Answer:
u should know this, it is an opinion
We were not able to see microtubules, centrioles, rough endoplasmic reticulum, smooth endoplasmic reticulum, plasma membrane, ribosomes, golgi apparatus, vesicle, mitochondrion and chloroplast.
The liver is your largest internal organ. About the size of a football, it's located mainly in the upper right portion of your abdomen — beneath the diaphragm and above your stomach — but a small portion extends into the upper left quadrant.
excretory system: removes waste from blood.
respiratory system: obtains oxygen so the energy in the nutrients can be extracted.
circulatory system: transports nutrients from small intestine to the othet tissues.
nervous system: regulates and controls digestive functioning.
( Am not completly sure, but i think this is the answer)