Answer:
Oxygen
Explanation:
The circulatory system gets oxygen from the respriatory system and circulates it throughout the body.
Answer:
Control : Sample B
Independent: Ultraviolet Light (UV) exposure
Dependent: Likelihood to get skin cancer
Explanation:
A control group is the sample or subjects that you do not test. A control group will help you determine whether the changes in your subject or sample happens because of what was tested on them. In the case of your problem, the control sample B is the control group because you will not expose them to the UV light. If the likelihood of skin cancer will be the same as the ones exposed to UV light, then that means UV light may not be a factor to likelihood of skin cancer. The control group also serves as a baseline this way.
Independent variable is the variable that you manipulate in the testing. Meaning it is what the expermineter will change to see if it has an effect on the testing subject. In this case, UV light exposure then becomes the independent variable because you want to see if the difference in exposure determines the likelihood of getting skin cancer.
Lastly, the dependent variable is the one that you do not change in the experiment, but it could change "depending" on the changes of the independent variable. The scenario then shows that the likelihood of getting cancer is the dependent variable because you do not change this (not like one could) but it could be affected by the exposure to the UV light.
In this case two kinds of selection might be applicable to this situation. For example, if the population of grey mice are more exposed to predators due some materials used in the dam then that would be an example of disruptive selection. But if the population of gray mice is less visible to predators and if the population grow, then it will be an example of Stabilizing selection. Basicaly meant, this type of situation is also known as codominancy or codominant type.