Short-spined sea urchin fossils were found directly above long spined sea urchin fossils in a layer of rock. what do the differences between the two sets of sea urchin fossils suggest about them?

a. the longer spines developed as the shorter-spined sea urchins grew older.

b. the longer-spined sea urchins existed before the shorter-spined sea urchins.

c. the shorter-spined sea urchins stretched their spines to ward off predators.

d. the shorter spines did not protect the sea urchins well enough and they died off.

Mike was adopted, and his biological family history is unknown. although he is healthy, he would like some understanding of his genetic makeup, including potential health risks and genes that he could pass on to his children. mike has heard about commercial laboratories that can compare segments of your dna to those of people with common hereditary diseases in order to give you some idea of how susceptible you are to the diseases. the results of these types of tests are highly inconclusive. if mike's dna showed that he shares similarities in a segment of dna with people who have a given disease, his chances of developing that disease or passing it on to his children may be slightly elevated, but they are not 100 percent. these tests can cost more than $2,500 and are not covered by many insurance companies. do you think that mike should undergo the genetic tests? explain your answer. what are the potential pros and cons of having such tests done? describe how the availability of these genetic tests might affect the frequency of genetic diseases in individuals and populations.

Does mitochondria still meet the definition of a eukaryote why or why not?

What advantage does a crop that undergoes vegetative reproduction have over plants that start from the seed? 1points a they store nutrients. b they can travel farther. c they experience more genetic variation. d they only occur in high-resource environments.