The afternoon bell rings. Students pile out of the classroom, hurry down the hall, and step outside into bright sunshine. Some smile up at the blue sky. Others squint and reach for their sunglasses. But a few have another reaction—a…a…achoo! Does that story sound familiar? It's a real thing—some people sneeze whenever they suddenly step into bright light. Scientists call this condition the photic sneeze reflex (PSR). (Photic means "having to do with light.") An Age-Old Mystery People have been trying to sniff out the truth about "sun sneezing" for a very long time. More than 2,000 years ago, people in ancient Greece studied it. Experts have come up with other explanations since then. But even today, scientists aren't exactly sure what causes PSR. The Reason for the Sneezin' Most experts believe photic sneezes result from some mixed-up signals to the brain. Two nerves in the head are neighbors. They're called the trigeminal nerve and the optic nerve. Each has a different job. The trigeminal nerve sends messages from the nose to the brain. Here's how it works: Say there's dust irritating your nose. The trigeminal nerve signals your brain. Then, you sneeze to get rid of the troublesome stuff. Nearby is the optic nerve, which sends messages from the eyes to the brain. The optic nerve senses bright light and signals the brain. This usually makes people's pupils get smaller. But, for photic sneezers, it may have another effect. Scientists think that the two electrical signals cross. The trigeminal nerve gets its neighbor's signal—so, you sneeze! No dust needed. Who Has ACHOO? Scientists have much more to learn about PSR. But it's believed that between 10 and 35 percent of people have it. This trait is genetic, which means it's passed down from parents to children. PSR has another name, too, and it's a tongue twister. Scientists call it autosomal-dominant compelling helio-ophthalmic outburst syndrome. That's ACHOO for short! QUESTION 1 QUESTION 1 OF 4 1 / 4 Think about the article. Which is true? A.People have been studying sunny sneezes for a long time. B.The trigeminal and optic nerves share the same purpose. C.The trigeminal and optic nerves are located far apart in the body. D.Scientists agree that more than half of people have sunny sneezes.
A.People have been studying sunny sneezes for a long time.
QUESTION 2 QUESTION 2 OF 4 2 / 4 Suppose you were writing a summary of the article. Which would be most important to put in the summary? A.People in ancient Greece studied "sun sneezing" 2,000 years ago. B.Experts think that sunny sneezes affect 10 to 35 percent of people. C.Some people sneeze in bright light as a result of mixed-up signals. D.The trigeminal and optic nerves send electrical signals to the brain.
C. Some people sneeze in bright light as a result of mixed-up signals.
Which passage from the article best supports the idea that sunny sneezes run in the family? A.This trait is genetic, which means it's passed down from parents to children. B.But even today, scientists aren't exactly sure what causes PSR. C.The optic nerve senses bright light and signals the brain. D.The trigeminal nerve sends messages from the nose to the brain.
A.This trait is genetic, which means it's passed down from parents to children.
