Do stars emit light only during night?

Who observed that stomata open in light and close in night?

A tree is believed to be releasing oxygen during night time. Do you believe the truthfulness of this statement?

Who did observe that stomata open in light and close in the night:

The colour of the emitted light on an LED depends on …………

A safety vest helps to keep the workers who are working by the roadside safe. This especially so during the nights. Why?