Semester 1 Review - Part 1

Batches of seeds are soaked in salt of different concentrations, and germination is counted for each batch. What is the independent variable?

• the counted germination for each batch

• batch of seeds

• soaked seeds

• different concentrations of salt

Answer explanation

The independent variable is what is changed in the experiment. Here, the different concentrations of salt are manipulated to observe their effect on germination, making them the independent variable.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

In an experiment to test the effect of light on plant growth, plants are exposed to different durations of light. What is the dependent variable?

• different durations of light

• amount of water given

• type of plant

• growth of the plant

Answer explanation

The dependent variable is what is measured in an experiment. In this case, the growth of the plant is affected by the different durations of light, making it the dependent variable.

Tags

NGSS.MS-LS1-5

In a study to determine the effect of temperature on enzyme activity, what is the independent variable?

• enzyme activity

• temperature

• reaction time

• type of enzyme

Answer explanation

In this study, the independent variable is the factor that is manipulated to observe its effect on enzyme activity. Here, temperature is varied to see how it influences enzyme activity, making it the independent variable.

Tags

NGSS.HS-PS1-5

Students are tasked with observing the changes in the night sky over a three-month period. Which approach would be MOST effective for their study?

• Assign each student a different constellation to observe throughout the period.

• Use a camera to take a picture of the entire sky every night.

• Focus on a specific constellation and track its movement each night.

• Observe the sky only on clear nights to ensure visibility.

Answer explanation

Focusing on a specific constellation allows students to track its movement systematically, providing clear data on changes over time. This targeted approach is more effective than observing multiple constellations or only on clear nights.

Tags

NGSS.MS-ESS1-1

Which method would be MOST effective for tracking the phases of the moon over a month?

• Observe the moon every night and record its shape.

• Take a picture of the moon once a week.

• Use a telescope to observe the moon on clear nights only.

• Assign different students to observe the moon on different nights.

Answer explanation

Observing the moon every night allows for consistent tracking of its phases, capturing the gradual changes in shape. This method provides the most comprehensive data compared to less frequent observations.

Tags

NGSS.MS-ESS1-1

A student predicts that similar ice cubes will melt faster in a microwave than in a pot on the stove. How should this hypothesis be tested?

• Measure and compare the volume of the pot and the microwave.

• Determine the volume of liquid water made by each ice cube.

• Observe and record the time for each ice cube to completely change to liquid.

• Identify and record the temperature of each ice cube before each trial.

Answer explanation

To test the hypothesis, the student should observe and record the time it takes for each ice cube to completely melt. This directly measures the melting rate in both the microwave and the pot, providing clear comparative data.

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-4

A student observes that dogs tend to scratch more frequently during the summer months. What would be the most logical question for the student to explore based on this observation?

• How does humidity affect the scratching behavior of dogs?

• How does the length of daylight affect the scratching behavior of dogs?

• How does temperature influence the scratching behavior of dogs?

• How does the presence of other animals affect the scratching behavior of dogs?

Answer explanation

The observation of increased scratching in summer suggests a link to environmental factors. Temperature is a primary factor that can affect dogs' comfort and skin conditions, making it the most logical question to explore.

A researcher accidentally spilled some hydrochloric acid and transferred the remaining acid to a new, clean bottle. What precaution should she take next?

• Dispose of the old acid bottle immediately.

• Clearly label the new bottle with its contents.

• Store the new bottle in a dark place.

• Mix the acid with water to dilute it.

Answer explanation

Clearly labeling the new bottle with its contents is crucial for safety and to prevent accidental misuse. This ensures that anyone handling the bottle is aware of the hazardous material it contains.

Tags

NGSS.HS-ETS1-3

Match the following

• metric ruler

• observe cells

• triple beam balance

• measure temperature changes

• microscope

• measure volume

• graduated cylinder

• measure length

• thermometer

• measure mass

Tags

NGSS.MS-LS1-1

NGSS.MS-PS1-4

NGSS.MS-PS1-5

NGSS.MS-PS3-4

In a scientific experiment, which of the following practices would best ensure the accuracy of the results?

• document all observations immediately

• selectively use data that fits the hypothesis

• discard any data that does not match expectations

• conduct the experiment only once

Answer explanation

Documenting all observations immediately ensures that data is accurately recorded and reduces the risk of forgetting details, which is crucial for reliable results. The other options compromise data integrity.

Tags

NGSS.MS-LS2-4

NGSS.MS-PS1-2