Why do guard cells have chloroplasts?

Guard cells become turgid as water (H2O) diffuses in by osmosis, and flaccid as water diffuses out. The water in a system will diffuse to the side of the membrane with the more negative (-), or lower, water potential. Water potential is influenced by solute (ion) concentration and pressure. read more

Guard cells require ATP to function, as do all cells. Chloroplasts conduct photosynthesis to make simple sugars for energy and structure. Mitochondria conduct respiration, oxidizing simple sugar to make ATP for cellular activity. read more

If the chloroplasts are functional, sugars would be produced, changing the osmotic potential within the guard cell. Water would enter in response to this change in potential and the guard cells would open the stoma wider. read more

Best Answer: Because guard cells have chloroplasts, they make sugars when the light is bright enough. Then the guard cells have more sugars than the surrounding cells, water enters the guard cells to equal out the water concentration, and the guard cells swell to open the stomata. read more