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.

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. what really drives osmosis? view available hint(s)osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. what really drives osmosis? the first law of thermodynamicsthe difference in the height of water columns on either side of a selectively permeable membranethe difference in water concentration across a selectively permeable membranethe difference in sugar or ion concentration across a selectively permeable membrane

List five ways we are indebted to phytoplankton