There is about 1,000 times as much DNA in a human cell as in a bacterial cell, but only 5 times as many genes. What accounts for this discrepancy? The DNA packing is much more complex in a prokaryotic cell A human cell has much more non coding DNA Most of the genes in a human cell are turned off Human cells are much larger than bacterial cells

Phenotypic plasticity

Explanation:

Humans have evolved over thousands of years to adapt to various environmental changes. For example, when we are in an environment that requires certain level of adaptation our off spring often formalizes epigenetic traits that lows them to overcome small changes in the environment. Over time certain genes that are turned on may remain on and eventually the ones that are off remains off. This give rise to some genes that "don't work"  after millions of years of such evolution we end up with a complex genome with more DNA than "working genes".

there are more non-coding DNA in human cells.

Explanation:

The discrepancy is due to presence of non-coding DNA-introns in the cells of human. Generally not all the  DNA molecules contain genes that codes for proteins in human. Only a fragment, about 1 % , of the DNA molecule contains the genes that codes for protein to be expressed. Larger percentage of the whole segments of the  DNA molecules contains 'Junk' DNA,called introns, which do not code for any protein thus reducing the numbers of genes for coding  in the DNA molecule of  human cells..

Nonetheless they perform other regulatory and control activities  during gene expression for protein synthesis. Example are the promoters and enhancers  which provides binding to initiate and promote transcription,Silencers, which provides sites for repressing transcriptions, and Insulators  that provides binding sites for control of transcription by proteins.

, Thus despite the fact that these genes  do not code for any proteins, their abundant presence (almost 90% in the human DNA),help to control and sustain gene expression.

that is wrong, its not thymus.