerical data.

Question 25Scientific Inquiry, Investigation, and Processes of Science

A student hypothesizes that tomato plants given more hours of sunlight will produce more tomatoes. Which prediction is most directly derived from this hypothesis?

  1. Tomato plants need sunlight to survive and produce healthy leaves
  2. Eight-hour plants will yield more tomatoes than four-hour plants Correct answer.
  3. Tomatoes taste better when grown in sunlight
  4. The number of tomatoes will increase regardless of how much sunlight the plants receive

Explanation

A prediction is a specific, testable statement about what should be observed if the hypothesis is correct. Comparing tomato production under 8 hours and 4 hours of sunlight directly tests the proposed relationship.

Question 26Scientific Inquiry, Investigation, and Processes of Science

A student tests how the amount of sunlight affects the height of bean plants. She grows three groups under different light durations while keeping water, soil type, and temperature the same. Which factor is a controlled variable in this investigation?

  1. Duration of sunlight
  2. Number of groups
  3. Height of the plants
  4. Amount of water Correct answer.

Explanation

A controlled variable is a factor kept the same across all groups so that it does not influence the outcome. Water amount is held constant while sunlight duration is deliberately varied.

Question 27Scientific Inquiry, Investigation, and Processes of Science

During a measurement activity, a student obtains the following volumes for the same sample: 20.1 mL, 20.2 mL, 20.0 mL, and 36.5 mL. What is the most appropriate next step before analyzing the data?

  1. Change the other three values so they match 36.5 mL
  2. Average all four values and report the result without comment
  3. Discard the 36.5 mL value immediately without any further checking
  4. Check the 36.5 mL value and repeat the trial Correct answer.

Explanation

The 36.5 mL value is far from the other measurements and is likely an outlier. Good practice is to check for measurement error and repeat the trial before deciding whether to exclude the value.

Question 28Scientific Inquiry, Investigation, and Processes of Science

A student wants to compare the absorbency of three brands of paper towels. Which procedure would provide the fairest comparison?

  1. Use a large piece of the thickest brand and soak it for the longest time
  2. Use different-sized pieces and estimate the water by touch
  3. Use equal pieces, soak them equally, and measure absorbed water Correct answer.
  4. Use one piece per brand and squeeze each piece by hand

Explanation

A fair comparison requires keeping the paper towel size, soaking time, and measurement method the same for every brand. Only then can differences in absorbed water be attributed to the brand.

Question 29Scientific Inquiry, Investigation, and Processes of Science

A class builds a physical model of the solar system in which the planets are spaced evenly along a hallway. Which statement best identifies a limitation of this model?

  1. It cannot show that the planets orbit around the Sun
  2. It shows the planets as having different sizes from one another
  3. It requires too many materials to be useful in a classroom
  4. It misrepresents the relative distances between planets Correct answer.

Explanation

Physical models often cannot show all features at true scale. In this solar system model, even spacing and likely inaccurate planet sizes mean relative distances and sizes are not represented faithfully.

Question 30Scientific Inquiry, Investigation, and Processes of Science

A research team reports results that conflict with a widely accepted scientific theory. What is the most appropriate response from the scientific community?

  1. Revise the theory without reviewing any of the data
  2. Ignore the results because the theory is already well established
  3. Examine the evidence and try to replicate the findings Correct answer.
  4. Accept the new results immediately because they are newer

Explanation

Scientific claims are evaluated on evidence, not on novelty or tradition. Other scientists should scrutinize the methods and try to replicate the results before accepting or rejecting a theory.

Question 31Scientific Inquiry, Investigation, and Processes of Science

A student is planning a science-fair investigation. Which question can be answered by collecting empirical evidence?

  1. Is cutting down trees for lumber wrong?
  2. Does water amount affect bean plant height? Correct answer.
  3. Which music is most enjoyable to hear?
  4. Should the school day start later?

Explanation

A testable scientific question must be answerable by observation or measurement rather than by opinion, ethics, or personal preference. The water-amount question can be investigated by measuring plant height under different watering amounts. The other choices ask for value judgments or preferences.

Question 32Scientific Inquiry, Investigation, and Processes of Science

A student places identical bean plants in four rooms that differ only in temperature and records each plant's height after two weeks. Which factor is the independent variable?

  1. The type of bean plant used
  2. The amount of light each plant receives
  3. The temperature of each room Correct answer.
  4. The height of each plant after two weeks

Explanation

The independent variable is the factor the investigator deliberately changes. In this experiment the rooms differ in temperature, so temperature is the independent variable. Plant height is the dependent variable, while plant type and light are held constant.

Question 33Scientific Inquiry, Investigation, and Processes of Science

A student needs to monitor the temperature of a water sample every five minutes during an investigation. Which instrument is most appropriate?

  1. A metric ruler
  2. A graduated cylinder
  3. A triple-beam balance
  4. A thermometer Correct answer.

Explanation

Temperature is measured with a thermometer. A graduated cylinder measures liquid volume, a balance measures mass, and a ruler measures length.

Question 34Scientific Inquiry, Investigation, and Processes of Science

At sea level, pure water boils at 100 °C. A student boils four water samples and records 98 °C, 98 °C, 98 °C, and 98 °C. Which statement best describes these measurements?

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

Explanation

Precision refers to how close repeated measurements are to one another, while accuracy refers to how close a measurement is to the accepted value. All four readings are 98 °C, so they are very consistent and therefore precise. Because the accepted boiling point is 100 °C, the readings are not accurate.

Question 35Scientific Inquiry, Investigation, and Processes of Science

A student tests how fertilizer brand affects the number of tomatoes produced by plants. She uses the same tomato variety, the same size pots, the same soil, and the same watering schedule for all plants. Which factor is a controlled variable in this investigation?

  1. The tomato variety used Correct answer.
  2. The growth rate of the plants
  3. The number of tomatoes produced
  4. The brand of fertilizer applied

Explanation

A controlled variable is held constant so it cannot explain differences among treatment groups. The tomato variety is the same for all plants, making it a controlled variable. Fertilizer brand is the independent variable, and tomato number and growth rate are dependent variables.

Question 36Scientific Inquiry, Investigation, and Processes of Science

A student observes that bread stored in a warm cabinet grows mold faster than bread stored in a refrigerator. Which statement is the best scientific hypothesis to test this observation?

  1. Mold grows faster on bread than on fruit.
  2. Warmth increases mold growth on bread. Correct answer.
  3. Mold is caused by invisible spirits in the air.
  4. Bread should always be kept in the refrigerator.

Explanation

A scientific hypothesis is a testable explanation for an observation. The statement that warmth increases mold growth can be tested by comparing mold growth at different temperatures. The other choices are a different comparison, a recommendation, or an untestable claim.

Question 37Scientific Inquiry, Investigation, and Processes of Science

A student wants to estimate the average height of grass in a large school lawn. Which sampling method is most likely to give a representative estimate?

  1. Measure the tallest grass blades near the fence.
  2. Randomly measure blades at several lawn locations. Correct answer.
  3. Measure one blade near the classroom door.
  4. Measure only the grass in a shaded area under a tree.

Explanation

A representative sample should reflect the whole lawn rather than only unusual or convenient spots. Randomly measuring blades at several locations reduces bias and better estimates the average height. The other methods sample only tall, shaded, or single-location grass.

Question 38Scientific Inquiry, Investigation, and Processes of Science

A student records the height of a bean plant every day for four weeks. Which type of graph is most appropriate for showing how the plant's height changes over time?

  1. A line graph Correct answer.
  2. A bar graph
  3. A histogram
  4. A circle graph

Explanation

A line graph is used to show continuous change over time, with time on the horizontal axis and plant height on the vertical axis. Circle graphs show parts of a whole, bar graphs compare categories, and histograms show frequency distributions.

Question 39Scientific Inquiry, Investigation, and Processes of Science

A student plans to test which paper towel brand absorbs the most water. Which operational definition of absorbency would make the test most objective?

  1. How absorbent the towel feels when touched
  2. The price of a roll of the towel
  3. How quickly the towel dries after use
  4. The mass of water absorbed by a standard-sized towel square after a set soaking time Correct answer.

Explanation

An operational definition specifies exactly what will be measured and how. Defining absorbency as the mass of water taken up by a standard-sized towel square after a set soaking time makes the comparison objective and repeatable. The other choices rely on feel, drying speed, or price, which do not directly measure water uptake.

Question 40Scientific Inquiry, Investigation, and Processes of Science

A student wants to test whether a new fertilizer increases plant growth. She plants five seeds in fertilized soil near a sunny window and five seeds in unfertilized soil in a dark closet. She waters all plants equally. What is the main flaw in this investigation?

  1. Five seeds are too many for each group.
  2. Fertilizer and light both differ between groups. Correct answer.
  3. The investigation includes a control group.
  4. The plants are watered equally.

Explanation

In a controlled experiment, only the independent variable should differ between groups. Here the fertilized plants are near a sunny window while the unfertilized plants are in a dark closet, so light and fertilizer both differ. Any growth difference cannot be attributed specifically to the fertilizer.

Question 41Scientific Inquiry, Investigation, and Processes of Science

During a pond study, a student writes four statements in a notebook. Which statement is an inference rather than a direct observation?

  1. The frog is hiding because it is afraid. Correct answer.
  2. Three tadpoles are swimming near the shallow bank.
  3. The pond water feels colder than the air.
  4. The frog is sitting under a leaf near the pond edge.

Explanation

An inference is a conclusion or interpretation drawn from observations, not something directly sensed. The students cannot directly observe fear, so the statement about why the frog is hiding is an inference. The other statements describe what can be seen or felt.

Question 42Scientific Inquiry, Investigation, and Processes of Science

In science, a theory such as the theory of evolution is best described as which of the following?

  1. A proven fact that scientists can never revise
  2. An untested first guess about how nature works
  3. A well-supported explanation based on evidence Correct answer.
  4. The personal opinion of most scientists

Explanation

A scientific theory is a broad explanation that has been repeatedly tested and is supported by multiple lines of evidence. Theories are not mere guesses, and they can be revised if new evidence requires it. They are also not established by majority opinion.

Question 43Scientific Inquiry, Investigation, and Processes of Science

A student measures a bean plant's height as 0.45 meters. What is this height in centimeters?

  1. 4.5 cm
  2. 450 cm
  3. 4500 cm
  4. 45 cm Correct answer.

Explanation

One meter equals 100 centimeters. To convert meters to centimeters, multiply the number of meters by 100, so 0.45 × 100 = 45 cm. Moving the decimal two places to the right gives the same result.

Question 44Scientific Inquiry, Investigation, and Processes of Science

A student investigates whether water temperature affects how quickly sugar dissolves. She uses 100 mL of water at four temperatures, adds 5 g of sugar each time, and stirs at the same rate. Which factor is held constant in this investigation?

  1. The amount of sugar added Correct answer.
  2. The number of temperatures tested
  3. The temperature of the water
  4. The time needed for the sugar to dissolve

Explanation

A controlled variable is a factor that is kept the same for every trial so it cannot explain differences in the outcome. The amount of sugar is held at 5 g each time, while water temperature is deliberately changed. Dissolving time is the measured outcome, not a controlled variable.

Question 45Scientific Inquiry, Investigation, and Processes of Science

A student is designing an investigation for a science fair. Which hypothesis can be tested by collecting measurable data?

  1. Bean plants in blue light will grow taller than those in red light. Correct answer.
  2. Bean plants are the most beautiful plants in the school garden.
  3. Bean plants enjoy being watered in the morning more than in the evening.
  4. Bean plants grow better when they are happy.

Explanation

A testable hypothesis must predict a measurable difference between conditions that can be observed in an investigation. Comparing plant height under blue and red light provides numerical data that can support or refute the prediction. Preferences, beauty, and happiness cannot be measured objectively in this context.

Question 46Scientific Inquiry, Investigation, and Processes of Science

Four groups of radish plants receive different amounts of a nutrient solution. After three weeks, the mean heights are: 0 mL: 6.2 cm; 5 mL: 9.4 cm; 10 mL: 9.5 cm; 15 mL: 9.3 cm. Which conclusion is best supported by these data?

  1. Radish plants grow tallest when they receive no nutrient solution at all.
  2. Nutrients help, but amounts above 5 mL add little height. Correct answer.
  3. Adding more than 5 mL of solution prevents any further radish growth.
  4. The nutrient solution has no effect on radish height.

Explanation

The data show that all nutrient treatments produced greater mean heights than the 0 mL control, so the nutrient solution helped. The 5, 10, and 15 mL results are nearly the same, indicating little added benefit above 5 mL. No treatment reduced height below the control.

Question 47Scientific Inquiry, Investigation, and Processes of Science

A student measures the boiling point of a liquid five times and calculates the average of the five readings. What is the main reason for repeating the measurement?

  1. To change the independent variable
  2. To reduce random measurement error Correct answer.
  3. To make the hypothesis easier to prove
  4. To increase the size of the sample being boiled

Explanation

Repeating a measurement and averaging the results helps reduce the influence of random errors such as slight reading differences or small fluctuations in the environment. It does not make a hypothesis automatically correct or alter the variable being tested. Replication improves the reliability of the measured value.

Question 48Scientific Inquiry, Investigation, and Processes of Science

A standard mass has an accepted value of 50.0 g. A student uses a balance three times and records 47.1 g, 47.2 g, and 47.1 g. Which description best fits these measurements?

  1. Accurate but not precise
  2. Precise but not accurate Correct answer.
  3. Both accurate and precise
  4. Neither accurate nor precise

Explanation

Precision refers to how close repeated measurements are to one another, while accuracy refers to how close they are to the accepted value. The three readings are tightly clustered near 47.1 g, so they are precise. They are about 2.9 g below the accepted 50.0 g value, so they are not accurate.

Question 49Scientific Inquiry, Investigation, and Processes of Science

A study finds that towns with more ice-cream sales also have more swimming-pool drownings. Which conclusion is most scientifically defensible?

  1. The variables are correlated, but hot weather may explain both. Correct answer.
  2. Drowning causes people to buy more ice cream.
  3. The correlation proves that ice-cream sales and drowning are unrelated.
  4. Eating ice cream directly causes drowning, so sales should be restricted.

Explanation

A correlation shows that two variables change together, but it does not by itself show that one causes the other. Hot weather could increase both ice-cream sales and swimming, producing the observed association. Scientific conclusions must consider plausible confounding variables before claiming causation.

Question 50Scientific Inquiry, Investigation, and Processes of Science

A scientist publishes a report of an investigation in a peer-reviewed journal. Why is a detailed description of the procedure included in the report?

  1. To hide the parts of the study that did not work
  2. To allow other scientists to repeat the investigation Correct answer.
  3. To make the report longer than other scientists' reports
  4. To guarantee that the hypothesis is correct

Explanation

Published methods must be detailed enough for other scientists to evaluate and repeat the investigation. Repetition by independent researchers is a central way that scientific claims are tested and strengthened. The procedure section is not intended to inflate length, guarantee correctness, or conceal problems.