Microtubules and microfilaments are elongated structures that cross the cell, giving support to the cell, and carries organelles and objects throughout the cell. Their supporting structure would be most like which system of a multicellular organism?

Their supporting structure would be most likely the MUSCULOSKELETAL SYSTEM of the multicellular organisms.

Explanation:

The musculoskeletal system found in multicellular organisms are made up of structures which provides support, protection and allows for various movements. These structures include:

--> Muscles

--> Cartilage

--> Ligaments

--> Tendons and

--> Joints

Furthermore, Microtubules and microfilaments are the major components of cytoskeleton. They are the structures that gives a cell it's shape and helps organise it's parts. As described in the question, they are elongated structures that cross the cell, giving SUPPORT to the cell, and carries organelles and objects throughout the cell.

Therefore, since the Microfilaments and Microtubules provides support and shape at the cellular level it can be most likened to the musculoskeletal system of multicellular organisms which performs the same functions.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.