IB Biology DNA structure and replication

Which letter (A–D) indicates where a new nucleotide would attach?

• A

• B

• C

• D

Meselson and Stahl conducted experiments using the isotopes 14N and 15N which showed that DNA replication is semi-conservative. What would they have observed about the distribution of isotopes in the DNA after one round of replication if DNA replication was conservative rather than semi-conservative?

• Only 14N DNA

• Only 15N DNA

• All DNA half 14N and half 15N

• Half the DNA with only 14N and half with only 15N

Which are necessary to make DNA replication semi-conservative?

I. Separation of the strands by RNA polymerase

II. Complementary base pairing

III. Use of a pre-existing strand as a template

• I and II only

• I and III only

• II and III only

• I, II and III

What is a similarity between DNA and RNA?

• Both are polymers of nucleotides.

• Both are composed of antiparallel strands.

• Both contain adenine, cytosine and thymine.

• Both contain ribose sugar.

What usually distinguishes DNA from RNA?

• A

• B

• C

• D

The diagram shows a dinucleotide. Which type of bond is identified by the arrow?

• Phosphate

• Hydrogen

• Covalent

• Peptide

What links the pairs of complementary bases in a DNA double helix?

• Covalent bonds

• Hydrogen bonds

• Ionic bonds

• Peptide bonds

How does DNA replicate?

• The deoxyribose of a free nucleotide is linked to the phosphate of the last nucleotide in the chain.

• The phosphate of a free nucleotide is linked to the deoxyribose of the last nucleotide in the chain.

• Nucleotides are linked in a 3′ to 5′ direction and the new strands are anti-parallel to the template strands.

• Nucleotides are linked in a 5′ to 3′ direction and the new strands are parallel to the template strands.

Tags

NGSS.HS-LS3-2

What is the relationship between enzymes and DNA?

• Enzymes contain the code for DNA.

• Enzymes act on DNA during translation.

• Both enzymes and DNA have similar shapes.

• The structure of enzymes is determined by DNA.

Tags

NGSS.HS-LS1-1

Which of the following statements is/are correct for DNA replication?

I. It occurs during interphase.

II. It is semi-conservative.

III. It is a stage in protein synthesis.

• I only

• II only

• I and II only

• I, II and III