Question

A time course is developed to follow the fate of the vascular bundles in the stem of dicots. Sections along the stem are fixed, stained, and observed under a microscope. What happens to the vascular bundles in the stem of a dicot as the plant matures?

a. The vascular bundles join to form growth rings.
b. The vascular bundles divide into primary xylem and primary phloem.
c. The vascular bundles divide into secondary xylem and primary phloem.
d. The vascular bundles die out.

Answer 1

In a mature dicot stem, vascular bundles grow together and form distinctive growth rings, with secondary xylem and secondary phloem developing from the vascular cambium.

Step-by-step explanation:

As a dicot plant matures, the vascular bundles in its stem undergo significant changes. The xylem and phloem in these bundles are arranged in distinct strands and are located around the periphery of the ground tissue when observed in a cross-sectional view. In dicots, as the plant grows, individual vascular bundles grow together and form growth rings, which are characteristic of plants that live more than one year. This process involves the development of secondary xylem and secondary phloem from the vascular cambium, which expands the region between the previously formed primary xylem and primary phloem.

As a dicot plant matures, the vascular bundles in its stem undergo changes. The vascular bundles are initially arranged in a ring close to the margin of the stem. These bundles consist of xylem and phloem tissues which are responsible for transporting water, nutrients, and sugars throughout the plant. As the plant grows, the individual vascular bundles join together and produce growth rings, resulting in the characteristic arrangement of vascular tissue in the stem of dicots.