biolab mcq

Choose the correct answer:

Nucleotide BLAST is a computer program that searches for sequence similarities.

In the result of a Nucleotide BLAST search, if a shorter length of query sequence is used, what happens to the E-value?

The E-value is expected to increase.

What can affect the migration rate of DNA molecules in an agarose gel electrophoresis?

All of the above

Which of the following is a correct description of restriction enzymes?

They are DNA endonucleases.

Which of the following descriptions about bacteria population growth is TRUE?

During the log phase, the cells are actively dividing and experiencing exponential growth.

As you increase the total magnification of a light microscope, which of the following is true?

Depth of field decreases.

Which of the following statements about DNA agarose gel is true?

The DNAs can be stained by ethidium bromide and visualized under UV.

Which of the following is a palindromic sequence?

5’ GAATTC 3’

Large DNA fragments (e.g., >10 kb) will be better separated in which % of agarose gel?

0.8%

Which of the following phases takes the longest time to complete?

Interphase

During which phase of meiosis would you expect to see crossing-over between two non-sister chromatids?

Prophase I

A student is trying to make a 1:20 dilution of an overnight yeast culture with sterile water to a final volume of 50 mL. What should he do?

Mix 2.5 mL of overnight culture with 47.5 mL of water.

Which of the following cannot be seen clearly or appear the smallest at 400X total magnification?

Bacteria

Which of the following statements is true?

Meiosis can be used for reproduction in certain organisms.

Which method counts only live cells?

Standard plate count

Which of the following methods is NOT a proper way to sterilize?

Clean the bench surface by wiping with 70% alcohol.

If you want to make 50 mL of 0.8% agarose gel, how many grams of agarose powder should you weigh?

0.4 grams

Which of the following is true about restriction digest of DNAs?

The buffer used in the restriction enzyme digest provides both the necessary cations and also the optimal pH for the enzyme to function properly.

Which of the following is NOT a way of increasing contrast in light microscopy?

Using immersion with the 100X objective lens.

A diploid cell contains a total of 20 chromosomes. At the end of mitosis, there will be ___ chromosomes in each of the daughter cells, and at the end of meiosis, there will be ___ chromosomes in each gamete.

First blank: 20; second blank: 10

Which of the following is TRUE?

1. There is no intron sequences in cDNA.