A layer of smooth cartilage at their ends, which cushions the bones and prevents them from rubbing directly against one another. The whole joint is also enclosed in a synovial capsule, which is full of synovial fluid. The synovial fluid acts like the oil in an engine, lubricating the joint and preventing the cartilage from becoming worn down.
The ultimate source of energy (for most ecosystems) is the sun<span>. The ultimate fate of energy in ecosystems is for it to be lost as heat. Energy and nutrients are passed from organism to organism through the food chain as one organism eats another.</span>
The correct sequence is; Glycolysis-pyruvate-acetyl CoA-krebs cycle-electron transport chain.
Glycolysis is a sequence of reactions for the breakdown of glucose to two molecules of pyruvic acid under aerobic conditions, Krebs cycle is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into carbon dioxide and chemical energy in the energy carriers, while electron transport chain involves a series of complexes that transfer electrons from electron donors to electron acceptors via redox reactions and couples this transfer with the transfer of protons across a membrane.
Answer : A metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
Explanation :
The group 16 element are oxygen, sulfur, selenium, tellurium and polonium.
The general electronic configuration of group 16 elements is, 
As we now that there are total 6 electrons in p sub-shell. So, a metal in group 16 can become a chemically stable ion by gaining 2 electrons.
Hence, a metal in group 16 of the periodic table can become a chemically stable ion by gaining 2 electrons.
