问题 选择题

现代生物进化理论的基础是(  )

A.自然选择学说

B.中性学说

C.自然发生说

D.用进废退学说

答案

A、达尔文把在生存斗争中,适者生存、不适者被淘汰的过程叫做自然选择.自然选择过程是一个长期的、缓慢的、连续的过程.由于生存斗争不断地进行,因而自然选择也是不断地进行,通过一代代的生存环境的选择作用,物种变异被定向地向着一个方向积累,于是性状逐渐和原来的祖先不同了,这样,新的物种就形成了.由于生物所在的环境是多种多样的,因此,生物适应环境的方式也是多种多样的,所以,经过自然选择也就形成了生物界的多样性,因此,现代生物进化理论的基础是自然选择说,符合题意.

B、中性学说由日本遗传学家木村资生于1968年提出一种学说,认为由突变产生的等位基因对于物种生存既无利也无害,这些突变在自然选择上是中性的,因此,在分子水平进化中自然选择几乎不起作用,不符合题意.

C、自然发生说认为不洁的衣物会滋生蚤虱,污秽的死水会自生蚊,肮脏的垃圾会自生虫蚁,粪便和腐臭的尸体会自生蝇蛆.总之,生物可以从他们所在的物质元素中自然发生,而没有上代,不符合题意.

D、用进废退学说是法国博物学家拉马克最早提出来的生物进化学说,这个学说的中心论点是:环境变化是物种变化的原因.环境变化了使得生活在这个环境的生物,有的器官由于经常使用而发达,有的器官则由于不用而退化.这些变化了的性状能够遗传下去,也就是说,获得性能够遗传,不符合题意.

故选:A

阅读理解

Some years ago, writing in my diary used to be a usual activity. I would return from school and spend the expected half hour recording the day’s events, feelings, and impressions in my little blue diary. I did not really need to express my emotions by way of words, but I gained a certain satisfaction from seeing my experiences forever recorded on paper. After all, isn’t accumulating memories a way of preserving the past?

When I was thirteen years old, I went on a long journey on foot in a great valley, well-equipped with pens, a diary, and a camera. During the trip, I was busy recording every incident, name and place I came across. I felt proud to be spending my time productively, dutifully preserving for future generations a detailed description of my travels. On my last night there, I wandered out of my tent, diary in hand. The sky was clear and lit by the glare of the moon, and the walls of the valley looked threatening behind their screen of shadows. I automatically took out my pen…

At that point, I understood that nothing I wrote could ever match or replace the few seconds I allowed myself to experience the dramatic beauty of the valley. All I remembered of the previous few days were the dull characterizations I had set down in my diary.

Now, I only write in my diary when I need to write down a special thought or feeling. I still love to record ideas and quotations that strike me in books, or observations that are particularly meaningful. I take pictures, but not very often—only of objects I find really beautiful. I’m no longer blindly satisfied with having something to remember when I grow old. I realize that life will simply pass me by if I stay behind the camera, busy preserving the present so as to live it in the future.

I don’t want to wake up one day and have nothing but a pile of pictures and notes. Maybe I won’t have as many exact representations of people and places; maybe I’ll forget certain facts, but at least the experiences will always remain inside me. I don’t live to make memories—I just live, and the memories form themselves.

小题1:Before the age of thirteen, the author regarded keeping a diary as a way of ______.

A.observing her school routine

B.expressing her satisfaction

C.impressing her classmates

D.preserving her history小题2:What caused a change in the author’s understanding of keeping a diary?

A.A dull night on the journey.

B.The beauty of the great valley.

C.A striking quotation from a book.

D.Her concerns for future generations.小题3:What does the author put in her diary now?

A.Notes and beautiful pictures.

B.Special thoughts and feelings.

C.Detailed accounts of daily activities.

D.Descriptions of unforgettable events.小题4:The author comes to realize that to live a meaningful life is ______.

A.to experience it

B.to live the present in the future

C.to make memories

D.to give accurate representations of it

多项选择题