sentences: push is a kind of force & a pull is a kind of force ->  a force is a kind of push or pull on an object  a force is a kind of push or pull on an object & force requires energy ->  a push or pull requires energy  a push or pull requires energy & muscles push / pull bones to move the bones ->  muscles require energy to move bones  muscles require energy to move bones & muscle cells are a part of muscles ->  muscle cells require energy for muscle movement  push is a kind of force0 & organelle are a part of a cell ->  a mitochondrion is a part of a cell  a mitochondrion is a part of a cell & mitochondrea play a large role in energy processes within a body ->  mitochondria are a part of a cell that play a large role in energy processes in the body  mitochondria are a part of a cell that play a large role in energy processes in the body & if something plays a large role in a process, then that something is required for that process ->  mitochondria are a part of a cell that are required for energy processes in the body  muscle cells require energy for muscle movement & mitochondria are a part of a cell that are required for energy processes in the body ->  muscle cells require mitochondria for energy processes  muscle cells require mitochondria for energy processes & if something requires something else, then that something is likely to have many of that something else -> muscle cells are likely to have many mitochondria