USABO竞赛真题资料分享 对你来说难不难

明年4月初就来迎来2022USABO竞赛（BIO USACN）啦，复习任何考试，真题总是要刷的，本文就带来几道2013年USABO竞赛真题，别担心，都是选择题，量也不大，可以快速地来测测自己目前的水平。

2013USABO竞赛真题精选

7.Which of the following is a way in which the cell increases gene expression in thenucleus?

A.Acetylation of histone tails

B.DNA methylation

C.Locating a gene within heterochromatin

D.Dephosphorylating DNAE.Alternative splicing

8.Below are the structures of five amino acids. Select the amino acid that would contributemost significantly to stability of the tertiarystructure of a protein.

9.Which of the following statementsabout cellular ultrastructure is FALSE?

A.Nonmotile eukaryotic cilia are composed of 9 doublets of microtubules in a ring, with nomicrotubules in the center (‘9+0’).

B.Bacterial flagella are composed of 9 doublets of microtubules in a ring, with twomicrotubules in the center (‘9+2’).

C.Motile eukaryotic cilia are composed of 9 doublets of microtubules in a ring, with twomicrotubules in the center (‘9+2’).

D.Centrioles are composed of nine triplets of microtubules arranged in a ring.

E.The basal bodies of eukaryotic flagella are composed of nine triplets of microtubulesarranged in a ring.

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10.In a secret cabinet of a lab, you find two Petri dishes in storage and a mysterious labnotebook. In an effort to identify the bacteria, you run some tests (taking all necessarysafety precautions) and look through the lab notebook. You find that the two Petridishes contain the same type of nutrient medium and both bacteria seem to beEscherichia sp.,but that the bacteria in plate 1 are producing large amounts of a varietyof neurotoxins. The bacteria in plate 2 are not

Given that Strain 2 is normalE.coli(the control) and Strain 1 is a genetically engineeredstrain ofE.coli, which line is most likely to represent strain 1, and why?

A.Line B, since strain 1 should exhibit lower than normal growth efficiency.

B.Line B, since strain 1 should exhibit higher than normal growth efficiency.

C.Line A, since strain 1 should exhibit lower than normal growth efficiency.

D.Line A, since strain 1 should exhibit higher than normal growth efficiency.

E.TheE. coliline should represent both, since Strain 1 should have the same growth efficiencyas a normalE.colistrain.

USABO准备小技巧

首先对英文试卷的阅读能力不能太差，专业名词也得突击一下，然后就是不必过于忙于刷题，将基础知识点过一遍再练习也不迟。

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