题目

以抗螟非糯性水稻(GGHH)与不抗螟糯性水稻(gghh)为亲本杂交得F1，F1自交得F2，F2的性状分离比为9∶3∶3∶1，则F1中两对等位基因在染色体上的位置关系是（ ）A. B. C. D. 答案：【答案】C【解析】基因分离定律和自由组合定律的实质：进行有性生殖的生物在进行减数分裂产生配子时，位于同源染色体的等位基因随同源染色体分离而分离，分别进入不同的配子中，随配子独立遗传给后代，同时位于非同源染色体的非等位基因进行自由组合；按照自由组合定律，基因型为GgHh个体1、 As a teenager, I felt I was always letting people down. I was rebellious(反叛的) on the outside, ___36___ on the inside I wanted people to ___37____ me.   Once I left home to hitchhike(搭便车) to California with my friend Penelope. The trip wasn’t ____38___, and there were many times I didn’t feel safe. One situation in particular left me __ 39___ to still be alive. When I returned home, I was different ― not so outwardly sure of myself.   I was happy to be home. But then I noticed that Penelope, who was ____40___with us, was wearing my clothes. And my ___41___ seemed to like her better than me. I wondered if I would be ____42___ if I weren’t there. I told my mom, and she explained that ____43____ Penelope was a lovely girl, no one could ____44___ me. I pointed out, “She is more patient and is neater than I have ever been.” My mom said these were wonderful ___45____ but I was the only person who could fill my ___46___. She made me realize that even with my ___47___, ― and they were many ― I was a loved member of the family who couldn’t be replaced.   I became a searcher, ___48___ who I was and what made me unique. My ___49___of myself was changing. I wanted a solid base to start from. I started to resist pressure to ___50 ___in ways that I didn't like any more, and I___51___who I really was. I came to feel much more___52___ that no one can ever take my place. Each of us ___53___ a unique place in the world. You are special, no matter what others say or what you may think. So __54___about being replaced. You ___55___ be 36. A. and B. but   C. so D. for 37. A. hate B. replace C. receive   D. like 38. A. easy  B. hard   C. fun   D. long 39. A. unwilling B. regretful   C. grateful D. willing 40. A. playing B. eating C. staying   D. traveling 41. A. family B. friends C. relatives D. neighbors  42. A. loved B. mentioned   C. cared   D. missed 43. A. since  B. as C. while D. unless 44. A. scold B. compare   C. replace   D. match 45. A. qualities   B. aspects   C. matters D. times 46. A. character   B. role C. task   D. form 47. A. faults  B. advantages   C. manners  D. pities 48. A. looking for B. looking back  C. seeking out   D. giving up 49. A. picture   B. view   C. sense   D. image 50. A. think B. learn C. change   D. act 51. A. hated  B. celebrated   C. wished   D. expected 52. A. sure B. doubtful C. happy D. lonely 53. A. takes  B. catches   C. seizes D. holds 54. A. talk B. forget C. care D. argue 55. A. mustn’t   B. shouldn’t   C. can’t   D. needn’t