<span>One type of organisms known as sponges have collar cells that trap food and ingest it by ___ or by the enzymes of lysosomes. The word that would best complete the sentence is "phagocytosis". This is also most commonly known as the food-eating that is the process of engulfing food. </span>
Paratism is the practice of living as a parasite in or on another organism. Mutualism is the way two organisms of different species exist in which each individual benefits from the activity of the other.
One explanation could be the differences in climate (environmental factors). The climate in northern Mexico could support the reproduction of the mosquito species, which is a vector of the dengue virus. Other environmental conditions that influence its endemicity could include living conditions and sanitation. The other possiblity could be that the people in the US have developed immunity for the disease, therefore, are unaffected even when infected by the virus.
<span>Pacinian corpuscles are rapidly adapting mechanoreceptors so they respond only at the onset and offset of the stimulus. The Pacinian corpuscle has a single afferent nerve fiber. Its end is covered by a sensitive receptor membrane whose sodium channels will open when the membrane is deformed in any way. Pressure thus causes sodium to enter the neuron and create a generator potential. If this potential reaches a certain threshold nerve impulses are formed. This impulse is now transferred along the axon with the use of sodium channels and sodium/potassium pumps in the axon membrane. The magnitude of the stimulus is encoded in the frequency of impulses generated in the neuron. So the more massive or rapid the deformation of a single corpuscle, the higher the frequency of nerve impulses generated in its neuron.</span>