Homework SourseDr Mathers thinks that copper deficiency may cause a loss in
Dr. Mathers thinks that copper deficiency may cause a loss in bone density. He knows that copper deficiency causes a loss of pigmentation in hair in bicolored black & white rats after four weeks (see pictures below). He gives you a list of available materials and asks that you help design his experiment.
Materials:
20 bicolored (black & white) rats
2 diets: adequate copper diet and a low copper diet
Individual cages for each rat
A scale to weigh the rats
A bone density scanner
In this experiment, the bicolored rats should be ____________separated into ______________equal groups. The group that is fed the low copper diet is the ____________group, whereas the group that is fed the adequate copper diet is the ____________ group. The amount of copper is the _________ variable, bone density is the ___________ variable, and weight and coat color are _____________ variables.
2)Which of the following are important to Dr. Mather\'s experiment?(MULTIPLE ANSWERS)
Noting any color change in each group.
Do a bone scan on each rat after the experiment.
Before and after the experiment, weigh the cage with the control rats inside (you can deduct the weight of the cage later to get the total weight of the experimental rats).
Do a bone scan on each rat prior to beginning the experiment.
Setting up 2 cages - one cage for all the controls, one cage for all the others. Making sure they have food and water each day, and plenty of room to run around for exercise.
Before and after the experiment, weigh the cage with the experimental rats inside (you can deduct the weight of the cage later to get the total weight of the experimental rats).
Weigh each rat after the experiment.
Sort the rats into 2 groups - all the white rats in one group, all the black rats in another.
Keeping all other variables equal (eg. separate cages, same amount of water, same amount of exercise, etc
Weigh each rat before the experiment.
Which of the following would be supporting evidence that a low copper diet causes loss of bone density in bicolored rats?(multiple answers)
The experimental rats weighed less after the experiment; whereas the control rats remained the same weight.
The experimental rats turned white, while the control rats remained bicolor.
The bone density scan showed bone loss in the control rats; whereas there was no bone loss in the experimental rats.
The control rats turned white, while the experimental rats remained bicolor.
The control rats weighed less after the experiment; whereas the experimental rats remained the same weight.
The bone density scan showed bone loss in the experimental rats; whereas there was no bone loss in the control rats.
3) At the end of the experiment, when Dr. Mather\'s grad student took final weight measurements and a bone density scan of each rat, he euthanized them since he was done with the experiment. But when he went to look at the bone density scans to collect the data, he realized there was no data - the scanner was broken and he didn\'t realize it at the time. With the rats dead and gone, he can\'t collect that data now. Is there any data that he did collect that would help support the hypothesis of the experiment? ONLY ONE ANSWER
No, but he could just make-up bone density data to match the hypothesis because he\'s sure Dr. Mather\'s hypothesis is correct - no one would ever know the difference.
No, the experiment is unsalvageable - he\'ll have to start over with new rats.
Yes, he could compare the weights of the two groups - if there was a loss in bone density, one would also expect a loss in weight. This wouldn\'t fully support the hypothesis, but it would give him enough data to know whether or not it was worth repeating the experiment.
Yes, he could compare data on rats that lost coat color to see if they correlated with the low-copper diet, and the data on the rats that were still bicolored to see if they correlated with the adequate copper diet. This wouldn\'t fully support the hypothesis, but it would give him enough data to know whether or not it was worth repeating the experiment.
| A) | Noting any color change in each group. | |||||||||||||||||||||||||||||||
| B) | Do a bone scan on each rat after the experiment. | |||||||||||||||||||||||||||||||
| c) | Before and after the experiment, weigh the cage with the control rats inside (you can deduct the weight of the cage later to get the total weight of the experimental rats). | |||||||||||||||||||||||||||||||
| D) | Do a bone scan on each rat prior to beginning the experiment. | |||||||||||||||||||||||||||||||
| e) | Setting up 2 cages - one cage for all the controls, one cage for all the others. Making sure they have food and water each day, and plenty of room to run around for exercise. | |||||||||||||||||||||||||||||||
| f) | Before and after the experiment, weigh the cage with the experimental rats inside (you can deduct the weight of the cage later to get the total weight of the experimental rats). | |||||||||||||||||||||||||||||||
| g) | Weigh each rat after the experiment. | |||||||||||||||||||||||||||||||
| H) | Sort the rats into 2 groups - all the white rats in one group, all the black rats in another. | |||||||||||||||||||||||||||||||
| I) | Keeping all other variables equal (eg. separate cages, same amount of water, same amount of exercise, etc | |||||||||||||||||||||||||||||||
| Weigh each rat before the experiment. Which of the following would be supporting evidence that a low copper diet causes loss of bone density in bicolored rats?(multiple answers)
3) At the end of the experiment, when Dr. Mather\'s grad student took final weight measurements and a bone density scan of each rat, he euthanized them since he was done with the experiment. But when he went to look at the bone density scans to collect the data, he realized there was no data - the scanner was broken and he didn\'t realize it at the time. With the rats dead and gone, he can\'t collect that data now. Is there any data that he did collect that would help support the hypothesis of the experiment? ONLY ONE ANSWER
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Solution
1). In this experiment, the bicolored rats should be _separated into __equal groups. The group that is fed the low copper diet is the ___test__group, whereas the group that is fed the adequate copper diet is the __control___ group. The amount of copper is the __independent___ variable, bone density is the __dependent___ variable, and weight and coat color are __ratio__ variables.
Independent variable is the one which we can manipulate, means we can control it or cannot be controlled always (means a fixed one). Independent variable does not depend on dependent variable, but the dependent variable alters with independent variable (explanatory variable is used as a predictor of response variable). The independent variable is always plottted on X- axis.
