2022USABO竞赛考试真题解析！

USABO昨天考完啦！同学们发挥的怎么样？

小编非常理解大家急切对答案的心情，所以给大家奉上2022 USABO真题+答案快来扫码领取吧！

今年的试题难度如何？着重考察的知识点有哪些？……

为了帮助大家更好地总结回顾或备考学习，我们采访了机构生物导师，给大家带来关于USABO试卷的整体分析！

机构导师点评

今年USABO题目的结构和风格与往年类似，依然对阅读速度和知识量的要求极高。

难度上与往年持平，大概三分之一的知识点超出《Campbell Biology》覆盖内容。前几题较难，考生需要保持心态稳定，但考卷中段（15-30题)出现较多送分题。

细胞、遗传、动植物生理依然是考试的主体，没有太多超纲知识点，但复杂程度明显较国际考提升一个数量级，这些是考生最应当花时间提升的部分。

化学结构方面依然是雷打不动的两道题（2、5题），主要考察了amino acid的性质，这对记忆力要求比较高，需要考生背下所有amino acid的性质（non-polar、positively charged和negatively charged)、缩写和全称。

Animal diversity方面考察了两道题（49、50题），要求考生掌握动物进化过程中body cavity的演变过程和代表动物，最后一道题是与phylogeny结合的填充题，需要考生对各个进化支点中的代表性动物较为熟悉。

Cell communication方面的知识考查方式较为隐蔽，难点在于理解题目意思，需要掌握tyrosine kinase receptor的性质。

植物方面有两道送分题，Pfr对于开花的影响依然是考试重点，需掌握其原理，Campbell在这方面讲的并不详细。

总体来说今年的难度与往年持平，预祝大家考出好成绩！

2022 USABO真题详解

真题抢先看，快来对答案吧！没有参考的同学们也可以用真题资料挑战一下自己！（文末可领取完整版真题+答案+视频解析）

Q1.

Linezolid was the first of the oxazolidinone antibiotics to enter clinical use and targets the 23S rRNA ribosomal subunit of Gram-positive bacteria. Staphylococcus aureus has been observed to develop resistance to linezolid by methylation of A2503 in the 23S rRNA. This is an example of antibiotic resistance via:

A. Changes in antibiotic target by mutation.

B. Multidrug efflux pumps.

C. Reduced permeability.

D. Protection by modification.

E. Inactivation by transfer of a chemical group

⏩ 答案：D

Q2.

Which of the following amino acid sequences is MOST likely to be found in a transmembrane domain of a membrane spanning protein?

A. ACLTRLELTFH.

B. APGRHEIPGR.

C. AEDHEDTPGE.

D. AFTAYCLIFFAL.

E. AMMGDEGETM.

⏩ 答案：D

Q3.

In 2006, Dr. Shinya Yamanaka demonstrated that mature cells could be made into pluripotent stem cells (iPSCs) by inserting four transcription factors: Sox2, Oct4, Klf4 and c-Myc. These transcription factors enable the production of a variety of proteins, including telomerase. He did this by constructing a retrovirus with the genes for these transcription factors, which was then introduced into human fibroblasts. Which of the following is NOT correct about iPSCs?

A. Genomic integration of these transcription factors can result in mutation of the host cell genome.

B. After the iPSC divides 1000 times, the daughter cells will still be able to divide.

C. Inserting at a locus with high histone deacetylation prevents the host cell from becoming pluripotent.

D. iPSCs are more susceptible to immune rejection than allografts transplants.

E. Expression of the four transcription factors off plasmids instead of through retroviral transduction reduces the risk of cancer.

⏩ 答案：D

Q4.

The Hedgehog (Hh) signal transduction pathway that plays an essential role during the development of vertebrate embryos and organogenesis. Hh signaling is involved in STEM cell maintenance. Abnormal regulation of this pathway is linked to tumorigenesis, more specifically the development of tumors resistant to chemotherapeutics. Current research is looking into chemicals that target this pathway to serve as a more effective cancer treatment mechanism. Given what you know about signal transduction pathways, what might be the primary targets for potential therapeutics within the Hh pathway?

A. Inhibiting proteins in this pathway from interacting with each other.

B. Irreversibly binding genes that are regulated by the Hh pathway.

C. Mimicking the signaling molecule, ensuring the pathway is always “turned on”.

D. Increasing the production of the receptor protein.

E. Targeting the ribosome to prevent protein synthesis.

⏩ 答案：A

Q5.

You are working in a drug discovery lab that is developing small-molecule inhibitors of the telomerase protein as a potential cancer therapy. Shown below is a model of the key catalytic site of the human telomerase protein. You are responsible for designing a tripeptide molecule that can bind to residues Lys 626, Val 867, and Asp 868. Which of the following tripeptides will bind the strongest to these three amino acids? Assume that the first amino acid in the tripeptide will bind to K626, the second amino acid will bind to V867, and the third will bind to D868.

A. Asp - Ser – His.

B. Glu - Pro – Asn.

C. Asp - Val – Glu.

D. Glu - Ile – Arg.

E. Arg - Ser – Phe.

⏩ 答案：D

完整版USABO真题+答案+视频解析扫描文末二维码领取！

USABO试题对于知识量和阅读速度要求很高，可以同时准备的BBO也有一定的考查深度！而生物的专业词汇非常多，也是需要攻克的一大难关！准备参加未来USABO/BBO的同学，可以早早准备起来哦！

机构也为大家准备了

USABO/BBO班课

助你提升学术能力，高效备赛！

USABO/BBO班课

*以上部分班课可接受插班生

*该学术挑战活动主办方为海外机构，不与任何中国的大学、中学或小学升学加分活动挂钩，其成绩不会作为任何中国中小学升学或评优的依据，仅定位为针对中学生物爱好者的课外兴趣活动和国际生物教学交流活动。