Question

Which of the following statements is wrong about symmetry, while the other three are correct?
A. Any plane that passes through the center does not divide the body into equal halves in most sponges.
B. The body of an arthropod can be divided into identical halves into two planes.
C. Any plane passing through the central axis of the body divides Hydra into two identical halves.
D. The body of an annelid can be divided into identical halves in only one plane.

Answer 1

Hint:Symmetry is a criteria of classification of organisms.
Some animals are asymmetrical, which means they cannot be divided into two equal halves in any plane.
Some animals show radial symmetry, which means, any plane passing through the central axis of the body will divide the body into two equal halves.
Some animals show bilateral symmetry, which means, their body can be divided into equal halves only in one plane.

Complete answer:Sponges are asymmetrical. Their body cannot be divided into equal halves. They have no front or back, and no right or left side. The choanocytes are specialized cells that use flagella to move a current of water through the sponge, the water leaves through the osculum. Sponges have a simple skeleton.
Arthropods are bilaterally symmetrical protostomes. So, their bodies cannot be divided into identical halves into two planes.
Hydra has a tubular, radially symmetric body and divides the body into two identical halves.
Annelids are all bilaterally symmetrical animals that divide in only one plane.

So, the answer is B. The body of an arthropod can be divided into identical halves into two planes, which is wrong from the above sentences.

Note:In biology, symmetry pertains to an attribute of organisms showing regularity in parts on a plane or around an axis.
 An organism that is symmetrical would have a balanced distribution of duplicate parts on each side of the axis. In most instances, the parts are not exact but a near repetition.