2024届高考英语外刊阅读天天练七选五专题二十八

高考英语外刊阅读天天练：七选五专题二十八 ① How many arms do sea stars have? The answer seems obvious: five arms. ____1___But if that is your answer, bad news:You’re wrong. Simply put, the sea star, also known as starfish, appears to be mostly just a head. With most other animals, everything from a whale to a mouse, it’s easy to tell which end is its head and which is its tail. __2_____ But sea stars are trickier. These animals, called echinoderms, have a five old symmetry, meaning their bodies can be divided into five equal sections. Zoologists have long struggled to relate body plans of sea stars and other echinoderms with those of most other animals. Which part is the “head” and which is its “tail” was anyone’s guess. Making the mystery all the more confounding is that sea stars, despite their strange appearance, aren’t that distantly related to humans, sharing an ancestor 600 million years ago. ___3____ Baby sea stars bob for weeks to months in the ocean before suddenly reconfiguring their bodies into their adult fivefold shape. _____4___ One technique involved incubating a sea star in a fluorescent probe that clung to specific sections of RNA. The other involved slicing a sea star into thin pieces, sequencing the RNA in each slice and reconstructing the creature into a three dimensional map on a computer. Focusing on genes known to be associated with the head, torso and tail in other animals, the team discovered that sea stars are composed of cells that are almost entirely head. _____5___ 【The Washington Post(November 14, 2023)】 A.The next step, the team said, is to study the body plans of sea urchins, sea cucumbers and other sea star relatives. B.Sea star larvae, like people, are actually bilaterally symmetric. C.The sea star is like a disembodied head walking about the sea floor on its lips. D.Anyone who has stumbled across one splayed on the seashore knows this. E.The research team was able to probe this long-standing question about the body of a sea star because of the plum