Question 1

Which of the following statements best explains why the frog is more closely related to the human than to the shark, according to a cladogram?

Accepted Answer

The frog and human share a most recent common ancestor not shared with the shark.

Question 2

Which gene is most commonly used as a standard DNA barcode for animal species identification?

Accepted Answer

A 648 base pair fragment of the mitochondrial cytochrome c oxidase 1 (COI) gene

Question 3

A researcher wants to identify bacteria in a soil sample without culturing them. Which molecular technique should they use?

Accepted Answer

Amplify and sequence the 16S rRNA gene using PCR

Question 4

Which of the following is NOT a correct step in the Polymerase Chain Reaction (PCR) process?

Accepted Answer

Transcription: converting DNA to RNA at 37°C

Question 5

Why is the 16S rRNA gene considered the 'gold standard' for bacterial identification?

Accepted Answer

It is highly conserved across all bacteria, but contains hypervariable regions that allow for species-specific identification.

Question 6

Which of the following best describes the purpose of DNA barcoding in modern biology?

Accepted Answer

To identify and distinguish species using short, standardized DNA sequences

Question 7

A scientist is using the PhyloChip to analyze a water sample. What is the main advantage of this technology?

Accepted Answer

It can simultaneously detect thousands of different prokaryotic 16S rRNA gene sequences in a single experiment.

Question 8

Which of the following is a correct application of the BLAST algorithm in microbial identification?

Accepted Answer

Comparing a sequenced 16S rRNA gene to a database to find the closest match

Question 9

In a time-series analysis of a polluted river, which molecular approach would best reveal changes in microbial community composition over time?

Accepted Answer

Community fingerprinting using 16S rRNA gene sequencing

Question 10

Which of the following statements about phylogenetic trees is correct?

Accepted Answer

The most recent common ancestor determines the closeness of relationships, not the number of nodes between taxa.

Question 11

Which DNA region is commonly used as a barcode for plant species identification?

Accepted Answer

A 600 bp fragment of the rbcL gene and an 800 bp segment of the matK gene

Question 12

A medical laboratory is trying to rapidly identify a bacterial pathogen from a patient sample. Which method would be most efficient and cost-effective?

Accepted Answer

16S rRNA gene sequencing

Question 13

Which of the following is a limitation of using the 16S rRNA gene for bacterial identification?

Accepted Answer

It may not distinguish between very closely related bacterial species.

Question 14

Which of the following best describes the role of primers in PCR?

Accepted Answer

They provide a starting point for DNA synthesis by DNA polymerase.

Question 15

A soil sample appears to contain many different microorganisms when cultured. What would likely be discovered if 16S rRNA barcoding was used instead?

Accepted Answer

Many more microbial species would be detected than by culturing alone.

Question 16

Which of the following is a real-world application of DNA barcoding in environmental science?

Accepted Answer

Monitoring biodiversity in coral reef ecosystems by identifying species from water samples

Question 17

Which of the following equations correctly represents the basic formula for the number of possible DNA sequences of length $$n$$?

Accepted Answer

$$4^n$$

Question 18

Which of the following is a key reason why the 16S rRNA gene was used by Carl Woese to define the three domains of life?

Accepted Answer

It is present in all cellular organisms and contains both conserved and variable regions.

Question 19

Which of the following best describes the function of a microarray (such as the PhyloChip) in microbial ecology?

Accepted Answer

It allows simultaneous detection of thousands of microbial taxa by hybridizing DNA to specific probes.

Question 20

Which of the following is a correct statement about the use of hypervariable regions in 16S rRNA gene sequencing?

Accepted Answer

They provide species-specific signature sequences for bacterial identification.

L 6.3: Classification Systems: Morphological and Molecular Data in Modern Evolutionary Biology

Study Guide - Practice Questions

Study Guide - Flashcards