Narrator: Listen to part of a lecture in a biology class. Professor: Today we're going to talk about a fascinating adaptation in some fish species: the ability to change sex. This phenomenon, called sequential hermaphroditism, occurs in many reef fish. For example, clownfish live in groups with a dominant female, a breeding male, and several non-breeding males. When the female dies, the breeding male changes into a female, and the largest non-breeding male becomes the new breeding male. In contrast, some species like the bluehead wrasse are protogynous, meaning they start as females and change to males. This often happens when a dominant male disappears, prompting the largest female to transform. This change is not just behavioral; it involves hormonal shifts and even changes in the gonads. The trigger is usually social, not age-related. So, these fish have a remarkable plasticity, allowing them to maximize reproductive success in dynamic environments.
❓ คำถาม According to the professor, what triggers the sex change in sequential hermaphrodites?
A. A) The age of the fish reaching a certain threshold.
B. B) The social environment, such as the loss of a dominant individual.
C. C) A sudden change in water temperature.
D. D) The availability of food in the surrounding area.
✅ คำตอบที่ถูกต้อง
B) The social environment, such as the loss of a dominant individual.
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
