Question

If we kept the plant in a dark room until 2 hours after dawn then

• A. The stomata would open anyway
• B. The stomata would stay closed until they received the light stimulus
• C. The stomata would stay closed all day
• D. Photosynthesis would increase

Answer 1

The correct option is B The stomata would stay closed until they received the light stimulus

If we kept the plant in a dark room for 2 hours after dawn it, the stomata would obviously stay enclosed till receiving the sunlight because of the opening and closing of the stomata is controlled by the guard cells. In the light, guard cells take up water by osmosis and become turgid. Because their inner walls are rigid they have pulled apart, opening the pore. In the darkness, water is lost and the inner walls move together closing the pore. Because of this, the transpiration rate is increased by an increase in light intensity.
So, the correct answer is option B.