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Intrusive igneous rocks cool from magma slowly because they are buried beneath the surface, so they have large crystals.
Extrusive igneous rocks cool from lava rapidly because they form at the surface, so they have small crystals.
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The correct option is A.
The DNA from one specie differ from the DNA of another specie on the basis of their base ratio. The base ratio refers to the percentage of purine to pyrimidine in a DNA molecule. The base ratio is the one that is responsible for the variability that is observed in chromosomes from different species.
Answer:
A person who receives a gene for sickle cell disease from one parent and a normal gene from the other has a condition called "sickle cell trait." Sickle cell trait produces no symptoms or problems for most people. Sickle cell disease can neither be contracted nor passed on to another person.
