National Science Standards - National Academy of Science 

Grades 5-8

   Structure and Function of Living Things

Living systems at all levels of organization demonstrate the complementary nature of structure and function.

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1. Adaptation

Cells carry on the many functions needed to sustain life. They grow and divide, thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs.

NatureWorks Episodes

9. The Wildlife Web I 
10. The Wildlife  Web II

   Reproduction and Heredity

Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

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All Animal Focus Sections

The characteristics of an organism can be described in terms of a combination of traits. Some traits are inherited and others result from interactions with the environment.

NatureWorks Episodes

1. Adaptation

   Regulation and Behavior

All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment.

NatureWorks Episodes

1. Adaptation
All Animal Focus Sections

Behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. Behavioral response is a set of actions determined in part by heredity and in part from experience.

NatureWorks Episodes

1. Adaptation
All Animal Focus Sections

An organism's behavior evolves through adaptation to its environment. How a species moves, obtains food, reproduces, and responds to danger are based in the species' evolutionary history.

NatureWorks Episodes

1. Adaptation
2. Coloration
3. Natural Communication
4. Migration
9. The Wildlife Web I 
10. The Wildlife  Web II

   Population and Ecosystems

A population consists of all individuals of a species that occur together at a given place and time. All populations living together and the physical factors with which they interact compose an ecosystem.

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5. Habitat
6. Marine Communities
7. Fresh Water Communities 
8. Terrestrial Communities
9. The Wildlife Web I 
10. The Wildlife  Web II
11. Decomposers and Scavengers
12. Population Dynamics
14. Niche

Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some micro-organisms are producers--they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem.

NatureWorks Episodes

9. The Wildlife Web I 
10. The Wildlife  Web II
11. Decomposers and Scavengers
12. Population Dynamics

For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs.

NatureWorks Episodes

9. The Wildlife Web I 
10. The Wildlife  Web II

The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

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12. Population Dynamics

   Diversity and Adaptations of Organisms

Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.

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13. Species Diversity

Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.

NatureWorks Episodes

1. Adaptation
2. Coloration
3. Natural Communication
4. Migration
13. Species Diversity
All Animal Focus Sections

Extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient to allow its survival. Fossils indicate that many organisms that lived long ago are extinct. Extinction of species is common; most of the species that have lived on the earth no longer exist.

NatureWorks Episodes

16. Life at Risk

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