DNA Sequencing Process: DNA sequencing is the process of determining the precise order of nucleotides (A, G, C, and T) in a DNA molecule. Modern DNA sequencing is typically performed using automated methods, such as the Sanger sequencing method (chain termination method) or Next-Generation Sequencing (NGS).

Sanger Sequencing (Chain Termination): This method involves using DNA polymerase to replicate a DNA template. Modified nucleotides called chain terminators are incorporated into the newly synthesized DNA strands. These terminators halt the DNA synthesis at specific points, creating fragments of varying lengths. These fragments are then separated by size using gel electrophoresis, and the order of the bases in each fragment is determined by analyzing the pattern of the fragments.

Next-Generation Sequencing (NGS): NGS technologies allow for the simultaneous sequencing of millions or even billions of DNA fragments. Various NGS platforms exist, but they generally involve amplification of DNA fragments, followed by sequencing using fluorescently labeled nucleotides or other detection methods. The resulting sequence data is then generated digitally.

Classification using Sequence Data: Once the DNA sequence is obtained, it is compared to the sequences of DNA from other organisms. This comparison is often done using bioinformatic software and databases. The software aligns the sequences and identifies regions of similarity and difference.

Role of Computer Analysis: Computer analysis plays a crucial role in classifying organisms based on DNA sequences. Bioinformatics tools are used to:

• Align Sequences: Align DNA sequences from different organisms to identify regions of similarity and difference.
• Build Phylogenetic Trees: Construct phylogenetic trees that depict the evolutionary relationships between organisms based on sequence data. These trees are built using algorithms that analyze the patterns of mutations and sequence changes.
• Compare to Databases: Compare the DNA sequence of an unknown organism to DNA sequences in existing databases to determine its classification.
• Identify conserved regions: Identify regions of DNA that are highly conserved across species, indicating important functional elements.

Following the key:

1. Wings are grey... Go to 2
2. Wings are brown... Go to 5
3. Wings have distinct yellow spots... Biston betularia (Peppered Moth)

The student's moth has grey wings, so they follow the instruction to go to step 2. However, step 2 directs them to look for brown wings. This indicates an error in the provided key. The key is incomplete or contains contradictory information. Based *solely* on the provided key, the student cannot definitively identify the moth. However, if we assume the key is otherwise correct, and that the student has correctly identified the moth as having grey wings, the key leads to the conclusion that the moth is Biston betularia. This highlights the importance of checking for inconsistencies in a dichotomous key.

The binomial system of naming species, developed by Carl Linnaeus, is an internationally agreed upon system used by biologists to give each species a unique two-part name. This system ensures clarity and avoids confusion caused by common names, which can vary regionally. The scientific name consists of two parts: the genus name and the species name.

• The genus name is always capitalized and represents a broader group of closely related organisms.
• The species name is always lowercase and follows the genus name.
• The entire scientific name is always italicized (or underlined if handwritten).

For example, the scientific name for humans is Homo sapiens. Homo is the genus, and sapiens is the species. This naming convention provides a universal and unambiguous way to identify any organism, regardless of where it is found. It reflects the evolutionary relationships between species, as organisms within the same genus are more closely related than those in different genera. This system is crucial for accurate scientific communication and classification.