Which piece of scientific knowledge best supports the idea of the cell theory that cells come from existing cells? Cells are the smallest structures that carry out specialized functions in a living organism.
Chromosomes are copied during the replication process.
Multicellular organisms have chromosomes located in membrane-bound nuclei.
Some members of a species display a trait due to mutations in genetic coding.

when it is at an intermediate population density

the answer to the blank provided is “an autosomal gene that is required for the expression of genes on the x chromosome”.

testis-determining factor, abbreviated as td, which is more popularly known as sex-determining region y or sry protein, is a dna-binding protein or  gene-regulatory protein/transcription factor, encoded by the  sry gene. it is the gene responsible for the initiation of male gender determination in humans.