1)If you wish to carry out a cladistic analysis of a group of species, then there are several types of information that you might find useful. Which one of the following choices describes a type of information that would be least useful in a cladistic analysis?
A) An identified outgroup which while related to the other taxa being compared lacks their synapomorphies.
B) Identification of homologies present in the groups being compared.
C) A means to absolutely date the time in the past when the groups being compared were represented by their common ancestor.
D) Knowledge that the groups being compared do consist of at least part of a monophyletic group.
E)Knowledge of the state of each characteristic to be used in the analysis for each of the groups being compared.
2) When studying the systematics of selected groups of eukaryotes, the DNA from each taxon is isolated and sequenced using typical molecular biological procedures. Which one of the following incorrectly describes an issue related to carrying out such a study?
A) A means to identify common homologies within the DNA sequences needs to be available.
B) A large enough section of DNA must be used so that similar sequences reflect a shared ancestry instead of being produced by chance.
C) The DNA that is isolated must not be contaminated by DNA from other sources.
D) A different gene must be isolated from each of the species being examined.
E) DNA that is typical for each species should be obtained, and not DNA from an extremely unusual individual.
In order to determine the least useful type of information in a cladistic analysis, we need to understand the purpose and requirements of the analysis.
1) In cladistics, the goal is to classify organisms based on their shared characteristics and evolutionary relationships. The key principle is to group organisms based on shared derived characteristics, also known as synapomorphies. The most useful information in a cladistic analysis would be identifying homologies present in the groups being compared (Choice B) and knowledge of the state of each characteristic for each group being compared (Choice E). These are the essential data points that allow for the identification and comparison of shared derived characteristics.
Now let's analyze the given options:
A) An identified outgroup which, while related to the other taxa being compared, lacks their synapomorphies. This option provides information about an outgroup, which is a taxon outside the group being analyzed but related to it. Including an outgroup helps to determine which characteristics are shared derived characteristics within the group being compared. While this information may not directly contribute to identifying shared derived characteristics within the group, it is still a helpful piece of information in a cladistic analysis and can guide the classification process.
C) A means to absolutely date the time in the past when the groups being compared were represented by their common ancestor. While having absolute dating information would indeed be useful in understanding the timeline of evolutionary events, it is not necessary for conducting a cladistic analysis. Cladistics focuses more on the pattern of shared derived characteristics rather than the exact timing of common ancestors.
D) Knowledge that the groups being compared do consist of at least part of a monophyletic group. This information is important in a cladistic analysis. Monophyletic groups are essential for tracing evolutionary relationships accurately. Knowing that the groups being compared consist of at least part of a monophyletic group helps ensure that any shared derived characteristics are valid for the analysis.
Based on the analysis above, the least useful type of information in a cladistic analysis would be:
C) A means to absolutely date the time in the past when the groups being compared were represented by their common ancestor.
Moving on to the second question:
2) The question is about the issues related to studying the systematics of selected groups of eukaryotes using DNA sequencing.
A) A means to identify common homologies within the DNA sequences needs to be available. This statement is true. Identifying common homologies is crucial for understanding the shared characteristics and evolutionary relationships between different taxa. DNA sequencing allows for the identification of shared genetic information and enables the comparison of DNA sequences for homologies.
B) A large enough section of DNA must be used so that similar sequences reflect a shared ancestry instead of being produced by chance. This statement is also true. Using a larger section of DNA increases the chances of finding shared genetic information that is truly reflective of shared ancestry, as opposed to random chance similarities.
C) The DNA that is isolated must not be contaminated by DNA from other sources. This statement is accurate. Contamination from other DNA sources can lead to incorrect conclusions, so it is crucial to ensure the purity of the isolated DNA.
D) A different gene must be isolated from each of the species being examined. This statement is not true. While studying different genes can provide additional insights, it is not necessary to isolate a different gene from each species to study systematics using DNA sequencing. One can analyze the same gene in different species to determine their relationships.
E) DNA that is typical for each species should be obtained, and not DNA from an extremely unusual individual. This statement is true. It is essential to obtain DNA from representative individuals of each species to ensure the accuracy and relevance of the data gathered. DNA from extremely unusual individuals may introduce biases or anomalies that could distort the analysis.
Based on the analysis above, the statement that incorrectly describes an issue related to carrying out a study of systematics using DNA sequencing is:
D) A different gene must be isolated from each of the species being examined.
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