* Plants live on land, algae primarily in water: The cuticle is a waxy, protective layer that coats the outer surface of plant leaves and stems. Its primary function is to prevent water loss through evaporation. This is crucial for plants living in terrestrial environments, where water is scarce and the air is dry. Algae, on the other hand, live in water, where water loss is not a significant concern. In fact, a thick cuticle would hinder their ability to absorb water and nutrients from the surrounding environment.
* Cuticle's role in gas exchange: While the cuticle helps retain water, it also presents a barrier to the exchange of gases (like carbon dioxide and oxygen). Plants have evolved specialized openings called stomata on their leaves to regulate gas exchange. These stomata can open and close to allow for the passage of gases while minimizing water loss. Algae don't have stomata, as they can readily exchange gases directly through their cell membranes.
In summary:
* Cuticle is an adaptation for terrestrial life that prevents water loss.
* Algae do not need a cuticle because they live in water and can readily exchange gases.
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