Which existed during the Precambrian era? Protists
Birds
Plants
Mammals
Reptiles
Eukaryotes
Prokaryotes

protists

plants

eukaryotes

prokaryotes

Explanation:

besides a few groups that survive until the present, there were little multi-cellular life forms during the precambrian era

image result for how many calories of energy will 20 grams of carbohydrates provide in one gram provides 4 calories

consuming the right balance of protein, carbohydrates and fat can you maintain a healthy weight and optimize your energy levels. protein and carbohydrates both contain 4 calories per gram, while fat provides 9 calories per gram.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint