Chapter 5 — DNA and Genetic Information · Biology. These are 10 questions from the Magmo3 bank on this lesson, from easy to hard. Solve each one, then open "Show answer and explanation". Magmo3 has 33 questions on this lesson, each with an explanation.
Which scientist carried out the transformation experiment on pneumonia bacteria?
Correct answer: (C) Griffith
Explanation: In 1928, Griffith found that some factor from heat-killed virulent (S) bacteria converts non-virulent (R) bacteria into virulent ones. He called this bacterial transformation.
In Griffith's experiment, the strain that causes the mouse to die when injected while alive is:
Correct answer: (B) the virulent S strain
Explanation: Live virulent S kills the mouse. Live R alone is non-virulent (it causes pneumonia but not death), and heat-killed S alone does not kill it either.
A bacteriophage is composed mainly of:
Correct answer: (A) DNA and a protein coat
Explanation: The phage is simple: an outer protein coat and DNA inside.
When Griffith injected the mouse with heat-killed S bacteria together with live R bacteria, the result was:
Correct answer: (D) the mouse died and live S bacteria were found in it
Explanation: The R was transformed into virulent S by a substance from the dead S, so the mouse died and live S was found in it.
The shared conclusion from the experiments of Avery and of Hershey and Chase is that:
Correct answer: (A) DNA is the genetic material
Explanation: Both experiments confirmed that DNA, not protein, is the genetic material.
When Avery and his colleagues broke down the protein and RNA in the extract, transformation:
Correct answer: (C) continued normally
Explanation: Breaking down the protein and RNA did not affect transformation, meaning they are not the genetic material.
The conclusion Hershey and Chase reached was that what entered the bacteria and formed new phages was the:
Correct answer: (D) DNA
Explanation: The phosphorus-labeled DNA entered the bacteria, while the sulfur-labeled protein remained outside.
If the radioactivity of sulfur had appeared inside the bacteria in the Hershey-Chase experiment, this would have indicated that:
Correct answer: (A) the protein entered and could be the genetic material
Explanation: Sulfur labels the protein, so if it had entered, that would mean the protein entered; but this did not happen, and what entered was the DNA.
Suppose the blender step were left out of the Hershey–Chase experiment with sulfur-labelled phages. Where would most of the radioactivity end up after centrifuging?
Correct answer: (C) In the pellet, because the empty coats stay attached to the bacteria
Explanation: The blender's job is to shake the empty protein coats off the bacterial surface. Without it, the coats stay stuck to the bacteria and settle with them in the pellet. The result would wrongly suggest that protein entered.
Measurements in one animal species gave the DNA per nucleus as: liver cell 6.6 units, kidney cell 6.6 units, sperm 3.3 units. Protein per nucleus differed from tissue to tissue. Which conclusion do these data support?
Correct answer: (C) DNA is constant in body cells and halved in gametes, as genes should be
Explanation: The genetic material should be equal in all body cells of a species and half as much in gametes, which carry one set of chromosomes. DNA fits this pattern; protein, which varies between tissues, does not.
The first 10 questions in every subject are free, each with an explanation.