If the placenta asks as a barrier, a filter, why do you think that some toxins and infectious agents are able to pass by, and affect fetal development?

Answer in a couple of paragraphs, 1 or 2 at the most if anything! 20 points + brainliest--> explain what all the systems in your body do to work together < --list of systems needed: circulatory systemrespiratory systemdigestive systemexcretory systemnervous system