Over its lifetime, a low mass star consumes its core hydrogen and converts it into helium. The core shrinks and heats up gradually and the star gradually becomes more luminous. Eventually nuclear fusion exhausts all the hydrogen in the star's core
Photoperiodism is a plant's response to the number of hours of darkness in its environment. b. Plants that flower when exposed to less than 10–12 hours of darkness are called long-day plants.
