ATP is adenosine triphosphate, it is like a fully charged battery in a cell, ADP is basically ATP that has been drained of its energy from a chemical reaction. It is like a dead battery that can be recharged later ;)
B because B is the nucleus which is the storage location of DNA
Sister chromosome exchanges are recombination events that occur between homologous chromosomes and are often the result of exposure of the cell to DNA damaging agents.
Cross over, or recombination, is the exchange of chromosome segments between non sister chromatids in meiosis. Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.
Answer:
Energy is contained within the pond ecosystem and is transferred within the system.