裸子植物的雄配子体只具一个精子，所以不能进行双受精。( )

【名词&注释】

雄配子体(male gametophyte)、万有引力(universal gravitation)、禾谷类作物(cereal crops)、裸子植物(gymnosperm)、匀速圆周运动(uniform circular motion)、人造地球卫星(artificial earth satellite)、人造卫星(satellite)、双韧维管束(bicollateral bundle)、初生木质部(primary xylem)、第一宇宙速度(first cosmic velocity)

[单选题]裸子植物的雄配子体只具一个精子，所以不能进行双受精。( )

A. 正确
B. 错误

查看答案&解析 点击获取本科目所有试题

举一反三：

[单选题]33________

A. seats
B. passengers
C. flight
D. airplane

[单选题]若集合A={x|-2x1}，B={x0x2}则集合A ∩ B=（ ）

A. {x|-1x1} B．{x|-2x1}
B. {x|-2x2}
C. {x|0x1}

[单选题]______________________________________________________________________A dictionary entry has many elements: multiple definitions, syllabication, preferred spelling and pronunciation (some words have more than one acceptable spelling and pronunciation), and part-of-speech labels. Some entries also include plurals and capitalized forms, synonyms, antonyms, and derivatives. Americanisms and etymologies may be provided along with usage notes, cross-references, and idioms.

A. Varieties of college dictionaries
B. Accessing dictionaries electronically
C. Elements under a word item
D. Complete editions of dictionaries
E. Using dictionaries for particular fields
F. F. Features of college dictionaries

[单选题]关于万有引力及其应用，下列表述正确的是

A. 人造地球卫星运行时不受地球引力作用
B. 两物体间的万有引力跟它们质量的乘积成反比
C. 两物体间的万有引力跟它们的距离成反比
D. 人造卫星^(satellite)在地面附近绕地球作匀速圆周运动所必须具有的速度，称为第一宇宙速度^{(first cosmic velocity)}

[单选题]双韧维管束^{(bicollateral bundle)}中，内韧皮部与初生木质部^{(primary xylem)}之间不存在形成层。( )

A. 正确
B. 错误

[单选题]禾谷类作物的叶包括( )等部分。

A. 叶柄、叶鞘、叶片、托叶
B. 叶柄、叶舌、叶耳、叶片
C. 叶鞘、叶舌、叶耳、叶片
D. 托叶、叶鞘、叶舌、叶耳、叶片

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