The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n) group at the 5' end and a(n) group at the 3' end.

The words which complete the two spaces are:

Explanation:

So the complete sentence will read as follows:

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a free hydroxyl or phosphate group at the 5' end and a free hydroxyl group at the 3' end.

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answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.