The purpose of RNA is to transfer amino acids to ribosomes for incorporation into a polypeptide undergoing synthesis.
All three would decrease the size of the population of the organism. If an organism suddenly has a new predator, the organism's population will decline and it is likely that the members of the prey's population would disperse in an attempt to survive. Disease would just kill off the population in general, maybe the organism's population would distribute itself differently in order to avoid catching the disease. Competition would decrease the amount of food, water, and/or land available to the organism's population causing it to decrease or change habitats in an attempt to find another food source
The part of the human ear that conducts air between the middle ear and the back of the throat to equalize pressure on either side of the eardrum is called the eustachian tube.
Eustachian tube connects the middle ear with the nasal cavity. It allows pressure release of the middle ear, preventing trauma that caused by high pressure differences called barotrauma. Eustachian tube is normally closed to prevent bacteria inside nasal cavity enter the ear. It only opened in a certain condition like swallowing.