C
Have you ever wondered how ginger cats get their bright-coloured fur? Two teams of scientists in Japan and the US now think they have the answer—and it has all to do with cats' genes(基因).
Genes are sections of DNA—a chemical that carries all the information about a living thing and its characteristics(特点). They decide things like eye and hair colour. The teams of scientists have now located the orange gene that makes ginger cats' fur look so different from any other cats.
The scientists compared the DNA of cats with ginger fur to those that were other colours. They discovered that ginger ones have a part of DNA missing from a gene called ARHGAP36. This change makes the gene more active and it instructs the cats' cells to produce a lighter colour which leads to ginger fur.
★. The orange gene is carried within the X chromosome(染色体). Like all mammals(哺乳动物), male cats have one X and one Y chromosome and females have two X chromosomes. A female cat needs both of her parents to carry the orange gene for her to also be orange, but male cats only need their mum to have the orange gene.
Scientists from Stanford University in the US and Kyushu University in Japan worked on the study. The Japanese team raised money for the study from thousands of cat lovers, including some school children who gave their pocket money.
()61. Why are male cats more likely to be ginger?
A. Because they have two X chromosomes.
B. Because they only need the orange gene from their mum.
C. Because they get the orange gene from both parents.
D. Because their Y chromosome carries the orange gene.
()62. What causes the lighter colour of ginger cats' fur?
A. The ARHGAP36 gene being less active.
B. A part of DNA being added to the ARHGAP36 gene.
C. The ARHGAP36 gene becoming more active.
D. The X chromosome carrying a new gene.
()63. Which of the following can replace "located" in Paragraph 2?
A. Missed.
B. Found.
C. Changed.
D. Created.
()64. Which of the following can be put in "★"?
A. The study also found out why ginger cats are more likely to be male.
B. Female ginger cats are much cuter than male ginger cats.
C. Scientists don't know why there are more male ginger cats.
D. The secret of orange genes only exists in mammals.
()65. What might be the best title for the passage?
A. The Habits of Ginger Cats
B. Different Colours of Cats Worldwide
C. How to Train Ginger Cats?
D. The Key to Ginger Cats' Colour

61. B 【解析】细节理解题。根据“Like all mammals...but male cats only need their mum to have the orange gene.”可知,公猫更容易成为橘色是因为它们只需要从妈妈那里获得橘色基因。故选 B。
62. C 【解析】细节理解题。根据“They discovered that...the cats’ cells to produce a lighter colour which leads to ginger fur.”可知,ARHGAP36 基因变得更活跃导致了橘猫的细胞产生更浅的颜色,从而形成橘色的皮毛。故选 C。
63. B 【解析】词义猜测题。根据“The teams of scientists have now located the orange gene that makes ginger cats’ fur look so different from any other cats.”并结合语境可知,科学家应该是“发现”了这种基因,“located”与“Found”意义相同。故选 B。
64. A 【解析】句子还原题。根据“The orange gene...gene for her to also be orange, but male cats only need their mum to have the orange gene.”可知,该段主要解释了公猫更容易是橘色的原因,因此空格处是该段的总起句,A 选项可作为该段的总起句。故选 A。
65. D 【解析】标题归纳题。文章主要围绕橘猫的毛色展开,解释了其毛色形成与基因的关系,包括相关基因的作用以及染色体对毛色的影响等。D 选项“橘猫毛色的关键”最适合作为本文标题。故选 D。