competition plays a very important role in ecology and evolution. The best competitors are the ones who survive and get to pass on their genes.
Answer:
Hormones act as first messenger but not as second messengers.
Explanation:
Second messenger act as signaling molecule which are secreted in response to various biological signals generated by first messenger such as hormones,neurotransmitters etc.Second messengers include various bioactive molecules such as cyclic AMP(cAMP),cyclic GMP(cGMP),inositol triphosphate(IP3),diacylglycerol(DAG),calcium ions(Ca2+) etc.
Hormones are extracellular signaling molecules whereas second messengers are intracellular signaling molecules.
The correct answer is B. Hypothalamus.
Explanation
The hypothalamus is a part of the brain that is located below the thalamus, it is an area of the brain where several and very important homeostatic regulatory functions of the organism are integrated. Its main function is to link the autonomic nervous system with the endocrine system. Other functions are to control body temperature, control thirst and urine production (water balance in the body), control food intake, control uterine contractions and milk ejection in mammals, the coordination of the nervous system Autonomous, which affects smooth muscle and cardiac activity, influences behavior and expression of emotions. Therefore, the correct answer is B. Hypothalamus