Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for the Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science exam. Utilize flashcards and multiple-choice questions with hints and explanations to succeed in your certification.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

What controls the size of the stomata in leaves?

Palisade mesophyll
Spongy mesophyll
Guard cells
Epidermis

The correct answer is: Guard cells

The size of the stomata in leaves is controlled by guard cells. These specialized cells flank each stoma (the small openings on the leaf surface) and regulate its opening and closing, which in turn controls gas exchange and water loss. When guard cells take up water and become turgid, they swell and bend away from each other, causing the stoma to open. Conversely, when they lose water and become flaccid, they relax and move closer together, leading to the closure of the stoma. This dynamic adjustment allows the plant to optimize its gas exchange while minimizing water loss, particularly in varying environmental conditions. The other options, while important to leaf structure and function, do not directly regulate the opening and closing of stomata. Palisade mesophyll primarily facilitates photosynthesis, spongy mesophyll aids in gas exchange due to its air spaces, and the epidermis serves as a protective layer for the leaf. Thus, it is the guard cells that play the critical role in controlling the size of the stomata.