问题 问答题 简答题

植物种质资源保存的方式有哪些?与传统方式相比较,离体保存的优点是什么?

答案

参考答案:

1)原地保存

2)异地保存:种植保存;贮藏保存;基因文库保存;离体保存

优点:(1)很高的增殖率;

(2)无菌和无病虫环境,不受自然灾害的影响;

(3)保存的材料体积小,占用空间小,节省大量的人力、物力及财力;

(4)不存在田间活体保存存在的像异花授粉、嫁接繁殖而导致的遗传蚀变现象;

(5)有利于国际间的种质交流及濒危物种的抢救和快繁。

单项选择题
完形填空

When I was a boy,  every holiday that I had seemed wonderful.In those days the sun seemed to shine always brightly   31  the water was always warm. Sometimes we left the beach and walked in the country,  32  ruined houses and dark woods and climbing trees. There were   33  in one’s pockets or good places where one could   34  ice creams. Each day seemed a lifetime.

Although I am now thirty-five years old, my idea of a good   35  is much the same as it was. I   36  like the sun and warm sand and the sound of waves beating the rocks. I no longer wish to   37  any sand house or sand garden, and I dislike sweets.   38 , I love the sea and often feel sand running through my fingers.

Sometimes I   39  what my ideal holiday will be like when I am old. All I want to do then, perhaps, will be to lie in bed, reading books about   40  who make houses and gardens with sands, who watch the incoming tide, who make themselves sick of too many ice creams.

31. A. and              B. yet              C. but             D. or

32. A. exploring          B. examining        C. repairing     D. measuring

33. A. sweets          B. sand            C. ice-creams    D. money

34. A. make            B. sell               C. buy             D. offer

35. A. house           B. holiday            C. garden         D. tide

36. A. hardly            B. almost            C. still             D. perhaps

37. A. destroy          B. fix               C. use             D. build

38. A. But             B. However         C. Otherwise     D. Besides

39. A. wonder        B. feel                 C. understand     D. believe

40. A. children        B. boys                  C. girls            D. grown-ups