How to find experimental design in biology
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ACT Science › How to find experimental design in biology
The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
What factor would weaken the design of this experiment?
Plant 1 requires more light than Plant 2 and Plant 3 in order to reach maximum growth.
All four mediums contain different soil nutrients.
All three plants require equal amounts of oxygen and water.
Plant height growth was measured by a computer program.
The water used by the plants had mineral levels tested through out the experiment.
Explanation
Since the experiment design leaves light constant for all three plant species, a factor such as a different light preference for one plant species would weaken the control environment for the experiment.
The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
What factor would weaken the design of this experiment?
Plant 1 requires more light than Plant 2 and Plant 3 in order to reach maximum growth.
All four mediums contain different soil nutrients.
All three plants require equal amounts of oxygen and water.
Plant height growth was measured by a computer program.
The water used by the plants had mineral levels tested through out the experiment.
Explanation
Since the experiment design leaves light constant for all three plant species, a factor such as a different light preference for one plant species would weaken the control environment for the experiment.
The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
Based on the chart, soil Medium C has what effect on plant growth?
Soil Medium C is beneficial for Plant 1, but has negative effects on Plant 2 and Plant 3.
Soil Medium C is beneficial for all three plant types.
Soil Medium C is beneficial for Plant 2, but detrimental for Plant 1 and Plant 3.
Soil Medium C does not seem to have a noticable effect on Plant 1, but has a beneficial effect on Plant 2 and Plant 3.
Soil Medium C has a negative effect on the height growth of all three plants.
Explanation
Plant 1 is the only plant that had an increased height growth in Medium C. Plant 2 and Plant 3 had decreased height when in Medium C.
The chart above shows the height growth of three different plant species after a period of 2 weeks. Each plant species was grown in 4 different soil mediums. All the plants were grown in the same environment with equal amounts of light, water, and oxygen.
Based on the chart, soil Medium C has what effect on plant growth?
Soil Medium C is beneficial for Plant 1, but has negative effects on Plant 2 and Plant 3.
Soil Medium C is beneficial for all three plant types.
Soil Medium C is beneficial for Plant 2, but detrimental for Plant 1 and Plant 3.
Soil Medium C does not seem to have a noticable effect on Plant 1, but has a beneficial effect on Plant 2 and Plant 3.
Soil Medium C has a negative effect on the height growth of all three plants.
Explanation
Plant 1 is the only plant that had an increased height growth in Medium C. Plant 2 and Plant 3 had decreased height when in Medium C.
Mitochondria make 90% of the energy needed by the body to sustain life. The Mitochondrial Free Radical Theory of Aging (MFRTA) theorizes that individuals who live longest produce fewer mitochondrial oxygen reactive species than individuals that have a shorter life span. Therefore, lifespan will increase if fewer mtROS are produced, and lifespan will decrease if more mtROS are produced. An experiment was done to test this theory, and the results are shown in the chart below. Four test groups of flies were involved, two groups consisted of females, and two groups consisted of males.
| | Test group 1 | Test group 2 | Test group 3 | Test group 4 | | | ------------------- | ---------------- | ---------------- | ---------------- | ------- | | # of mtROS | 3.9 | 2.5 | 3.2 | 2.7 | | Lifespan | 110 days | 120 days | 95 days | 89 days |
Does this data support or dispute the MFRTA theory?
The data does not support the MFRTA theory because it was not able to show an inverse relationship between the number of mtROS and the lifespan of the organisms.
The data supports the theory because some test groups had low numbers of mtROSs and also had long lifespans.
The data does not support the theory because it shows an inverse relationship between the mtROS amount and the length of lifespan.
The data does not support the theory because the experiment does not test the information needed to address the MFRTA theory.
The data supports the theory because it shows an inverse relationship, a high mtROS amount correlates to a high lifespan.
Explanation
According to the theory, test group 1 had the greatest number of mtROS, therefore it should have the shortest lifespan. However, it has a lifestpan of 110 days, the second longest life span in the experiment.
Mitochondria make 90% of the energy needed by the body to sustain life. The Mitochondrial Free Radical Theory of Aging (MFRTA) theorizes that individuals who live longest produce fewer mitochondrial oxygen reactive species than individuals that have a shorter life span. Therefore, lifespan will increase if fewer mtROS are produced, and lifespan will decrease if more mtROS are produced. An experiment was done to test this theory, and the results are shown in the chart below. Four test groups of flies were involved, two groups consisted of females, and two groups consisted of males.
| | Test group 1 | Test group 2 | Test group 3 | Test group 4 | | | ------------------- | ---------------- | ---------------- | ---------------- | ------- | | # of mtROS | 3.9 | 2.5 | 3.2 | 2.7 | | Lifespan | 110 days | 120 days | 95 days | 89 days |
What information would weaken the experiment's results?
An experiment suggesting there is a high-percent error in measuring mitochondrial oxygen reactive species.
An experiment consisting of a control group of both males and females.
A separate experiment done with a different test species that had similar results.
An experiment suggesting mitochondria make more than ninety percent of the body's energy.
An experiment testing the lifespan of flies in an oxygen-deprived environment.
Explanation
An experiment casting doubt on the accuracy of mtROS measurement, which is the independent variable, would drastically weaken the experiment's results.
Mitochondria make 90% of the energy needed by the body to sustain life. The Mitochondrial Free Radical Theory of Aging (MFRTA) theorizes that individuals who live longest produce fewer mitochondrial oxygen reactive species than individuals that have a shorter life span. Therefore, lifespan will increase if fewer mtROS are produced, and lifespan will decrease if more mtROS are produced. An experiment was done to test this theory, and the results are shown in the chart below. Four test groups of flies were involved, two groups consisted of females, and two groups consisted of males.
| | Test group 1 | Test group 2 | Test group 3 | Test group 4 | | | ------------------- | ---------------- | ---------------- | ---------------- | ------- | | # of mtROS | 3.9 | 2.5 | 3.2 | 2.7 | | Lifespan | 110 days | 120 days | 95 days | 89 days |
Does this data support or dispute the MFRTA theory?
The data does not support the MFRTA theory because it was not able to show an inverse relationship between the number of mtROS and the lifespan of the organisms.
The data supports the theory because some test groups had low numbers of mtROSs and also had long lifespans.
The data does not support the theory because it shows an inverse relationship between the mtROS amount and the length of lifespan.
The data does not support the theory because the experiment does not test the information needed to address the MFRTA theory.
The data supports the theory because it shows an inverse relationship, a high mtROS amount correlates to a high lifespan.
Explanation
According to the theory, test group 1 had the greatest number of mtROS, therefore it should have the shortest lifespan. However, it has a lifestpan of 110 days, the second longest life span in the experiment.
Mitochondria make 90% of the energy needed by the body to sustain life. The Mitochondrial Free Radical Theory of Aging (MFRTA) theorizes that individuals who live longest produce fewer mitochondrial oxygen reactive species than individuals that have a shorter life span. Therefore, lifespan will increase if fewer mtROS are produced, and lifespan will decrease if more mtROS are produced. An experiment was done to test this theory, and the results are shown in the chart below. Four test groups of flies were involved, two groups consisted of females, and two groups consisted of males.
| | Test group 1 | Test group 2 | Test group 3 | Test group 4 | | | ------------------- | ---------------- | ---------------- | ---------------- | ------- | | # of mtROS | 3.9 | 2.5 | 3.2 | 2.7 | | Lifespan | 110 days | 120 days | 95 days | 89 days |
What information would weaken the experiment's results?
An experiment suggesting there is a high-percent error in measuring mitochondrial oxygen reactive species.
An experiment consisting of a control group of both males and females.
A separate experiment done with a different test species that had similar results.
An experiment suggesting mitochondria make more than ninety percent of the body's energy.
An experiment testing the lifespan of flies in an oxygen-deprived environment.
Explanation
An experiment casting doubt on the accuracy of mtROS measurement, which is the independent variable, would drastically weaken the experiment's results.
There is a certain species of rabbit that is known to reproduce quickly. 250 of these rabbits were introduced into a new environment, and their population was measured in ten year intervals.
What assumption did the scientists make in this experiment?
There will be no external variables that may affect the population of the rabbits
This species of rabbit will evolve to adapt to the new environment
All brown rabbits reproduce at a faster rate than white rabbits
This species of rabbit will reproduce at the same rate, regardless of environment
Explanation
The scientists are attempting to isolate the rabbits and measure their population growth to discover some sort of rate of population increase. They are assuming that there will be no external forces acting upon the rabbits that might create fluctuations in population (disease, famine, predators, etc.)
The problem does not mention color, so that assumption is incorrect. The problem also does not compare reproductive rates in environments, so that assumption is incorrect. Finally, there is no mention of evolution or new traits, so that assumption is incorrect.
There is a certain species of rabbit that is known to reproduce quickly. 250 of these rabbits were introduced into a new environment, and their population was measured in ten year intervals.
What assumption did the scientists make in this experiment?
There will be no external variables that may affect the population of the rabbits
This species of rabbit will evolve to adapt to the new environment
All brown rabbits reproduce at a faster rate than white rabbits
This species of rabbit will reproduce at the same rate, regardless of environment
Explanation
The scientists are attempting to isolate the rabbits and measure their population growth to discover some sort of rate of population increase. They are assuming that there will be no external forces acting upon the rabbits that might create fluctuations in population (disease, famine, predators, etc.)
The problem does not mention color, so that assumption is incorrect. The problem also does not compare reproductive rates in environments, so that assumption is incorrect. Finally, there is no mention of evolution or new traits, so that assumption is incorrect.