9. write another analogy that describes the
process of electron carriers.

Electron carriers can be in oxidized or reduced form. NAD+ is the oxidized form of electron carrier. FAD is another example of electron carrier. In regards to analogy, laundry basket with warm laundry.

Explanation:

The electron carriers travels from higher energy or higher electron level to lower energy or lower electron level. The laundry basket which contains warm laundry shows astonishing analogy to the process of electron carriers. The laundry basket here is represented by the electron carrier. The electrons in higher energy level are represented by the warm laundry that have undergone through a process of highly energy generative movements.

d. planting trees

the trees take in carbon to make oxygen.