Notes:
Para 1: Two type of living organism. Muti Cellular: Eukaryotic (Complex Cell and well formed nucleus). True Bacteria:Prokrayotic (lack nucleus). Tree of life had only two stems.

Para 2: Tree of life has 3 stems. Archebachetria far antedates common ancestors of true bacteria.

1. The passage is primarily concerned with
(A) detailing the evidence that has led most biologists to replace the trichotomous picture of living organisms with a dichotomous one
Wrong. Passage says other way round.
(B) outlining the factors that have contributed to the current hypothesis concerning the number of basic categories of living organisms
Correct.

(C) evaluating experiments that have resulted in proof that the prokaryotes are more ancient than had been expected
Wrong. Passage suggest Archebachetria are older than prokaryotes (true bacteria).

(D) summarizing the differences in structure and function found among true bacteria, archaebacteria, and eukaryotes
Wrong. First para discusses “differences in structure and function found among true bacteria, and eukaryotes”. Moreover it is not complete passage in itself.

(E) formulating a hypothesis about the mechanisms of evolution that resulted in the ancestors of the prokaryotes
Wrong. There is no hypothesis formulated. Only result of studies are given.


2. According to the passage, investigations of eukaryotic and prokaryotic cells at the molecular level supported the conclusion that
This is explained in first para. From “Here prokaryotic and eukaryotic cells have
many features in common” to end of the para 1 it is all about molecular similarities and differences.
(A) most eukaryotic organisms are unicellular
Wrong. This is explained initially at start of the para but not with regard to molecular structure.

(B) complex cells have well-formed nuclei
Wrong. This is explained initially at start of the para but not with regard to molecular structure.

(C) prokaryotes and eukaryotes form two fundamental categories
Seems Correct. Para 1 says “The differences between the groups and the similarities within each group made it seem certain to most biologists that the tree of life had only two stems”

(D) subcellular structures are visible with a microscope
Question is asking about “molecular” level so nothing to do with “sub cellular” although this is true. As explained in para 1.

(E) prokaryotic and eukaryotic cells have similar enzymes
Wrong. Para 1 says “the amino acid sequences of various enzymes tend to be typically prokaryotic or eukaryotic” means they are different.


3. According to the passage, which of the following statements about the two-category hypothesis is likely to be true?
Referring notes we see para 1 tells “tree of life” has two stems, but para 2 tells that “tree of life” has 3 stems. So “two-category hypothesis” is not promising, it is flawed.

(A) It is promising because it explains the presence of true bacteria-like organisms such as organelles in eukaryotic cells.
Wrong

(B) It is promising because it explains why eukaryotic cells, unlike prokaryotic cells, tend to form multicellular organisms.
Wrong

(C) It is flawed because it fails to account for the great variety among eukaryotic organisms.
2 category hypotheses is false because there is 3 categories not because earlier hypothesis cannot account for eukaryotic organisms.

(D) It is flawed because it fails to account for the similarity between prokaryotes and eukaryotes
2 category hypotheses is false because there is 3 categories not because it fails to account for similarity. In fact study does says at few instances these two seems similar.

(E) It is flawed because it fails to recognize an important distinction among prokaryotes.
Seems Correct. There is a third divison which is kind of “prokaryotes” but predates it.


4. It can be inferred from the passage that which of the following have recently been compared in order to clarify the fundamental classifications of living things?
Para 2 says “New techniques for determining the molecular sequence of the RNA of organisms”. So most probably it is study of molecular sequences of RNA.
(A) The genetic coding in true bacteria and that in other prokaryotes
Wrong. “True Bacteria” and “prokaryotes” are same thing. But in all possibility study was done of all three structures.

(B) The organelle structures of archaebacteria, true bacteria, and eukaryotes
Hold it. Look promising.

(C) The cellular structures of multicellular organisms and unicellular organisms
Wrong. “Muticelluar” and “unicellular” are Eukaryotes only and we need all the 3 structures.
(D) The molecular sequences in eukaryotic RNA, true bacterial RNA, and archaebacterial RNA
Looks promising. I will drop B and select this as best choice.

(E) The amino acid sequences in enzymes of various eukaryotic species and those of enzymes in archaebacterial species
Wrong. May be true. But new study also concluded about “true bacteria” so I will discount this.


5. If the “new techniques” mentioned in line 31 were applied in studies of biological classifications other than bacteria, which of the following is most likely?
(A) Some of those classifications will have to be reevaluated.
Seems OK. As study of bacteria revealed different classification so there are chances that study of other life form may also yield similar support.

(B) Many species of bacteria will be reclassified.
It classified bacteria into 2 class not into many species. Moreover question is asking about “biological classifications other than bacteria” not on bacteria.

(C) It will be determined that there are four main categories of living things rather than three.
Wrong. May be true, may be not. Not supported. Moreover question is asking about “biological classifications other than bacteria” not on bacteria.

(D) It will be found that true bacteria are much older than eukaryotes
Wrong. May be true, may be not. Not supported. Moreover question is asking about “biological classifications other than bacteria” not on bacteria.

(E) It will be found that there is a common ancestor of the eukaryotes, archaebacteria, and true bacteria.
Wrong. May be true, may be not. Not supported. Moreover question is asking about “biological classifications other than bacteria” not on bacteria.


6. According to the passage, researchers working under the two-category hypothesis were correct in thinking that
(A) prokaryotes form a coherent group
Wrong not supported.

(B) the common ancestor of all living things had complex properties
Wrong. Not supported.

(C) eukaryotes are fundamentally different from true bacteria
Seems Correct.

(D) true bacteria are just as complex as eukaryotes
Wrong. Not supported.

(E) ancestral versions of eukaryotic genes functioned differently from their modern counterparts
Wrong. Not supported.


7. All of the following statements are supported by the passage EXCEPT:
(A) True bacteria form a distinct evolutionary group.
True. “there are organisms that are significantly different both from the cells of eukaryotes and from the true bacteria”
(B) Archaebacteria are prokaryotes that resemble true bacteria.
True. “the archae bacteria , which are also prokaryotes and which resemble true bacteria”
(C) True bacteria and eukaryotes employ similar types of genetic coding.
Ture. “RNA of organisms have produced evolutionary information about the degree to which organisms are related”
(D) True bacteria and eukaryotes are distinguishable at the subcellular level
True. “The distinction between eukaryotes and bacteria, initially defined in terms of sub cellular structures visible with a microscope”
(E) Amino acid sequences of enzymes are uniform for eukaryotic and prokaryotic organisms.
False (so correct answer). “the amino acid sequences of various enzymes
tend to be typically prokaryotic or eukaryotic”



8. The author’s attitude toward the view that living things are divided into three categories is best described as one of
Para 2 says “it now appears that there are three stems in the tree of life”. Which inidiates that author is sort of accepting it.
(A) tentative acceptance
Correct.

(B) mild skepticism
Wrong. There is no point which indicates author is skeptic about the claim.

(C) limited denial
Wrong. Author is accepting it and not denying it.

(D) studious criticism
Wrong. Author is accepting it and not criticizing it.

(E) whole hearted endorsement
Wrong. Although author does accept it but no where in passage it suggest that author is very positive about it.

Buddy please post OAs. I would like to confirm my answers.

Dude its awesome thanks so much. I need to clarify one thing in question 7. Is E wrong just because it did not use the term "various". And since it did not use that term is that sentence mean all of the enzymes??