1. <span>They all have endoskeletons.
2.</span><span>They have brains protected by skulls.
3.</span><span>They have closed circulatory systems.</span>
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.
Learn more about experiment:brainly.com/question/11256472
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Hypothesis: large servings might encourage children of today to eat more data and sugars than children ate a generation ago
Answer:
she is in a submersible near the ocean floor.
