Give at least three proofs that algae belong to the Plant Kingdom, a group of lower plants.

1) Algae belong to the Plant Kingdom, because these are autotrophic photosynthetic organisms with a characteristic cellular structure: the presence of chloroplasts, vacuoles and a cell wall. 2) Algae are lower plants, because they have no organs (no roots, no stems, no leaves), their vegetative body is a thallus, or thallus. They have unicellular gametangia. 3) Algae, like lower plants, do not have tissues (or, there is no differentiation of the body into tissues).