CPA #4 Questions Flashcards
who discovered the existence of protozoa and bacteria?
Antoni van Leeuwenhoek
when were bacteria and protozoa discovered?
protozoa 1674; bacteria 1676
define spontaneous generation
supposed production of living organisms from non-living matter
who coined the idea of spontaneous generation? when?
Aristotle 350 b.c.
who dealt the mortal blow to spontaneous generation?
Louis Pasteur
what was Pasteur’s experiment?
boiled infusions long enough to kill everything; bent neck of flask into “s” shape; allowed air into flask, contained everything needed for life, but did not allow microbes to enter; flask remained sterile 18 months later
how can an exposed Petri dish or exposed test tube alter results of experiment?
dust and microbes in the air can get into tube/ dish and contaminate the experiment
what is the scientific method?
use of observations of controlled experiments to answer questions; observations lead to proposing questions; proposed questions lead to hypothetical answers; combination of question and answer lead to designing an experiment to prove hypothetical answer; based on true results, initial hypothetical question is accepted, rejected, or modified.
what is germ theory of disease? who discovered it? when?
idea that microorganisms are responsible for disease; discovered by Pasteur in 1857
what is the purpose of Koch’s postulates?
they are designed to prove that a specific agent causes a specific disease
list Kochs postulates (4)
- the suspected agent present in every case of the disease.
- that agent must be isolated and grown in pure culture
- the cultured agent must cause the disease when inoculated into healthy susceptible experimental host
- the same specimen should be found in the diseased experimental host
what is the agent in Koch’s postulates?
refers to any fungus, protozoan, bacterium, virus, or other pathogen
explain Semmelweis hypothesis of cadaver particles
hypothesis that medical students carried cadaver particles from autopsy studies into delivery room; particles from cadavers caused puerperal fever (caused by Streptococcus) in women giving birth.
how did Semmelweis hypothesis lead to reduction of nosocomial infections
enforcing hand washing with chlorinated lime water led to the mortality rate dropping in the following year by 17%
how did immunization begin with an unethical experiment
Edward Jenner (1796) inoculated a boy with our from a cowpox lesion in order to protect from contracting smallpox; Jenner had infected not with smallpox pus to prove his theory; experiments on human subjects that intentionally exposed them to deadly pathogens are illegal
