Why do you think it can be difficult for scientists to determine whether an apparent relationship between species is an example of symbiosis? Use evidence from the article to support your answer.

The graph shows the changing levels of hormones during menstruation and ovulation. Which hormone has the most influence on a safe pregnancy?

How does scientists use ice to study ancient climates

How many valence electrons are in a single hydrogen (H) atom and in a single oxygen (O) atom

What do antioxidants do for us? How do we get antioxidants? Do some research into food products or supplements that are said to be good for us

They don't have a science option but: As light travels from air to water to glass, it will refract. The best explanation for this would be A) Glass is less transparent than water, which is less transparent than air.

What type of selection favors the average individuals in a population

Which of the following ideal criteria for elimination of a disease is addressed by the following statement: Hepatitis B may establish a chronic infection that can lead to transmission of the disease even in the absence of symptoms? A.

3. Which of the following direct quotations is punctuated properly? A. "Way to go, Sean," the coach shouted. "That was a great run"! B. "Way to go, Sean", the coach shouted. "That was a great run!" C. "Way to go, Sean," the coach shouted.

During Evolution, a process of change over time, do individuals or populations evolve?

What respiratory illness can be caused by bacteria?