Define What Is Meant by a Threat to Internal Validity

question 13

Essay

Define what is meant by a threat to internal validity.

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Definitions:

Toxins

Poisonous substances produced by living cells or organisms that can cause disease when introduced into the body tissues.

Complement System

A part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism.

Clonal Selection

Lymphocyte activation in which a specific antigen causes activation, cell division, and differentiation only in cells that express receptors with

Mitotic Expansion

The increase in cell number through the process of mitosis, where a single cell divides to form two genetically identical daughter cells.