《2026年水木金卷高考模拟试卷精编英语》

C
Giving blood regularly may not just be saving the lives of other people, it could also be improving your own blood's health at a genetic level, according to a new study. A team of researchers compared samples from 217 men who had given blood more than 100 times in their lives, to samples from 212 men who had donated less than 10 times, to look for any variance in blood health.
While the differences were subtle, the frequent donors' blood was more likely to have beneficial mutations(突变) in a gene called DNMT3A. Other mutations in DNMT3A have been previously linked to blood cancer. "Our work is a fascinating example of how our genes interact with the environment as we age," says stem cell biologist Dominique Bonnet, from The Francis Crick Institute in the UK. Specifically, the team looked at blood stem cells, which produce more blood cells on demand. As we get older, these mechanisms can start to break down, leading to problems with blood cancers such as leukemia(白血病).
Blood loss triggers the production of the hormone erythropoietin(促红细胞生成素激素). In lab tests on blood stem cells treated with erythropoietin, the researchers found those with the DNMT3A mutation produced blood faster than those without the mutation. This suggests frequent blood loss leads to more production of the mutated blood cells. Research in mice shows the DNMT3A mutation results in healthier blood levels after the stress of blood loss. "Activities that put low levels of stress on blood cell production allow our blood stem cells to renew and we think this favors mutations that further promote stem cell growth rather than disease," says Bonnet.
However, there are limitations to consider. Blood donors are more likely to be healthier anyway (it's a condition of giving blood), so figuring out any additional health benefit is tricky, because it might actually come from being in better shape to begin with. "Our sample size is quite modest, so we can't say that blood donation definitely decreases the occurrence of pre-leukemic mutations," says Bonnet. In the US, there's such an urgent need for blood donors that someone needs blood or platelets (small fragments in blood) every two seconds. Having healthier blood is an added bonus.
While waiting for more detailed studies to confirm these findings, the study tells us more about how blood cancers can get started in the first place. "We're now aiming to work out whether these different types of mutations play a role in developing leukemia or not, and whether they can be targeted therapeutically," says stem cell biologist Hector Huerga Encabo, from The Francis Crick Institute.
46. What was the primary focus of the study mentioned in the passage?
A. The genetic differences between frequent and occasional blood donors.
B. The role of erythropoietin in blood cell production.
C. The relationship between blood donation and leukemia.
D. The therapeutic applications of DNMT3A mutations.
47. According to the research, blood loss affects blood stem cells in that _.
A. it triggers the production of cancerous cells in the DNMT3A gene
B. it accelerates the growth of cells with beneficial DNMT3A mutations
C. it benefits the overall health condition of the donors
D. it weakens the regenerative capacity of blood stem cells
48. What can be inferred about the DNMT3A gene from the passage?
A. Its activity is primarily regulated by environmental factors.
B. Most mutations in DNMT3A are harmless and non-functional.
C. The gene is only responsible for blood cancer development.
D. Its beneficial mutations may enhance blood cells' production efficiency.
49. What limitation does the study acknowledge?
A. Donors' genetic backgrounds were not fully accounted for.
B. Donors' pre-existing health conditions might influence results.
C. Erythropoietin levels were not measured in the experiment.
D. Mouse models cannot accurately reflect human genetic mechanisms.
50. Based on the passage, the research team's next goal is _.
A. to develop a new drug targeting DNMT3A mutations
B. to conduct large-scale human trials of erythropoietin therapy
C. to determine which DNMT3A mutations directly cause leukemia
D. to analyze environmental factors influencing blood donation behavior

答案： C 46.A 细节理解题。题干意为:本文中提到的这项研究的主要关注点是什么?根据第一段中“A team of researchers compared samples from 217 men who had given blood more than 100 times in their lives, to samples from 212 men who had donated less than 10 times, to look for any variance in blood health.”可知,该研究的主要关注点是比较频繁献血者和偶尔献血者的样本,以寻找他们血液健康方面的差异,即基因差异。故选A。
47.B 细节理解题。题干意为:根据这项研究,失血影响造血干细胞是因为 。根据第三段中“Blood loss triggers the production of... blood loss leads to more production of the mutated blood cells.”可知,失血会加速带有有益DNMT3A突变的细胞的生长。故选B。
48.D 推理判断题。题干意为:关于DNMT3A基因,从这篇文章中可以推断出什么?根据第三段中“In lab tests on blood stem cells treated with erythropoietin, the researchers found those with the DNMT3A mutation produced blood faster than those without the mutation.”可知,带有DNMT3A突变的细胞比没有突变的细胞产生血液的速度更快。由此可推知,DNMT3A基因的有益突变可能会提高血细胞的生产效率。故选D。
49.B 细节理解题。题干意为:这项研究承认了什么什么局限性?根据第四段中“Blood donors are more likely to be healthier anyway (it’s a condition of giving blood), so figuring out any additional health benefit is tricky, because it might actually come from being in better shape to begin with.”可知,研究承认献血者先前的健康状况可能会影响研究结果。故选B。
50.C 细节理解题。题干意为:基于这篇文章,研究团队的下一个目标是 。根据最后一段中“We’re now aiming to work out whether these different types of mutations play a role in developing leukemia or not”可知,研究团队的下一个目标是确定哪些DNMT3A突变直接导致白血病。故选C。