What three processes take place in the digestive system?

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

During the day, plants produce by splitting water molecules in the light-dependent reactions of photosynthesis. at the same time, plants use cellular respiration to produce some of the needed by the light-independent reactions to make sugars. during the night, plants produce because takes place.

Explain how organisms could be harmed by high levels of salt from roadways?