Question 1: Define Archaea and explain how they differ from Bacteria and Eukaryotes.

Answer: Archaea are a group of single-celled microorganisms classified as a domain of life, distinct from Bacteria and Eukaryotes due to differences in their genetic sequences, membrane lipid structures, and cell wall compositions.

Question 2: Describe two unique features of Archaea that allow them to survive in extreme environments.

Answer: Archaea possess unique lipids in their cell membranes that are stable at high temperatures and can produce enzymes like extremozymes that function in extreme pH, salinity, or temperature conditions.

Question 3: Explain the primary method used to classify Archaea in microbiology laboratories.

Answer: Classification is primarily based on genetic analysis, such as sequencing of the 16S rRNA gene, which reveals differences in DNA sequences compared to other domains.

Question 4: Calculate the total magnification if an Archaea cell is observed under a microscope with a 40x objective lens and a 10x eyepiece.

Answer: Total magnification = 40x * 10x = 400x

Question 5: Identify the variable in an experiment where scientists test the survival of Archaea at different salt concentrations.

Answer: The independent variable is the salt concentration.

Question 6: What safety precautions should be considered when working with extremophile Archaea in a laboratory setting?

Answer: Use of protective gloves and eye protection, proper sterilisation procedures, and working within a biosafety cabinet to prevent contamination and exposure.

Question 7: Describe a practical experiment to isolate Archaea from a hot spring sample.

Answer: Students should collect a hot spring water sample, filter it to remove larger organisms, then incubate the filtrate in a high-temperature, high-salt selective medium conducive to Archaea growth. After incubation, techniques such as microscopy or genetic testing can confirm the presence of Archaea.

Question 8: Given the following data: Sample A contains 10^6 Archaea cells per millilitre, while Sample B contains 10^4 cells per millilitre. What is the fold difference in cell count between the two samples?

Answer: Fold difference = 10^6 / 10^4 = 100

Question 9: Analyse the following scenario: Archaea are found thriving in a saline environment with pH 2. Explain what adaptations might enable their survival.

Answer: Their adaptations may include specialised cell membrane lipids that resist low pH, enzymes that function optimally in acidic conditions, and mechanisms to regulate internal pH to prevent acid damage.

Question 10: Identify an industry or technology that utilises Archaea and briefly explain its application.

Answer: Archaea are used in biotechnology for producing extremozymes for industrial processes, such as PCR amplification, where heat-stable enzymes like Taq polymerase are essential.

Question 11: Explain why studying Archaea contributes to our understanding of early life on Earth.

Answer: Studying Archaea helps us understand the characteristics of ancient microorganisms, their adaptations to extreme environments similar to early Earth, and the evolution of life, as they may resemble primordial life forms that contributed to Earth's early biosphere.