What are soft and hard callus? what are their functions?

If someone could do the first couple, just so i can see how it's done that would be great! 20 points. complete a dichotomous key for the 10 leaves on the common leaves sheet. the chart provided here allows for 11 pairs of statements. depending on how you build your dichotomous key, you may or may not need all of them, or you may need to add some.

Environmental differences within ecosystems are generally caused by

Are the earth's ocean floor and continents the same age geologically? why or why not?