What is bioaccumulation — Reading Comprehension

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This engaging 4th-grade science reading passage, with audio integration, introduces students to the important ecological concept of bioaccumulation. The passage explains, in simple terms, how harmful substances like chemicals and heavy metals can accumulate in living organisms. It defines key terms such as bioaccumulation and biomagnification, using easy-to-understand analogies like a sponge soaking up water. The content aligns with the NGSS standard LS2.A: Interdependent Relationships in Ecosystems, helping students understand how organisms interact with their environment and how these interactions can be affected by pollution. The passage also includes a fun fact to capture students' interest and is followed by eight multiple-choice questions to assess their comprehension at different DOK levels. The questions test everything from literal recall to the application of learned concepts to new scenarios. With its audio-integrated format, this resource is perfect for diverse learning needs, providing a comprehensive and accessible way to explore how pollutants move through ecosystems.

CONTENT PREVIEW

Have you ever wondered what happens to pollution once it enters our planet's ecosystems? Our Earth is a complex and wonderful place, but sometimes harmful substances, like chemicals and heavy metals, can find their way into the environment. These toxins can cause a process called bioaccumulation. Bioaccumulation is when a living thing, like a plant or animal, takes in a substance from its environment faster than it can get rid of it. Think of it like a sponge soaking up water. Over time, the sponge holds more and more water, and its concentration of water increases. In the same way, an organism's body can build up more and more toxins.

Bioaccumulation can happen in many ways. A fish might absorb chemicals through its gills as it breathes, or a bird might swallow tiny plastic pieces that have been floating in the ocean. These substances often get stored in the animal’s fatty tissues. Because these toxins don’t easily leave the body, they can reach levels that are much higher than the levels in the water or soil around the animal. For example, if a small fish lives in water with a tiny amount of mercury, over its lifetime it will absorb that mercury, and the amount inside its body will slowly increase.

When one animal eats another, the toxins can be passed along. This is called biomagnification. The amount of the substance becomes more and more concentrated as it moves up the food chain. Imagine a tiny fish with a small amount of mercury. A bigger fish eats many of those tiny fish. That bigger fish now has the mercury from all the little fish it ate! If a bigger predator, like a bird or a bear, then eats many of those bigger fish, the amount of mercury in the top predator's body will be even higher. This is why predators at the top of the food chain, including humans, are at the greatest risk from bioaccumulation and biomagnification.

Fun Fact: The famous phrase “mad as a hatter” came from hat makers in the 1800s who suffered from mercury poisoning due to the mercury used in their trade, which bioaccumulated in their bodies over time.

What is bioaccumulation?

The process of an animal eating foodThe build-up of a substance inside a living thingThe way plants make their foodThe movement of water in a river

Where do toxins often get stored in an animal's body?

In their bones and teethIn their fatty tissuesIn their skin and furIn their digestive system

According to the passage, what is the difference between bioaccumulation and biomagnification?

Bioaccumulation is slow, while biomagnification is fastBioaccumulation is about plants, while biomagnification is about animalsBioaccumulation is the build-up within one organism, while biomagnification is the increase up the food chainBioaccumulation only happens in water, while biomagnification happens on land

Why are animals at the top of the food chain at the greatest risk from bioaccumulation?

They eat a lot more food than other animalsThe toxins become more concentrated as they move up the food chainThey live in more polluted environmentsTheir bodies cannot get rid of any toxins

If a tiny fish has a small amount of a toxin, what might happen to that toxin's concentration in a bigger fish that eats many of those tiny fish?

It will disappearIt will stay the sameIt will become more concentratedIt will be broken down and become helpful

Imagine a deer eats leaves that have a small amount of pesticide on them. Over time, the deer's body builds up these toxins. What process is this?

PhotosynthesisBiomagnificationBioaccumulationExcretion

A hawk eats several mice, and each mouse has a small amount of a chemical in its body. Based on the passage, what would you expect to happen to the chemical's concentration in the hawk?

The chemical will have no effect on the hawkThe hawk's body will break down the chemical completelyThe chemical's concentration will become higher in the hawkThe hawk will pass the chemical to its prey

A scientist is studying a river. She finds that the big fish have very high levels of mercury, but the water itself has very low levels. What is the most likely reason for this?

The fish are creating the mercury themselvesThe fish are eating other animals that have accumulated the mercuryThe mercury is only dangerous to the small animalsThe water is not being tested correctly for the toxins