Question

which sentence describes a bone cell and a nerve cell in a petunila plant?
a. they have the same genes, and all of those genes are expressed.
b. each cell contains only the genes that are needed for the unique function.
c. their genes change as their structures change during cell differentiation.
d. they have identical dna, but each cell expresses a different set of genes.

Explanation:

• Option A: All genes are not expressed in every cell. Different cells have different functions and thus express different subsets of genes. So, this option is incorrect.
• Option B: All cells (except some special cases like mature red blood cells in humans which lose their nucleus) contain the full set of genes of the organism. They do not just have the genes needed for their function. This option is wrong.
• Option C: Gene content does not change during cell differentiation. The process of cell differentiation is due to differential gene expression, not a change in the genes themselves. So, this option is incorrect.
• Option D: Bone cells and nerve cells (and all other somatic cells of an organism) have the same DNA (genome) because they are derived from the same zygote. However, they express different sets of genes. For example, bone - specific genes (like those for collagen in bone matrix) are highly expressed in bone cells and not in nerve cells, while nerve - specific genes (like those for neurotransmitter synthesis) are highly expressed in nerve cells. This option is correct.

Answer:

D. They have identical DNA, but each cell expresses a different set of genes.