Answer:
The experiment should have more different subject groups, with each group consuming a different amount of beta carotene.
Explanation:
When designing an experiment, to determine the effect of the amount of a substance, the experimental design should be done to accommodate more than two experimental group with each group treated with different amount of the substance and also a control group. This will enable the researcher to determine the effect of the different ranges of amount.
In the example, in other to determine if vitamin A is dependent of the amount of beta carotene consumed, there should be more different subject groups, with each group consuming a different amount of beta carotene.
B. The Threshold describes the minimum level of stimulus required to ctive a neuron. Hope that helps
Pretty sure the answer would be C, because you need the warm and cold air to mix.
The answer is the endocrine system.
The brainest answer would be apprenticed.
