Why do artificial plant-growth light have a light spectrum that favor the blue and red portions of the spectrum?

It's because the main photosynthesis component (Chlorophyll) mostly absorbs red and blue portions. It reflects the green portions which is why most plants are green

Glucose, also called grape sugar, blood sugar or corn sugar, is among the simplest and one of the primary naturally occurring sugars. produced naturally by plants as the primary photosynthesis product, it is heavily used by living beings as a main energy source and is necessary for cellular respiration. chemically, it is a monosaccharide carbohydrate and serves as a building block for complex sugars like starch.