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读下列图片，回答问题。 小题1:万里长城雄伟壮观，给人以巨大的美感。它的美属于 A．动态美 B．色彩美 C．形象美 D．听觉美 小题2:长城是我国首批世界文化遗产，下列属于世界文化自然双重遗产的是 ①龙门石窟 ②湖南武陵源风景名胜区 ③泰山 ④四川峨眉山—乐山大佛 A．①④ B．①② C．③④ D．②③ 小题3:长城横亘在北方辽阔的土地上，宛如一条巨龙盘踞在起伏的群山之巅。要欣赏长城的雄伟壮观，就要 A．登高望远 B．置身其中 C．选择特定的观景位置 D．在适当的距离处仰视
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【单选题】Which pair of words best describes the feeling during the first stage of culture shock?
A.
Lonely and depressed.
B.
Bored and homesick.
C.
Happy and thrilled.
D.
Angry and frustrated.
【单选题】Which pair of words/phrases indicates contrast?
A.
Gigantic structure great desert expanse
B.
A call for prayer men and women with the shisha
C.
Chaos maddening
D.
Coffee shops pyramids
【单选题】Which pair of words is NOT a minimal pair?
A.
cat / bat
B.
put / but
C.
jig /pig
D.
sit / bit
【单选题】Which pair of words contains synonymous roots?
A.
Bilirubin & cholesterol
B.
Pepsin & gastralgia
C.
Phagocyte & cytometer
D.
Oligodontia & stomatitis
【单选题】Which pair of words contains synonymous prefixes?
A.
Dyspepsia & prothrombin
B.
Esophagus & endocrine
C.
agranulocyte & perihepatitis
D.
sublingual &melancholy
【多选题】How does crossing-over occur between the duplicated maternal and paternal chromosomes in each bivalent?
A.
In sexually reproducing organisms, the pairing of the maternal and paternal chromosomes is accompanied by homologous recombination, a process in which two identical or very similar nucleotide sequences exchange genetic information. A similar process takes place when homologous chromosomes pair during the long prophase of meiosis I. In this case, the recombination occurs between the non-sister chromatids in each bivalent, rather than between the identical sister chromatids within each duplicated chromosome. In the process, the maternal and paternal homologs can physically swap homologous chromosomal segments, an event called crossing-over.
B.
Crossing-over is a complex, multistep process that is facilitated by the formation of a synaptonemal complex. As the duplicated homologs pair, this elaborate protein complex helps to hold the bivalent together and align the homologs so that strand exchange can readily occur between the non-sister chromatids. Each of the chromatids in a duplicated homolog (that is, each of these very long DNA double helices) can form a crossover with either (or both) of the chromatids from the other chromosome in the bivalent.
C.
By the time meiotic prophase ends, the synaptonemal complex has disassembled, allowing the homologs to separate along most of their length. But each bivalent remains held together by at least one chiasma (plural chiasmata), a structure named after the Greek letter chi, χ, which is shaped like a cross. Each chiasma corresponds to a crossover between two non-sister chromatids. Most bivalents contain more than one chiasma, indicating that multiple crossovers occur between homologous chromosomes. In human oocytes—the cells that give rise to the egg—an average of two to three crossover events occur within each bivalent.
D.
Crossovers that take place during meiosis are a major source of genetic variation in sexually reproducing species. By scrambling the genetic constitution of each of the chromosomes in the gamete, crossing-over helps to produce individuals with novel assortments of alleles. But crossingover also has a second important role in meiosis: it helps ensure that the maternal and paternal homologs will segregate from one another correctly at the first meiotic division.
【单选题】Which pair of words is alliterative?
A.
pain, Spain
B.
flower, float
C.
apple, April
D.
fast, last
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