8th Grade Q3 Science Review

Helen is studying the growth of two different types of plants. She planted two of each type of plant in locations with different levels of sunlight: full sun, partial shade, and full shade. For five weeks, Helen records the number of new leaves on each plant.

Which of the following statements correctly describes the independent and dependent variables in Helen's experiment?

• The independent variable is the amount of sunlight, and the dependent variable is the number of new leaves. 

• The independent variable is the kind of plant, and the dependent variable is the amount of sunlight.

• The independent variable is the amount of sunlight, and the dependent variable is the kind of plant.

• The independent variable is the number of new leaves, and the dependent variable is the amount of sunlight.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

The following bar graph shows the population of bacteria under different temperature ranges.  What can be concluded about the bacteria from reading this graph?

• They thrive at exactly 30°C.

• They cannot tolerate temperatures above 50°C.

• They prefer temperatures between 20°C and 30°C.

• They prefer warmer temperatures to cooler temperatures.

Tags

NGSS.MS-LS1-5

Consider the following hypothesis, “Drinking too many soft drinks causes calcium deficiency in teens.” A scientist plans an experiment to test the hypothesis. What is the outcome variable (dependent variable)?

• the type of soft drink consumed

• the amount of soft drinks the teens drink

• the number of teens in the test

• the level of calcium in the teens

Ena is measuring the pH of various liquids to see if they are acids or bases. Although she is following the same procedure each time, she notices that when she tests a particular liquid she obtains a result she does not expect. She is not sure that the result is accurate.

What should Ena do to improve the reliability of the data she collects?

• change her hypothesis

• perform repeated trials on each liquid

• measure a smaller volume of each sample

• research more information about acids and bases

Tags

NGSS.MS-PS1-2

Why are replications of an experiment necessary?

• to try different procedures

• to test different equipment

• to increase the number of variables

• to ensure that the experiment is reproducible

A student is studying the reactivity of different metals in hydrochloric acid (HCl). The chart below was recorded after using each of the metals in different temperatures of the acid.

Which of these is the dependent variable in these tests?

• bubbles

• cold HCl

• copper

• warm HCl

Tags

NGSS.MS-PS1-2

Alita wants to know if the color of ice cream affects its taste. She has three batches of vanilla ice cream. Batch 1 has no food coloring, Batch 2 has red food coloring, and Batch 3 has green food coloring. She asks 10 people to taste the three batches of ice cream and choose their favorite. What is the independent variable in Alita's investigation?

• color of the ice cream

• taste of the ice cream

• number of batches of ice cream

• number of people tasting the ice cream

A biologist is investigating the effects of growth hormone on the rate of metamorphosis in butterflies.

Which of the following methods of investigation would work best for the biologist investigating any possible effects?

• models

• controlled experiments

• systematic observations

• random sampling of populations

Eduardo is a conservation biologist. He needs to develop a plan to preserve wetlands. He begins his project by studying the data in the following chart.

How is Eduardo using scientific methods in developing a plan?

• He is analyzing a hypothesis about causes and effects.

• He is proposing an experiment about causes and effects.

• He is analyzing data about causes and effects.

• He is using intuition to determine causes and effects.

Tags

NGSS.MS-ETS1-3

NGSS.MS-LS2-4

Paul’s class investigated the effects of friction on the motion of a toy car. Using ramps with different surfaces, students determined the amount of time, in seconds (s), for the toy cars to reach the bottom of each ramp. All variables were controlled except the tested variable (independent variable). One group of students concluded that toy cars on a sandpaper surface are the fastest.

What conclusion should students make from their test based on the data?

• The results support the conclusion.

• The results fail to support the conclusion.

• The conclusion is valid for the data recorded.    

• More data need to be added to the conclusion.  

Tags

NGSS.MS-PS2-2