Answer & Explanation:
<u><em>Prokaryote</em></u>: a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Prokaryotes include the bacteria and cyanobacteria.
<u><em>Characteristic of prokaryote</em></u>: lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration.
<em><u>Eukaryote</u></em>: an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. Eukaryotes include all living organisms other than the eubacteria and archaebacteria.
<u><em>Characteristic of eukaryote</em></u>: larger than prokaryotic cells and have a “true” nucleus, membrane-bound organelles, and rod-shaped chromosomes. The nucleus houses the cell's DNA and directs the synthesis of proteins and ribosomes
Answer:
only 30% of total energy will be useful ..
So, Useful energy =

13.5J energy is useful
I believe it is because the sun is directly over us which cause more heat since it is beating down. be sure to get a second opinion