How are most animals used in medical research bred?

• A. Most animals are bred specifically for research to ensure known genetic histories and specific traits.
• B. They are captured from the wild.
• C. They are purchased from random breeders with unknown histories.
• D. They are all clones.

Answer: (A)

Most animals used in medical research are bred specifically for research to ensure known genetic histories and specific traits. This controlled breeding creates animals with predictable genetics and health backgrounds, which helps researchers isolate the effects of the experimental variable rather than differences in an animal’s makeup. By using dedicated breeding colonies and reputable suppliers, scientists can choose particular strains or lines, ensure standardized age and sex, and perform health and pathogen screening. This genetic and phenotypic consistency improves reproducibility and statistical reliability across studies.

In contrast, taking animals from the wild would introduce unknown genetics and exposure to unfamiliar pathogens, making results variables that are hard to interpret. Buying from random breeders with unknown histories similarly adds unpredictable genetic variation and health status. Cloning is not the typical method for supplying most laboratory animals due to costs, ethical and welfare considerations, and the fact that cloned animals do not by themselves resolve variability issues across diverse experiments.