Arthropod Dominance in Animal Kingdom — NEET Biology
📚 Practice ConceptWhat are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Which of the following statements are NOT correct regarding circulatory systems and body cavities in the animal kingdom, based on NCERT guidelines? S1: Annelids possess a closed circulatory system where blood is circulated through a series of vessels, in contrast to arthropods. S2: Arthropods are classified as coelomate animals, but they primarily exhibit an open circulatory system. S3: In an open circulatory system, blood is pumped out of the heart and directly bathes the cells and tissues of the organism. S4: All animals with an organ-system level of organization invariably possess a closed circulatory system to ensure efficient nutrient and waste transport. S5: The absence of a circulatory system is characteristic of organisms like Porifera and Coelenterata, which have cellular or tissue levels of organization.
View solution & NCERT explanation
Correct answer: A — Only S4 is not correct
The core concept revolves around the types of circulatory systems (open vs. closed) and their occurrence in different phyla, as well as the concept of coelom. S1: "Aquatic annelids like Nereis... A closed circulatory system is present." (4.2.6) and "(ii) closed type in which the blood is circulated through a series of vessels..." (4.1.1). "Circulatory system is of open type" for Arthropods (4.2.7). This statement is correct. S2: "Animals possessing coelom are called coelomates, e.g., annelids, molluscs, arthropods..." (4.1.4). "Circulatory system is of open type" for Arthropods (4.2.7). This statement is correct. S3: "(i) open type in which the blood is pumped out of the heart and the cells and tissues are directly bathed in it" (4.1.1). This statement is correct. S4: Arthropods exhibit an organ-system level of organization (4.2.7) but have an open circulatory system (4.2.7). Annelids have organ-system level and a closed system (4.2.6). Therefore, the statement that *all* animals with organ-system level invariably possess a closed circulatory system is incorrect. S5: Table 4.2 for Porifera and Coelenterata lists "Absent" for Circulatory System. This statement is correct. Therefore, only statement S4 is NOT correct. The final answer is A. Only S4 is not correct. Recap: Circulatory systems can be open or closed, with arthropods having an open system despite being coelomates. Not all animals with organ-system level of organization have a closed circulatory system.
What does NCERT say about What are reasons that?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.