IB Biology: A1.2-Chargaff's Data on the Purines and Pyrimidines

What was Phoebus Levene's hypothesis regarding the composition of DNA?

• The relative amounts of purines and pyrimidines in DNA would be unequal.

• The four nucleotides in DNA would occur in equal numbers.

• DNA has a double helix structure.

• DNA is the genetic material.

What did Erwin Chargaff discover about the nucleotide composition of DNA?

• The four different nucleotides were present in equal numbers.

• The percentage of adenine (A) was always equal to the percentage of guanine (G).

• The four different nucleotides were not present in equal numbers.

• DNA is composed of a single strand.

What does the concept of falsifiability mean in the context of scientific hypotheses?

• A hypothesis must be proven true through experimentation.

• A hypothesis can be shown to be false through empirical testing.

• A hypothesis is always correct if it is widely accepted.

• A hypothesis cannot be tested or disproven.

How did Erwin Chargaff's data impact the understanding of DNA structure?

• It confirmed Levene's tetranucleotide hypothesis.

• It showed that DNA was made of proteins.

• It falsified the tetranucleotide hypothesis and helped deduce the double helix structure.

• It proved that DNA was not the genetic material.