求助两道短阅读的题目

AnEscapistUID: 3546519

Researchers are finding that in many ways an individual bacterium is more analogous to a component cell of a multicellular organism than it is to a free-living, autonomous organism. Anabaena, a freshwater bacteria, is a case in point. Among photosynthetic bacteria, Anabaena is unusual: it is capable of both photosynthesis and nitrogen fixation. Within a single cell, these two biochemical processes are incompatible: oxygen produced during photosynthesis, inactivates the nitrogenase required for nitrogen fixation. In Anabaena communities, however, these processes can coexist. When fixed nitrogen compounds are abundant, Anabaena is strictly photosynthetic and its cells are all alike. When nitrogen levels are low, however, specialized cells called heterocysts are produced which lack chlorophyll (necessary for photosynthesis) but which can fix nitrogen by converting nitrogen gas into a usable form. Submicroscopic channels develop which connect the heterocyst cells with the photosynthetic ones and which are used for transferring cellular products between the two kinds of Anabaena cells.

1.        The passage supports which of the following inferences about heterocysts?
(A) Heterocysts do not produce oxygen.
(B) Nitrogen gas inactivates heterocysts.
(C) Chlorophyll increases the productivity of heterocysts.
(D) Heterocysts allow nitrogen fixation and photosynthesis to occur in the same cell.
(E) Heterocysts are more important for Anabaena’s functioning than are photosynthetic cells.

2.        The author uses the example of Anabaena to illustrate the
(A) uniqueness of bacteria among unicellular organisms
(B) inadequacy of an existing view of bacteria
(C) ability of unicellular organisms to engage in photosynthesis
(D) variability of a freshwater bacteria
(E) difficulty of investigating even the simplest unicellular organisms

答案：A和B

第一题从文章中可知H中缺少chlorophyll (necessary for photosynthesis)，又不是一点都没有，所以我选的D
第二题我选的A，答案说among unicellular organisms不对，所以选B。

求各位解释下，谢谢！！！

linacreUID: 2468672

第一题的D错在occur in the same cell, 因为固氮需要Submicroscopic channels develop which connect the heterocyst cells... 而且全文主题在第一句已经表明：more analogous to a component cell of a multicellular organism than...
第二题如果A对，全文应该叙述bacteria在单细胞生物中的独特性，换言之，即比较bacteria与其他单细胞生物。但明显主题是bacteria不应是表现为像一个独立细胞而像一个多细胞生物中的一个组成部分。B相比更好是因为认为bacteria是独立生物这个观点是不足的，因为 in many ways an individual bacterium is more analogous to a component cell of a multicellular organism。

AnEscapistUID: 3546519

linacre 发表于 2014-7-27 08:46
第一题的D错在occur in the same cell, 因为固氮需要Submicroscopic channels develop which connect the h ...

看了你的解释，又看了下原文，已经明白了。谢谢~~~