Many cactus plants, such as the species shown in the illustration, use a special type of photosynthesis called cam photosynthesis. this specialized process allows the cactus plant to keep the stoma or leaf openings closed during the day. most other plant species keep their stoma open during daylight hours. which is the most likely reason that cactus use this special photosynthetic process?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.