Question

    The fact that your hair turns grey because of stress is nothing more than an old wives' tale. It's true that stress isn't good for you, but it's not going to turn you into a silver fox just yet. In fact, the answer comes from the cells in your hair. These are what decide the color and, eventually, the fade to grey.

Most of us start to notice our first grey hairs by the time we hit our thirties. A general rule to go by is that by the age of 50,half of the population will have lost the color in 50 percent of their hair.

But why does it happen? Firstly, we need to understand how hair gets its color.

Your hair is made up of cells called melanocytes(黑色素细胞) which produce pigments(色素) as they grow into the hair fiber. There are two different types of melanins: eumelanins and pheomelanins. The former produces black and brown pigments, while the latter produces red and yellow pigments. The exact amount of these pigments decides whether a person has black, brown, blonde or red hair.

As we age, the ability of the melanocytes to produce more pigments weakens. That's because our hair grows in different periods.

The growing period lasts between three and five years, after which our follicles(毛囊) turn off for about three months to rest and get ready to grow more hairs. This goes round and round and, after a time, our bodies aren't as good at producing new hairs.

Scientists are continuing to try and find ways to prevent greying hair. A team of scientists in France is working to try and stop the melanocytes from being damaged at the end of each hair cycle. They are trying to use a special enzyme(酶) to protect the cells from damage. If successful, it could lead the way for new products that keep our hair full of color for years to come.

1.The phrase “an old wives' tale” in Paragraph 1 probably mean________？

A.a wrong belief B.useful talk

C.a scientific rule D.helpful experience

2.What do we know about red hair?

A.It doesn't turn grey as people get older.

B.It contains more pheomelanin’s than eumelanin’s.

C.The amount of pigments in it doesn't change over time.

D.People with red hair have weaker ability to produce pigments.

3.What do the French scientists aim to do?

A.To repair damaged hair follicles.

B.To protect hair cells against damage.

C.To shorten the hair cycle to protect the hair.

D.To study the relationship between health and hair color.

4.What can we infer from the article?

A.Grey hair has nothing to do with stress.

B.Grey hair is a symbol of declining health.

C.It takes three months for new hair to grow.

D.The growth and color change of hair depend on cells.

Answer

1.A

2.B

3.B

4.D

【解析】

这是一篇说明文。文章主要说明了人们头发颜色产生的原因，头发是由一种叫做黑素细胞的细胞组成的，当它们生长到头发纤维中就会产生色素。说明了两种黑色素细胞，以及头发生长的过程。科学家们仍在努力寻找防止头发变白的方法。

1.词义猜测题。根据后文It's true that stress isn't good for you, but it's not going to turn you into a silver fox just yet.可知压力确实对你没有好处，但它不会把你变成一个银狐。由此可知，你的头发因为压力而变白的事实不过是一种错误的观念。故划线短语意思为“一种错误的观念”故选A。

2.推理判断题。根据第四段中There are two different types of melanin’s: eumelanin’s and pheomelanin’s. The former produces black and brown pigments, while the latter produces red and yellow pigments. The exact amount of these pigments decides whether a person has black, brown, blonde or red hair.可知有两种不同类型的黑色素：真黑色素和褐黑素。前者生产黑色和棕色色素，后者生产红色和黄色色素。这些色素的确切含量决定了一个人的头发是黑的、棕色的、金色的还是红色的。由此判断出，红头发含有比真黑色素更多的褐黑素。故选B。

3.细节理解题。根据最后一段中A team of scientists in France is working to try and stop the melanocytes from being damaged at the end of each hair cycle. They are trying to use a special enzyme to protect the cells from damage.可知法国的一组科学家正在努力阻止黑色素细胞在每次发丝周期结束时受损。他们试图使用一种特殊的酶来保护细胞免受损害。由此可知，法国科学家的目标是保护头发细胞免受伤害。故选B。

4.推理判断题。根据第四段中Your hair is made up of cells called melanocytes which produce pigments as they grow into the hair fiber.可知你的头发是由一种叫做黑素细胞的细胞组成的，当它们生长到头发纤维中就会产生色素。由此可推知，头发的生长和颜色的变化取决于细胞。故选D。