Question

Which procedure describes a properly controlled experimental investigation a scientist could have conducted?A. Ten iris plants are planted in an outdoor garden, and they all receive the same amount of sunlight and water each day.B. Five leopard frogs are fed only grub worms, while five toads are fed a mixture of grub worms and fish meal.C. A researcher takes a poll to determine the most popular brand of automotive tire.D. Twenty mice are fed high-protein diets, another 20 mice are fed their usual diet, and their weights are measured after three weeks.

Answer 1

Introduction to Biology: Scientific method, experiment.

An experiment is the part of the scientific method where the hypothesis is tested.

It should be made under controlled conditions, because usually the goal is to see how a variable is affected by other. To be able to observe this, is important to have a control group and an experimental group in the samen conditions, only changing the variable that is being study.

If we look at the answers, we see that in option A doesn't have a controled environment and doesn't change anything between the plants. Option B has two groups with diferent food, but it doesn't measures anything. Option C is non an experiment because is not changing anything. But option D has a control and an experiment group with different diets and it measures their effect.

So, the correct option would be D. Twenty mice are fed high-protein diets, another 20 mice are fed their usual diet, and their weights are measured after three weeks.