Question

question 14 (1 point)
what role do guard cells have in plants?
o a they store food for the embryo
b they protect against insects that eat plants
o c they control the size of stomata
d they transport oxygen through the plant

Explanation:

Guard cells are specialized cells in plant leaves. They surround stomata (pores). When guard cells swell (due to water uptake), stomata open; when they lose water and shrink, stomata close. This mechanism controls gas exchange (e.g., intake of \(CO_2\) for photosynthesis and release of \(O_2\)) and water loss (transpiration) in plants.

• Option a: Storing food for the embryo is a function of structures like cotyledons (in seeds), not guard cells.
• Option b: Protection against insects is more related to structures like thorns, trichomes (hairy outgrowths), or chemical defenses (e.g., production of toxins), not guard cells.
• Option c: As explained above, guard cells control stoma size.
• Option d: Transport of oxygen (and other substances like water and nutrients) through the plant is mainly the role of vascular tissues (xylem and phloem), not guard cells.

Answer:

C. They control the size of stomata