1- the sizes are exactly different between modern and dawn horse. it has increased in size. Dawn horse had feet and modern horse had hoovers.
2-increase in the size of the skull; a shift from cusps to complex ridges on the grinding surface of the premolars and molars, elongation of the face and of the space between the incisors and cheek teeth, an anterior shift of the cheek teeth so they lie forward of the eye, a deep lower jaw bone.
The Krebs Cycle is involved in cell respiration and produces NADH and FADH2 for the electron transport chain. So your answer would be "<u>Release energy for making ADP</u>".
