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Zoology Question 43 – AP-EAMCET 2025

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Assertion (A) : Arthropods are schizocoelomates. Reason (R) : Coelom in arthropods is formed by splitting of mesoderm. Identify the correct option from the following

Understand the different ways the coelom (body cavity) can form during embryonic development in animals.

Step 1: Define Schizocoelomates✦ Active

Schizocoelomates are a group of animals in which the coelom, or body cavity, is formed by the splitting of the mesoderm during embryonic development. This type of coelom formation is characteristic of protostomes, which include phyla like Annelida, Mollusca, and Arthropoda.

💡 Teacher's Secret Hint

Remember that the coelom is a fluid-filled body cavity completely lined by mesoderm. Its formation method is a key criterion for classifying animal phyla.

Step 2: Evaluate Assertion (A)○ Expand

The assertion states that 'Arthropods are schizocoelomates'. Based on the definition, arthropods, being protostomes, indeed form their coelom by the splitting of the mesoderm. Therefore, Assertion (A) is true.

Step 3: Evaluate Reason (R)○ Expand

The reason states that 'Coelom in arthropods is formed by splitting of mesoderm'. This statement accurately describes the process of schizocoelous coelom formation, which is characteristic of arthropods. Therefore, Reason (R) is true.

Step 4: Determine the relationship between A and R○ Expand

Since Assertion (A) states that arthropods are schizocoelomates, and Reason (R) explains that their coelom is formed by the splitting of the mesoderm, Reason (R) provides a direct and correct explanation for Assertion (A). The formation of the coelom by splitting of the mesoderm is precisely why arthropods are classified as schizocoelomates.

💡 Teacher's Secret Hint

When evaluating Assertion-Reason questions, first determine the truthfulness of each statement independently. Then, check if the reason logically explains the assertion. A good test is to insert 'because' between the assertion and the reason.

Step 5: Conclude the correct option○ Expand

Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation for Assertion (A). This corresponds to option 1.

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