TOEFL Reading Practice Test #42

Explanation:
In the passage, animals are said to "secrete" pheromones, which are chemical signals. In this context, "secrete" means to give off or emit, especially biologically.

(C) produce is correct because it matches this meaning.

(A) hide is incorrect—secreting is the opposite of hiding.

(B) intend is unrelated to emitting chemicals.

(D) collect is the reverse action; animals aren't gathering chemicals but releasing them.

Explanation:
The paragraph clearly states that the X-ray studies disproved the idea that the tines go into the VNO openings. Instead, the tongue places molecules on pads at the bottom of the mouth, which are then pressed against the VNO.

(D) is correct; it reflects this discovery.

(A) is true, but it was known before the X-ray studies—it wasn’t what the studies discovered.

(B) is also true but is background information, not a result of the study.

(C) is incorrect; nothing in the paragraph states this.

Explanation:
The context describes the tongue sensing chemical stimuli at two points at once, just like two ears detecting sound.

(B) is correct.

(A) confuses method with timing.

(C) refers to spatial separation, not timing.

(D) is unrelated to time or process.

Explanation:
The hypothesis explains that the forked tongue samples two spatially distinct points, enhancing the ability to detect gradients in odor trails.

(D) is correct.

(A) is incorrect because it's not about verifying one tine with the other.

(B) incorrectly assumes a backup function.

(C) falsely splits functions between tines.

Explanation:
Paragraph 5 states that snakes and lizards spread the tines apart while collecting odor molecules, which helps sample differences in the trail.

(C) is correct.

(A) is not mentioned anywhere.

(B) is not supported by the text.

(D) describes withdrawal, not trail-following.

Explanation:
The paragraph says forked tongues evolved independently at least twice, which supports the hypothesis as a useful adaptation.

(A) is correct.

(B) is not mentioned.

(C) is a generalization not made in the passage.

(D) is too narrow and unsupported.

Explanation:
The paragraph describes each tine connecting to a different brain hemisphere and the nuclei being linked, enabling comparison, like with hearing.

(C) is correct.

(A) misinterprets the analogy.

(B) is false—differentiation is preserved.

(D) contradicts the idea of comparing signals across hemispheres.

Explanation:
These insects use paired odor-detecting structures for the same purpose—tracking mates or prey.

(A) captures this parallel.

(B) contradicts the passage.

(C) is partially true but not the main point.

(D) misrepresents the comparison.

Explanation:
[■][1] – Incorrect:
This sentence is focused on the physical mechanism of how tongue tines gather odor molecules. Inserting a paraphrase here would interrupt the detailed description of chemosensory sampling.

[■][2] – Correct:
This is the ideal position because the inserted sentence summarizes the function of forked tongues and directly prepares the reader for the comparison between lizards that do and do not forage widely. The phrase “in other words” fits naturally here as a lead-in to that contrast.

[■][3] – Incorrect:
This point introduces the idea that forked tongues evolved multiple times. Inserting a functional summary here would shift focus backward and interrupt the evolutionary argument.

[■][4] – Incorrect:
This section discusses neurological anatomy and parallels with auditory processing. A sentence about odor trail tracking would not fit this more technical shift in topic.

Correct Answers:
B. Browman’s hypothesis was replaced by the hypothesis that forked tongues function as organs of spatial chemical perception.
C. The readings obtained by each tine are processed separately and can thus be compared, a feature shared by other systems of spatial perception.
E. The tines are a pair of sensory organs that allow snakes to detect the edges of odor trails laid down by prey or potential mates.

Explanations:

(B) introduces the newer, correct hypothesis.

(C) explains how the nervous system supports spatial comparison.

(E) describes the function of forked tongues in odor trail tracking.

(A) is too vague and unmentioned.

(D) misrepresents the VNO's functionality.

(F) is false—snakes do not secrete odor trails with the VNO.