Radon is a radioactive gas that seeps into homes from the soil. It is thought to be a cause of lung cancer. A research team investigates this hypothesis. The members of the team gather large amounts of data on basement radon concentrations and lung cancer rates and conclude that the more radon there is in a home, the more likely are people living in the home to develop lung cancer. After the study is published, other researchers criticize it by asserting that the studied neighborhoods with higher radon concentrations also have a higher percentage of older people and a higher percentage of cigarette smokers than the low-radon neighborhoods. Both advanced age and cigarette smoking increase the risk of lung cancer. This criticism, if correct, shows that the radon study suffered from
__________.
Fill in the blank(s) with the appropriate word(s).
Answer: uncontrolled variables
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What is depicted in the above diagram?
a. a sensory neuron b. an interneuron c. a motor neuron d. a neuroglial cell e. none of these
The most inclusive level of organization is exemplified by which of the following?
A. Heart B. Carbon atom C. DNA D. Zebra E. Red blood cell
In the microscope, you observe multinucleated amoeboid cells with sporangia that form spores. This is a(n)
A) ascomycete. B) cellular slime mold. C) Euglenozoa. D) tapeworm. E) plasmodial slime mold.
The role of the CDR in a TCR is to
a. anchor the TCR in the cytoplasmic membrane. b. link the alpha and beta chains. c. bind the MHC–peptide complex. d. do all of the above.