Structure of all bacteriaExplain dinoflagellateExplain protista

Bacteria are prokaryotes and unicellular

They can be gram positive or gram negative. This just means whether they are coloured by gram stain or no. Gram positive bacteria has a cell wall which can take up gram stain and hence it is gram positive, while gram negative bacteria do not take up gram stain.

Protista are eukaryotes but unicellular.

There are different types of protista. Amoeba, euglena, flagellates etc, usually classified on the basis of whether they can make their own food (autotrophs) or whether they depend on other organism for food(saprophytes).

Dino flagellates are a type of protista, they are so called because they use flagella for locomotion