Biology Regents Practice Exam

Why are root cells and leaf cells in plants not identical despite having the same genetic material?

1. They use different genetic bases for the synthesis of DNA

2. They use different parts of their genetic instructions

3. Select different cells to express

4. They delete different sections of their enzymes

The correct answer is: They use different parts of their genetic instructions

Root cells and leaf cells in plants are not identical, despite sharing the same genetic material, because they utilize different parts of their genetic instructions. This phenomenon is a result of gene expression, where specific genes are activated or deactivated depending on the cell type and its function. Root cells and leaf cells have distinct roles in the plant; for example, root cells are primarily involved in nutrient and water absorption, while leaf cells conduct photosynthesis. Therefore, each type of cell expresses only the genes that are relevant to its function. Although the genetic material is the same in terms of DNA content, the specific patterns of gene expression lead to different protein production and ultimately different cell structures and functions. Understanding that cells can share genetic material but still develop into different cell types due to selective gene expression is fundamental to the study of biology. This concept is crucial for grasping how multicellular organisms maintain diverse functions and structures despite having a common genome.