题干

大豆种叶,能为种子萌,发提供营养物质。小明认为:大豆种子子叶的完整程度会影响种子的萌发率。于是他进行相应的探究,请完成下列实验设计和问题交流。

【实验设计】

实验步骤

设计要求

①准备两个大小相同的洁净培养皿,分别标为A、B;选取大小相近、具有完整胚的活大豆种子40颗,经充分浸泡后,随机平均分成两组。

选择合适的实验器材

②将一组每粒大豆种子的子叶均除去一片后,平铺在A培养皿中;将另一组大豆种子____   。

设置对照实验

③将A、B两个培养皿放置在相同的适宜环境中,每天同时浇适量且等量的水。

控制实验条件

    ④每天观察并记录____  ,并进行统计分析。

观察和记录

【问题交流】

多次重复实验后,小明发现A、B两组种子大部分都萌发且萌发率基本相同,于是得出结论:大豆种子子叶的完整程度不会影响种子的萌发率。小红认为该实验还不足以支持小明的结论,还需要进一步实验,请设计简要的实验方案: ____   。

上一题 下一题 0.0难度 选择题 更新时间:2017-07-09 12:21:37

答案(点此获取答案解析)

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同类题2

有人对不同光照强度下两种果树的光合特性进行研究,结果如下表(净光合速率以的吸收速率表示,其他条件适宜且相对恒定)。下列相关分析,不正确的是
光强(mmol光子/
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
龙眼
光能得用率(%)
-
2.30
2.20
2.00
1.80
1.60
1.50
1.40
1.30
1.20
净光合速率
(wnol /
-0.60
2.50
5.10
6.55
7.45
7.90
8.20
8.50
8.50
8.50
茫果
光能得用率(%)
-
1.20
1.05
0.90
0.85
0.80
0.75
0.70
0.65
0.60
净光合速率
(wnol /
-2.10
1.10
3.70
5.40
6.50
7.25
7.60
7.60
7.60
7.60

同类题3

任务型阅读

    When it comes to the Internet, passwords which people often use are under fire.____ Research has shown that passwords are not a very good way to protect sensitive information.

    People would use some random characters, numbers and symbols. Furthermore, a unique password would be used for every site or application the user uses. Unfortunately, the more complex they become, the more people are likely to forget their passwords. The longer the passwords are, the more easily forgotten they are.____

    Google is trying to kill off the password on Android devices by introducing the Trust API, which does what simple passwords cannot. It gives developers a framework for securing their applications using a number of security systems and metrics (指标) on the device. A Trust Score will be generated based on the metrics the device gathers.____

    The Trust Score will be generated based on both metrics like your device location, face scanning, fingerprint and so on. Taken one at a time, these metrics are not secure. But taken together, these metrics will help define the real “you”.

    ____This summer, Google will be running tests with some banks to see if Trust API meets their needs before rolling out to all developers later this year. It may take another year for apps and popular sites to start using the Trust API.

This is a pretty exciting change. Passwords have been around for long and although the security of systems has been improved, the convenience of systems hasn't been improved much.____ Maybe that never-ending conflict between security and convenience will be able to take a break once the Trust system comes out.

A. Google appears to have the best of them.

B. Actually it's been under fire for a long time.

C. People tend to care more about its advantages.

D. Google has already been testing this on the real world.

E. Google has proved that the system is more convenient.

F. Therefore, they use the same password for each application.

G. It'll allow or refuse your application based on your trust score.