This is the chronicle of evolution over millions of years of geologic time engraved in the order which fossils appear in rock strata.
Explanation:
A rock would experience a temperature of 5500°C is about the core which is at a depth of 220km.
But let us use the earth's geothermal gradient to solve this problem.
The geothermal gradient is the rate at which temperature is increasing with depth.
The geothermal gradient 25°C/km
At 5500°C,
5500°C x
= 220km
But this is not so in nature, there are other heat sources that contributes to increasing temperature with depth such as radioactive heat and frictional heat.
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Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
Acetylcholine..
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