While at an amusement park, you inhale helium from a balloon to make your voice higher pitched. a friend says that helium reacts with and tightens the vocal cords to make your voice have the higher pitch. could he be correct? why or why not?

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Hedgerows have created a new ecosystem within britain’s a. farms b. cities c. forests d. industrial areas

What’s the student’s scientific question