The flowers generally so colourful and attractive. why?

Flowers that are bright in color are meant to attract birds, bees and other insects in order to help the plants reproduce. When they land on another flower some of that pollen will spread and voila! Pollination occurs.

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.