7th grade review

Krista is conducting an investigation to determine how much water is best for her sunflower plants. She uses five plants and gives each a different amount of water for six weeks. Each week, she measures the height of each plant. She records her findings in the chart below.

What information should be recorded below the weeks?

• the height of each plant every week

• the amount of sun each plant received

• the amount of water each plant received

• the time it took each plant to reach a certain height

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.

Matthew records the temperature outside for one day. From 10:00 a.m. to 12:00 p.m., the temperature rises 4°C. From 12:00 p.m. to 2:00 p.m., it rises another 3°C. From 2:00 p.m. to 4:00 p.m., it drops 2°C. Which of the following predictions about how the temperature will change between 4:00 p.m. and 6:00 p.m. is most reasonable?

• The temperature will rise 3°C.

• The temperature will drop 4°C.

• The temperature will drop 14°C.

Raul wants to know which species of grass will grow best in his yard. He plants four different types and waters them according to the directions on the package. All four receive the same amount of sunlight and are planted in the same type of soil. After a few days, he begins to see a difference in how fast the different types of grass are growing. What is the outcome variable (dependent variable) in Raul's investigation?

• the type of grass seed planted

• the cost of each type of grass seed

• the speed at which each type grew

• the light and water each type received

Lauren's parents have been recording Lauren's height since she was very young. Lauren wants to create a visual representation showing how her height has changed over time. Which type of graphic best shows how Lauren's height has changed over time?

• bar graph

• line graph

• pictograph

• circle graph

To compare how different types of soil absorbed water, Christian set up an experiment. He poked equal numbers and sizes of holes into the bottoms of three plastic cups. He filled one cup with sand, one with potting soil, and left one empty. He placed each cup in a stand over a beaker. Christian poured 400 mL (milliliters) of water into each of the cups. He then measured the amount of water collected in the beakers beneath each cup at 1 minute intervals for 3 minutes.

What is the control in this experiment?

• cup with the soil

• cup with the sand

• empty cup

• amount of water collected in the beaker

Maya and Leah decided to do their STEM Fair project on the effects of different soil nutrients on strawberries. They have several ideas about the design of their experiment. They will be using four potted plants. Which design would best answer the question the girls want to investigate?

• Add different amounts of the same nutrient to each and measure the size of the strawberries

• Add different amounts of the same nutrient to each and taste the strawberries.

• Add different amounts of different nutrients to each and taste the strawberries.

• Add the same amounts of different nutrients to each and measure the size of the strawberries.

The scientific method is a process that scientists use to investigate something in the natural world. Which of these best describes the difference between a scientist collecting data and analyzing data?

• When a scientist collects data the hypothesis is compared to the data. When a scientist analyzes data, data are analyzed, scientists predict future experiments.

• When a scientist collects data, he or she record the data from an experiment. When a scientist analyzes the data, he or she decides whether or not the data support the hypothesis.

• When a scientist collects data, the data include the observations made during the experiment. When a scientist analyzes the data, the scientist communicates his observations to other scientists.

• When a scientist collects data, the scientist develops new ideas for experiments. When a scientist analyzes the data, he or she looks at what could be improved in the investigation.

Experiments are often repeated many times by the same or different scientists. What is the most important reason more than one scientist should conduct an investigation using the same methods?

• If the results are the same, replication of the investigation helps to confirm the results.

• The competition makes the scientists work more carefully.

• More than one scientist is interested in the problem.

• Different scientists might perform the experiment differently.

A scientist is unsure about the accuracy of her experiment. She has checked her equipment and found it to be in good working order, checked her data and found it to be accurate, and reviewed her interpretation of the data, which she found to be logical. What should she do in addition to check the accuracy of her results?

• check the hypothesis

• interpret the data

• make a different conclusion

• repeat the experiment