Simplify the following text for a Grade 12 native English-speaking person.
Original: The Calvin cycle or Calvinâ `` Benson cycle or reductive pentose phosphate cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms .
Simplified: The Calvin cycle ( also known as the Calvinâ `` Benson cycle ) are chemical reactions that take place in chloroplasts during photosynthesis .