Explain how a mutation in the DNA sequence of a gene can cause that person to
become sick.

DNA mutations cause cancer or an inability for proper function of the immune system.

Explanation:

DNA is our blueprint, so if something is wrong on the blueprint, then our body will "collapse" like a building (well not always).  Let's say, the gene for immune system function is mutated and comes out wrong. That person might not be able to make white blood cells which fight off sickness. Other mutations can also cause cancer, which is a really bad form of sickness.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.