2023高二英语周报课标SDL32答案

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5.C【命题意图】本题考查杂交育种、诱变育种、单倍体育种技术,考查实验与探究能力及科学思维、科学探究素养。【解題思路】如果要获得hhRR植株,最简便的方法是采用杂交育种,两亲本杂交获得F1,然后F1相互交配获得F2,再采用测交选育出hhRR,A错误;如果要获得hhRR植株,最快捷的方法是单倍体育种,两亲本杂交获得F1,然后花药离体培养获得单倍体hR,再用秋水仙素处理幼苗,获得hhRR植株,其原理是染色体变异,B错误;如果采用诱变育种技术,将hhrr(或HHRR》亲本进行诱变处理,也可以获得hhRR植株不过基因突变具有随机性和不定向性,C正确;如果育种过程中需要筛选hhRR和hhRr的植株,最简便的方法是通过自交判断,但该植物是雌雄异株,所以要用测交选育出hhRR和hhRr,D错误。【易错点拔】本題容易忽略题干中的异花授粉,因此本題不能自交,可采用测交来判断纯合子和杂合子。

One possible versionSeveral minutes later, the ice broke suddenly and Harry's feet sank into the water. It was noep, but his legs got wet to the knees. Harry was so upset that the accident would delay hisschedule. He had to find some firewood to build a fire to dry his clothes. He pulled off his glovestook out his matches, and lighted the fire. Seeing the burning fire, he had thought he was safe. Butsuddenly, without warming, a heavy mass of snow dropped down. The flame of hope was put outUnluckily, his dog ran away and the fear of death came over Harry. He had no choice but torun to save himself. However, he did not feel his feet when they hit the ground. Having falleneveral times, he decided to rest a while. As he lay in the snow, he noticed he was not shaking. Hecould not feel his nose or fingers or feet. A feeling of horror came into his mind. It was when herealized he was going to die that he heard a bark and the noise his friends made

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