Answer:
The general structure of the endoplasmic reticulum is a network of membranes called cisterns, these bag-like structures are stretched together by the cytoskeleton. The phospholipid membrane surrounds the cystic space (or lumen), which is an extension of the nuclear space but is separated from the cytosol
Answer: The lungs are well supplied with blood due to lots of capillaries covering the alveoli, constantly maintaining a large diffusion gradient, air is able to pass easily down this gradient due to the alveoli having very thin walls (one cell thick).
or
The alveoli are adapted to make gas exchange in lungs happen easily and efficiently. Here are some features of the alveoli that allow this: they give the lungs a really big surface area. they have moist, thin walls (just one cell thick)
Hope this helps......... Stay safe and have a Merry Christmas!!!!!!!!!!! :D
Explanation:
<span>the high expense; electron microscopes are costly</span>
