Evaluating Scientific Explanations — Unit test Answers

Nami conducts an investigation on plants. She places a grow light on a timer to give the plants different amounts of light to see if this would affect their growth. Which term describes the amount of light in this investigation?

Which is a scientific claim?

Which model best represents a pattern?

Which describes data that is faked or misplaced?

Which kind of investigations allow for the control of variables?

Which is caused by distracted drivers and may most likely be reduced by brain-powered cars?

Which serves as evidence for a scientific claim?

Alisha organizes her data about the element lead into a table.Which did Alisha place in the wrong column?

Analyze the graph.

Which best describes the purpose of bar graphs?

Which professional most likely uses X-ray technology?

Which microscope is the most powerful and can map the atoms on the surface of an object?

Scientists in a particular field strive for the same quality of work because they know their peers will be reviewing their scientific claims. What does this review process help ensure?

Which characteristic should a good scientific question have?

Read the passage about the health risks of single-load liquid laundry packets.These packets are filled with concentrated, toxic chemicals. A 7-month-old in Florida died from swallowing the soap. Several soap and detergent companies are conducting studies to address these safety concerns; they want to reduce toxicity and to make the packets look less like candy. The U.S. Consumer Product Safety Commission (CPSC) is also performing studies to build more safety into these products.

Bena thinks that dissolving more salt in water causes the mixture’s freezing temperature to change.Which is the best type of scientific investigation for Bena to use to study this?

Read the passage about the fluoridation of drinking water.Since the early 1960s, fluoride has been added to many sources of drinking water to prevent cavities in teeth. This is called fluoridation. There are some who say that this is unnecessary and increases the risk of cancer.In 1993, the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council, part of the National Academy of Sciences, conducted an extensive study about the link between fluoridated drinking water and increased cancer risk. The study included data from more than 50 human disease studies and six animal studies. The Subcommittee concluded that none of the data showed a link between fluoridated drinking water and cancer. A 1999 report by the CDC supported these findings. The CDC report concluded that studies so far have produced "no credible evidence” of a link between fluoridated drinking water and an increased risk for cancer.

Which best blocks X-ray particles and can therefore be observed more closely through the use of this technology?

Lidia plans an experimental investigation to see how the thickness of a lens affects the point where a beam of light is focused. She plans to shine light through a lens and measure the distance to a screen that is placed where the beam focuses.What are the controls in Lidia’s investigation?

A pharmaceutical company claimed that experiments showed that its drug could effectively reduce the growth of cancer cells by 35 percent. However, when five independent laboratories conducted the same experiment, they measured a reduction rate of only 5–8 percent.How did these laboratories show that the pharmaceutical company’s claims were invalid?