Index fossils are found throughout the world and come from organisms which existed during limited periods of geologic time. Which of the following best describes what index fossils can be used to determine? A.
the way an organism went extinct
B.
the age of a layer of rock
C.
how an organism evolved over time
D.
when an organism first appeared on Earth

sex cells are usually half's then they find another half and make a fertilize egg

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation:

where in your body is there an enzyme that does function at a high or low ph? what is the name of that enzyme and its function?