The excretory system is responsible for removing waste and excess materials from the body in order to maintain homeostasis. This system includes the kidneys, ureters, urinary bladder, and urethra. The main functions of the excretory system are to eliminate waste products, regulate blood volume and pressure, control levels of electrolytes and metabolites, and regulate blood pH.
Use evidence and scientific reasoning to explain how characteristic animal behaviors (e.g., building nests to protect young from cold, herding to protect young from predators, attracting mates for breeding by producing special sounds and displaying colorful plumage, transferring pollen or seeds to create conditions for seed germination and growth) and specialized plant structures (e.g., flower brightness, nectar, and odor attracting birds that transfer pollen; hard outer shells on seeds providing protection prior to germination) affect the probability of successful reproduction of both animals and plants.