题目内容
（请给出正确答案）
A.interphase
B.prophase
C.metaphase
D.anaphase
E.telophase
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更多“Crossing over occurs during:”相关的问题
A、autotrophs
B、heterotrophs
C、prototrophs
D、omnitrophs
E、auxotrophs
coming out of cell phones，it isn't really safe to sleep，drink or talk.
Last week the entire Metro system in Washmgton had to close down because some- one might be blown onto the tracks during a hurricane.This week children in Washing- ton were not allowed to go to school for a whole day because streets were blocked by fallen trees and power 1ines，and traffic lights at some intersections weren't working.A previous generation might have walked around the fallen trees and looked both ways be- fore crossing the street，but the children of this generation clearly live in a much more dangerous world，and we need to protect them.
After Sept.11，2001，thousands of people swore off airplanes and began driving cars.In fact，the odds of being killed in a terrorist incident in 2002 were one in 9 mil- lion.In that same year，the odds of dying in a traffic accident were about one in 7,000.
By taking the precaution of not flying，many people died.
There are some clear psychological explanations for some of this.It's a fact that people fear man-made disasters(terrorism)far more than they fear natural disasters (hurricanes)，and they are more afraid of things they do not control，which is why driv- ing a car does feel safer than flying in an airplane.Also，although I have no proof，I'll hazard a guess that people are disproportionately frightened by things they read about in the newspaper.By contrast，they are disproportionately willing to discount the evidence
of their own experience.If you look around your neighborhood，you’1l notice that the
water is clean—which it wouldn't necessarily have been 100 years ago—and that the food isn’t rotten or stale.
Life is far safer for the average American than it ever has tor j ust about anyboay at any other time in human history—and maybe that explains the ludicrous precautions that city officials and federal bureaucrats and everyone else feels obligated to take nowadavs to satisfy the public's demands.Now that we'Ve eliminated most of the things that
the human race once feared，we've just invented new ones to replace them.
31.Children are not allowed to go to school for the following reasons EXCEPT .
A.fallen trees
B.fallen power lines
C.a coming hurricane
D.broken traffic lights
32.It can be learned from the passage that the previous generation .
A.knew better how to avoid danger
B.was less fussy about dangers
C.1ived in a more dangerous world
D.was better at protecting themselves
33.Which is the accepted psychological explanation for people's fear as mentioned in the passage?
A.People are more afraid of things they do not know than things they are familiar with.
B.People are more afraid of dangers reported in newspapers than those they experience.
C.People are more afraid of flying in an airplane than riding a train.
D.People are more afraid of terrorist disasters than natural disasters.
34.It is indicated in the passage that in the past
A.life was more enjoyable
B.water was less clean and fresh
C.foods were of better taste and quality
D.streets were safer for children to cross
35.The author believes that .
A.people are overreacting to dangers nowadays
B.people have good reason to fear the dangers today
C.life is full of dangers，especially after the 9.11 attacks
D.children should be better protected against dangers
A、8, 12000
B、9, 16000
C、9, 12000
D、8, 16000
A、fluorescent in situ hybridization
B、first induced strand hybrid
C、F1 insertion segment homolog
D、flanking insertion sequence hybrid
E、fluorescent insertion segment hybrid
A、assort randomly
B、can crossover and recombine
C、are allelic
D、co-segregate
E、will segregate independently
A、phenotypes that are similar
B、recombination frequencies of less than 50%
C、homozygosity when involved in a testcross
D、a greater number of recombinant offspring than parental offspring when involved in a testcross
E、a lack of recombinant offspring when a heterozygous parent is involved in a testcross
A、counting the number of recombinant and parental offspring when an individual who is heterozygous for two genes is involved in a testcross.
B、performing a chi-square test on the F2 progeny when an individual who is homozygous for two genes is initially crossed to an individual who is homozygous recessive for these two genes.
C、counting the number of offspring who are expressing the dominant phenotype when a heterozygous individual for two genes is involved in a testcross.
D、performing a chi-square test of the progeny of a cross between parents who are both heterozygous for the same two genes.
E、counting the number of offspring that are found in the cross of an individual who is heterozygous for two genes with another parent who is homozygous dominant for one of these genes and homozygous recessive for the other gene.
A、No, if two genes are on the same chromosome, they will be linked and the recombination frequency will be less than 50%.
B、Yes, if the two genes are close enough to each other, there will be a limited number of crossover events between them.
C、No, there will be very high crossover interference such that the recombination frequency will be reduced significantly.
D、Yes, if the genes are far enough apart on the same chromosome, a crossover will occur between them in just about every meiotic event.
E、Yes, but only if the two genes are both homozygous.
A、Genetic recombination of alleles is associated with physical exchange between chromosomes.
B、Genes are located on chromosomes and the map distance between them could often be measured by the number of nucleotides in the DNA.
C、Determining map distances in humans could be done by using pedigrees and calculating lod scores.
D、Association studies allow genes that have no obvious phenotype to be accurately mapped.
E、Crossing over does not occur in male Drosophila, so there is no genetic recombination.
A、4.2 m.u.
B、4.0 m.u.
C、16.4 m.u.
D、8.0 m.u.
E、50 m.u.
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