<span>Nitrogenous Base, Phosphate Group, and Pentose Sugar.</span>
The external ear structure is called the Pinna.
The Pinna helps to channel sound waves into the ear.
Many animals have the ability to move their pinna towards the direction of sound.
I have attached an image of a dog's ear to show you the external structure called the Pinna.
I hope this helps! I'm happy to answer any other questions you might have :)
[Image sourced from: https://www.msdvetmanual.com/dog-owners/ear-disorders-of-dogs/ear-structure-and-function-in-dogs]
The answer is 4 I’m pretty sure
UVB radiation increases? This damages the eyes, skin and immune system! Sorry! I just guessed because there were no choices that went along with the question!