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1万年前，科罗拉多大峡谷中的松鼠被一条河流分隔成两个种群，两个种群现在已经发生明显的分化。研究人员指出，经过长期演化可能形成两个物种，如下图所示。请分析回答下列问题：
原松鼠种群中黑毛基因A的基因频率为50%。环境变化后，峡谷北侧山高林密，生活于其中的松鼠种群中基因型为AA、Aa的个体数量在一年后各增加20%，基因型为aa的个体数量减少20%，则一年后a的基因频率约为（），基因型为aa的个体的比例约为（）。
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举一反三
【单选题】位于美国亚利桑那州西北部的科罗拉多大峡谷，全长446千米，平均宽度16千米，最深处2133米。峡谷两侧都是红色的含有代表性的生物化石的巨岩断层，这里的土壤大都是褐色，但当它沐浴在阳光中时，由于不同岩层中的矿物不同，色彩时而深蓝，时而又是赤色，变幻无穷，令人流连忘返。【图片】下列关于峡谷地貌的形成过程，正确的是
A.
固结成岩—风化剥蚀—侵蚀搬运
B.
高压变质—地壳抬升—风化剥蚀
C.
岩浆侵入—地壳抬升—侵蚀搬运
D.
外力沉积—地壳抬升—流水侵蚀
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
it was caused by some ancient convulsion
B.
its presence is an embarrassment to the state of Colorado
C.
it looks like an injury on the Earth’s suce
D.
it has caused many visitors to injure themselves
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
its shapes are constantly changing
B.
it contains approximately 14 million tons of rock
C.
its eruptions have increased in recent years
D.
it is being eroded by toxic waste and pollutants
【单选题】下图为“科罗拉多大峡谷成因示意图”，①～⑤表示了它的形成过程。读图完成下列各题。 地壳运动导致峡谷形态变化，一般观测峡谷形态变化情况的技术手段是（）
A.
全球定位系统
B.
雷达系统
C.
地理信息系统
D.
遥感技术
【单选题】1万年前，科罗拉多大峡谷中的松鼠（原种群中黑毛基因A的基因频率为50%）被一条河流分隔成两个种群，两个种群现在已经发生明显的分化。研究人员指出，经过长期演化两个种群可能形成两个物种，下列说法错误的是（ ）【图片】
A.
①②③④⑤⑥为生物进化提供原材料
B.
b 表示自然选择过程 ,是不定向的
C.
若环境变化后，种群中基因型为 AA 、 Aa 的个体数量在一年后各增加 20% ，基因型为 aa 的个体数量减少 20% ，则一年后 a 的基因频率为5/11
D.
没有D
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
Astronomy
B.
Botany(植物学)
C.
Geology
D.
Chemistry
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
it was caused by some ancient convulsion
B.
its presence is an embarrassment to the state of Colorado
C.
it looks like an injury on the Earth’s suce
D.
it has caused many visitors to injure themselves
相关题目：
【单选题】位于美国亚利桑那州西北部的科罗拉多大峡谷，全长446千米，平均宽度16千米，最深处2133米。峡谷两侧都是红色的含有代表性的生物化石的巨岩断层，这里的土壤大都是褐色，但当它沐浴在阳光中时，由于不同岩层中的矿物不同，色彩时而深蓝，时而又是赤色，变幻无穷，令人流连忘返。【图片】下列关于峡谷地貌的形成过程，正确的是
A.
固结成岩—风化剥蚀—侵蚀搬运
B.
高压变质—地壳抬升—风化剥蚀
C.
岩浆侵入—地壳抬升—侵蚀搬运
D.
外力沉积—地壳抬升—流水侵蚀
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
it was caused by some ancient convulsion
B.
its presence is an embarrassment to the state of Colorado
C.
it looks like an injury on the Earth’s suce
D.
it has caused many visitors to injure themselves
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
its shapes are constantly changing
B.
it contains approximately 14 million tons of rock
C.
its eruptions have increased in recent years
D.
it is being eroded by toxic waste and pollutants
【单选题】下图为“科罗拉多大峡谷成因示意图”，①～⑤表示了它的形成过程。读图完成下列各题。 地壳运动导致峡谷形态变化，一般观测峡谷形态变化情况的技术手段是（）
A.
全球定位系统
B.
雷达系统
C.
地理信息系统
D.
遥感技术
【单选题】1万年前，科罗拉多大峡谷中的松鼠（原种群中黑毛基因A的基因频率为50%）被一条河流分隔成两个种群，两个种群现在已经发生明显的分化。研究人员指出，经过长期演化两个种群可能形成两个物种，下列说法错误的是（ ）【图片】
A.
①②③④⑤⑥为生物进化提供原材料
B.
b 表示自然选择过程 ,是不定向的
C.
若环境变化后，种群中基因型为 AA 、 Aa 的个体数量在一年后各增加 20% ，基因型为 aa 的个体数量减少 20% ，则一年后 a 的基因频率为5/11
D.
没有D
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
Astronomy
B.
Botany(植物学)
C.
Geology
D.
Chemistry
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s suce, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
it was caused by some ancient convulsion
B.
its presence is an embarrassment to the state of Colorado
C.
it looks like an injury on the Earth’s suce
D.
it has caused many visitors to injure themselves
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