Narrator: Listen to part of a lecture in a biology class. Professor: So, we've been discussing how animals adapt to their environments. Today, let's consider the remarkable case of the wood frog, which lives in cold regions like Alaska and Canada. When winter comes, these frogs literally freeze solid. Up to 65% of their body water turns to ice, and their heart stops beating. They stop breathing, and no blood flows. For all practical purposes, they are dead. But when spring arrives and the ice thaws, the frogs come back to life within a few hours. How do they survive such a process? Well, the key is glucose, a type of sugar. As the frog's skin begins to freeze, its liver converts stored glycogen into massive amounts of glucose. This glucose enters the cells and acts like antifreeze, lowering the freezing point of the cell fluids and preventing the cells from shrinking and being damaged by ice crystals. It's a remarkable survival strategy, but it only works if the freezing happens gradually. If the temperature drops too quickly, the frog can't produce enough glucose in time, and it will die.
❓ Pregunta According to the professor, what is the main role of glucose in the wood frog's survival during freezing?
A. A: It provides energy for the frog to move during winter.
B. B: It prevents ice crystals from forming inside the frog's cells.
C. C: It raises the freezing point of the frog's body fluids.
D. D: It helps the frog's heart continue beating at low temperatures.
✅ Respuesta correcta
B: It prevents ice crystals from forming inside the frog's cells.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word