A species of Byropsis algae produces toxins to avoid being eaten by predators. However, in some cases, the toxins the...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

Sentence 1:

• A species of Byropsis algae
  • produces toxins
    • to avoid being eaten by predators.

Sentence 2:

• However,
  • in some cases,
• the toxins
  • the organism uses
    • to protect itself from predation
• actually [?] its attractiveness to predators.

Sentence 3:

• The Hawaiian sea slug, for example,
  • not only tolerates Byropsis toxins
  • but actually uses them
    • for protection
      • in the same way the algae does.

Understanding the Meaning

Let's start reading from the beginning:

The first sentence tells us:

• A species of Byropsis algae produces toxins to avoid being eaten by predators.
  • So this algae makes toxic chemicals as a defense mechanism.

Now the second sentence starts with a contrast:

• 'However, in some cases...'
  • This signals that something unexpected is coming.

The sentence continues:

• 'the toxins the organism uses to protect itself from predation'
  • We're talking about those same toxins
  • 'the organism uses to protect itself from predation' is giving us more information about these toxins - these are the protective toxins

Now here's where we need to fill in the blank:

• 'the toxins...actually ______ its attractiveness to predators.'

Let's look at our choices:

1. is increasing
2. increase
3. increases
4. has increased

What do we need here? Let's identify what word needs to match with what:

• The subject doing the action is 'the toxins' - that's plural
• So we need a plural verb form

• We're also describing a general scientific pattern that happens (not something currently in progress or something that already happened)
• So we need simple present tense

Looking at our choices:

• Only 'increase' is plural and simple present

So we need: increase

Now let's finish reading to see the complete picture:

• 'The Hawaiian sea slug, for example, not only tolerates Byropsis toxins but actually uses them for protection in the same way the algae does.'
  • This gives us a concrete example
  • The sea slug doesn't just tolerate the toxins - it actually benefits from them
  • This explains how the toxins can make the algae MORE attractive to certain predators (like this slug)

The complete meaning is:

• While the algae produces toxins to repel predators, paradoxically, these same toxins actually make the algae more attractive to some predators (like the Hawaiian sea slug) who use those toxins for their own protection.

What do we notice about the structure here?

• The subject is 'the toxins' (plural)
• There's a descriptive phrase in between - 'the organism uses to protect itself from predation' - that's giving us more information about which toxins we're talking about
• But the main structure is: 'the toxins...increase'
• The verb must match the subject 'the toxins,' not 'the organism' which appears in that middle descriptive part

So we need: Choice B: increase

GRAMMAR CONCEPT APPLIED

Matching Verbs to Their Subjects When Words Come Between Them

The verb in a sentence must match its subject in number (singular or plural). The tricky part is when other words or phrases come between the subject and the verb - you might be tempted to match the verb to a nearby noun instead of the actual subject.

The pattern to follow:

1. Find the true subject - what is doing the action?
2. Ignore intervening descriptions - phrases that give extra information about the subject
3. Match the verb to the subject

Example from everyday writing:

• Subject alone: The results show a pattern
• Subject with description: The results from the study show a pattern
• "from the study" describes which results, but doesn't change the subject
• Subject is still "results" (plural) → verb is "show" (plural)

Example with singular noun in between:

• Incorrect: The results from the study shows a pattern
• This wrongly matches "shows" to "study" (singular)
• Correct: The results from the study show a pattern
• Correctly matches "show" to "results" (plural)

In our question:

• Subject: "the toxins" (plural)
• Intervening description: "the organism uses to protect itself from predation"
• This tells us which toxins we're talking about
• "organism" is singular, but it's not the subject
• Verb: must be "increase" (plural) to match "the toxins"

The complete structure: The toxins [description] increase...