Q 01/05

In whose laboratory at the University of Tubingen did Friedrich Miescher isolate 'nuclein' in 1869?

A) Felix Hoppe-Seyler

B) Rudolf Virchow

C) Justus von Liebig

D) Robert Koch

Answer · why

A) Felix Hoppe-Seyler

Miescher got his white blood cells from pus on surgical bandages collected at a nearby hospital.

Q 02/05

The 1944 Avery-MacLeod-McCarty experiment showed DNA was the 'transforming principle' in which bacterium?

A) E. coli

B) Pneumococcus

C) Salmonella

D) Bacillus subtilis

Answer · why

B) Pneumococcus

At the time most biologists assumed proteins carried heredity, which is what the very word 'protein' had implied.

Q 03/05

The 1952 Hershey-Chase 'blender experiment' used what kind of virus to show DNA, not protein, enters the host?

A) Bacteriophage

B) Tobacco mosaic virus

C) Influenza

D) Adenovirus

Answer · why

A) Bacteriophage

Phage DNA entered the bacteria while most of the protein coat stayed outside and was knocked off in a blender.

Q 04/05

Chargaff's rules state that in DNA adenine equals thymine and guanine equals what?

A) Uracil

B) Adenine

C) Cytosine

D) Thymine

Answer · why

C) Cytosine

Erwin Chargaff's ratios were a crucial clue that led Watson and Crick to complementary base pairing.

Q 05/05

Meselson and Stahl's 1958 experiment labelled DNA with a heavy isotope of which element?

A) Nitrogen

B) Phosphorus

C) Carbon

D) Sulfur

Answer · why

A) Nitrogen

Nitrogen is in every DNA base, so 15N-labelled parent strands could be separated from lighter new ones by density.