Ospreys and other top predators are most severely affected by pesticides such as PCBs because they
a. Are especially sensitive to chemicals.
b. Have very long life spans.
c. Store the pesticides in their tissues.
d. Consume prey in which pesticides are concentrated.

Verified step by step guidance

1. Understand the concept of biomagnification: Biomagnification refers to the process by which the concentration of toxic substances, such as pesticides, increases as it moves up the food chain. Top predators, like ospreys, are most affected because they consume prey that has accumulated these substances.
2. Analyze the options provided: Each option represents a potential reason why ospreys and other top predators are severely affected by pesticides. Carefully evaluate each one based on biological principles.
3. Option a: 'Are especially sensitive to chemicals' - While sensitivity to chemicals can vary among species, this is not the primary reason top predators are affected by pesticides like PCBs. Sensitivity alone does not explain the accumulation of toxins.
4. Option b: 'Have very long life spans' - Long life spans can contribute to the accumulation of toxins over time, but this is not the main factor in why top predators are severely affected. The key lies in their position in the food chain.
5. Option c and d: 'Store the pesticides in their tissues' and 'Consume prey in which pesticides are concentrated' - These two options are closely related to biomagnification. Top predators consume prey that has already accumulated pesticides, leading to higher concentrations in their own tissues. This is the most biologically accurate explanation.

Key Concepts

Bioaccumulation

Bioaccumulation refers to the process by which organisms accumulate toxic substances, such as pesticides, in their bodies over time. This occurs when the rate of intake of the substance exceeds the rate of elimination. In top predators like ospreys, this can lead to high concentrations of harmful chemicals, as they consume prey that has already accumulated these toxins.

Trophic Levels

Trophic levels represent the hierarchical positions of organisms in a food chain, based on their feeding relationships. Ospreys, as top predators, occupy the highest trophic level, meaning they consume other organisms (like fish) that may have ingested pesticides. This positioning leads to increased exposure to toxins through a process known as biomagnification, where concentrations of harmful substances increase at each successive trophic level.

Chemical Sensitivity

Chemical sensitivity refers to the vulnerability of certain species to the effects of environmental pollutants. Ospreys and other top predators may exhibit heightened sensitivity to chemicals like PCBs due to their physiological traits and ecological roles. This sensitivity can result in adverse health effects, including reproductive issues and weakened immune responses, exacerbated by their long life spans and accumulation of toxins.