Compare all the organisms. What trend do you see?
The proportions of DNA bases vary greatly among organisms.
The proportions of DNA bases are similar in closely related organisms, but different in organisms that are not closely related.
The proportions of DNA bases are similar among all organisms.
| Organism | A | T | G | C |
|--------------|------|------|------|------|
| Human | 30.9 | 29.4 | 19.9 | 19.8 |
| Chicken | 28.8 | 29.2 | 20.5 | 21.5 |
| Grasshopper | 29.3 | 29.3 | 20.5 | 20.7 |
| Sea urchin | 32.8 | 32.1 | 17.7 | 17.3 |
| Wheat | 27.3 | 27.1 | 22.7 | 22.8 |
| Yeast | 31.3 | 32.9 | 18.7 | 17.1 |
| E. coli | 24.7 | 23.6 | 26.0 | 25.7 |
Answer (2)
Calculate the range of proportions for each base (A, T, G, C) across all organisms.
Compare the base proportions of closely related organisms (Human and Chicken) and distantly related organisms (Human and E. coli).
Observe that the ranges are significant, indicating considerable variation.
Conclude that the proportions of DNA bases vary greatly among organisms.
Explanation
Analyzing the Problem We are given a table showing the relative proportions of DNA bases (Adenine, Thymine, Guanine, and Cytosine) in different organisms. Our task is to analyze this data and determine the most accurate trend among the given options. The options suggest that the proportions may vary greatly, be similar among closely related organisms, or be similar among all organisms.
Calculating the Ranges To determine the trend, we first calculate the range of proportions for each base across all organisms. The range is the difference between the maximum and minimum proportion for each base. From the tool, we have:
Range of A: 8.1
Range of T: 9.3
Range of G: 8.3
Range of C: 8.6
These ranges indicate a considerable variation in the proportions of each base across the different organisms.
Comparing Base Proportions Now, let's consider the relationships between the organisms. Humans and chickens are both vertebrates and thus more closely related than humans and E. coli (a bacterium). Comparing their base proportions:
Human: A (30.9), T (29.4), G (19.9), C (19.8)
Chicken: A (28.8), T (29.2), G (20.5), C (21.5)
These proportions are relatively similar. However, when we compare these to E. coli:
E. coli: A (24.7), T (23.6), G (26.0), C (25.7)
The proportions are quite different from those of humans and chickens.
Determining the Trend Based on the calculated ranges and the comparison of base proportions between related and unrelated organisms, we can conclude that the proportions of DNA bases vary greatly among organisms. While closely related organisms may have somewhat similar proportions, the overall trend shows significant variation.
Final Answer Therefore, the most accurate statement is: The proportions of DNA bases vary greatly among organisms.
Examples
Understanding the variation in DNA base proportions is crucial in various fields such as evolutionary biology and forensic science. For example, in evolutionary studies, comparing the DNA base composition of different species can provide insights into their phylogenetic relationships. In forensic science, DNA profiling relies on identifying unique genetic markers, and understanding base proportions can aid in the analysis of DNA samples.
The proportions of DNA bases vary significantly among different organisms, with closely related organisms like Humans and Chickens showing similar base proportions, while distantly related organisms like Humans and E. coli show notable differences. This highlights the diversity in genetic makeup across species. Therefore, the most accurate statement is that the proportions of DNA bases vary greatly among organisms.
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