An anterior pituitary gland
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)
The answer is
letter C.
<span>
The interdependence
of body systems is essential because all systems work together to maintain
homeostasis. Homeostasis in body systems refers the regulation of internal
conditions keeping it stable and relatively constant. In humans this refers to
its ability to maintain stability in its internal environment while responding
to changes in external conditions. It serves as a sensor that detects changes
in the conditions that need to be regulated to meet the demands of the
condition and give the necessary feedback. Regulation of body temperature and
the balance between acidity and alkalinity are examples of homeostasis in the
human body.</span>
A decrease in dissolved oxygen.
This is because oxygen is a byproduct of photosynthesis. If the plants are in water, some of the oxygen they produce will become dissolved in it. Without those plants, you have less dissolved oxygen.
