Sir Issac Newton was the one who purposed the gravity theory.
The correct answer are valves. As lymphnodes become larger and deeper they turn into lymph vessels that develop one-way valves. These valves prevent the back flow of blood throughout the vessel and ensure that the lymph only flows in one direction.
<span>The order that taxonomy is written is : Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
A good mnemonic (without domain) is King Phillip Came Over For Good Spaghetti.
Tiger: Eukarya, Animalia, Chordata, Mammalia, Carnivora, Felidae, Panthera (Panthera tigris)
Freshwater Angelfish: Eukarya, Animalia, Chordata, Actinoptergii, Perciformes, Cichlidae, Pterophyllum (Pterophyllum scalare)</span>
