Glucagon, secreted by alpha cells of pancreatic islets, increases blood glucose through glycogenolysis and gluconeogenesis.
The glomerulus is a network of capillaries where ultrafiltration occurs, filtering small molecules like glucose, ions, and urea from blood into Bowman's capsule.
The combination of eight legs, chitinous exoskeleton, and book lungs is diagnostic of Class Arachnida (spiders, scorpions, ticks).
Cnidocytes contain nematocysts that discharge and inject toxins, allowing cnidarians to capture and immobilize prey organisms.
The combination of exoskeleton, jointed appendages, and open circulatory system is diagnostic of Arthropoda.
Feathers are unique to birds and provide insulation and aerodynamic surfaces essential for flight, while other options are found in other vertebrate classes.
Snails (gastropod mollusks) characteristically have both a radula (feeding structure) and a ventral muscular foot for locomotion.
Insects undergo complete metamorphosis with distinct larval, pupal, and adult stages, a characteristic holometabolous development.
Annelida is characterized by true body segmentation (metamerism) and a complete digestive system with distinct mouth and anus, unlike other options.
Insects characteristically have three body regions (head, thorax, abdomen) and three pairs of legs on the thorax. Other arthropods vary in body segmentation and leg numbers.