题干

为研究城市环境污染对某植物生命活动的影响,研究者测定了不同污染程度下某植物叶片光 合色素的相关指标,结果如下表所示.

不同环境条件下叶片光合色素含量

叶绿素a(单位:mg/g)

叶绿素b(单位:mg/g)

类胡萝卜素a(单位:mg/g)

相对清洁区

2

1

0.5

轻度污染区

1.8

0.8

0.5

中度污染区

1.4

0.6

0.5

重试污染区

1.2

0.5

0.5

(1)叶绿体中色素可用____ 提取;如图为四种色素在滤纸条上的分离结果,其中____ (填标号)色素带含有镁元素.

(2)据表分析污染加剧导致植物____,会直接影响光合作用的光反应阶段;植物受污染会导致产生乙烯增多,乙烯可对抗____(某种激素)的作用;污染可引起某些酶活性改变,如改变细胞呼吸第一阶段____ (名称)相关酶活性,从而影响植物的生长发育.

(3)环境污染可导致玉米黄粒变白粒、紫粒等,这属于____ 突变类型,玉米籽粒多种颜色的出现体现了基因突变____ 特点.

上一题 下一题 0.0难度 选择题 更新时间:2017-05-06 08:21:25

答案(点此获取答案解析)

有机溶剂(无水乙醇),cd,叶绿素的含量逐渐下降,生长素,糖酵解,生化,不定向性

同类题4

阅读下列短文,从各题所给的四个选项(A B C D)中,选出最佳选项。

B

    Do you shop online with websites like Taobao? The money you pay doesn't go directly to the seller. Instead, it goes through Alipay, which keeps your money for a while. After you receive your goods and click the "confirm receipt" button, Alipay then gives the money to the seller.

    The process is called "third party online payment". There is a transfer station, or a third account, between sellers and buyers to make online shopping safe. Buyers don't need to worry about paying for goods and then receiving nothing. Sellers also get rid of the risk of receiving no money after sending out goods.

    These transfer stations are usually set up by payment service companies such as Alipay, Tenpay and Yeepay. Among them, Alipay is the biggest in China. It has more than 270 million active users, according to Xinhua.

    While most online sellers and shoppers like the third party online payment system, banks are not very happy. That is because companies like Alipay are fighting over money with the banks. Users can invest in financial products through Alipay and make money. Thus lots of people choose to put money in Alipay rather than in banks.

    But WeChat payment is not the same. WeChat doesn't have its own account. When paying through WeChat, the buyers' money goes directly to the sellers. That's why so many people are excited about receiving and handing out "red envelopes" or gift money to their friends on WeChat.

    Whether Alipay or WeChat payment, they are all trying to attract more users and make online shopping easier. These two companies are also promoting payments through fingerprints. New payment methods such as quick response codes have become popular too.

同类题5

阅读下面的文章,完成下列各题。

心底藏着艺术家

奚  淞

    父亲突然去世,我慌忙搭机飞返台北。令我惊骇的是母亲:她身着未换洗的灰布丧服,花白而蓬乱的头发上,胡乱别着一朵不成形的白棉线花,看见我,枯黄的脸微颤,仅咧开嘴,显示了无言而深切的哀恸。

    ①我在巴黎三年,任性地做自己艺术家的梦,不觉间,岁月竟来催讨所有积欠的债了。父亲去世后,母亲能健康而平安地活下去,应比一切都重要。

    我从旧书摊买来一大堆内容轻快的杂志和小说给母亲,希望能转移她那郁结于心的哀伤。翻开书页,她的视线茫然滑开。我这才发现:她不只是失去了阅读的习惯,视力也坏到早该配老花眼镜了。我烹煮了一些肉类食物,笑闹着端到她面前,想引起她的食欲。母亲万般无奈地咬嚼两下,趁我转身,又偷偷把食物吐在碗里。我这才发现:她不只是因悲伤而忌肉食,她的牙齿早已缺损,并没有人催促她去装假牙。

    谁想到一直照顾人的母亲,其实已经到了需要人照顾的时候呢?

    配眼镜、装假牙,母亲都顺从地做了。可是,更多的时候,母亲像是无事可做,只是一支烟接着一支烟地抽,从笼罩的烟雾里,追寻往事的踪影。

    为逝者折纸钱的时候,母亲的手才又活了起来。②银亮的冥纸,在她的手上灵巧转动,瞬间成为平整的元宝,翻飞飘落在她膝间的竹篓里。

    看母亲折纸钱的手,学美术的我有了新的狂想:为什么不让她学画画呢?趁着一股孩子般胡闹的狂劲,我把画架、画板、画纸、画夹和彩笔都准备好,一股脑儿地堆置在母亲面前。看到这一切郑重的装备,母亲呆了。

    以后,好一段时日,我假装不在意,却偷偷观察母亲的动态。我看到她在画架前徘徊、犹疑,终于怯生生地拿起铅笔,试着在纸上轻淡地画了如花生米般大小的孩子,然后匆匆忙忙涂抹掉,生怕别人看见。

    我没想到,真有这么一天,母亲会认真而着迷地画起画来呢。她从旧书里翻出一些过时的画片,以刺绣般的耐心,一笔一笔地临摹。

    一天,母亲在房里独自大笑起来。许久没听到母亲笑声的我,惊奇地冲进房,只看她一边笑,一边遮掩画纸。

     “画得好丑,难看死了。”母亲笑着说。

    我看到了,画的是一个20世纪三四十年代穿旗袍的女人,侧身站立在镂花的窗边。稚拙的线条擦了又改,直到那苗条的女郎天真地笑起来。原来,母亲临摹的是金嗓子歌后周璇的旧照。当周璇高歌《龙华的桃花》时,也正是父亲母亲在上海相识、相恋的年代!

    从记忆深处寻到图像,母亲的郁结似乎找到了宣泄的出口。她居然一张又一张地画起画来,起初画妇人、孩子,然后狂热地画起花来,黑白的画面上,开始添加颜色,由淡雅趋于绚烂。

    看母亲蓬着花白的头发,鼻端架着老花眼镜,聚精会神地凑近艳丽的花朵细心描绘,有时竟连炉上煮着饭菜都忘了,我才知道:在母亲心底,也藏着一个从未被人注意过的艺术家呢!这艺术家是待子女长成、丈夫去世后,才被释放出来的。

(摘自上海文艺出版社《姆妈,看这片繁花》)