Calories in and of themselves aren't a reliable way of describing energy density in food. It doesn't reflect what actually happens in your body (look up bomb-calorimeter for how people figure out calorie content in foods). So based on this, the question is a bit of a non-sequitur. But if you disregard that and go with a regular answer, it really depends on what kind of calories you're ingesting because foods get digested in a function of different amounts of time. Carbohydrates will get digested and converted into glucose almost immediately - being very close to 100% energy efficiency. Fats are the slowest as your body needs to produce bile in order to digest it - not enough bile = undigested fat = unused calories. Proteins are turned into either amino acids (not an energy source per se) or converted into glucose like carbs but instead through gluconeogenesis which is a less efficient form of glucose conversion than carbohydrates (since your liver/kidneys need to produce the enzymes to convert it). The efficiency of protein is likely in the range of 50-60% calories. This is just the tip of the iceberg though - your metabolism also plays a part as to how much and when these calories are either used, stored, and excreted by your body. Ever got the meat sweats? That's your body burning excess energy through thermogenesis when you eat too much protein. So it really depends why you're asking because the answer will differ for each scenario.
Answer:
Myelination.
Explanation:
Brain acts as one of the most important organ of the body that helps in receiving the stimuli and interpret the information in the form of signal. Two main types of neuron are myelinated neuron and unmyelinated neuron.
The myelinated neuron increases the conductivity of the impulse. The myelinated neurons are much more active than the unmyelinated neuron. In case of the quick thinking and instant actions, the myelinated neurons play an important role.
Thus, the answer is myelination.
They are colloquially known as identical twins. Technically, they are monozygotic twins.