问题 探究题

在4个洁净的罐头瓶上分别贴上写有1、2、3、4的标签,然后在4个瓶中各放入2张餐巾纸,并在餐巾纸上均匀的放上10粒种子,然后按照下表中的处理方式操作,请分析回答:(11分)

1234

 

拧紧瓶盖

洒入少量清水

使餐巾纸湿润,

然后拧紧瓶盖

倒入较多清水,

使种子淹没在清水中,然后拧紧瓶盖

洒入少量清水,

使餐巾纸湿润,

然后拧紧瓶盖

置于室温环境中置于室温环境中置于室温环境中放在低温处(如冰箱内)
(1)本实验的假设是:                                             

(2)    号瓶的种子不会萌发,       号瓶的种子会萌发。

(3)有    组对照实验,分别是                  

(4)根据   号和   号实验结果的对比分析,说明种子萌发时需要充足的空气。

(5)可能得出的结论是:                                             

(6)放入10粒种子,而不是1粒的原因                 。

(7)1号与2号瓶进行对照,所探究的问题是                     

答案

(1)种子萌发需要适量的水,充足的空气,适宜的温度

(2)134、2

(3)3、12、23、24

(4)23

(5)种子萌发需要适量的水,充足的空气,适宜的温度

(6)避免实验的偶然性

(7)种子的萌发需要水吗?

题目分析:(1)对照实验,只有一个变量,其它量皆相同,实验中所探究的问题就是变量,结论、假设和问题具有相似性,本实验的假设是种子的萌发需要适量的水、充足的空气和适宜的温度。

(2)1号瓶子内的种子缺少适量的水,因此不能萌发,3号瓶子内的种子缺少充足的空气,因此不能萌发,4号瓶子内的种子温度太低,因此不适宜种子的萌发,因2号瓶具备了种子萌发的条件,因此2号瓶种子萌发,因此本实验的实验现象2号瓶中的种子萌发,1、3、4号瓶中的种子不萌发。

(3)(4)(7)对照实验又叫单一变量实验,只有一个量不同,其它量皆相同的实验,只有一个变量,这就是实验中所有探究的问题,是可以改变的量,对照实验的对照组一般是条件正常的,变量没有变化的一组,实验组是变量有变化的一组,因此本实验设计中可组成:1号与2号不同的量是水分,2号与3号不同是量是空气,2号与4号不同的量是温度,3组对照实验,对照组是2号瓶,主要是起对照作用。

(5)实验结论是种子的萌发需要适量的水、充足的空气和适宜的温度。

(6)每组实验都是用10粒种子做实验,不可以只用1粒种子做实验,因为结果会存在偶然性,误差大。

点评:此题为科学探究题,解答的关键是熟知影响种子萌发的外界条件:一定的水、适宜的温度、充足的空气和有关探究实验的步骤等。

单项选择题
阅读理解

阅读理解。

     Construction workers in Southern California have made a wild discovery. They were digging at a building

site in San Timoteo Canyon (峡谷) when they unearthed hundreds of ancient animal fossils. Researchers say

the bones hold important clues about the history of the region.

     Nearly 1, 500 fossils were recovered from the dusty canyon. The remains are about 1.4 million years old.

They include the bones of a new species of deer, several small rodents (啮齿目动物) and more. A giant cat

fossil was also found. Scientists believe the animal was an ancestor of the saber- toothed tiger. Signs of plant

life were uncovered as well.

     "This is a huge find," says Rick Greenwood, a scientist studying the site. "I don't think most people had

any idea that those types of animals were wandering around here more than a million years ago."

     San Timoteo Canyon is located about 85 miles from Los Angeles. The area of the canyon where the fossils

were found was once part of a green river valley. Today, the region is dry and plant life is rare.

     Most of the fossils are well preserved. Experts say a muddy lake bed may have trapped thirty animals that

wandered over for a drink. The mud helped to protect the animal fossils.

     The remains are a million years older than those discovered at the famous La Brea Tar Pits in Los Angeles.

Scientists studying the bones will be able to learn more about how the animals adapted to changes in the

environment.

     "We have a confused view of what this time period was like," says another scientist. "A discovery like this

could really be an important contribution."

     About 35 different animal species are represented in the fossil collection. Scientists began removing bones

from the site last fall. The project was completed this summer. Starting next year, the fossils will be on display

at the Western Science Center in the nearby city of Hemet, California.

1. What does the passage mainly focus on?

A. The secret of ancient animals' deaths.

B. The preparation for a future fossil exhibition.

C. A great discovery of fossils.

D. The history of San Timoteo Canyon.

2. From what Rick says, we know ______.

A. fossils were discovered in the canyon for the first time.

B. the canyon in ancient times was quite different.

C. more research work will be carried on in the canyon.

D. the river water helped to protect the animal fossils.

3. Compared to the discovery at the La Brea Tar Pits, the canyon-involved fossils ______.

A. are far older

B. include more species

C. are better preserved

D. make experts more confused

4. What do we know about the fossils from the passage?

A. All of them are of new species.

B. Some of them have been destroyed. 

C. They were looked for under experts' guidance.

D. They will be on show in the near future.