Biochemical Sciences Quiz

In experiment 7, onion cells were used to extract DNA. What type of cell does onion belongs to?

• Prokaryotes

• Heterokaryotes

• Eukaryotes

• Dikaryotes

What is the purpose of putting all the sample on ice during the experiment 7?

• To prevent DNA being degraded quickly by nuclease enzymes

• To allow efficient DNA extraction

• To increase the efficiency of onion cells to lyse

• To keep the homogenizing solution in fresh condition

In experiment 7, what is the range of ratio of optical absorbance (260nm / 280nm) needed in order to obtain pure DNA?

• Less than 1.8

• Close to 1.8

• Greater than 1.8

• Between 2.0 to 2.3

In experiment 7, what is the role of salts such as sodium citrate used in the homogenizing solution during DNA extraction procedure?

• To create neutral solution and prevent DNA degradation

• To serve as buffer system if acidic condition is present

• To bind to the negatively charged DNA backbone and create neutral charge

• To create osmotic pressure, allowing DNA to come out from the cells

In experiment 7, what is the function of adding soap in the homogenizing solution?

• To create bubbles and stabilise the cells during the grinding process

• To provide slippery surface area for efficient grinding process

• To allow the lysis process of the plant membrane and cell wall

• To prevent any enzymatic activity from degrading or destroying the DNA

In experiment 7, which one of the following reagents was used to precipitate the DNA released from the onion’s tissues?

• Acetone

• Ethanol

• Formamide

• Water

In experiment 7, why do we need to stir slowly using glass rod after white strands precipitated DNA was formed?

• To mix the solution efficiently and homogenously

• To promote larger clump of precipitated DNA to settle down

• To prevent precipitated DNA from settled down

• To allow stabilisation of DNA to take place more efficiently

In experiment 7, what is the name of equipment used to measure the DNA sample?

• Light meter

• UV reader

• Laser meter

• Spectrophotometer

Which of the following substance that is targeted for measurement by using 260nm wavelength?

• DNA

• Protein

• Oil

• Salts

Which of the following substance that is targeted for measurement by using 280nm wavelength?

• DNA

• Protein

• Oil

• Salts