Nov. 30th HW

A farmer wants to compare the effects of a new fertilizer to his current fertilizer on his crop of butter beans. One year, he fertilizes ¼ of his crop (A) with the new fertilizer, ¼ of his crop (B) with the fertilizer he used in the past, ¼ of his crop (C) with a mixture of the two fertilizers and ¼ of his crop (D) with no fertilizer. Assuming all other factors - sunlight, rainfall, soil composition, etc. - are the same as previous years, what is the control group in this experiment?

• Group C

• Group D

• Group A

• Group B

Tags

NGSS.MS-ETS1-1

To eliminate the possibility of hidden

or unknown variables, the scientist must run a _______ experiment.

• control

• preliminary

• test

• variable

Stress can be measured by the amount of a certain chemical found in saliva. Subjects must be sure to get saliva samples twice a day at least 1 hour after eating or brushing teeth. In a study of 100 subjects, researchers tried to find a correlation between stress levels and the wake up time of the individual. Which factor would NOT be an effective control that experimenters should add to the experiment?

• Subjects are given the same diet.

• Subjects are selected in similar age groups.

• Subjects are selected with the same occupation.

• Subjects are awakened at the same time every day.

Tags

NGSS.MS-ETS1-1

NGSS.MS-ETS1-2

Kenny has a sore throat and visits the

doctor. The nurse collects a throat swab, places the swab on a petri dish, and then places the petri dish into an incubator. Why would she culture them

at 37°C?

• because at this high temperature

  any harmful bacteria would be killed

• because bacteria need a variety of temperatures to survive long enough to be studied

• because growth at 37°C would be ideal for revealing bacteria that are human pathogens

• because the bacteria could safely be studied but would not reproduce at this temperature