Cells are the most simple level of organization, as tissues contain cells, organs contain tissues and systems contain organs, so R would be your answer.
A) <u>Mutation</u> is the original source of variations for plants and other organisms which develops differences among their respective species
Explanation:
Genetic variation leads to the natural differences between each individual and among individuals of a species. The main cause for this variation is due to alleles that cause variations in the composition of genes or the DNA sequences.
A mutation is a genetic variation which leads to the creation of a new allele in a species population. Each variation in the DNA sequence leads to an allele formation and each allele leads to a difference in character or trait between individuals since they are the alternate version of the original genes.
Although genetic variations could be brought about by crossing over, random fertilization, or independent assortment; mutation is the original source because it provides the basic raw material for all the evolutionary changes.
Tissues
Tissues are somewhat more complex units than cells. By definition, a tissue is an organization of a great many similar cells with varying amounts and kinds of nonliving, intercellular substance between them.
Some fossil snakes have remnants of hip bones and legs even though these animals had no legs. These remnant structures are best described as:<u> vestigial structures</u>.
Vestigial structures are organic structures that do not appear to fulfill any important biological function in the organism that possesses them.
- These structures are preserved as an inheritance of the evolutionary process, because at some point in the history of evolution an ancestor of the current species had that structure.
- These types of structures, which can be bones, organs, structures in the skin or any other part of the body, no longer offer any meaningful function for the body.
- The presence of vestigial structures in animals is considered proof that evolution and natural selection exists.
Therefore, we can conclude that some fossil snakes have remnants of hip bones and legs even though these animals had no legs. These remnant structures are best described as vestigial structures.
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The hypothesis is the question you are trying to answer or the problem you need to figure out, it is kind of like a starting point
