During T cell maturation, the t cells must pass two tests. first, immature t cells that can recognize MHC molecules are Selection. Second, immature t cells that recognize and bind to molecules normally found in the body are Activation.
Selection is the first test that T cells must pass. During this process, immature T cells that can recognize MHC molecules are selected. MHC molecules are found on the surface of cells and are involved in antigen presentation. When T cells come into contact with MHC molecules, they are able to recognize the molecules and begin the process of selection. During selection, the T cells that recognize MHC molecules are chosen over those that do not. This helps ensure that the cells that are selected are those that can properly respond to antigens.
The second test that T cells must pass is activation. During activation, T cells that recognize and bind to molecules normally found in the body are selected. These molecules are called self-antigens and can include proteins, carbohydrates, and lipids. When T cells come into contact with self-antigens, they are able to recognize the molecules and begin the process of activation. During activation, the T cells that recognize self-antigens are chosen over those that do not. This helps ensure that the cells that are selected are those that will not attack the body’s own cells.
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Answer:
Explanation:
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone.[1] These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.
Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle.[2] These convection cells bring hot mantle material to the surface along spreading centers creating new crust. As this new crust is pushed away from the spreading center by the formation of newer crust, it cools, thins, and becomes denser. Subduction begins when this dense crust converges with less dense crust. The force of gravity helps drive the subducting slab into the mantle.[3] As the relatively cool subducting slab sinks deeper into the mantle, it is heated, causing hydrous minerals to break down. This releases water into the hotter asthenosphere, which leads to partial melting of asthenosphere and volcanism. Both dehydration and partial melting occurs along the 1,000 °C (1,830 °F) isotherm, generally at depths of 65 to 130 km (40 to 81 mi).[4][5]
Some lithospheric plates consist of both continental and oceanic lithosphere. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Neither continental plate will subduct. It is likely that the plate may break along the boundary of continental and oceanic crust. Seismic tomography reveals pieces of lithosphere that have broken off during convergence
There are two broad classes of seismic waves: body waves and surface waves. Body waves travel within the body of Earth. They include P, or primary, waves and S, or secondary, waves. P waves cause the ground to compress and expand, that is, to move back and forth, in the direction of travel.
Answer: B
Explanation: the sun is made of gas, which doesn't all spin together at the same speed like a solid rock would.
