31.(18分)

   (1)D··········································································································· 2分

   (2)水·········································································································· 2分

   (3)B············································································································ 2分

     载畜量(注:答“放牧量”可得分)······················································ 2分

   (4)对人类有益···························································································· 2分

   (5)B2和C2·································································································· 2分

     分解者不能在短时间内将聚乙烯降解成无机物········································ 2分

   (6)呼吸作用所消耗····················································································· 2分

     光合作用产生的O2与呼吸消耗的O2······················································· 2分

30.(18分)

   (1)碳源、氮源、水、无机盐、生长因子······················································ 2分

   (2)诱导基因突变························································································· 2分

   (3)初级······································································································· 2分

     合成精氨酸···························································································· 2分

     不能将鸟氨酸转变成瓜氨酸···································································· 2分

   (4)抗原······································································································· 2分

     酶制剂··································································································· 2分

     沉淀带(沉淀)····················································································· 2分

31.(18分)图22是生态系统能量流动模式图,其中柱宽大致与能量流动的数量成比例。请回答下列问题:

   (1) 若该图表示森林生态系统,则流经该生态系统的总能量A会明显大于草原生态系统,出现这种差异的主要原因是森林生态系统       (单选)。

   A.以木本植物为主

   B.土壤肥沃

   C.营养结构复杂

   D.群落具有明显的分层结构

   (2) 影响森林和草原在地球上分布的主要生态因素是       

   (3) 若该图表示草原生态系统,当图中      (填字母)的柱宽过大时,会导致草场退化、沙化等现象的出现。因此,合理确定草场的      ,才能保证畜牧业生产的可持续发展。

   (4) 若该图表示农田生态系统,怎样利用农作物秸杆中的能量是一个值得研究的问题。

如果将秸杆做废弃物燃烧就不能充分利用秸杆中的能量,而将秸杆做饲料喂牲畜,再利用牲畜的粪便进行沼气发酵,就会使秸杆中的能量更多地流向      的部分一同时,其中的物质也能被充分利用。

   (5) 若该图表示城市生态系统,如果居民的生产、生活产生了过多的废弃物,图中  

(填字母)的柱宽就会明显加大,相应地就出现了环境污染。例如白色污染(聚乙烯)已经成为一个严重的社会问题,从生态系统物质循环的角度来看,造成白色污染的根本原因是                   

   (6) 若该图表示湖泊生态系统,如果要调查生态系统的能量流动情况,可采用黑白瓶法。该方法是从湖泊的一定深度取水样,测其初始的溶氧量。然后将水样分装在透光的白瓶和不透光的黑瓶中,黑白瓶都放回取样深度,一段时间后取出,再测其溶氧量。此时,黑瓶中溶氧量的变化是瓶中生物       的氧气量,而白瓶中溶氧量的变化是瓶中生物           之差,这些数值可用来研究该水层是否存在光能自养生物,以及它们固定太阳能的多少等问题。

(2)HOOC-CH2-CH2-COOH+2NaOH→-CH2-CH2-COONa+2H2O

    ············································································································ 2分

   FeC4H4O4································································································ 2分

30.(18分)科学家用脉孢霉(一种真菌)为实验材料,对基因的功能进行了深入的研究。

   (1) 野生型脉孢霉在基本培养基上即可生长,基本培养基只含有野生型脉孢霉生长所必

需的最低限度的营养成分。基本培养基中所含的营养要素可以归纳为:       

   (2) 科学家用X射线处理野生型脉孢霉后,发现部分菌株在基本培养基上不能生长。用

X射线处理脉孢霉的目的是       

   (3) 为确定这部分菌株在基本培养基不能生长的原因,科学家们继续做实验:在基本培养基中补充了某种物质,原来不能生长的菌株有的能够生长了。从而获得了三种与野生型菌株不同的突变型菌株A、B、C。实验结果见下表:


鸟氨酸
瓜氨酸
精氨酸
A
生长
生长
生长
B
-
生长
生长
C
-
-
生长

实验分析:在哺乳动物的肝脏中,精氨酸是经过“前体→鸟氨酸→瓜氨酸→精氨酸”的途径合成的。受这种生化观点的启发,科学家们认为:野生型脉孢霉可以利用基本培养基中的某类物质(前体),合成了一系列氨基酸,这些氨基酸应该属于脉胞霉的    代谢产物。

    三种突变型菌株均能在添加了精氨酸的培养基中生长,说明它们均丧失了      的功能。突变菌株B可在添加了瓜氨酸的培养基中生长,但不能在添加鸟氨酸的培养基中生长,原因是它               

   (4) 生化反应都由特定的酶来催化,一个基因突变导致了一个生化反应的不能进行,科学家们由此提出了“一个基因控制合成一个酶”的假说。在进一步的猜测中,有一种观点认为基因突变使细胞合成了一种结构发生改变而失去活性的“酶”。于是有人继续探讨这个问题。一种免疫反应可检测到失活“酶”的存在,科学家们利用这种方法做了下面的实验。

    第一步 设法得到影响上述生化反应的酶,将其纯化制成酶制剂,注射到家兔体内,获得相应的抗酶抗体(能和正常的酶及失活的“酶”发生沉淀反应)。酶制剂在免疫学上属于      

     第二步 在培养皿的琼脂上挖四个圆孔(如图21所示),在0号圆孔中加入抗酶抗体,在2号圆孔中加入野生型菌株提取物,3号圆孔中加入某突变菌株提取物,则1号圆孔中需加入       作为对照。

    第三步0、1、2、3号圆孔中的物质各自在琼脂中扩散,观察1、2、3号圆孔与0号圆孔之间是否出现          。

     实验结果分析:若出现                   结果时,则支持“基因突变使细胞合成了一种失去活性的‘酶’”的推断。

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