Which of the following methods is effective at killing bacterial endospores?

A. Transduction: Transduction is gene transfer mediated by bacteriophages (viruses that infect bacteria); Griffith’s experiment did not involve phage activity.

B. Conjugation: Conjugation requires direct cell-to-cell contact and transfer of DNA (often plasmids) via a pilus; Griffith’s work did not depend on cell contact.

C. Transformation: Transformation is the uptake and incorporation of free DNA from the environment by a bacterium; Griffith observed non-encapsulated cells acquiring traits from heat-killed encapsulated cells, which is transformation.

D. Cloning: Cloning refers to producing genetically identical copies or isolating a gene in laboratory techniques; this term does not describe Griffith’s natural gene uptake observation.

A. Apoenzymes: Apoenzymes are the protein portion of an enzyme that require a cofactor to become active; this term describes part of an enzyme rather than its cellular location or whether it functions inside the cell.

B. Exoenzymes: Exoenzymes are secreted outside the cell to act on extracellular substrates; this term indicates extracellular action rather than intracellular function.

C. Constitutive enzymes: Constitutive enzymes are produced continuously at a fairly constant rate regardless of substrate presence; this describes regulation, not specifically intracellular location.

D. Regulated enzymes: Regulated enzymes change their level or activity in response to environmental conditions or signals; this term refers to control mechanisms rather than being intrinsically intracellular.

E. Endoenzymes: Endoenzymes function within the cell (intracellular enzymes) to catalyze metabolic reactions inside the cytoplasm or organelles.