Usually if we are talking about needles and body fluids, They are usually put into a box that is labeled hazard! And they dispose of the materials in a special trash can! :) Hope this helps!
Answer:
They difference in phenotypes is dependent on the genes. The more dominant gene will overpower a recessive gene, or if there are two recessive genes together, that will be the phenotype. When things are cross breaded they introduce different genotypes that allow for different looking phenotypes.
Example: Dominant blue flower (Bb) mixed with recessive yellow flower (bb)
B b
b Bb bb
b Bb bb
There is a 50/50 chance the offspring will be either blue or yellow