SPANISH SPEAKERS ?? Can u help me out pls

What kind of molecules is being released by cellular respiration and used in photosynthesis?

Proyecto: ¡a conversar! this project serves two purposes: to practice using spanish vocabulary that deals with shopping and bargaining to practice describing or giving information in spanish in writing remember, when you're asked to write in spanish, if you know a spanish-speaker, possibly a native speaker, it's to have that person read what you wrote and you make corrections and maybe give you a few ideas on how you can improve your writing skills in spanish. use the spanish vocabulary in this project to you with the conversation you'll write.

Which word would most logically connect these two sentences?