Question

Phylum	Level of organization	Digestive system	Respiratory system
Aschelminthes	A	Complete	Absent
Echinodermata	Organ system	B	Present
Platyhelminthes	Organ	Incomplete	C
Annelida	Organ system	Incomplete	D

Select the option with correct identification of A, B, C, and D.

• A. A - organ, B - Complete, C-Present, D - Absent
• B. A - organ system, B - Complete , C - Absent , D - Absent
• C. A - organ system, B - Incomplete , C - Absent , D - Present
• D. A - organ system, B - Incomplete , C - Present , D - Absent

Answer 1

Answer: (B)

I. Levels of the organization - It is of various types
A. Cellular level - Division of labour is there between the cells but are not tissues. These are in the form of loose cell aggregates. Example: Sponges (Porifers)
B. Tissue level - Cells that are organized to perform the same function act as tissues. Examples: Coelenterates.
C. Organ level - Tissues grouped together to form organs. Examples: Platyhelminthes.
D. Organ system level - Organs associated to form functional systems. Examples: Annelids, arthropods, molluscs, echinoderms, and chordates.
II. Digestive system is
A. Incomplete with a single opening (blind sac body plan) that acts as anus and mouth both. e.g. Coelenterates and Platyhelminthes.
B. Complete with two openings (tube within tube plan) which behave as anus and mouth separately. e.g. from Aschelminthes up to Chordates.
III. Specific respiratory structures and respiratory system is well developed from phylum Arthropoda.