Differences in development of leaf and root cells from genetically identical cells are due to what process?

• A. Differential gene expression.
• B. Random mutation.
• C. DNA sequence changes in different cells.
• D. Environmental factors change DNA.

Answer: (A)

Differential gene expression drives the development of leaf versus root cells from genetically identical cells. Even though every cell starts with the same DNA, different cells activate different sets of genes in response to positional cues and regulatory signals. Transcription factors, signaling molecules, and epigenetic marks determine which genes are on or off in a given cell, guiding it toward a leaf or a root identity.

Mutations would change the DNA sequence itself, which is not how normal development creates distinct tissues. Environmental factors don’t rewrite DNA; they can influence gene activity through signaling and epigenetic changes, but the genome remains the same.