Which nucleic acid base contributes significantly to the absorbance at 260 nm?

• A) Adenine
• B) Thymine
• C) Guanine
• D) Cytosine

Which buffer is used in the digestion step of DNA extraction from whole blood?

• A) Proteinase K buffer
• B) SDS buffer
• C) Tris EDTA buffer
• D) TNE buffer

The purpose of the phase separation step in organic DNA extraction is:

• A) To wash the DNA with ethanol
• B) To dilute the DNA pellet
• C) To lyse white blood cells
• D) To remove proteins

Which anticoagulant is commonly used for blood collection in DNA extraction?

• A) EDTA
• B) Citrate
• C) Heparin
• D) Oxalate

Which of the following steps is used to remove the digested protein from the sample?

• A) DNA precipitation
• B) Phase separation with PCI
• C) Dilution of the pellet
• D) Washing with ice-cold ethanol

What type of gel is commonly used for separating nucleic acids in gel electrophoresis?

• A) Cellulose gel
• B) Polyacrylamide gel
• C) Gelatin gel
• D) Agarose gel

In spectrophotometry, at which wavelength is nucleic acid quantification commonly performed?

• A) 280 nm
• B) 260 nm
• C) 450 nm
• D) 340 nm

What is the purpose of adding Tris EDTA buffer during the lysis of red blood cells in DNA extraction from whole blood?

• A) To extract proteins
• B) To break down white blood cells
• C) To preserve DNA integrity
• D) To precipitate

At what temperature DNA pellet is dried in protein extraction?

• A) 50°C
• B) 4 °C
• C) 25°C
• D) At room temperature

How does ethidium bromide stain nucleic acids in gel electrophoresis?

• A) Covalent bonding
• B) Intercalation
• C) Hydrogen bonding
• D) Oxidation

Which of the following is a type of DNA that can be extracted using DNA extraction methods?

• A) Mitochondrial DNA
• B) Messenger RNA
• C) Ribosomal RNA
• D) Transfer RNA

What is the purpose of the loading dye used in gel electrophoresis?

• A) Stabilize DNA fragments
• B) Visualize DNA bands
• C) Enhance conductivity
• D) Increase gel resolution

What is the pH of 1M Tris-HCI?

• A) 7.4
• B) 8.0
• C) 6.5
• D) 7.0

What is the significance of a DNA ladder in gel electrophoresis?

• A) It stabilizes the gel matrix
• B) It enhances the conductivity of the gel
• C) It serves as a loading control
• D) It provides a reference for fragment size

How DNA concentration is estimated using a spectrophotometer?

• A) By measuring absorbance at 280 nm
• B) By measuring absorbance at 230 nm
• C) By measuring absorbance at 260 nm
• D) By measuring absorbance at 320 nm

Which of the following is a non-enzymatic method of DNA extraction?

• A) PCR amplification
• B) Reverse transcription
• C) Salting-out method
• D) Proteinase K digestion

What is the absorbance ratio used to assess the purity of nucleic acid samples?

• A) A340/A260
• B) A280/A450
• C) A260/A340
• D) A260/A280

How should the RNA pellet be stored after hydration?

• A) At -40 to -80°C
• B) In the presence of RNase
• C) At room temperature
• D) At 4°C

What should be added to DNA samples before loading them onto the gel?

• A) Gel loading dye
• B) Ethidium bromide
• C) Agarose
• D) TAE buffer

What should be done after adding 100% isopropanol to sample during RNA extraction using Trizol reagents?

• A) Add 500ul of Trizol reagents to the sample
• B) Incubate the sample at 37°C for 10 minutes
• C) Centrifuge the sample at 10,000g for 5 minutes at 4 °C
• D) Discard the sample