高考英语二轮专题检测精品练习：阅读理解（5）

　　A

　　(2017届·合肥一模)

　　Can people change their skin color without suffering like pop king Michael Jackson？Perhaps yes.Scientists have found the gene that determines skin color.

　　The gene comes in two versions，one of which is found in 99 per cent of Europeans.The other is found in 93 to 100 per cent of Africans，researchers

　　at

　　the

　　Pennsylvania State University report in the latest issue of Science.

　　Scientists have changed the color of a dark­striped zebrafish (斑马鱼) to gold by inserting a version of the pigment (色素) gene into a young fish.As with humans，the skin color of zebrafish is determined by pigment cells，which contain melanin (黑色素)．The number，size and darkness of melanin per pigment cell determine skin color.

　　It appears that，like the golden zebrafish，light­skinned Europeans also have a mutation (变异) in the gene for melanin production.This results in less pigmented skin.

　　However，Keith Cheng，leader of the research team，points out that the mutation is different in human and zebrafish genes.

　　Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra­violet rays of the sun，which can cause skin cancer.

　　But when modern humans leave Africa to live in northern latitudes，they need more sunlight on their skin to produce vitamin D．So the related gene changes，according to Cheng.

【2016届高考英语二轮专题检测精品练习：阅读理解（5）】相关文章：

★ 2017届高考英语二轮复习课时训练：18（含解析）

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习书面表达专题训练：训练6 议论文＋记叙文（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (13)

★ 2017高考四川省广安市英语阅读理解一轮系列训练：17（含解析）

★ 高考英语二轮复习如何提高高考英语听说能力

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 7 B卷 Word版含解析

★ 贵州省贵阳市2014高考英语（新人教版）一轮阅读训练（30）附答案

★ 2014届高考英语一轮复习课时作业(三十三)选修6Module 3《Music》（外研版）

★ 山东省济宁市2016年高考英语复习：高一英语语法归纳总结

★ 安徽省淮南市2014高考英语一轮单项选择及文章训练（8）及答案