Question

question 4
double-stranded dna looks a little like a ladder that has been twisted into a helix or spiral. the side supports of the ladder are
a. alternating bases and sugars.
b. alternating sugars and phosphates.
c. individual nitrogenous bases.
d. alternating bases and phosphate groups.

question 5
dna is held together in a double helix by the force of
a. ionic bonds.
b. hydrogen bonds.
c. covalent bonds.
d. the twists.

question 6
at the end of dna replication, two dna molecules are produced, each one consisting of a parental dna strand and a new dna strand. this process is known as ______ replication.
a. conservative
b. semiconservative
c. complementary
d. dispersive

Explanation:

• Question 4: DNA structure: The "sides" of the DNA "ladder" are made of alternating sugar (deoxyribose) and phosphate groups. Bases pair in the middle (like the rungs). So, options A, C, and D are incorrect as they don't match the sugar - phosphate backbone structure.
• Question 5: DNA double - helix bonding: Hydrogen bonds hold the two strands of DNA together. Ionic bonds are not the main force here. Covalent bonds are within the sugar - phosphate backbone, not between the two strands. The "twists" are a result of the overall structure, not the force holding it together.
• Question 6: DNA replication type: Semiconservative replication means that each new DNA molecule has one old (parental) strand and one new strand. Conservative replication would have one molecule with two old strands and one with two new strands. Complementary is related to base - pairing, not the replication mode. Dispersive replication would have fragments of old and new DNA in each strand in a more random, non - strand - based way.

Answer:

• Question 4: B. alternating sugars and phosphates.
• Question 5: B. hydrogen bonds.
• Question 6: B. semiconservative.