Scientific Method and Graphing Review

Ulcers: Mystery Solved

Stomach ulcers are painful sores that develop in the stomach. Doctors once thought that ulcers were caused by stress. In the 1980s, a pair of physicians, Barry J. Marshall and J. Robin Warren, questioned the cause of ulcers. They found the bacterium Helicobacter pylori in the ulcer tissue of their patients. Even though they repeatedly presented their findings to colleagues, they were ignored until Marshall performed an astonishing experiment: He drank broth containing the bacteria and made himself sick with an ulcer! He then cured himself by taking an antibiotic.

The results were published in 1985, but it took another 10 years for doctors to regularly use antibiotics to treat ulcers. Marshall and Warren received a Nobel Prize in 2005 for this discovery.

Which choice represents a possible hypothesis for Marshall's experiment?

• Does Helicobacter pylori cause stomach ulcers in people?

• If a person takes an antibody, then they will not develop an ulcer.

• Does exposure to infectious bacterial cells make people sick?

• If a patient is infected by Helicobacter pylori, then they will get an ulcer.

Ulcers: Mystery Solved

Stomach ulcers are painful sores that develop in the stomach. Doctors once thought that ulcers were caused by stress. In the 1980s, a pair of physicians, Barry J. Marshall and J. Robin Warren, questioned the cause of ulcers. They found the bacterium Helicobacter pylori in the ulcer tissue of their patients. Even though they repeatedly presented their findings to colleagues, they were ignored until Marshall performed an astonishing experiment: He drank broth containing the bacteria and made himself sick with an ulcer! He then cured himself by taking an antibiotic.

The results were published in 1985, but it took another 10 years for doctors to regularly use antibiotics to treat ulcers. Marshall and Warren received a Nobel Prize in 2005 for this discovery.

The work of Marshall and Warren shows that

• hypotheses made by physicians are always correct

• scientific explanations are revised based on new evidence

• peer review always leads to the immediate acceptance of results

• conclusions must always be consistent with those made by other scientists

Since the early 1990s, proton pump inhibitors (PPIs) have been widely used to treat acid reflux disease. Although clinical tests in the 1980s deemed PPIs to be safe for humans, in 2012 the FDA announced warnings that long-term use of PPIs could increase the risk of bone fractures, kidney disease, and some intestinal infections.

Which statement best explains why the safety of PPIs is now in question when clinical experiments in the 1980s provided evidence that they were safe?

• Researchers have been able to collect more data than were available in the 1980s.

• Fewer people had acid reflux in the 1980s compared to today.

• The medication containing PPIs has changed since the 1980s when tests were done.

• The original experiments in the 1980s used only test animals and did not use human subjects

A student designed an experiment to determine if air temperature had an effect on the rate of photosynthesis in corn plants.

The independent variable in this experiment is the

• air temperature at which the corn plants were grown

• amount of carbon dioxide used by the corn plants

• volume of oxygen produced by the corn plants

• number of corn plants used

Tags

NGSS.MS-LS1-5

NGSS.MS-LS1-6

In the early 1600s, a scientist planted a willow tree that weighed 5 pounds in 200 pounds of dry soil. He placed it outside and watered it for 5 years. At the end of that time, he observed that the tree had gained 164 pounds 3 ounces, while the soil had lost just 2 ounces.

From this, he concluded that plants gain weight from the water they take in. His conclusion was based on

• the input of scientists from many countries doing similar studies

• the application of advanced technologies to the study of a problem

• careful observation, measurements, and inferences from his data

• an extensive knowledge of the process of photosynthesis

Tags

NGSS.MS-LS2-1

A student set up an experiment to test the effect of the number of seedlings planted in one pot on the rate of growth. All conditions in the experiment were the same, except for the number of plants in each pot. The results are shown in the graph below.

The dependent variable was

• the number of plants per plot

• time in days

• average plant growth

• the amount of water per pot

Tags

NGSS.MS-LS1-5

A student set up an experiment to test the effect of the number of seedlings planted in one pot on the rate of growth. All conditions in the experiment were the same, except for the number of plants in each pot. The results are shown in the graph below.

According to the graph, which statement is true concerning the growth of the plants?

• The plants in the pot with only 5 plants grew to be an average of 40 cm tall in 30 days

• The plants in the pot with only 10 plants grew to be an average of 30 cm tall in 20 days.

• The plants in the pot with 15 plants grew an average of 20 cm taller after a period of 10 days.

• The plants in the pot with 20 plants grew an average of 20 cm taller after a period of 40 days.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

A student wanted to investigate the effect of light on the rate of ripening of tomatoes. She set up four pots of the same size with identical amounts of soil, water, and type of tomato plants. Each plant was exposed to a different intensity of light as shown in the table below.

The independent variable in this experiment is the

• type of tomato plant

• amount of soil provided

• color of tomatoes

• light intensity

Tags

NGSS.MS-LS1-5

To report the final results, which label would be most appropriate for the third column of the data table?

• Height of Tomato Plants (cm)

• Average Ripening Time (days)

• Average Weight of Tomatoes per Plant (grams)

• Acidity of Tomatoes (pH)

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

The bar graph below shows the height of a plant at the end of each week of a five-week growth period. Which statement represents a valid conclusion based on the information in the graph?

• The plant was given water during the first three weeks, only.

• The plant will grow faster during the sixth week than it did during the fifth week.

• The plant grew fastest during the first three weeks, and then it grew slower.

• The plant grew slowest during the first three weeks, and then it grew faster.

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1