问题 读图填空题

已知果蝇刚毛和截毛是一对伴性遗传的性状,刚毛基因(B)对截毛基因(b)为显性。为了弄清楚该基因位于图中的哪一个区,某人做了以下杂交实验:

(1)实验一:从刚毛和截毛性状在雌性和雄性中都有来看,排除该基因位于Ⅱ-1区的可能,理由是________________。

(2)实验二:若选择雌性刚毛和雄性截毛杂交,当该基因位于Ⅰ区和Ⅱ-2区两种不同情况下,产生的子代的表现型及其比例是否相同?____________,表现型及比例是_________,故无法判断。

(3)实验三:选择的杂交组合还可以是___________,通过一次杂交,如果后代___________,则该基因位于Ⅰ区;如果后代_____________,则该基因位于Ⅱ-2区。

答案

(1)若位于Ⅱ-1区则属于伴Y染色体遗传,雌性中不应存在该性状

(2)相同      若雌性刚毛个体为纯合体,则雌性刚:雄性刚=1:1;若雌性刚毛个体为XBXb,则后代表现型及其比例均为雌刚:雄刚:雌截:雄截=1:1:1:1

(3)雌性截毛、雄性刚毛     全部为刚毛    雌果蝇全部为刚毛而雄果蝇全部为截毛

阅读理解

A popular student in her small high school, Katie started college, expecting to do well in her courses and be best friends with her roommates. But things didn’t turn out that way. Psych 101, the course she thought would be a first-semester favorite, turned out to be a struggle.

Living away from home tends to be the toughest adjustment for first-year students. You may feel homesick in your first weeks or months. It can help to call, write, or email your parents and friends, making them know how you’re going. You can also talk with your roommates. As first-year students themselves, they’re probably experiencing many of the same fears and worries that you’re dealing with .

But what if you don’t get along well with your roommates?

In some cases, it can be a good thing if you and your roommates aren’t much alike. Different views on things may be helpful, so respect your differences no matter what.

If you and your roommates don’t get along well, it can help to find someone who you feel does understand you, which should be easy on a campus with so many people. Many schools have student organization nights where all of the campus clubs gather and promote their organizations, so you can meet people with the same interests there as you. You’ll also meet tons of people in class or in your dorm building.

As homesickness, painful throats, sprained (扭伤的) ankles and wisdom teeth that act up are common among college students, you should check out your student guidebook or your school’s website to find out information about the university health center.

If you think you cannot deal with your problems, make a stop at the school counseling (咨询)center. First-year troubles are something the counselors know well. You can get help there.

小题1:From Paragraph 1 we can infer that __________.

A.Katie had been worried about the changes before starting her college life.

B.Katie felt satisfied when her college life started.

C.Katie wasn’t used to the new environment in college at first.

D.Katie has fallen behind in her study after the first semester in college.小题2:What’s the author’s first suggestion on dealing with homesickness?

A.Adjust to it gradually.

B.Never share fears with your parents.

C.Talk to your roommates about it.

D.Get along with your roommates.小题3:Which of the following ways of dealing with roommates is RIGHT?

A.Not trying to change them.

B.Avoid making friends with them.

C.Developing the same interest as them.

D.Not talking with them.小题4:From the passage, we can know that_________

A.It’s easy for the first-year students to adapt to the college life.

B.First-year students can get along well with roommates quickly.

C.The university center can only help the first-year students solve problems.

D.The school counseling center is familiar with the problems the first-year students face.小题5:What’s the main idea of the text?

A.Freshmen may meet many problems.

B.Communication is important in college.

C.How you can adjust to your first year in college.

D.How schools help freshmen to get used to college life.

单项选择题