Research scientists are trying to clone a gene. In order to accomplish this task they join two pieces of DNA. Which class of the enzymes below might accomplish this task?

A: oxidoreductase
B: ligase
C: hydrolase
D: isomerase
E: lyase

B. Ligase

Explanation:

Ligase is the class of enzyme that catalyzes the joining/linking of two large molecules. This involves the formation of a new chemical bond between the molecules.

DNA ligase is an example of a ligase. It catalyzes the linking of DNA strands through the formation of a phosphodiester bond. DNA ligase can either link two complementary fragments of DNA or repair the breakage of single stranded DNA that occurs as a result of replication of double stranded DNA.

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.