Final answer:
The use of starch for storage and cellulose in cell walls by both land plants and algae suggests a close evolutionary relationship and a common ancestry within the group Archaeplastida, which includes both green algae and land plants.
Step-by-step explanation:
The observation that both land plants and algae use starch as a storage medium and cellulose in their cell walls can suggest a close evolutionary relationship between the two groups. This is supported by the presence of shared characteristics, such as chlorophyll a and b, and the production of starch and cellulose.
The Archaeplastida, which include green algae (Chlorophyta) and land plants, are evidence of these shared traits, indicating a common ancestry from a single photosynthetic organism that began to use sunlight for energy, convert it to glucose, and store it as starch for later use.