Why are green algae placed in the Protista while plants are placed in a separate kingdom? October 4, 2022 by 8i9x6 The green algae use chlorophyll a,while plants use chlorophyll b. Green algae have a cell wall of chitin,while plants have cell walls of cellulose. Plants enclose and protect the embryo within the seed,while green algae do not. All plants are vascular,while all green algae are nonvascular. Algae reproduce only asexually,while plants reproduce sexually. See Answer Plants enclose and protect the embryo within the seed,while green algae do not.