Q 1.4 DNA as the substance of the gene

Frederic Griffith discovered transformation in his experiments on mice and Pneumococcus bacteria. He injected the mice with combinations of harmless, R-strain bacteria and disease-causing S-strain bacteria. Which combination of bacteria killed the mice and showed that transformation occurred?

• Heat-killed R-strain and live S-strain

• Heat-killed S-strain and live R-strain

• Heat-killed bacteria of both strains

• Live bacteria of both strains

Which statements describe a bacteriophage? Select all that apply.

• It is a type of virus that infects bacteria.

• It is a type of bacteria that infects viruses.

• It is a virus consisting of a protein coat and a DNA core.

• It is a bacterial strain consisting of protein and a DNA core.

The diagram illustrates the bacteriophages used in the Hershey-Chase experiment. What was the purpose of marking the bacteriophages with phosphorus-32 and sulfur-35?

• To track the movements of DNA and sugars

• To track the movements of DNA and proteins

• To remove DNA and sugars from the bacteriophages

• To combine DNA and proteins into a single molecule

What are three tasks that DNA must be able to perform in all organisms? Select three answer choices.

• It must store genetic information.

• It must discard foreign genes.

• It must instruct cells to produce needed molecules.

• It must copy itself.

• It must move to locations throughout the cell.

When does transformation occur?

• When an organism receives foreign RNA that is transformed into DNA

• When DNA is transformed into RNA

• When bacteria are killed with heat

• When a cell receives foreign DNA that is expressed as a new characteristic

A nucleotide of DNA may contain adenine, guanine, cytosine, or thymine. What is each of these components?

• 5-carbon sugar

• Nitrogenous base

• Phosphate group

• Nucleic acid

The image shows a nucleotide, a building block of the DNA molecule. From left to right, what are the names of the components?

• 5-carbon sugar, nitrogenous base, phosphate group

• Nucleic acid, 5-carbon sugar, amino group

• 5-carbon sugar, nitrogenous base, carboxyl group

• Nitrogenous base, 5-carbon sugar, phosphate group

Analyze the data about nitrogenous base content of DNA from various species. Which three statements are supported by the data?

• In any one species, the amount of adenine closely approximates that of thymine.

• In any one species, the amount of guanine closely approximates that of cytosine.

• The amount of A, T, G, and C in DNA is constant among species.

• The amount of A, T, G, and C in DNA varies among species.

Rosalind Franklin’s photographs of the X-ray diffraction pattern of DNA provided important clues about the structure of the DNA molecule. What was revealed by the photograph that enabled Watson and Crick to build their model of the DNA molecule? Select all that apply.

• The nitrogenous bases form the backbone on the outside of each DNA strand.

• The DNA strands are twisted around each other.

• There are two strands in the DNA molecule.

• The nitrogenous bases are near the center of the DNA molecule.

The diagram shows a section of double-stranded DNA, and includes the bonds that hold the two strands together. Chemical bonds are represented by dotted lines (label 1) and solid lines (label 2). What types of bonds are represented by the dotted lines and the solid lines in the diagram?

• The dotted lines represent hydrogen bonds; the solid lines represent ionic bonds.

• The dotted lines represent covalent bonds; the solid lines represent hydrogen bonds.

• The dotted lines represent ionic bonds; the solid lines represent covalent bonds.

• The dotted lines represent hydrogen bonds; the solid lines represent covalent bonds.