In a checking account, deposits go and debits go . A out, in B both go in C in, out

a)      When a prey is eaten by a predator, the tissue that is ingested by the predator is broken down in the digestive system of the organism to smaller molecules that can be absorbed by the organisms. These molecules, lipids, amino acids and glucose are used by the predator to build its tissues and in the provision of energy.

b)      Because not all energy is used efficiently, some are lost because of the ingested food not being fully digested and absorbed, hence waste is passed as fecal matter. During the process of digestion and biological processes, a higher percentage of energy is also lost as heat in the process.  

c)       Due to this inefficiency in the transfer of energy from trophic level to another up the energy pyramid, which is lost as heat , there are fewer organisms up the trophic levels than below the trophic levels. Hence the characteristic shape of the energy pyramid.  

d)      Since only 10% of energy is passed from one trophic level to another in the form of biomass, then if we had 10,000 primary consumers in an ecosystem, the highest number of secondary consumers in that ecosystem would be 1,000.