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Natural Selection — Reading Comprehension

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MS-LS4-4
MS-LS4-6

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This comprehensive passage introduces middle school students (grades 6-8) to the concept of natural selection, aligning with NGSS standards MS-LS4-4 and MS-LS4-6. Students will learn how variation, heredity, overproduction, and differential survival drive the adaptation and evolution of populations. The passage explains the underlying mechanisms of natural selection using accessible language and real-world examples, such as the peppered moth during the Industrial Revolution, antibiotic-resistant bacteria, and pesticide-resistant insects. The resource includes a glossary, Spanish translation, differentiated version for struggling readers, and multiple activities including a quiz and graphic organizers. Audio integration is available for all passages and activities, supporting diverse learning needs. This resource is ideal for science teachers seeking engaging, standards-aligned content on evolution and adaptation.

CONTENT PREVIEW

moth, insect, large, cream, brown, pattern, wild, wing, camouflage, wall, queensland, australia, camouflage, camouflage, camouflage, camouflage, camouflage — "The moth's pattern allows it to camouflage with its surroundings and not be spotted by prey, increasing its likelihood of survival" by sandid / Pixabay.

Natural selection drives the adaptation of species to their environments over generations. It explains why certain traits become common in a population while others disappear. For example, biologists observed that after the Industrial Revolution in England, dark-colored peppered moths became more common than light-colored ones. This change occurred because pollution darkened tree bark, making light moths more visible to predators. The process of natural selection reveals how species change as their environments change.

How Natural Selection Works
Natural selection occurs when some individuals in a population have traits that give them an advantage for survival and reproduction. Four main requirements must be met for this process: variation exists among individuals; traits are heritable (passed from parents to offspring); more offspring are produced than can survive; and there is differential survival based on traits. For example, bacteria in a hospital may vary in their ability to survive antibiotics. Those with a random mutation that makes them resistant will survive and reproduce, passing on this trait. Over time, the population evolves, and more bacteria have this resistance.

Examples and Broader Implications
Natural selection does not act on entire species at once; it acts on individuals, but the effects appear in populations over generations. Insects exposed to pesticides show similar processes. Some individuals are naturally resistant and survive chemical treatments, leading to populations that are harder to control. These patterns show how natural selection can affect agriculture, medicine, and health. Scientists use data from experiments—like measuring the percentage of resistant insects after pesticide use—to track these changes. For example, if 5% of insects survive a pesticide one year, and 50% survive a few years later, natural selection is making the population more resistant.

Natural Selection and Evolution
Charles Darwin’s key insight was that the environment “selects” which traits are passed on. He observed that different environments favor different traits, leading to adaptation. Natural selection explains how populations evolve over time, even though individual organisms do not change their traits during their lifetimes. This principle is central to understanding biological diversity, agriculture, and public health strategies, such as rotating antibiotics to slow bacterial resistance. Recognizing how natural selection operates helps scientists predict changes in populations and develop solutions to environmental challenges.

In summary, natural selection is a powerful process that shapes life on Earth. By understanding how it works, we can see the connections between genetics, environment, and the survival of species.

Interesting Fact: Scientists have observed natural selection in action, such as bacteria evolving resistance to antibiotics within just a few years—demonstrating evolution can happen much faster than many people think.

What is natural selection?

A process by which organisms with helpful traits survive and reproduce more oftenA way plants make foodA method animals use to find waterA type of mutation in DNA

Which of the following is needed for natural selection to occur?

Variation among individualsAll organisms being identicalNo offspring producedTraits that cannot be inherited

According to the passage, what happened to peppered moths during the Industrial Revolution?

More dark-colored moths survived and became commonAll moths became extinctLight-colored moths became more commonMoths stopped reproducing

In the passage, what does the word 'heritable' mean?

Able to be passed from parents to offspringHard to seeOnly found in plantsCaused by pollution

What is 'differential survival' in the context of natural selection?

When some individuals survive better due to their traitsWhen all individuals survive equallyWhen new species are createdWhen traits are not inherited

Why do populations, not individuals, evolve according to the passage?

Because changes in traits build up in populations over generationsBecause individuals can change their traitsBecause populations never changeBecause only individuals can inherit traits

What is one real-world example of natural selection mentioned in the passage?

Bacteria becoming resistant to antibioticsClouds forming in the skyRocks breaking apartWater boiling

If 5% of insects survive a pesticide one year, and 50% survive a few years later, what does this show?

Natural selection is increasing resistance in the populationPesticides are making insects weakerAll insects are identicalInsects do not reproduce

Natural selection acts on individuals, but evolution occurs in populations. (True/False)

TrueFalse

All traits that help survival are passed on to the next generation. (True/False)

TrueFalse