It would be Newton's "3rd" Law that explains why my hands hurt when I clap loudly, since this states that every action as an equal and opposite reaction.
When using the term 'life form' I assume you are speaking of animals, bacteria, etc. Scientists take years to find their desired conclusion because of how the environment tends to change quite frequently (Depending on where the creature lives). The earth is constantly revolving and rotating, which causes changes in the environment. These changes affect the animals behavior, eating habits, and overall chances of survival. A factor that must also be considered is that scientists have to examine these creatures in their natural habitat which can be an issue depending on where they live. For example, if I were to study the behavioral patterns of a Leopard, it would be extremely difficult to do so because the Leopards are specifically keen at camouflaging in their environment. That would make observing its behavioral patterns very frustrating and time consuming. In a way, mother nature is always against us.
(Hope this helps)
Excessive calorie intake during pregnancy can result in a fetus that has high birth weight. Pregnant women have indeed higher energy requirements but only by 300 calories daily. Eating an excessive amount of calories daily during pregnancy can lead to an increased weight gain that can result in an increased birth weight. Excessive weight gain during pregnancy can also endanger the progression of the pregnancy and the delivery of the baby.