_Hydrogen_ ...............is the answer.
<u>Explanation:</u><u> </u>
In general, field of study refers to gaining the knowledge in a particular branch. On the other hand, science means the system where we can attain the knowledge about the universe. This always delivers with theoretical and experimental descriptions in a detailed manner about natural phenomenon.
This handles with each and every aspects about living organisms and environment. This paves the way to know more details in particular part. Hence, field of study like physics, engineering also referred a science in this manner.
Fluid filled sacs in the knee are specifically called Bursa or Bursae. Bursae is plural for Bursa.
A bursa is a closed fluid filled sac that function as a gliding surface to reduce friction between tissues of the body. Knee bursitis occurs when there is irritation or inflammation in one one of the knee bursa. The procedure of removing fluid-filled sac is called bursectomy. When the bursa become infected with bacteria, this condition is called septic bursitis.
Endocytosis even though there are two types of this
I do believe it's a recessive trait. I hope that helps