21. The piece of equipment, that introduces DNA into cells via DNA-coated microprojectiles is known as

A. laser
B. DNA probe
C. gene gun
D. inoculating needle

22. An animal, that has gained new genetic information from the acquisition of foreign DNA, is considered as

A. a chimera
B. a transgenic animal
C. a vector
D. an enzyme that links DNA molecules

23. The advantage of using DNA polymerases from thermophilic organisms in PCR is that

A. the DNA polymerases of these bacteria are much faster than those from other organisms
B. the DNA polymerases of these bacteria can withstand the high temperatures needed to denature the DNA strands
C. the DNA polymerases of these bacteria never make mistakes while replicating DNA
D. all of the above