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What Is Biodiversity? — Reading Comprehension

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This comprehensive science reading passage for grades 6-8 introduces students to biodiversity and explores its importance at genetic, species, and ecosystem levels. The text explains how biodiversity is measured, why certain areas like tropical rainforests and coral reefs are hotspots, and what factors contribute to high biodiversity. Students learn about methods such as species richness and relative abundance, as well as current scientific estimates of Earth’s species. The passage connects biodiversity to ecosystem stability and human well-being, emphasizing real-world applications and implications for conservation. Aligned with NGSS standards MS-LS2-5 and MS-LS4-4, the resource includes a glossary, differentiated and Spanish versions, comprehension and writing activities, and graphic organizers. Audio integration supports accessibility and multiple learning styles. This lesson is ideal for classrooms aiming to deepen scientific understanding of biodiversity and its role in sustaining life on Earth.

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bees, honey bees, pollinate, pollination, collect pollen, bluebell, proud of the snow, blue star, scilla luciliae, insects, pollen, blue flowers, world bee day, bees, bees, bees, bees, bees — Biodiversity shapes the health and stability of life on our planet. Image by Nennieinszweidrei / Pixabay.

Biodiversity shapes the health and stability of life on our planet. Scientists have discovered that Earth’s living things are not just countless in number, but also incredibly varied, from tiny bacteria to towering redwood trees. This variety is not random; it forms the foundation of functioning ecosystems and supports all life, including humans. Understanding biodiversity helps us address challenges such as disease, food security, and climate change.

Levels of Biodiversity: Genes, Species, and Ecosystems

Biodiversity exists at three main levels. First, genetic diversity refers to the differences in DNA within a single species. For example, two wolves may look similar, but their genes can vary in ways that affect their survival and adaptability. Second, species diversity is the number and variety of species found in a particular place. In a coral reef, thousands of fish, coral, and invertebrate species interact in complex ways. Third, ecosystem diversity describes the variety of habitats, such as forests, deserts, and wetlands. Each habitat provides unique resources and supports different communities of organisms. These levels interact: genetic diversity within species boosts their chances of survival, while many species together create stable ecosystems.

Measuring Biodiversity and Hotspots

Scientists measure biodiversity using two main tools. Species richness counts the total number of different species in an area, while relative abundance looks at how evenly individuals are distributed among those species. Regions with especially high biodiversity are called hotspots. Tropical rainforests, for example, cover less than 7% of Earth’s land but contain over 50% of known species. Coral reefs, the island of Madagascar, and the Mediterranean basin are other famous hotspots. Scientists estimate there may be 8 to 10 million species on Earth, but most have not yet been discovered or described.

Why Some Places Have More Biodiversity

Biodiversity is not spread evenly across the planet. Areas near the equator tend to have more species because of warm temperatures, high rainfall, and stable climates. A region’s evolutionary history also matters. Tropical regions have been stable for millions of years, allowing life to diversify. Additionally, a greater variety of habitats—like mountains, rivers, and forests—supports more species. Human activity can threaten biodiversity by destroying habitats, introducing invasive species, and changing climate patterns. As biodiversity decreases, ecosystems become less resilient to changes and may provide fewer benefits, such as clean air and water.

Why Biodiversity Matters

Biodiversity is essential for ecosystem services that humans rely on. Diverse genetic resources help crops resist disease and adapt to changing conditions. Species interactions maintain soil fertility, pollinate plants, and regulate pests. Protecting biodiversity also preserves opportunities for new medicines and technologies. By studying and conserving biodiversity, scientists and communities can ensure the health and sustainability of life on Earth for future generations.

Interesting Fact: Scientists discover about 15,000 to 18,000 new species each year, but millions are still waiting to be found!

What is biodiversity?

The variety of all living things on EarthThe number of trees in a forestThe amount of rainfall in an areaA type of ecosystem found in rainforests

Which of the following is NOT a level of biodiversity?

Genetic diversitySpecies diversityClimate diversityEcosystem diversity

Why are tropical rainforests called biodiversity hotspots?

They have more than 50% of known species but cover less than 7% of landThey have the fewest species on EarthThey receive the most rainfallThey are the coldest places on Earth

What does genetic diversity mean in the passage?

Differences in DNA within a speciesThe number of habitats in an areaVariety of species in a rainforestNumber of organisms in an ecosystem

What is the definition of a hotspot in this context?

A region with very high biodiversityA place with warm temperaturesAn area with no plant lifeA type of ecosystem in deserts

Which factor does NOT increase biodiversity in a region?

Stable climate over millions of yearsHigh variety of habitatsHuman destruction of habitatsWarm temperatures and high rainfall

What is one effect of decreasing biodiversity?

Ecosystems become less resilientThe number of species increasesThere are more hotspotsGenetic diversity increases

True or False: Scientists have already discovered all species living on Earth.

TrueFalse

True or False: Ecosystem diversity means having many different species in one area.

TrueFalse