问题 填空题

如图为桃花的结构示意图,请据图分析回答.

(1)该图表示的是桃花的______过程,花谢以后要结桃子,还要经历的另一个重要生理过程是______.

(2)假设该桃树控制花色的基因组成为Bb(B为红色,b为白色),请你判断图中①结构内的花粉所携带的基因是______,该花经过发育后所形成的种子长成的植株,再开出花的颜色可能是______.花色在遗传学上称为______.

(3)桃树体细胞的染色体数目是16条,那么图中②结构内的染色体数目是______条.

答案

(1)我们知道植物要完成结果长种子必须经历的两个过程是传粉与受精.而图中表示的是桃花的自花传粉过程.

(2)对于有性生殖的生物来说,部分细胞在生殖器官中进行一种特殊的分裂,使遗传物质在新生细胞中减半,在花药中的细胞原来成对的染色体、基因会分开存在于不同的细胞中,故花粉说携带的基因将是B或b,同理,在②卵细胞中基因也将是B或b,那么形成受精卵时的可能基因组合为BB(红色)、Bb(红色)、bb(白色),所以形成的种子长成的植株,再开出花的颜色可能是 红色或白色.而花色在遗传学上称为性状.遗传图解为:

(3)由于部分细胞在生殖器官中进行一种特殊的分裂,使遗传物质在新生细胞中减半,在花药中的细胞原来成对的染色体、基因会分开存在于不同的细胞中,所以在卵细胞中应有8条染色体.

故答案为:(1)传粉  (双)受精

(2)B或b 红色或白色 性状

(3)8

单项选择题
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LONDON (Reuters Life!) ---- Forget about talking your children into considering life as a doctor or a teacher and start training them for the talent show.

A survey of British parents showed the aspirations (志向) of their children are greatly different from what they dreamed about when considering who they wanted to be when they grew up.

Although astronaut (宇航员) still remains fairly high on the list of careers (事业) kids dream about these days, others like doctor and teacher have been taken the place of by the desire (欲望) to win good name and money as a sporting hero, pop star or actor.

The parents of children aged 5 to 11 said the choice of lawyer had dropped by only one place on a top 10 list to sixth, while teacher had dropped to ninth from top in the last 25 or more years.

The survey for British TV channel “Watch” found a great difference between the genders (性别) of today’s young people when compared with their parents’ dreams 25 years or more ago.

Playing professional football, being an astronaut and joining the firefighting service topped the boys’ choices, while girls are more likely to be dreaming of taking to the stage as a pop star or actress or joining the medical profession.

When asked what they would like their children to do for a living, today’s parents still like the academic (学术的) professions (职业), with law and medicine scoring highly, while being a boss came third.

Parents also praised job happiness above wealth (财富) when it comes to their hopes for their children.

Nearly 70 percent of the parents surveyed thought that they failed to follow their dreams when it came to their career, with 37 percent thinking it was caused by a lack of aspiration and not having the necessary conditions.

1. From the passage we know that most parents still hope that in the future their children can take up ______.

A. jobs such as musicians, singers and dancers

B. jobs related to academic professions like lawyers and doctors

C. jobs in which they will not be endangered

D. jobs which will be well paid only

2. The first paragraph is to advise parents to ______.

A. change their children’s dreams     B. correct their children’s dreams

C. follow their children’s dreams         D. forget their children’s dreams

3. According to the survey for British TV channel “Watch”, which of the following is the boys’ best career choice?

A. A pop star      B. An actor        C. A doctor         D. A firefighter 

4. What can be learnt from the passage?

A. Parents’ hope for their children’s career did not change too much.

B. Parents pay much attention to the income of their children.

C. Less than half of the parents who were surveyed didn’t follow their dreams.

D. Most parents didn’t have the necessary conditions to realize their dreams.

5. What is the main idea of the passage?

A. Many reasons cause the change of children’s dreams.

B. Parents’ dreams are different from children’s.

C. Parents are changing their own dreams.

D. Children’s dreams are always changing.