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单选题 The main current hypothesis on the origin of life on earth holds that_____
学科：生物专业英语
时间：2023-12-13 05:38:25
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题目1单选题
Ribozymes_______A. are RNA moleculesB. all of the aboveC. act as catalystsD. can build RNA molecules
题目2单选题
The oldest fossils yet discovered are______A. 1.5 billion years oldB. 5 billion years oldC. 3.5 billion years oldD. 2.5 billion years old
题目3单选题
The main current hypothesis on the origin of life on earth holds that_____A. life arose by natural selectionB. meteorites brought prokaryotic cells to earthC. life arose by physical evolutionD. life arose spontaneously by chemical evolution
题目4单选题
Eukaryotic organisms are believed to have evolved______A. 1.5 million years agoB. 1.5 billion years agoC. 4.5 billion years agoD. 4.5 million years ago
题目5单选题
At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal groups. Which of the sentences below best expresses the essential information in the above sentenceA. The animals found in the Tommotian fossil bed were once thought to belong to a variety of modern animal groups, but now they are thought to have descended from a single groupB. It is unclear whether the Tommotian fossils from the early Cambrian period represent unique body forms or whether they should be assigned to various modern animal groupsC. Though at first they thought otherwise, paleontologists now agree that the animals in the Tommotian have body forms from which modern animals have descendedD. Animals in the Tommotian fossil beds were initially assigned to modern animal groups but are now thought to belong to groups that emerged and died out during the Cambrian period
题目6单选题
Conditions that promote fossilization of soft-bodied animals include very rapid covering by sediments that create an environment that discourages decomposition. The underlined word"promote"in the sentence is closest in meaning to______A. affectB. complicateC. encourageD. prevent
题目7单选题
Animals originated relatively late in the history of Earth—in only the last 10 percent of Earth's history. During a geologically brief 100-million-year period, all modern animal groups (along with other animals that are now extinct) evolved. The underlined word"relatively"in the sentence is closest in meaning to______A. comparativelyB. surprisinglyC. collectivelyD. characteristically
题目8单选题
The exact Chinese meaning of "taxonomy" is______A. 分类科学B. 分类群C. 分类学D. 分类单位
题目9单选题
The rapid origin and diversification of animals is often referred to as "the Cambrian explosion." The underlined word "diversification" in the sentence is closest in meaning to______A. steady decline in numberB. gradual increase in body sizeC. emergence of many varietiesD. sudden disappearance
题目10单选题
The geologic timescale is marked by significant geologic and biological events, including the origin of Earth about 4.6 billion years ago, the origin of life about 3.5 billion years ago, the origin of eukaryotic life-forms (living things that have cells with true nuclei) about 1.5 billion years ago, and the origin of animals about 0.6 billion years ago. The underlined word "significant" in the sentence is closest in meaning to______A. numerousB. unexplainedC. importantD. sudden
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