Question

how are organ systems organized in the body?
multicellular organisms usually have many organ systems. these systems work together. the systems carry out all the jobs needed for the survival of an organism.
for example, plants are multicellular organisms. the cells in leaves need water to live. many leaves cannot absorb water directly. water diffuses into plant roots. it is transported through the stem to the leaves by parts of the root system and the shoot system.
animals are multicellular organisms. in the human body, there are many major organ systems, as shown in the figure below. each organ system depends on the others and cannot work alone. for example, the cells in the muscle tissue of the stomach cannot survive without oxygen. the stomach cannot get oxygen on its own. it must work together with the respiratory and circulatory systems.
scientific vocabulary
diffuse
(verb) to spread out; move freely through
scientific vocabulary
oxygen
(noun) a gas in air that is necessary for most plants and animals to live

Explanation:

Since the problem (the image and text) is about the organization of organ systems in the body, focusing on biological structures and functions, the subfield is Biology (under Natural Science). As there's no specific question, but if we assume a question like "What discipline/subfield does this content belong to?", here's the answer:

The content discusses organ systems in multicellular organisms (plants, animals, humans), cell - tissue - organ - system - organism hierarchy, and biological processes (diffusion, organ system interactions). These are core topics of Biology.

Answer:

Natural Science - Biology