7. (a) (i) Why is a dicotyledonous (dicot) plant so called? ......................................................................... - Leaving Cert Biology - Question 7 - 2014

One key function of vascular tissue in plants is to transport water and nutrients. Xylem tissue is responsible for the upward movement of water and dissolved minerals from the roots to other parts of the plant, while phloem tissue transports the products of photosynthesis (such as sugars) from the leaves to the rest of the plant.

The plant that was used for this observation is a herbaceous plant, for example, a young sunflower (Helianthus annuus) or a common bean (Phaseolus vulgaris).

A herbaceous (non-woody) stem was used because it is easier to cut into thin sections compared to a woody stem. The softer tissues of a herbaceous plant allow for more precise slicing, making it more suitable for microscopic examination.

To prepare the stem section, I first selected a young herbaceous plant and used a sharp knife to cut a thin slice of the stem. I then placed the slice in a drop of water on a microscope slide to keep it hydrated. A cover slip was gently lowered onto the sample to flatten it and eliminate air bubbles, ensuring optimal visibility under the microscope.

To examine the section of stem with the microscope, I turned on the light source and adjusted the mirror to improve illumination. I started with a low power objective lens to locate the sample, then switched to a higher power objective for detailed observation. Focusing the microscope involved adjusting the coarse focus knob initially, followed by the fine focus to get a clearer view of the vascular tissues.

In the diagram, I would represent a transverse section of the dicot stem showing three main types of tissue: the ground tissue in the center, with the xylem on one side and phloem on the other. Labels on the diagram would clearly indicate 'Ground Tissue,' 'Xylem,' and 'Phloem,' each associated with their respective parts in the structure.