问题 问答题 简答题

与其它遗传标记相比,分子标记的优点?

答案

参考答案:

(1)直接以DNA的形式表现,在生物体的各个组织、各个发育阶段均可检测到,不受季节、环境限制,不存在表达与否等问题

(2)数量极多,遍布整个基因组,可检测座位几乎无限

(3)多态性高,自然界存在许多等位变异,无须人为创造

(4)表现为中性,不影响目标性状的表达

(5)许多标记表现为共显性的特点,能区别纯合体和杂合体。

阅读理解
As we know, some children live in the countryside, and some live in the city. Their lives are a little different, but they also have many of the same dreams.
 
In the countryside
In the city
Ways of going to school
On foot or by bike
By bus or car
Teaching tools
Recorders(录音机) and radios
DVD, TVs, recorders, radios, loud-speakers, CAI
Eyesight
Less than 45% are near-sighted(近视)
About 75% are near-sighted
After-class activities
Playing with balls
English corners and other school clubs
Homework
Homework can usually be finished at school
Homework never ends
Chores(杂事) to do
Washing, cleaning, farming, looking after younger sisters or brothers, cooking
Usually no chores
Family
Big families
Small families
Dream jobs
Teachers, drivers, scientists, nurses…
Scientists, doctors, computer programmers, managers …
小题1:The survey was done among the ______ between the countryside and the city.
A.parentsB.studentsC.teachers D.drivers
小题2:The children in the city usually do ________ according to the survey.
A.cookingB.cleaningC.washingD.no housework
小题3:About ________ of children in the countryside have good eyesight, while ________ of children in the city have good eyesight.
A.55%; 25%B.45%; 25%C.45%; 75%D.55%; 75%
小题4:Which is NOT mentioned in the survey?
A.Homework.B.Subjects.C.Dream jobs.D.After-class activities.
小题5:Which of the following is RIGHT according to the survey?
A.A classroom in the countryside often has TV sets.
B.Children in the countryside often join the school clubs.
C.Children in the city often have much homework to do.
D.Children in the city often have big families.
问答题 简答题