What do all plants have in common?

Plants are multicellular eukaryotes. Their cells contain a nucleus and membrane-bound organelles, including the chloroplasts, where photosynthesis takes place. Plant cells have cell walls made of cellulose, a carbohydrate. Plants are not motile.

Explanation:

The three main parts of a seed are the seed coat, embryo and the endosperm. The seed coat is what protects the embryo and contains all the features to form a new plant. The endosperm nourishes the embryo until it can sustain itself and produce its own food.