Apostrophe, Possessive, & Plural Practice Test

PASSAGE II: The Invention of Velcro

¹ In 1941, a Swiss electrical engineer named George de Mestral went for a hunting trip in the Alps with his dog. Upon returning home, he noticed that his clothes and his (11) dog's fur, were covered in hundreds of tiny burrs from the burdock plant. Most people would have simply picked the burrs off and thrown them away. De Mestral, (12) consequently, was curious. He placed one of the burrs under a microscope to discover the secret to its incredible (13) stickiness.

² What he saw fascinated him. The outside of the burr was covered in hundreds of tiny, stiff hooks. These hooks perfectly latched onto the flexible, looped fibers of his clothing and his dog's hair. De Mestral immediately recognized the potential for a new type of fastener, (14) one, that could rival the zipper. He envisioned a two-sided material: one side featuring stiff hooks, and the other side featuring soft loops. When the two strips were pressed together, the hooks would catch the loops, creating a strong but reversible bond.

³ Turning this vision into a reality, (15) though, proved to be a daunting task. De Mestral traveled to Lyon, France, a center of textile manufacturing, to seek help. Most weavers laughed at his idea, but one artisan agreed to create a prototype. Initially, they tried using cotton, but the cotton loops wore out too quickly. De Mestral then turned to a recently invented synthetic material (16) called: nylon. Nylon was durable and, when treated with heat, could be permanently molded into rigid hooks.

⁴ It took De Mestral ten years to perfect the manufacturing process. He had to invent a special loom that could cut the nylon loops at just the right angle to create the hooks. Finally, in 1955, he patented his invention. He named it Velcro, a portmanteau of the French words velours (velvet) and crochet (hook). (17)

⁵ At first, the fashion industry rejected Velcro, considering it ugly and cheap-looking. (18) The zipper was much more popular. The invention's true breakthrough came in the 1960s when NASA began using it. Astronauts found Velcro incredibly useful for securing tools, equipment, and even food pouches in zero gravity. (19) Due to the fact tht NASA endorsed it, the apparel industry took notice. Skiers began wearing jackets with Velcro closures, and soon, it was being used on children's shoes, blood pressure cuffs, and backpacks. Today, this brilliant example of biomimicry—(20) the design of materials modeled on biological entities—is a staple of modern life.

PASSAGE V: The Yellowstone Effect

¹ For nearly seventy years, the gray wolf was completely absent from Yellowstone National Park. Hunted to local extinction in the 1920s, the predator's removal triggered a cascade of negative ecological consequences. Without wolves to keep them in check, the park's elk population exploded. (41) Elk which had overpopulated the park grazed heavily on young willow and aspen trees. As the trees disappeared, so did the songbirds and beavers that relied on them for habitat. By the late twentieth century, Yellowstone’s ecosystem was severely unbalanced. (49)

² In 1995, wildlife biologists initiated a controversial program to reintroduce the gray wolf to the park. The scientists predicted that the wolves would cull the elk herds, but what happened next surprised even the most optimistic ecologists. The wolves triggered a phenomenon known as a "trophic cascade," where an apex predator's presence creates a ripple effect throughout the entire food web. (42)

³ The wolves began hunting the elk, which significantly reduced the grazing pressure on the valleys and gorges. (43) Growing along the riverbanks, the elk avoided the open areas where they were most vulnerable. Because the elk were constantly on the move, the young willow and aspen saplings finally had a chance to mature.

⁴ As the forests (44) had recovered, the ecosystem began to transform. The renewed tree growth provided ample wood for beavers, whose population rapidly increased. The beavers built dams, creating deep, cold pools of water that provided ideal habitats for fish, otters, and muskrats. Furthermore, the carcasses of elk hunted by wolves provided a reliable food source for scavengers, including ravens, bald eagles, and grizzly bears. (45) As a result of the consequence of this, the entire biodiversity of the park stabilized.

⁵ Perhaps the most astonishing consequence of (46) the wolfs return was the alteration of Yellowstone’s physical geography. Because the stabilizing vegetation prevented soil erosion, the park’s rivers actually changed course, becoming deeper and more fixed in their channels. The intricate web of predator and prey relationships (47) are fascinating, proving that sometimes, introducing a fearsome predator is the only way to heal a broken landscape. (48)