Living components in a river ecosystem would include all plants, all animals, all microorganisms. Every fish species, every arthropod species, every reptile and amphibian species, all the birds, etc.
I'm guessing Liver.
If it was in the stomach, we wouldn't get belly aches. If it were in the large intestine, we wouldn't poop. So that's my guess.
Answer:
The observable traits expressed by an organism are referred to
EXPLANATION:
An organism's underlying genetic makeup, consisting of both physically visible and non-expressed alleles, is called its genotype. Mendel's hybridization experiments demonstrate the difference between phenotype and genotype.