Answer:
Gravity.
Explanation:
Without air, living organisms would suffocate and die.
Without water, living organisms would dehydrate and die.
Without energy, living organisms would die instantly.
Without space, living organisms would be squished together and die.
The only logical answer left is gravity.
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.
Answer:
The cells at the end of meiosis II must have half the number of chromosomes because, if they didn't have, the reunion of both gametes with diploid number of chromosomes for example, in gametes would form twice the number chromosomes.
Answer:
a gun that either fires or it doesn't
Answer:
Receptors are highly specific and only have high affinity for those ligands for whom they are specific.
Explanation:
Receptors are proteins that receive a stimulus or bind a ligand and mediate effects via receptor effector system.
Receptors are macromolecules that are highly specific.
The affinity between the ligand and the receptors is determind by the disassociation constant Kd.
The receptors produce maximun effect when an appropriate specific stimulus is present.
Different recptors types are present for different ligands.
For example, muscrinic receptors are specific for acetycholine and adrenergic receptors are specific for adrenaline/nor adrenaline.
It is important to know the specificity so that the body remains in a state of balance.
