Listen to part of a lecture in an environmental science class. Professor: Today we're discussing a fascinating example of ecological adaptation: the saguaro cactus, native to the Sonoran Desert. What's remarkable is how this plant has evolved to thrive in extreme heat and drought. First, its root system is shallow and wide-spreading, allowing it to capture even light rainfall quickly. Second, the saguaro's accordion-like pleats allow it to expand and store water when available, sometimes increasing its weight by up to a ton. But perhaps the most interesting adaptation is its relationship with nurse trees. Young saguaros often grow under the shade of mesquite or paloverde trees, which provide protection from intense sun and frost. However, as the cactus matures, it may outcompete the nurse tree for water and nutrients, eventually causing the tree's death. This mutualistic-turned-competitive relationship highlights the delicate balance in desert ecosystems. Now, let's consider the implications for conservation...
❓ 質問 According to the professor, what is one result of the saguaro's relationship with nurse trees?
A. The saguaro always benefits the nurse tree by providing shade.
B. The nurse tree may eventually be killed by the saguaro's competition.
C. The saguaro's roots grow deep to avoid competing with the nurse tree.
D. The nurse tree's death is caused by a lack of rainfall.
✅ 正解
The nurse tree may eventually be killed by the saguaro's competition.
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