Question

the overall shape of dna is a:

a circular chromosome

b single strand

c double helix

d twisted protein

question 2
what is similar about all four nucleotides in dna?

a they are made only of sugars

b they all have the exact same nitrogen base

c they only appear on one strand of dna

d they all contain a phosphate, sugar, and a nitrogen base

question 3
the two sides of the dna molecule are called:

a sugar - phosphate backbones

b amino acid chains

c protein ladders

d nitrogen bases

Explanation:

Question 1

DNA's structure is known to be a double helix, with two strands twisted around each other. Option a is for circular chromosomes (like in prokaryotes, but not DNA's overall shape), option b is incorrect as DNA is double - stranded, and option d is incorrect as DNA is not a twisted protein.

A nucleotide in DNA consists of a phosphate group, a deoxyribose sugar, and a nitrogen base. Option a is wrong as nucleotides have more than just sugar. Option b is wrong as the four nucleotides have different nitrogen bases. Option c is wrong as nucleotides are on both strands (in base - pairing).

The two sides of the DNA molecule are made up of alternating sugar (deoxyribose) and phosphate groups, forming the sugar - phosphate backbones. Option b is for proteins (amino acid chains are for proteins), option c is incorrect (DNA isn't protein ladders), and option d is the rungs (the bases) not the sides.

Answer:

c. double helix

Question 2