Digital SAT: Fact 3

1. In the early twentieth century, biologist Nettie Stevens studied insects called mealworms to investigate how biological sex is determined. While examining their chromosomes, she found that female mealworms had two large chromosomes of the same kind, whereas males had one large chromosome and one much smaller chromosome. Stevens concluded that this chromosomal difference, rather than an environmental factor such as nutrition or temperature, was connected to whether an individual developed as male or female.

According to the text, what did Stevens’s research indicate about mealworms?

2. In the early twentieth century, archaeologist Hiram Bingham traveled through Peru while searching for Inca sites described in historical accounts. Local residents guided him to ruins high in the Andes that were later identified as Machu Picchu. Although the site was known to people living nearby, Bingham’s photographs and published descriptions brought it to the attention of scholars and readers outside the region.

According to the text, what role did Bingham play in the history of Machu Picchu?

3. In the 1800s, nurse Florence Nightingale collected data on deaths among British soldiers during the Crimean War. She found that far more soldiers were dying from preventable diseases than from battle wounds. To make this information clear to government officials and the public, Nightingale presented the data in visual diagrams that showed how poor sanitation in military hospitals contributed to many deaths. Her work helped build support for reforms in hospital cleanliness and recordkeeping.

According to the text, why did Nightingale use visual diagrams?

4. In the early twentieth century, botanist Agnes Arber studied the structure of flowering plants, paying particular attention to leaves. Rather than treating leaves as simple, flat parts of a plant, Arber argued that they could take many specialized forms, including tendrils, spines, and parts of flowers. Her work helped show that plant organs that look very different from one another may actually be variations of the same basic structure.

According to the text, what did Arber’s work suggest about certain plant structures?

5. In the late nineteenth century, inventor Josephine Cochrane developed a mechanical dishwasher after becoming frustrated that handwashing often chipped fine dishes. Her machine held plates and cups in wire compartments while jets of hot, soapy water sprayed them clean. Although Cochrane originally imagined the device would appeal to households, early versions were purchased mainly by hotels and restaurants, where large numbers of dishes had to be washed quickly.

According to the text, why were hotels and restaurants especially interested in Cochrane’s dishwasher?

6. In the early twentieth century, engineer Elmer Sperry developed gyroscopic compasses for ships. Traditional magnetic compasses could be affected by nearby metal on a vessel, which sometimes made them less reliable on large steel ships. Sperry’s gyrocompass used the rotation of the Earth to point toward true north, giving navigators a more dependable way to determine direction at sea.

According to the text, why was Sperry’s gyrocompass useful for navigation?

7. In the nineteenth century, physician Elizabeth Blackwell became the first woman in the United States to earn a medical degree. After facing difficulty finding hospital positions because many institutions would not hire female doctors, Blackwell helped establish the New York Infirmary for Women and Children. The infirmary provided medical care to patients while also creating training opportunities for women who wanted to become physicians.

According to the text, why was the New York Infirmary for Women and Children significant?

8. In the early twentieth century, physicist Ernest Rutherford and his colleagues tested a model of the atom by directing tiny positively charged particles at a thin sheet of gold foil. Most of the particles passed straight through, but a small number bounced back at sharp angles. Rutherford concluded that atoms must be mostly empty space, with most of their mass concentrated in a small, dense, positively charged center called the nucleus.

According to the text, what did Rutherford conclude from the gold foil experiment?

9. In the late nineteenth century, chemist Svante Arrhenius studied how carbon dioxide in the atmosphere might affect Earth’s temperature. He proposed that carbon dioxide helps trap heat and that changes in the amount of the gas could influence the planet’s climate. Although his calculations were limited by the tools available at the time, Arrhenius’s work was an early attempt to describe the relationship between atmospheric gases and global temperature.

According to the text, what was significant about Arrhenius’s work?

10. In the 1800s, mathematician Charles Babbage designed a proposed calculating machine called the Difference Engine. The machine was intended to produce mathematical tables automatically, reducing the kinds of errors that often occurred when such tables were calculated and copied by hand. Although Babbage never completed a full working version during his lifetime, later reconstructions showed that his design could perform the calculations he had envisioned.

According to the text, why did Babbage design the Difference Engine?