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Performance Benchmark L.8.D.3
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Life Science
Structure of Life
Organisms and Their Environment
Diversity of Life
Content Areas
Nature of Science (NOS)
Life Science
Earth Science
Physical Science

Students know an organism’s behavior is based on both experience and on the species’ evolutionary history.  E/S

Evidence suggests that species change over time.  This process of change is called biological evolution and can be attributed to genetic and/or environmental influences.  Individuals that are better suited to their environment are more likely to survive and reproduce than other less fit members of the same species.  In essence, nature “selects” those individuals with beneficial traits. This mechanism of biological evolution is called natural selection and was developed by Charles Darwin.  Natural selection is affected by the following factors: overproduction, competition for survival, variation, adaptation, and genetic mutation.  Additionally, differences among individuals within a species can yield advantages and/or disadvantages in survival and/or reproduction.

Most species produce far more offspring than the environment can support.  This is to assure that at least some of the offspring survive to adulthood and have the opportunity to reproduce.  Many offspring fall victim to predators while others die competing for limited resources or due to an illness.  Very few offspring reach adulthood compared to the number produced.  For example, scientists estimate that only one in 1,000 sea turtle hatchlings will survive to become an adult.

Figure 1.Sea turtle hatchlings. Only 1 in 1,000 will survive to become an adult.

Competition for Survival
In addition to food, resources including water, shelter, territory, and mates are also limited.  The struggle among organisms for these resources is called competition.  As organisms compete, those that are better adapted to the conditions in the environment are more likely to survive and reproduce.  This is referred to as fitness. The most fit individuals survive and pass on the better suited genes to the next generation.  Consequently, those organisms that are unable to meet their needs will most likely perish or not reproduce. This concept is also known as survival of the fittest. An incorrect assumption is that the largest, strongest, and fastest individuals are the most fit. That is not always the case. Adaptations to an environment may be structural or behavioral. An organism that is camouflaged and hides well may be more fit than its larger, faster competitor. 

Figure 2. Animals competing for a water source.

The offspring of each generation are not exactly alike.  Differences in traits among individuals of the same species are called variations.  Variations result from random mutations and genetic recombination during sexual reproduction.  Some variations make individuals better suited for survival in their environment.  As a result, those individuals are more likely to survive and reproduce.  The offspring in turn may inherit the helpful trait thus passing it on to their offspring. Over time, helpful variations gradually accumulate in a species, while unfavorable ones decrease or may disappear. Figure 3 illustrates the variations that Darwin noted among the finches that lived on the Galapagos Islands.

Figure 3. Darwin’s finches are a classic example of variation among species.   

Characteristics that help an organism survive in its environment and reproduce are called adaptations.  Adaptations can help an organism get food, avoid predators, reproduce, move from place to place, build shelters and raise offspring.  Adaptations can be physical or behavioral. The shape and color of a flower or the long trunk of an elephant are examples of structural adaptations.  A spider’s web spinning ability or a bird’s courting dance are examples of behavioral adaptations.

Desert plants, such as the golden barrel cactus, have adaptations that enable them to withstand the harsh conditions of the desert. For example, the cactus has spines instead of leaves in order to help prevent water loss through transpiration. The spines also serve to partially shade the cactus from the intense sunlight in the desert. The pleated surface of the cactus allows it to expand and store water from the small amount of rain that falls.

Picture of ball-shaped cacti with yellow spines and wooly hairs, golden barrel cactus.
Figure 4. Golden Barrel Cactus.

Genetic mutations
Any change in a gene or chromosome is called a mutation.  Mutations can introduce changes in an individual and be a source of genetic variety.  Helpful mutations improve an individual’s chances for survival and reproduction and may be passed on to future generations.  If a mutation is harmful, the individual may die before producing offspring with the inherited mutation. However, harmful mutations may also be passed along to offspring. The figure below shows the result of the albinism, a genetic mutation which causes a lack of pigmentation in the eyes, skin, and hair. Albinism is a harmful mutation because the tiger will not be able to camouflage itself while trying to hunt for prey.


Figure 5. Albino versus normal pigmented Bengal tiger.

For more information on inheriting genetic mutations,
see MS TIPS Benchmark L.8.A.2

To learn more about the mechanisms that promote variations in gene pools visit the
HS TIPS Benchmark L.12.D.5

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Performance Benchmark L.8.D.3

Students know an organism’s behavior is based on both experience and on the species’ evolutionary history.  E/S

Common misconceptions associated with this benchmark

1. Students incorrectly believe that “survival of the fittest” means survival of the biggest, strongest, and most advanced.

In terms of evolution, fitness refers to an organism’s ability to live long enough to reproduce.  The “fit” or better suited characteristics are then passed on to the next generation.  Adaptability determines an organism’s level of fitness, not size, strength, and intelligence.  As the environment changes, then the fitness of the individual will be judged on how well it can cope with the new situation.  The following example illustrates this: “…if your environment contained a pack of hungry lions, yourself and a tortoise, the tortoise is a lot more likely to survive a lion-attack than you are. You might be bigger, stronger, faster and brainier than the tortoise, but he's the one with retractable limbs and a hard, thick shell. “

The following webpage contains an animation illustrating evolution in a changing environment.

2. Students inaccurately believe that humans evolved from apes.

Humans belong to a group of primates called hominids.  All primates share the following characteristics: grasping hands and feet, forward facing eyes, and large brains.  The first primate fossils appeared about 55 million years ago.  Scientists believe apes are humans nearest primate relative and that they share a common ancestor that lived 8 million years ago.  Over time, this common ancestor evolved into multiple species resulting in a hominid family tree with many branches.  Therefore, humans evolved alongside apes, not from them.

Figure 6. Diagram emphasizing humans evolved alongside other apes, not from them.

The evolution of humans and chimpanzees is illustrated in the following animation:

3. Students incorrectly believe that individual organisms evolve or mutate into something else.

Evolution applies to an entire species over many generations.  Individual organisms do not evolve.  An organism’s genotype does not change.  There are variations, including mutations that occur among individuals within a species.  Advantageous variations may result in an individual being more fit or better suited to its environment (survival of the fittest).  These helpful traits may be passed on to future generations (natural selection).  However, an organism cannot spontaneously change into another organism.
To use a rough analogy, think of the design of our vehicles. They have changed from horse-drawn carts, through the Ford Model T, to our modern cars. Vehicle design has changed over time, but the individual vehicles themselves do not alter. A Model T will not slowly become a Pontiac Firebird if you leave it in the garage long enough, but as time goes by, the "species" of motor vehicles does change.”

For more information on this misconception and others, go to

4. Students incorrectly believe that there are an insufficient number of transitional fossils that exist to support evolution.

A transitional fossil suggests an evolutionary relationship between organisms.  It acts as an intermediate or “missing link” possessing characteristics of organisms that lived both prior to it and after it.  In the sequence of evolutionary history, transitional fossils fill in the gaps.  Archaeopteryx, for example, is considered a transitional organism between dinosaurs and birds.  The fossilized remains of archaeopteryx exhibit both reptilian (toothed beak, wing claw, and a long tail with many vertebrae) and avian (wings with flight feathers) characteristics.  Other examples include the transitions from land animal to early whale, and from early ape to human.

Figure 7. Illustration depicting reptilian and avian characteristics
in the transitional organism archaeopteryx.

Visit the following webpage for interactive examples of transitional organisms

More information regarding evolution and fossil evidence can be found in the
MS TIPS Benchmarks L.8.D.2

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Performance Benchmark L.8.D.3

Students know an organism’s behavior is based on both experience and on the species’ evolutionary history.  E/S

 Sample Test Questions

1st Item Specification: Know some mechanisms of biological evolution (e.g., naturalselection, competition and survival, variation and adaptation, and genetic mutation).

Depth of Knowledge Level 1

  1. The gradual change in a species over time is called
    1. mutation.
    2. evolution.
    3. migration.
    4. variation.
  1. Scientists infer that related species inherited many of the same genes from
    1. relative dating.
    2. a common ancestor.
    3. sedimentary rock.
    4. different ancestors.
  1. Which term refers to the process by which organisms, that are better adapted to their environment, are more likely to survive and reproduce?
    1. Variation
    2. Competition
    3. Overproduction
    4. Natural selection
  1. Natural selection can lead to evolution because within a species
    1. useful variations accumulate over time.
    2. unfavorable variations accumulate over time.
    3. all individuals are developmental organisms.
    4. all individuals have identical traits.

Depth of Knowledge Level 2

  1. Which factor does NOT affect the process of natural selection?
    1. Overproduction
    2. Competition
    3. Variation
    4. Fossilization
  1. Which of the following is an example of a behavioral adaptation?
    1. The webbed feet of a duck.
    2. The spines of a cactus.
    3. A spider spinning a web.
    4. The trunk of an elephant.

2nd Item Specification: Know that differences among individuals within a species can yield advantages and/or disadvantages in survival and/or reproduction.

Depth of Knowledge Level 1

  1. Differences among individuals of the same species are called
    1. traits.
    2. predators.
    3. variations.
    4. selections.
  1. Changes in a gene or chromosome which can lead to variations in an individual are called
    1. alleles.
    2. mutations.
    3. offspring.
    4. camouflage
  1. An inherited characteristic that improves the chances for an organism to survive and reproduce is a(n)
    1. adaptation.
    2. evolution.
    3. response.
    4. stimulus.
  1. Variation within a species makes some individuals better suited for survival in their environment.  This is known as
    1. survival of the fittest.
    2. artificial intelligence.
    3. circadian behavior.
    4. insight learning.

Depth of Knowledge Level 2

  1. Birds have different shaped beaks for eating certain types of food.  The shape of a bird’s beak is an example of
    1. camouflage.
    2. an adaptation.
    3. conditioning.
    4. a stimulus.
  1. Albino organisms do not have any pigment in their skin.  This is considered a harmful mutation because these organisms
    1. get lost in the snow.
    2. easily attract a mate.
    3. will most likely create a new species.
    4. cannot hide well from predators.

Constructed Response L.8.D.3       

  1. Generally, a change in a species is caused by genetic variation. With each new generation there is a new combination of genes, and over time, different species can develop. Sometimes, a sudden change in a gene can occur within an organism. This change is called a mutation.
    1. Explain how some mutations can be helpful.
    2. Explain how some mutations can be harmful.
    3. Comment on what role mutations play in the evolution of a species, and support your thoughts with evidence. 

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Performance Benchmark L.8.D.3

Students know an organism’s behavior is based on both experience and on the species’ evolutionary history.  E/S

Answers to Sample Test Questions

  1. B, DOK Level 1
  2. B, DOK Level 1
  3. D, DOK Level 1
  4. A, DOK Level 1
  5. D, DOK Level 2
  6. C, DOK Level 2
  7. C, DOK Level 1
  8. B, DOK Level 1
  9. A, DOK Level 1
  10. A, DOK Level 1
  11. B, DOK Level 2
  12. D, DOK Level 2

Constructed Response L.8.D.3 Score Rubric:

3 Points

 Response addresses all parts of the question clearly and correctly.

If the mutation is helpful, then the organism will be better suited for survival in its environment. As a result, the organism is more likely to survive and reproduce, passing the trait on to future generations. Eventually the species changes, which may result in the evolution of a new species. If the mutation is harmful, the organism will probably die before passing on the trait. Thus, having no effect on the evolution of the species.

2 Points

 Response addresses all parts of the question and includes only minor errors.

1 Point

 Response does not address all parts of the question.

0 Points

 The response is totally incorrect or no response.

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Performance Benchmark L.8.D.3

Students know an organism’s behavior is based on both experience and on the species’ evolutionary history.  E/S

Intervention Strategies and Resources

The following list of intervention strategies and resources will facilitate understanding of this benchmark.

1. Becoming Human

This is an interactive website that explores the story of human evolution.  The website’s learning center provides lesson plans, a glossary, and an extensive bibliography of print and web resources to help with the teaching of human evolution.

To access the Becoming Human contents page, go to

2. Evolving Planet

This on-line resource is designed and maintained by the Field Museum of Natural History in Chicago, Illinois. The museum was founded in 1893 to house the biological and anthropological collections assembled for the World's Columbian Exposition.  Visitors to Evolving Planet can take a tour through time and learn all about evolution.  This website addresses the importance of evolution, examines issues such as natural selection and intelligent design, and debunks popular misconceptions about evolution.  Educational resources include suggested reading materials and links to additional websites.

Below is a direct link to the Evolving Planet’s all about evolution webpage.

3.Teaching Evolution Resource Kit

Rutgers, the State University of New Jersey, prepared a Teaching Evolution Resource Kit for the Evolution Workshop in 2006.  It is available in a 24 page downloadable pdf document.  The kit presents notable examples of mechanisms of evolution and explores areas of controversy and debate including common misconceptions.  Web-based and print resources are sited, as well as, teaching tips and links to lesson plans.

To view Rutgers’ Teaching Evolution Resource Kit, go to

4. Understanding Evolution

This website is a collaborative project of the University of California’s Museum of Paleontology and the National Center for Science Education.  It is an education website teaching the science and history of evolutionary biology. This site defines evolution, how it works, how research in evolutionary biology is performed, and how ideas in this area have changed over time. For educator resources visit Understanding Evolution for Teachers.

The Understanding Evolution homepage can be viewed at

5. PBS Series: Evolution

The PBS website offers a multimedia library related to the eight-hour miniseries Evolution. Video clips and web activities are available, as well as, on-line courses for teachers and on-line lessons for students.  The Evolution series' goals are to heighten public understanding of evolution and how it works, to dispel common misunderstandings about the process, and to illuminate why it is relevant to all of us.

The following is a direct link to PBS’ Evolution.

6. Concept Cartoons About Evolution

This website contains a list of cartoons that illustrate and explain evolutionary concepts. The cartoon were developed by Dianne Anderson and Kathleen Fisher to use as prompts for discussing common misconceptions held by students. The cartons could also be used as an assessment tool.  

The concept cartoons are available at

7. The Virtual Fossil Museum: Fossils Across Geological Time and Evolution

This website is an education resource that provides information about the diversity of life. Links are available to learn information about such topics as geologic time, tree of life, paleobiology, evolution, and fossils.

In order to access the wealth of information on this site, go to

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Benchmark Related Vocabulary