Question

The lowest level of organisation among eumetazoans is

• A. Cellular level
• B. Tissue level
• C. Organ level
• D. Organ system level

Answer 1

The correct option is B

Tissue level

Kingdom Animalia is primarily classified into two groups - organisms that do not have true tissues, called parazoa, and those with true tissues, called eumetazoa. Only sponges would belong to the group parazoa, as they exhibit a cellular level of organisation (where the body is made up of just cells which are not organised into tissues). Eumetazoans can be classified further, on the basis of the level of organisation of their body. These different levels are tissue level (cells are organised into tissues but not into organs), organ level (tissues make up different organs in the body) and organ system level (organs performing related functions make up an organ system, and all the organ systems make up the fully functional organism).