问题 选择题

在“伞藻的移接实验”中,科学家将伞形帽伞藻的假根(含细胞根)切下,将菊花形帽伞藻的柄切下,然后将菊花形帽伞藻的柄移接到伞形帽伞藻的假根上,一段时间后,他们发现这一“移接体”长出了

A.菊花形帽

B.伞形帽

C.既有伞形帽,又有菊花形帽

D.不会长帽了

答案

答案:B

题目分析:细胞核是遗传的控制中心。伞藻是一类大型的单细胞海生藻类,细胞核位于基部的假根内,成熟后伞藻的顶部长出一个伞帽,伞帽的形状因伞藻的种类而不同。由题意知:该实验嫁接的部位是伞柄,所以遗传物质并没有改变,嫁接后保留伞藻的遗传物质,伞藻的帽呈伞形,选项B符合题意。

阅读理解

阅读理解。

    Almost 40 years ago, a community service organization started providing eye care in

Gujarat State, in western India.

    The Rotary Club of Navsari operates an eye hospital and 9 area eye centers in and

around Navsari, whose services are for the poorest people. The group opened the hospital,

the Rotary Eye Institute of Navsari, in 1970. Institute officials say India has only about

one ophthalmologist for every 120,000 people. The Institute, however, has ten such

specially trained eye doctors. It has restored or improved the eyesight of thousands of

patients. Many people far from the city. Teams from it travel as far as 150 kilometers to

see patients. People go to their nearest camp, for conditions including glaucoma (青光眼),

night blindness and other problems. Some people are found to have cataracts, abnormal

growths on the eye that can lead to loss of eyesight. India has about 13 million people

with the condition. Cataract patients get free operations to correct the problem.

    Rotary groups also operate eye banks. Doctors at these centers replace damaged eyes

with the healthy eyes of donors who have just died. One such center is the Rotary Rajan

Eye Bank. It operates in cooperation with the Rajan Eye Care Hospital in Chennai. The Eye

Bank opened in 1996. Hundreds of patients have received new corneas from donors since

then. The cornea is the clear front part of the eye that transmits light. 2 million people

in India are blind because of problems of the cornea. The Rotary Rajan Eye Bank holds

continuing eye donation campaigns. It urges people to leave the gift of sight to others

when they die.

1. Which of the following is TRUE about the Rotary Club of Navsari? [ ]

A. The Rotary Club of Navsari is a community service organization.

B. The Rotary Eye Institute of Navsari has only one eye doctor.

C. The Rtary Club of Navsari includes 9 area eye centers in big cities.

D. The Rotary Club of Navsari offers free operation to all the poor patients.

2. The underlined word "ophthalmologist" in Paragraph 2 refers to _____. [ ]

A. a physician who specializes in eyes

B. a worker working in countryside

C. a patient suffering eye problems

D. a volunteer working in eye centers

3. We can infer form the passage that _____. [ ]

A. there are 13 million Indians having eye problems in total

B. the Rotary Eye Instiute of Navsari is located in the center of India

C. the medical treatment is convenient for the local residents

D. Transportation in Navsari is difficult

4. According to the last paragraph, the Rotary Rajan Eye Bank gets new corneas mainly

   by _____. [ ]

A. cloning

B. donating

C. cooperating

D. forcing

5. The author develops the passage mainly by _____. [ ]

A. providing typical examples

B. making a definition

C. comparing two different areas

D. presenting two examples and drawing a conclusion

单项选择题