Block 2: Algae

Introduction

Alga is a collective term for all chlorophyll bearing organisms which are thalloid. Their body is showing no differentiation into true tissues or organs (such as roots, leaves or stem) and is thus called a thallus. This term is used even if the plant is unicellular. Algae have chloroplasts and produce their own carbohydrates by photosynthesis, as plants do. Due to their phylogenetic position, the green algae are considered as  ancestors of plants and older classification systems placed Algae in the Plantae kingdom. However, algae lack tissue differentiation and thus have no true roots, stems, or leaves. Despite those differences, this group will be studied in this module which is normally allocated to true plants.