Question

what is different about each of the four nucleotides?
a they each have a different phosphate shape
b each one has a different nitrogen base
c they each carry different amino acids
d each one contains a different sugar
question 5
which shape represents phosphate molecules in most dna models?
a circle
b triangle
c pentagon
d square
question 6
which shape represents deoxyribose sugar molecules in most dna models?
a circle
b pentagon
c square
d hexagon

Explanation:

Question (about four nucleotides):

Nucleotides are composed of a phosphate group, a sugar (deoxyribose in DNA or ribose in RNA), and a nitrogen base. The four nucleotides in DNA (adenine, thymine, cytosine, guanine) or RNA (adenine, uracil, cytosine, guanine) differ in their nitrogen bases. Phosphate groups are the same in structure for nucleotides, so option a is wrong. Amino acids are related to proteins, not nucleotides, so option c is wrong. The sugar (deoxyribose or ribose) is the same for all nucleotides of a particular nucleic acid (DNA or RNA), so option d is wrong. Thus, the correct answer is the one with different nitrogen bases.

In typical DNA models, phosphate groups are represented by circles, deoxyribose sugar by pentagons, and nitrogen bases by rectangles or other shapes. Triangles, pentagons (for sugar), and squares don't represent phosphate. So the shape for phosphate is a circle.

In DNA models, deoxyribose sugar is typically represented by a pentagon. Circles are for phosphate, squares are not for sugar, and hexagons don't represent deoxyribose. So the shape for deoxyribose sugar is a pentagon.

Answer:

b. each one has a different nitrogen base

Question 5 (shape of phosphate in DNA models):