Stomata, tiny pore structures in a leaf that absorb gases needed for plant growth, open when guard cells surrounding each...

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

First sentence:

• Stomata,
  • tiny pore structures in a leaf that absorb gases needed for plant growth,
  open
  • when guard cells surrounding each pore swell with water.

Second sentence:

• In a pivotal 2007 article,
• plant cell biologist [?] Yuree Lee [?]
  • showed
    • that lipid molecules called phosphatidylinositol phosphates
      • are responsible for signaling guard cells to open stomata.

Understanding the Meaning

Let's start with the first sentence to get the context:

• 'Stomata, tiny pore structures in a leaf that absorb gases needed for plant growth,'
  • So stomata are tiny holes in leaves that take in gases plants need to grow.
• 'open when guard cells surrounding each pore swell with water.'
  • These stomata open up when certain cells around them fill with water.

Now the second sentence tells us about a scientific discovery:

• 'In a pivotal 2007 article,'
  • There was an important article published in 2007.

This is where we have the blank:

• 'plant cell biologist ____ Yuree Lee ____ showed that...'

Let's look at the choices:

• We're deciding whether to put commas before "Yuree Lee," after "Yuree Lee," both, or neither.

To see what works here, let's understand what this phrase is doing:

• 'plant cell biologist' is a general job title/description
  • This could refer to many different people.
• 'Yuree Lee' is a specific person's name
  • This tells us exactly WHICH plant cell biologist we're talking about.

Now let's understand the complete sentence:

• It's saying that this person (plant cell biologist Yuree Lee) showed/demonstrated something about lipid molecules.

What do we notice about the structure here?

• The name "Yuree Lee" is essential information
  • Without it, we wouldn't know which biologist the sentence is talking about
  • "Plant cell biologist" alone is too vague - there are many plant cell biologists
  • The name identifies the specific person
• When a name is essential to identifying who you're talking about, it becomes part of the unified subject
  • The title and name work together as one unit: "plant cell biologist Yuree Lee"
  • This unit is the subject that performs the action "showed"

Think of it like this:

• If I said "my friend called," you'd ask "which friend?"
• The name is needed to complete the identification
• So we say "my friend Sarah called" - no commas, because the name is essential

Here, "plant cell biologist" needs "Yuree Lee" to complete the identification of who we're talking about.

So we need no commas - the answer is Choice C: biologist Yuree Lee

The title and name form one unified subject that directly connects to the verb "showed."

Grammar Concept Applied

Using Commas with Names and Titles: Essential vs. Extra Information

When a name follows a title or description, you need to decide: Is the name essential to identify who you're talking about, or is it just extra information?

If the name is ESSENTIAL (restrictive) - you need it to know who the person is - NO commas:

• Example 1: "Physicist Albert Einstein developed the theory of relativity"
  • "Physicist" alone doesn't tell us which physicist
  • We need "Albert Einstein" to identify who
  • No commas needed
• Example 2: "Plant cell biologist Yuree Lee showed that..."
  • "Plant cell biologist" is too general
  • We need "Yuree Lee" to know which specific biologist
  • No commas needed

If the name is EXTRA information (non-restrictive) - the person is already identified and you're just adding their name as a bonus detail - use commas:

• Example 3: "The first person to walk on the moon, Neil Armstrong, became a legend"
  • "The first person to walk on the moon" already identifies exactly who (there's only one)
  • "Neil Armstrong" is just adding the name
  • Commas needed

In our question:

• "Plant cell biologist" = general description (could be many people)
• "Yuree Lee" = essential identification (tells us which specific one)
• Therefore: no commas ✓

This is called a restrictive modifier in grammar terms - information that's essential to the meaning and shouldn't be separated by commas.