Edward Jenner inferred that a person who once had small pox cannot have it once again. So something is there in these persons which grows after the initial infection which interferes with the secondary infection resisting it.
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Edward Jenner is called the Father of Vaccination. Jenner noticed that the milkmaids who deal with the cows all the time don't generally suffer from the cowpox or small pox. Then as an Experiment, he took some sample from the pustules of the cow having pox and then cleaned it and injected the sample into a healthy child. Then when everyone of the locality suffered from the same disease, that child remained healthy. So that lead to infer that there are something in the pustule which lead to resist the secondary infection of this disease. So this lead to the invention of vaccines.
Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent(s). Asexual reproduction produces new individuals without the fusion of gametes, genetically indentical to the parent plants and each other, when mutations occur
1. Divergent Plate Boundaries or Constructive Plate Boundaries. This is where two plates separate. Ridges are created when mantle convection rises up beneath it, with extreme heat, the crust will thin, and the igneous material beneath will eventually.
<span>2. Divergent, or destructive plate margins cause volcanoes. As the more dense plate subducts, it will melt at depth and the water driven off, will lower the melting point of the overlying mantle wedge, this will create a type of magma. Volcanic Island Arcs are formed at oceanic-oceanic destructive plate margins. The hot, bouyant magma, is less dense that the surrounding rock, so will rise to the surface, and will collect beneath the plate that hasn't been subducted. It will then, under increased pressure erupt under the sea. Over thousands to millions of years, it will keep erupting, to form islands. </span>
<span>3. Earthquakes are mainly caused at Transform boundaries and Divergent boundaries. At transform boundaries, two plates sliding past eachother, and the build up of friction could lead to earthquakes, if enough stress is built up and then suddenly released, then the energy is released as seismic waves or an earthquake. At divergent boundaries, earthquakes happen along the Benioff zone which is the slope of the subducting plate that is slowly being dragged into the mantle by mantle convection and slab pull. </span>
<span>4. Divergent boundaries cause orogenisis (mountain building). But only the continental-continental margin where two continental plates are colliding. Because they are the same density, they don't subduct, but they buckle, compress and uplift to form mountains. Just like the himilayas, when the Indian plate collided with the eurasian plate.</span>
The most appropriate statement that is explaining the effect and cause during muscle contraction is. “The release of calcium ions causes myosin and actin to attach to each other.” The activation of muscles helps in the generation of muscles that send out the signals to the neurons.
