7. Bioaccumulation & Biomagnification

What is bioaccumulation,

Bioaccumulation is the amount of pesticides that build up in the body of an organism over time.

why do certain pesticides bioaccumulate in organisms?

Certain pesticides bioaccumulate because they cannot easily be excreted (eliminated) from the body.

Give examples of substances that are known to bioaccumulate and biomagnify in ecosystems.

Examples include mercury, DDT, and PCBs (synthetic chemicals).

What is biomagnification, and how can it affect organisms in a food chain?

Biomagnification is the increase in the concentration of a toxin, such as a pesticide, as it moves up through the food chain. As predators consume prey, the concentration of the toxin can reach toxic levels in higher organisms.

How does biomagnification of pesticides like DDT impact top predators in an ecosystem?

Biomagnification of pesticides like DDT can cause top predators to accumulate toxic levels of the pesticide, which can lead to health problems, reproductive issues, or even death.

What is pesticide resistance, and how does it develop in pest populations?

Pesticide resistance occurs when a pesticide loses its ability to effectively control a pest population. This happens because some individuals in the population survive the pesticide application, reproduce, and pass on their resistance to offspring. Over many generations, the entire population can become highly resistant to the pesticide.

How does the overuse or long-term use of a pesticide contribute to resistance in pests?

• Prolonged or excessive use of a pesticide increases the chances that some pests will survive the application.

• These survivors reproduce,

• gradually increasing the proportion of resistant individuals in the population until the pesticide becomes ineffective.

What are the consequences of pests becoming resistant to pesticides? how it affects others?

• When pests become resistant, it can lead to decreased effectiveness of the pesticide,

• requiring higher doses or the use of more toxic chemicals,

• which can harm non-target species and the environment.

• It also increases the cost and effort needed to control pests.

What role does natural selection play in the development of pesticide resistance?

• Natural selection plays a key role in pesticide resistance.

• When a pesticide is applied, the individuals that survive have a genetic advantage.

• Over time, they reproduce and pass on their resistant traits to the next generation, l

• eading to a population that is more resistant to the pesticide.