Explanation:
From the studies done on seismic elastic waves, it has been discovered that the innermost core of the earth is a solid concentric layer. Seismic P and S waves can be propagated through solids but the s-waves are cut off in contact with a liquid medium. This is because s-waves are shear waves and fluids do not shear.
- At the outer core, the s waves is cutoff and it reappears in the region of the inner core.
- This shows that the inner core is solid.
- The inner core is made up of iron and nickel with some other siderophiles.
- At the inner core, the pressure is very great. Pressure here is about 350gigapascal.
- This huge pressure compresses matter into solids despite the very high temperature.
- Also, during the differentiation of the earth, the heavier minerals moves downward to the core due to their density. Metals in the core have density of about 13g/cm³.
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Answer:
Extension
Explanation:
Polymerase chain reaction is given by Kary Mullis and it contains three steps denaturation, annealing, and extension. In denaturation, the temperature is raised to 96° c so that the DNA can denature.
In annealing, the temperature gets reduced to 55°c so that the primer can bind to the complementary sequence. In extension, Taq polymerase is used to extend the new strand.
This enzyme is isolated from thermophilic bacteria and the temperature here is raised to 72°c so that the enzyme can extend the primer and make the complementary strand. So the right answer is extension.
All of the above options are correct because all the given three options are possible
<span>Answer: Opening of Na+ and K+
Explanation:
Acetycholine binding opens Na+ and K+ ion channels in the receptors that allow simultaneous passage of Naâş into the muscle fiber and Kâş out of the muscle fiber. More Naâş ions enter than Kâş ions exit, which produces a local change in the membrane potential called the end plate potential.
Binding of acetycholine to receptor proteins opens Na+ and K+ channels resulting in jump in resting membrane potential(RMP) from -90mV to +75mV forming an end-plate potential (EPP).</span>
