Reading Comprehension · Science
PrepTest 147 · Section 2 · Passage 1
Questions 1–7
Before you start
Open PrepTest 147, Section 2 in your official copy from LSAC and read the passage for Questions 1–7, using the structure guide below. The passage is not reprinted here.
Structure guide
- Passage A, P1: introduces a widely noticed but little-studied puzzle and insists it must have an explanation
- Passage A, P2: offers a first possible physical explanation, built step by step from established background
- Passage A, P3: offers a rival, psychological explanation
- Passage B, P1: announces that researchers think they have an answer
- Passage B, P2: gives background from earlier research and the previously held belief
- Passage B, P3: describes a recent experiment whose result overturns the old belief and suggests a cause
Step 2 · The kid passage
The Second-Crop Riddle
Piece A (Grandpa's garden club letter): Here is a garden riddle. Nearly every gardener has seen it, yet science books barely mention it. A bed that grew a crop once, then sat bare for a year, grows its next crop faster, even when you start from the same tiny seeds. Something must explain it. Maybe the soil keeps old root tunnels, so water slips down deeper and your new plants drink more from day one. Or maybe the soil has nothing to do with it, and it is all you. On round one, you watered timidly because you did not know what the bed could take. The second time, you know, so you plant thicker and water boldly, and bolder care brings faster crops.
Piece B (Priya's school paper story): Gardeners swear second crops come easier, and now scientists believe they know why. Soil feeds plants through millions of thin fungus threads. Earlier studies found that while plants grow, these threads multiply by joining up with sleeping spores tucked in the dirt. Experts assumed that when a bed went bare, the extra threads starved and vanished. In a new study, a lab grew beans in trays for two weeks, and the thread count climbed. Then the trays sat empty. The dirt dried and shrank to about half its old height, but the thread count never dropped. Because the threads survive, they may be ready to feed the next crop at once, a sort of memory hiding in the soil.
Step 4 · The courtroom tale
The People v. the Mystery of the Speedy Dog
Mr. Whitfield snapped his suspenders. "Your Honor, my client's dog, Pickles, got lost twice. The second time he trotted home in half the time. Folks call it a mystery." He offered two guesses. "Maybe his nose kept a scent trail. Or maybe it is all in his head: on trip one he was nervous, on trip two he was sure." Then the rival lawyer, Ms. Okafor, stood up. "We ran a test. We marked fence posts along a dog's route, waited through a rainy month, and the scent was still there. Experts thought rain washed it away." The judge nodded slowly. "Then 'mystery' fits a little less today than it did last week. Mr. Whitfield guessed. Ms. Okafor tested. Same question, different evidence."