What are organs and organ system?

The animals in which cells are organized into structural and functional units called as tissues, organs, and organ system are grouped under which subkingdom ?

What is organism?

Classify as ceils, tissues, organs, organ systems or organisms: Skin

Classify as ceils, tissues, organs, organ systems or organisms: Chlamydomonas

Classify as ceils, tissues, organs, organ systems or organisms: Leaf

Classify as ceils, tissues, organs, organ systems or organisms: Stomach

Classify as ceils, tissues, organs, organ systems or organisms: Stem

Classify as ceils, tissues, organs, organ systems or organisms: Amoeba

Classify as ceils, tissues, organs, organ systems or organisms: Blood

Classify as ceils, tissues, organs, organ systems or organisms: Bone