Why do plants store energy as carbohydrates and not as fats?

Question

In my introductory biology class, we are learning about biomolecules. The textbook says fats are a more efficient energy store than carbohydrates.So my question is - why would plants store their energy as carbohydrates and not as fats, if fats are a more efficient energy store?

Answer 1

Plants use both carbohydrates and fats to store energy. Plants that have leaves or similar leaflike structures use carbohydrates to store their energy during their lifespan. This is because of the two reactions that are producing ATP in the chlorophyl of the leaves of the plant. These two reactions are photosynthesis and cellular respiration.

Photosynthesis happens in chloroplast in the presence of sunlight and takes the available water and the carbon dioxide from the air and converts it into glucose, oxygen, and ATP.  

Carbon Dioxide + Water -------> Glucose + Oxygen + ATP(energy)

In the dark(mostly), the reaction goes in the opposite direction and we rename it cellular respiration. In cellular respiration the glucose and oxygen now generate carbon dioxide, water and ATP.  

Glucose + Oxygen -------> Carbon Dioxide + Water + ATP(energy)

The plant can easily convert the glucose from photosynthesis into carbohydrates and starch. The rest of the glucose that the plant does not use right away is converted into fats for additional storage. Many seeds for the next generation contain fats and carbohydrates as a means of storage of energy.