8.
We say a shape has more symmetries if there are more ways it can be rotated, flipped or
moved to get back the same shape. Below are images of four different macromolecules
labelled A to D. Order them from low to high symmetry.
a. D, C, A, B
b. B, A, D, C
c. D, B, C, A
d. A, D, C, B

The correct order of the four macromolecules from low to high symmetry is D, B, C, A.

Understanding symmetry in macromolecules

A shape is said to have higher symmetry when there are more ways to rotate, flip or move it so that it looks exactly the same as before the movement. In macromolecules, symmetry usually arises when many identical subunits are arranged regularly around an axis or a central point, as in viral capsids or symmetric protein oligomers.​

When comparing four shapes visually, the one that looks most irregular and “lopsided” has the fewest symmetry operations, while the one that looks most sphere‑like and uniformly patterned in all directions has the most symmetry.​

Why option C (D, B, C, A) is correct

Looking at the pictures, D is highly irregular: it is elongated with clear bends and no obvious axis or plane of symmetry, so it has the lowest symmetry. Shape B is still quite irregular but suggests at least a rough three‑armed arrangement, giving slightly more rotational symmetry than D.​​

Shape C is more compact and closer to a blob with repeated protrusions, so it can be rotated in more ways to look similar, indicating higher symmetry than B. Finally, A is nearly spherical and covered with a dense, repeating surface pattern, typical of highly symmetric assemblies such as icosahedral viral capsids, so it has the highest symmetry of all four. Putting this together gives the order D (lowest), B, C, A (highest), which matches option c.​​

Explanation of each option

Option a: D, C, A, B

This option correctly places D as the least symmetric but then ranks C below B, even though C is more compact and closer to a regular, repeating form than B. It also incorrectly puts B as the most symmetric, despite its clearly lopsided three‑lobed shape compared with the highly spherical, patterned A.​​

Option b: B, A, D, C

Here B is placed as the least symmetric, but D is visually more distorted and elongated with fewer possible symmetry operations. The option also claims A is only slightly more symmetric than B and far below C, which contradicts the obvious near‑spherical, highly repetitive structure of A.​​

Option c: D, B, C, A

This option starts with D, the most irregular shape, as the lowest symmetry and ends with A, the almost perfectly spherical, highly patterned shape, as the highest symmetry. The intermediate ranking of B (moderate asymmetry) and C (more compact, more regular) matches the intuitive increase in the number of ways each molecule can be rotated or reflected to look the same, so this ordering is logically consistent and therefore correct.​​

Option d: A, D, C, B

Option d places A as the least symmetric, which is opposite of what the nearly spherical, regularly patterned appearance indicates. It also scatters D, C and B in an order that does not correspond to their visual regularity, so the progression from low to high symmetry is not satisfied.​​

How to quickly order shapes by symmetry in exams

• First, identify the most irregular shape (fewest obvious axes or planes of symmetry) and assign it lowest symmetry.​

• Next, look for partial regularity or repeated arms or lobes; more repetition means higher symmetry than a single bent chain.​

• Finally, choose the most spherical or highly patterned object as the highest symmetry, since such shapes allow many rotational operations that leave the appearance unchanged.