The corect answer with over 30 words gets brainliest! cystic fibrosis is a recessive gene disorder. the pedigree chart for a family known to have cystic fibrosis is shown. a half shaded circle is shown connected by a straight line to an unshaded square. underneath the half shaded circle are the letters aa which represent the genotype for the first parent. underneath the second parent the letters, aa, appear representing the genotype for the other parent. below this is another row of circles and squares. this 2nd row represents the offspring. starting from the left a half shaded circle is shown connected to an unshaded square, followed by an unshaded square, and then an unshaded circle. each of the circles and squares, offspring, are connected by a horizontal straight line that connects to the parent group above. the genotype is written under each of the offspring in order from left to right; aa, aa, aa, aa. what percentage of the offspring have observable disease? 0% 25% 50% 75%

The correct answer is 25%

Explanation:

The question is asking for the percentage of OFFSPRING. Out of the four only ONE does not carry or have Cystic Fibrosis. Everyone knows that 1 out of 4 as a percentage is 25%.

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Eclipse Experiences

Determination Wins

By Sara J. Schechner

How do you make an important scientific observation in the middle of a war? This was exactly the problem an astronomy professor at Harvard College in Massachusetts faced in 1780. The professor was Samuel Williams; the war was the American Revolution. The event he wanted to observe was a total solar eclipse on October 27, 1780.

Before 1780, no one in North America had been able to observe a total solar eclipse with scientific instruments. The reasons were twofold: bad weather and inaccurate maps. It was difficult to be in the right spot at the right time, especially with clear skies. Williams, however, was determined. He would see a total solar eclipse, even if that meant entering a war zone.

To Maine We Go!

During the summer of 1780, Williams used data related to the Moon's orbit. The data were used to calculate the path the Moon's shadow would take. He noted that the best place to observe the solar eclipse would be Penobscot Bay in Maine. There was a problem though. The British Navy controlled the area. In fact, a major battle had been fought there a year earlier. This was a battle in which the Americans suffered a devastating loss.

Science Before Politics

Williams refused to give up. He won support from many scholars. More importantly, he gained support from the state of Massachusetts. The state ordered the preparation of a 250-ton ship. This would be used to transport the professor and his students to Maine. John Hancock even wrote to the British Commander in Maine. He explained the importance of science, regardless of political views. The British Commander agreed. He granted Williams safe passage behind enemy lines.

A New Discovery

In October 1780, Williams and his team set out for Maine. They traveled with several instruments, including telescopes, a good clock, and a large quadrant. These are on display today at Harvard University.

Upon reaching Maine, Williams also saw something other than an eclipse. He recorded what is known as "Baily's Beads." Baily's Beads are dots of sunlight shining between mountains along the edge of the Moon. Through determination, Williams was able to capture the eclipse successfully and make a new discovery. His expedition is credited as the first solar eclipse expedition in North America.

Adapted from “Determination Wins” by Sara J. Schechner, from Dig Magazine, January 2017. © by Carus Publishing Company, d/b/a Cricket Media. Reproduced with permission.

Onsite in the 7th Century

By William Sheehan

The sight of pinkish and pearly light protruding around the moon during a total eclipse of the sun is unforgettable. This is true even for those who know what to expect. Imagine, though, experiencing an eclipse at a time when no one knew what it was.

We Can Only Imagine

Actually, we can do more than imagine. An eyewitness account of at least one eclipse-watcher has survived. His impressions of the event were luckily written down. The eclipse-watcher was a Greek named Archilochus. He was a poet and a soldier who lived in the seventh century B.C.E. In his poems, Archilochus tells us that he was born on Paros. This is one of the most beautiful of the Cyclades islands. This is a chain of islands dotting the Aegean Sea.

Yet, These Details Are All Generalities

There is no evidence of when Archilochus was born or when he died. All that we know is what he was doing on April 6, 648 B.C.E. That was the date of a total eclipse of the sun. The track of the sun began in the Atlantic, off the western coast of Africa. It then ran just south of the boot of Italy. Soon, it crossed Greece and the Black Sea. Finally, it reached up to Siberia. Where exactly on the path Archilochus was when he witnessed the eclipse is unclear. This is because, at that time, no one in Greece knew how to predict the timing of an eclipse. Thus, the event took Archilochus completely by surprise.

Archilochus Wrote About His Experience

Nothing in the world can surprise me now. Nothing is impossible or too wonderful. . . [the sky] has turned midday into black night by shielding light from the blossoming sun, and now dark terror hangs over mankind. Anything can happen. . .

The words offer us an insight into the life and times of Archilochus. It is important to reflect on this. We now realize that the sun and moon follow the same motions today that they did then. The words also show us that time does not alter human emotion. Archilochus felt surprise and awe. He also experienced terror and exhilaration upon seeing the sun disappear unexpectedly. Just like Archilochus, those of us lucky enough to see a total solar eclipse today feel similar emotions.

Adapted from “Onsite in the 7th Century” by Anthony Aveni, from Dig Magazine, January 2017. © by Carus Publishing Company, d/b/a Cricket Media. Reproduced with permission.