<span>Structurally, plant and animal cells are very similar because they are both eukaryotic cells. They both contain membrane-bound organelles such as the nucleus, mitochondria, endoplasmic reticulum, golgi apparatus, lysosomes, and peroxisomes. Both also contain similar membranes, cytosol, and cytoskeletal elements.</span>
John and Pat's occupation best explains the difference between their skin pigmentation. Since Pat works as a lifeguard, she is more exposed to the sun, which tans her skin. John, on the other hand, works in the theater, where he isn't exposed to sunlight that much, so he is much lighter than his twin, Pat.
<h2>Pericardium </h2>
Explanation:
Pericardium is the fibrous tissue that surrounds the heart and the roots of the great blood vessels
The pericardium's outer coat is called the parietal pericardium which is tough and thickened, loosely cloaks the heart, and is attached to the central part of the diaphragm and the back of the breastbone
Its inner coat is called the visceral pericardium or epicardium which is double, with one layer closely adherent to the heart and the other lining the inner surface of the outer coat
The intervening space between these layers is filled with pericardial fluid
This small amount of fluid acts as a lubricant to allow normal heart movement within the chest
