A pore whose opening is covered by a diaphragm is clearly visible. What role do the pores serve? What would be the role of the diaphragm?
Since this is not my area of expertise, I searched Google under the key words "pore and diaphragm function" to get these possible sources:
https://www.google.com/search?client=safari&rls=en&q=pore+and+diaphragm+function&ie=UTF-8&oe=UTF-8&gws_rd=ssl
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html