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高考四川省广安市英语阅读理解一轮系列训练：16（含解析）

★ 最新2016高考英语二轮复习的建议

★ 天津市武清区杨村第四中学2016届高考英语一轮复习语法专题二《倒装句专练》课件外研版

★ 【三维设计】2017届高考英语（江苏专用）二轮复习阅读理解解题技法示范课件：5

★ 【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）

★ 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

★ 浙江省湖州市2014高考英语阅读理解一轮（暑假）精炼（9）含答案

★ 2017届高考英语二轮复习课时训练：18（含解析）

★ 2014届高考英语一轮复习选修8参考答案（外研版）

★ 【优化方案】2017届高考英语二轮复习全国卷Ⅱ题型重组训练：第17组（含解析）