Statement I : Bioaccumulation is a process of progressive accumulation of heavy metals and pesticides in an organism. Statement I : Large fishes of the pond are found to have higher concentration of pesticides than planktons of the same pond.

Statement I is true as bioaccumulation refers to the buildup of toxins, such as heavy metals and pesticides, within the tissues of a single organism over time [3]. This occurs when the rate of intake from food and the environment exceeds the rate of excretion or metabolism. Statement II is also true and describes biomagnification, where the concentration of pollutants increases progressively as they move from one trophic level to the next [2]. In a pond ecosystem, large fishes (higher trophic level) typically exhibit higher pesticide concentrations than planktons (lower trophic level) because they consume many contaminated organisms [4]. However, Statement II is not the correct explanation for Statement I because bioaccumulation focuses on the concentration increase within an individual organism's lifespan, whereas Statement II illustrates the transfer and magnification across different levels of a food chain [3].

Sources

1. [3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > 29.1.6. DDT > p. 414
2. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > 2.5.2. Biomagnification > p. 16
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 13: Our Environment > 13.1.1 Food Chains and Webs > p. 212
4. [4] https://undergraduatescr.lagosstate.gov.ng/libweb/X7KEmL/4OK082/AmoebaSistersVideoRecapBiomagnificationAnswerKey.pdf