Lesson Worksheet: DNA Discovery and Structure Biology

In this worksheet, we will practice describing the structure of DNA and outlining contributions made to its discovery.


What experimental technique did Rosalind Franklin use when investigating the structure of DNA?

  • AElectron microscopy
  • BNext-generation sequencing
  • CX-ray diffraction
  • DInfrared spectroscopy
  • EGas chromatography


The diagram provided shows a simple outline of the structure of a single DNA nucleotide.

Which letter represents the deoxyribose sugar?

  • AY
  • BZ

Which letter represents the nitrogenous base?

  • AZ
  • BY


Between which DNA bases do 2 hydrogen bonds form?

  • AC and A
  • BC and T
  • CA and T
  • DC and G
  • EG and T


What type of bond forms between base pairs in DNA to hold the two strands together in a double helix?

  • AHydrogen
  • BIonic
  • CGlycosidic
  • DPhosphodiester
  • ECovalent


Between which DNA bases do 3 hydrogen bonds form?

  • AA and G
  • BG and T
  • CA and T
  • DC and T
  • EC and G


In a section of double-stranded DNA that contains 100 bases in total, 20 of these bases are thymine.

How many bases in this section are adenine?

How many bases in this section are guanine?


A strand of DNA has the sequence 53-ATATGCGC-.

State the corresponding sequence on the complementary strand, reading from the 3 to 5 direction.



What key piece of information about the structure of DNA was obtained from Rosalind Franklin’s experiments?

  • AAdenine pairs with thymine, and cytosine pairs with guanine.
  • BThe shape of DNA is a double helix.
  • CDouble-stranded DNA could be split into single strands by heating.
  • DThe backbone of DNA is comprised of phosphate molecules and nitrogenous bases.
  • EThe base pairs are held together with hydrogen bonds.


A simple diagram of the structure of DNA is provided. What part of this structure is indicated by label X?

  • ASugar–phosphate backbone
  • BTriglyceride chain
  • CRibosomal subunit
  • DNitrogenous bases
  • ERibose sugar backbone


Which of the following diagrams correctly demonstrates the structure of a section of DNA?

  • A
  • B
  • C
  • D
  • E

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