Solved by a verified expert:Question 15Which substances are examples of antigens?proteins andcarbohydratesnucleic acids andproteinslipids and proteinslipids and carbohydratesnucleic acids andcarbohydratesQuestion 16Which of these is not part of a neuron?dendritenucleuscellbodyaxonsynapseQuestion 17A spinal nerve containsaxons of sensoryneurons only.myelinated axons only.axons of motor neuronsonlydendrites onlyboth sensory and motoraxons.Question 18Dendritesare usually the longest nerve fibers.are coveredreceive signals from sensory receptors orother neurons.generate nerve impulses.are longer and less numerous than axons.Question 19The cells that deposit bone matrix are termedosteoclasts.osteocytes.osteons.osteoblasts.marrowcells.Question 20The ossicles are located in theinner earmiddle earauditorycanalouter earspiralorgan.Question 21Which of these animals has body supported by ahydrostatic skeleton?lobsterdeerfruit flyearthwormmillipede