Easter Island is a small 63-square-mile patch of land — more than a thousand miles from the next inhabited spot in the Pacific Ocean. In A.D. 1200 (or thereabouts), a small group of Polynesians — it might have been a single family — made their way there, settled in and began to farm. When they arrived, the place was covered with trees — as many as 16 million of them, some towering 100 feet high.
These settlers were farmers, practicing slash-and-burn agriculture, so they burned down woods, opened spaces, and began to multiply. Pretty soon the island had too many people, too few trees, and then, in only a few generations, no trees at all.
Answer:
Gravity?
Explanation:
Or it could be a non contact force.
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.
Pt.I
All living things needs some form of oxygen to live. In talking about a scuba diver, we are talking about a human, who uses their lungs to breathe, and did not develop the ability to breathe under water. Instead, when in a body of water, we tend to hold our breaths until an opportunity arises for us to exchange our carbon dioxide for oxygen.
Take into account the scuba gear. The scuba gear fits the user, and has a number of protection, including the suit counter-balancing any pressure applied by the deep, and the tank providing much needed oxygen to the user during delayed periods within the water.
Pt.II
<u>How does these two systems interact?</u>
Like as a human is breathing on land or even swimming, the human expels carbon dioxide, which forms into "air bubbles" that are then expelled into the water surrounding. The user then draws air from the pressurized air tank, and is able to breathe as such. This allows the user to stay underwater for much longer than just one breathe, and is able to travel farther inside the deep.
Inside this system, the Oxygen is first input into the oxygen tanks, which are then used by the diver. The diver would draw the oxygen from the tank (output), and he will then expel the used air into the surrounding water.
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m - Meter - Length.
s - Second - Time.
A - Ampere - Electric Current.
K - Kelvin - Temperature.
kg - Kilogram - Mass.
