Cytotoxic t-lymphocytes produce a substance called which creates holes in the cell membranes of target cells

The answer is perforin. This is a pore creating cytolytic protein located in the granules of cytotoxic T lymphocytes (CTLs) and NK cells. Upon degranulation, perforin attaches to the target cell's plasma membrane, and oligomerises in a Ca2+ dependent way to create pores on the target cell.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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