Final answer:
In plants, the leaves, specifically the mesophyll tissue, contain the highest concentration of chloroplasts due to their role in photosynthesis. The chloroplasts absorb light energy for photosynthesis, and the stroma within chloroplasts is the site for light-independent reactions.
Step-by-step explanation:
The highest concentration of chloroplasts is expected to be found in the leaves of plants. Chloroplasts are the organelles where photosynthesis occurs, and leaves provide a large surface area for light absorption. Due to leaves being the main sites for photosynthesis, which is the process by which plants synthesize food from light, water, and carbon dioxide, chloroplasts are abundant in the mesophyll tissue of the leaf. This is the layer with cells rich in chloroplasts that absorb light energy for photosynthesis. When examining a leaf under a fluorescent microscope, the mesophyll would fluoresce in the red region of the spectrum because of the presence of chlorophyll.
When considering a mutant plant with roots that grow in all directions, the absence of amyloplasts, which are involved in gravity perception, might be the cause of such disoriented growth. Amyloplasts contain dense starch grains that settle in response to gravity, helping the plant determine the direction down towards the soil.
When testing the effects of a new fertilizer on lawn growth, targeting the vascular bundles is important as they contain the xylem and phloem which transport nutrients and water throughout the plant. For an experiment isolating meristematic tissue, which is the region of active growth, samples from areas such as the tips of the roots or stems are ideal as they contain cells that are rapidly dividing.
Lastly, when investigating the light-independent reactions of photosynthesis in plant cells, these reactions occur in the stroma of the chloroplasts.