The series of proteins that carry electrons through the membrane of the mitochondria

Electron transport chain

Explanation:

In all eukaryotes electron transport chain is located in the inner mitochondrial membrane where it serves as the site of oxidative phosphorylation (production of ATP) through the action of ATP synthase.

Electron transport chain consists of protein complexes that transfer electrons from  donors to acceptors via redox  reactions. As a result of electron transport, protons (H+ ions) are pumped across a membrane and electrochemical proton gradient is formed. Proton gradiend is used for the ATP synthesis.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.