OG10 -- Passage 29 -- 关于181题的选项A

Passage 29

It was once assumed that all living things could be

divided into two fundamental and exhaustive categories.

Multicellular plants and animals, as well as many
unicellu-

lar organisms, are eukaryotic—their large, complex cells

(5) have a well-formed nucles and many organelles.
On the

other hand, the true bacteria are prokaryotic cell, which

are simple and lack a nucleus. The distinction between

eukaryotes and bacteria, initially defined in terms of

subcellular structures visible with a microscope, was
ulti-

(10) mately carried to the molecular level. Here
prokaryotic and

eukaryotic cells have many features in common. For

instance, they translate genetic information into
proteins

according to the same type of genetic coding. But even

where the molecular processes are the same, the details
in

(15) the two forms are different and
characteristic of the respec-

tive forms. For example, the amino acid sequences of
vari-

ous enzymes tend to be typically prokaryotic or
eukaryotic.

The differences between the groups and the similarities

within each group made it seem certain to most biologists

(20) that the tree of life had only two stems.
Moreover, argu-

ments pointing out the extent of both structural and
func-

tional differences between eukaryotes and true bacteria

convinced many biologists that the precursors of the

eukaryotes must have diverged from the common

(25)ancestor before the bacteria arose.

Although much of this picture has been sustained by

more recent research, it seems fundamentally wrong in one

respect. Among the bacteria, there are organisms that are

significantly different both from the cells of eukaryotes
and

(30)from the true bacteria, and it now appears
that there are

three stems in the tree of life. New techniques for
deter-

mining the molecular sequence of the RNA of organisms

have produced evolutionary information about the degree

to which organisms are related, the time since they
diverged

(35) from a common ancestor, and the
reconstruction of ances-

tral versions of genes. These techniques have strongly

suggested that although the true bacteria indeed form a

large coherent group, certain other bacteria, the
archaebac-

teria, which are also prokaryotes and which resemble true

(40) bacteria, represent a distinct evolutionary
branch that

far antedates the common ancestor of all true bacteria.

************************************************************************
181. All of the following statements are supported by the
passage EXCEPT:

(A)  True bacteria form a distinct evolutionary group.

(B)  Archaebacteria are prokaryotes that resemble true
bacteria.

(C)  True bacteria and eukaryotes employ similar types of
genetic coding.

(D) True bacteria and eukaryotes are distinguishable at the
subcellular level. (E)

(E)  Amino acid sequences of enzymes are uniform for
eukaryotic and prokaryotic organisms.

我对答案E没疑问，但对答案A有点疑惑。

L37-38先是让步说the true bacteria indeed form a large coherent group，然后又说archaebacteria represent a distinct evolutionary branch。

这个coherent group和distinct evolutionary branch明显是不同的概念，前者是老观点认为的two-category的一支，也就是prokaryotic，后者是新观点认为的从prokaryotic分离出的一支，也就是archaebacteria。
答案A说True bacteria form a distinct evolutionary group，这个distinct evolutionary group到底指的是前者还是后者呢？令人很费解

OG的解释也写得乱七八糟的我看不懂：

Lines 37-38 support the idea that “true bacteria indeed form a large coherent group” of the kind postulated by the two-category hypothesis-that, that they are a “distinct evolutionary group” (choice A).