A clade is a group of species that includes an ancestral species and all of its descendents
I think C) availability of water is your best answer because alot of organisms count on water as a major resource because they need it to survive so a lack or a gain in the amount of water will majorly effect an ecosystem.
The Americans colonies became free and independent states explanation: because they declared independence
The answer is diffusion.
The most important mechanism that enables oxygen and carbon dioxide (but as well other small molecules such as glucose, amino acids, wastes) across capillary walls is diffusion. Diffusion is a net movement of molecules through some barrier from an area of high concentration to the area of low concentration. When blood rich in oxygen reaches capillaries close to the cell, now there <span>is </span>more oxygen in the capillaries than in the cells and by diffusion, oxygen will pass capillary walls and enter the cell. Since blood in capillaries lacks in carbon dioxide, it will easily leave the cells and enter the blood. It should be taken into consideration that capillary walls may be fenestrated, continuous, and discontinuous which can affect movement through them.
