Answer:
In humans, the major precursors from which glucose can be synthesized from are:
1. glycerol from triacylglycerols
2. glucogenic amino acids from protein.
3. Oxaloacetate formed from CO2
4. Pyruvate foem pyruvate carboxykinase
All there's are routes through which the body obtains glucose to replenish body glucose levels
There is no pigment in the brain, so it is in it's natural colour, grey.
