If genes are on different chromosomes, the law of independent assortment states that - gene pairs always stay together

half an organism's gametes have one allele per pair

gene pairs segregate randomly and independently of each other.

one allele is always dominant

Gene pairs segregate randomly and independently of each other.

Explanation:

Genes are the basic units of hereditary and are located on chromosomes. According to Gregor Mendel's law of independent assortment  which states that the alleles of two (or more) different genes are sorted into gametes independently of one another. This means that the allele a gamete receives for one gene does not influence the allele the same gamete receives for another gene.

For example, in a the pea plants used by Mendel in his studies, the genes for seed shape and flower color were inherited independent of each other by the offspring of the parent pea plants. Therefore, Mendel concluded that the inheritance of each trait was independent of the other.

Excretory as in excretes things anus, bladder, etcetera release waste products.
In cells, the vacuole disposes of waste.
Sweat glands secrete, well, sweat, which can also release toxins from the body.
That's about all I can think of at the moment...