Final answer:
Introns are noncoding sections of DNA that are present in eukaryotic genes, but they are not conserved among all cells.
Step-by-step explanation:
Introns are noncoding sections of DNA that are present in eukaryotic genes. They are not conserved among all cells; their presence and number can vary between different organisms and even between different genes within the same organism.
For example, some genes in certain organisms may have more introns than others, while some genes lack introns altogether. Additionally, the sequences of introns can vary significantly even among related organisms.
Therefore, while introns are a common feature in many eukaryotic genes, they are not universally conserved among all cells.