Answer:
Lacks the right key to unlock many cells.
Explanation:
Avian influenza (H5 N1) rarely transmitted from poultry to humans because it lacks the right key to unlock many cells in the upper respiratory tract so due to this action the virus is rarely transmitted to humans. Sometimes it is lethal to humans due to absence of antibodies for this type of virus. It is rarely spread from person to person due to inability to enters the other human body.
A constant factor could be the dose of the drugs and the species of the rats used.
<h3>What is a constant factor?</h3>
In an experiment, a constant factor is one that is not allowed to change al through the experiment. This one must be held as the same and not allowed to vary. A constant factor could be the dose of the drugs and the species of the rats used.
The factor that would be different for the experimental group and the control group the administration of the new drug.
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13 is bass but I’m not sure what 14 is