Acase-control study was conducted to determine if an association exists between workers in uranium mines and loss of fertility due to reduced sperm count. a group of 200 men with low sperm count were identified from clinics located in areas with uranium mines. each selected case was matched with a randomly selected male control on the following factors: race, age, area of residence, and smoking status. what is the purpose of matching?

The diagram below represents a marine food web and a process that can harm the human population. each circle represents an organism and the smaller dots inside them represent a toxic substance. what is being represented and how does it harm the population? the diagram represents biological half-life, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents biomagnification, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents the process by which different organisms prey upon each other; this can impact the human population by reducing the number of organisms that do not contain the toxin. the diagram represents the way that toxins are metabolized by living organisms, with those at greater trophic levels able to metabolize more efficiently than those at lower levels. this means that those at higher tropic levels are safer for humans to consume compared to the organisms at lower trophic levels.

Environmental impacts on evolution : mastery test

Approximately what portion of the foods that we eat have been genetically modified in some way? a. fewer than 10% b. about 50% c. nearly 100%