What did Schleiden propose about plants?

Schleiden proposed that all plants are made of different kinds of cells, which is a foundational concept in the field of biology. He was one of the key figures in the development of cell theory, stating that the plant body is composed of various cell types that perform different functions. This idea helped to establish the understanding that cells are the basic unit of life in all living organisms, including plants. Schleiden emphasized that these cells are organized into tissues, which in turn form the organs of the plant.

The other options mention aspects that either do not primarily relate to Schleiden’s contributions or inaccurately represent plant biology. For example, while it is true that plants utilize photosynthesis to produce energy, this was not Schleiden's specific focus. Additionally, describing plants as having unique metabolic pathways does not align with his main proposition. Similarly, the suggestion that plants exhibit muscular movement does not fit within Schleiden’s theories, as plants do not have muscles or the capacity for movement in the way that animals do. This underscores the importance of understanding the central role that cells play in the structure and function of plant life as articulated by Schleiden.