豹的某个栖息地由于人类活动被分隔为F区和T区。20世纪90年代初,F区豹种群仅剩25只,且出现诸多疾病。为避免该豹种群消亡,由T区引入8只成年雌豹。经过十年,F区豹种群增至百余只,在此期间F区的()。
A. 豹种群遗传(基因)多样性增加
B. 豹后代的性别比例明显改变
C. 物种丰(富)度出现大幅度下降
D. 豹种群的致病基因频率不变
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直到1917年初,《新青年》在答读者问时还这样写道:“社会主义,理想甚高,学派亦甚复杂。惟是说之兴,中国似可缓于欧洲,因产业未兴、兼并未盛行也。”《新青年》之所以这样回答,主要是因为()。
A. 尚未看到社会主义实践成果
B. 中国经济落后于欧洲
C. 社会主义理论学派复杂
D. 对社会主义持怀疑态度
阅读下面短文,掌握其大意,然后从21—40各题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题纸上将该选项标号涂黑。During the war,my husband was stationed at an army camp in a desert in California.I went to live there in order to be 21 him. I hated the place .I had never 22 been so unhappy . My husband was ordered out on a long-term duty,and I was left in a tiny shack(棚屋) alone. The heat was 23 -almost 125 0F even in the shade of a cactus(仙人掌)。 24 a soul to talk to . The wind blew non-stop ,and all the food I ate ,and the evry air I breathed,were 25 with sand , sand , sand !I was so sorry for myself that I wrote to my parents. I told them I was 26 and coming back home.I said I couldn’t stand it one minute longer. I 27 be in prison! My father answered my 28 with just two lines-two lines that will always sing in my 29 - two lines that completely changed my life :Two men looked out from prison barsOne saw the mud ,the other saw the starsI read those two lines 30 I was ashamed of myself. I made up my mind I would find out what was good in my present 31 ; I would look for the starsI made friends with the natives,and their 32 amazed me. They gave me presents of their favorite artworks which they had 33 to sell to toueists . I studied the delightful forms of the cactus .I watched for the desert sunsets,and 34 for seashells that had been left there millions of years ago when the desert had been an ocean 35What brought about this 36 change in me ? The desert hadn’t changed , 37 I had .I had changed my 38 And by doing so ,I changed an unhappy experience into the most amazing 39 of my life . I was excited by this new world that I had dicovered I had looked out of my self-creatded prison and 40 the stars 36()
A. shocking
B. challenging
C. puzzling
D. astonishing
下列关于生物膜透性的叙述,正确的是()
A. 核糖体合成的分泌蛋白能够自由透过高尔基体膜
B. 细胞质中合成的光合作用相关蛋白须通过内质网输入叶绿体
C. 子叶细胞中包被脂肪颗粒的膜对葡萄糖具有选择透性
D. 细胞外高浓度的超氧化物歧化酶可以自由扩散进入细胞
下列与细胞相关的叙述,正确的是()。
A. 核糖体、溶酶体都是具有膜结构的细胞器
B. 酵母菌的细胞核内含有DNA和RNA两类核酸
C. 蓝藻细胞的能量来源于其线粒体有氧呼吸过程
D. 在叶绿体中可进行CO2的固定但不能合成ATP