问题 填空题

为了探究6-BA和IAA对某菊花品种茎尖外植体再生丛芽的影响,某研究小组在MS培养基中加入6-BA和IAA,配制成四种培养基(见下表),灭菌后分别接种数量相同、生长状态一致、消毒后的茎尖外植体,在适宜条件下培养一段时间后,统计再生丛芽外植体的比率(m),以及再生丛芽外植体上的丛芽平均数(n),结果如下表。 回答下列问题:

(1)按照植物的需求量,培养基中无机盐的元素可分为______和________两类。上述培养基中,6-BA属于______类生长调节剂。

(2)在该实验中,自变量是______,因变量是______,自变量的取值范围是_______。

(3)从实验结果可知,诱导丛芽总数最少的培养基是______号培养基。

(4)为了诱导该菊花试管苗生根,培养基中一般不加入________(填“6-BA”或“IAA”)。

答案

(1)大量元素  微量元素  细胞分裂素

(2)IAA浓度  丛芽外植体的比率(m)及再生丛芽外植体上的丛芽平均数(n)  0~0.5mg/L

(3)1

(4)6-BA

选择题
阅读理解

The Ivy League is an athletic conference comprising eight private institutions of higher education in the Northeastern United States. The term is most commonly used to refer to those eight schools considered as a group. The term is also connected with academic excellence, selectivity in admissions, and social elitism(精英主义).

The term became official, especially in sports terminology, after the formation of the NCAA Division I athletic conference in 1954, when much of the nation polarized around favorite college teams. “IV” was used because originally the league consisted only of four members. The use of the phrase is no longer limited to athletics, and now represents an educational philosophy inherent to the nation's oldest schools. In addition, Ivy League schools are often viewed by the public as some of the most prestigious universities worldwide and are often ranked amongst the best universities in the United States and worldwide. The eight institutions are Brown University, Columbia University, Cornell University, Dartmouth College, Harvard University, Princeton University, the University of Pennsylvania, and Yale University.

All of the Ivy League's institutions place near the top in the U.S. News & World Report college and university rankings and rank within the top one percent of the world's academic institutions in terms of financial endowment(捐助). Seven of the eight schools were founded during America's colonial period; the exception is Cornell, which was founded in 1865. Ivy League institutions, therefore, account for seven of the nine Colonial Colleges chartered before the American Revolution. The Ivies are all in the Northeast geographic region of the United States. All eight schools receive millions of dollars in research grants and other subsidies from federal and state government.

Undergraduate enrollments among the Ivy League schools range from about 4,000 to 14,000, making them larger than those of a typical private liberal arts college and smaller than a typical public state university. Ivy League university financial endowments range from Brown's $2.01 billion to Harvard's $26 billion, the largest financial endowment of any academic institution in the world.

71. From the passage, we know the word “Ivy” in “the Ivy League” was first chosen to refer to _______.

A. a plant       B. a number      C. a sport      D. a spirit

72. What is special about Cornell University in the League?

A. It is the oldest one.             B. It was founded by colonists.

C. It has the smallest endowment.   D. It is the youngest one.

73. Which meaning can the term “the Ivy League” convey today?

A. The largest enrollment.         B. The strongest government support.

C. The most expensive schools.       D. First-class education.

74. Which of the following statements is true?

A. There is no longer sports competition in the Ivy League.

B. Seven colleges were set up before the USA was founded.

C. Brown University has the smallest number of students.

D. Typical public state universities are larger than the Ivies.

75. Which of the following can be the best title of the passage?

A. The ABC of “The Ivy League”

B. Best Universities in the USA

C. The Financial Income of American Universities

D. How to Apply to an Ivy League University