Passage Summary:
P1: (Before) brain guided by electrical sig
(Alt) chemical
P2: Alt won acceptance but scientists wonder about mechanism
Now there comes convincing explanation about structure of receptor
P3: Mechanism
P4: Implication -> drug
Q1 Main point (A vs D)
(A) Evidence shows that the workings of the brain are guided, not by electrical signals, but by chemicals, and that subtle differences among the receptors for these chemicals may permit the selective treatment of certain brain disorders.
(D) Evidence shows that electrical impulses are transmitted between neurons chemically rather than electrically, and that subtle differences among the receptors for these chemicals may permit the selective treatment of certain brain disorders.
The latter part is the same, but the former part of D is more precise.
Q2 Attitude = medically significant
(A) certainty that its possible benefits will be realized (pos but notice maybe)
(B) optimism about its potential applications (pos - ans)
(C) apprehension about the possibility of its misuse (neg)
(D) concern that its benefits are easily exaggerated (neg)
(E) skepticism toward its assumptions about the brain (neg)
Q3 supported EXCEPT
(A) The secretion of certain chemicals plays a role in neuron communication.
(B) The flow of ions through neurons plays a role in neuron communication.
(C) The binding of neurotransmitters to receptors plays a role in neuron communication.
(D) The structure of receptors on neuron surfaces plays a role in neuron communication. (Ans = opposite)
(E) The size of neurotransmitter binding sites on receptors plays a role in neuron communication.
Q4 defined categories of neurons = neurons that impede or enhance effects (=brain disorder)
(A) possess channels for ions
(B) respond to drug treatment
(C) contain receptor molecules
(D) influence particular brain functions (Ans)
(E) react to binding by neurotransmitters
Q5 organization
(A) explanation of a theory; presentation of evidence in support of the theory; presentation of evidence in opposition to the theory; argument in favor of rejecting the theory; discussion of the implications of rejecting the theory (no evidence supporting former -> WRONG)
(B) explanation of a theory; presentation of evidence in support of the theory; explanation of an alternative theory; presentation of information to support the alternative theory; discussion of an experiment that can help determine which theory is correct (same as A -> WRONG)
(C) explanation of a theory; description of an obstacle to the theory’s general acceptance; presentation of an explanation that helps the theory overcome the obstacle; discussion of a further implication of the theory (YES -> ANS)
(D) explanation of a theory; description of an obstacle to the theory’s general acceptance; argument that the obstacle is insurmountable and that the theory should be rejected; discussion of the implications of rejecting the theory (insurmountable -> WRONG)
(E) explanation of a theory; description of how the theory came to win scientific acceptance; presentation of new information that challenges the theory; modification of the theory to accommodate the new information; discussion of an implication of the modification (even if theory stated is alt then presentation of new info that challenges theory is WRONG)
Q6 Purpose (Notice widely accepted = alternative!)
(A) propose a new theory about the workings of the brain (the author does not propose by himself! he just present the new one)
(B) introduce evidence that challenges a widely accepted theory about the workings of the brain (No given that it is alternative)
(C) describe the approach scientists use when studying the workings of the brain (No - only explanation, not approach)
(D) discuss new support for a widely accepted theory about the workings of the brain (YES - convincing explanation to alt)
(E) illustrate the practical utility of scientific research into the workings of the brain (No - only in last P)