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Botany Question 4 – AP-EAMCET 2025

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Assertion (A) : Algae will increase the level of dissolved oxygen in the immediate environment. Reason (R) : They form the food for aquatic animals. Identify the correct option from the following

Consider the primary biological processes performed by algae in an aquatic environment, particularly their metabolic activities and their position in the food web.

Step 1: Analyze Assertion (A)✦ Active

Assertion (A) states: "Algae will increase the level of dissolved oxygen in the immediate environment." Algae are photosynthetic organisms. During photosynthesis, they utilize carbon dioxide and release oxygen as a byproduct. This oxygen dissolves in the surrounding water, thereby increasing the dissolved oxygen levels. Therefore, Assertion (A) is true.

Step 2: Analyze Reason (R)○ Expand

Reason (R) states: "They form the food for aquatic animals." Algae are primary producers in aquatic ecosystems. They convert light energy into chemical energy, forming the base of the food web. Many aquatic animals, such as zooplankton and some fish, feed on algae. Therefore, Reason (R) is true.

Step 3: Determine the relationship between (A) and (R)○ Expand

We need to determine if Reason (R) correctly explains Assertion (A). Assertion (A) is about the production of oxygen by algae, which is a result of photosynthesis. Reason (R) is about algae serving as food for aquatic animals, which is related to their role as primary producers in the food web. While both statements are individually true, the fact that algae are food for aquatic animals does not explain *why* they increase dissolved oxygen. The increase in dissolved oxygen is a direct consequence of their photosynthetic activity, not their trophic role. Thus, (R) is not the correct explanation for (A).

💡 Teacher's Secret Hint

Remember to distinguish between a statement being true and it being a correct explanation for another true statement. Look for a direct cause-and-effect relationship.

Step 4: Select the correct option○ Expand

Based on the analysis, both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A). This corresponds to option 2.

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