AP BIOLOGY

Detailed explanation-1: -It usually occurs during night or in the morning when the absorption of water exceeds that of the transpiration. Due to which, root pressure is increased in xylem and water comes out through hydathodes. Thus, option B is the correct answer.

Detailed explanation-2: -They measure about 10–20 by 5–8 m and are open in the daytime but are more or less closed at night.

Detailed explanation-3: -Hydrathodes: The holes present at the leaf margin where vascular supply ceases are known as hydathodes. These are found in angiosperms. They are connected through intercellular gaps and xylem to release water droplets.

Detailed explanation-4: -A hydathode is a type of pore, commonly found in angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of the leaf. Water droplets are released from hydathodes on the leaf margin when the absorption of water exceeds transpiration.

Detailed explanation-5: -The epithem cells do not regulate opening and closing of hydathodes. Thus, hydathodes are unregulated openings and are always open.