Ch 5: Organisms and the Environment
About This Chapter
Organisms and the Environment - Chapter Summary
This chapter can teach you about levels of ecological organization through its online chapter on organisms and the environment. Through these video lessons, you can learn about food chains, predator/prey interactions and symbiotic relationships, such as mutualism and parasitism. You also can refresh your knowledge about ecological succession, from pioneer to climax communities, and various biomes, including deserts, coral reefs, tundras, taigas and savannas. Lessons also cover the nitrogen and carbon cycles and explore the following topics:
- Trophic levels and energy flow in an ecosystem
- Interspecific competition, competitive exclusion and niche differentiation
- Camouflage, mimicry and warning coloration
- Population density, survivorship and life histories
- Carrying capacity, migration and dispersion
- Dispersal, colonization and island biogeography
- Conservation biology, habitat fragmentation and metapopulations
- Introduced and invasive species and the ecological balance
The video lessons in this chapter on organisms and the environment are led by experienced professional educators. The videos are brief and engaging, and video tags are provided to allow you to jump to main points in the lesson.
Each lesson includes a self-assessment quiz, which you can take both before watching the video - to measure your initial knowledge of organisms and the environment - and after - to see how well you've absorbed the presented information.

1. The Environment, Levels of Ecology and Ecosystems
Do you know the difference between an environment and an ecosystem? In this lesson, you'll find out what makes an environment, and what makes an ecosystem. You'll also learn what ecology is and some of the ways that scientists study ecology using organisms, populations, communities, ecosystems and even the entire biosphere.

2. Ecosystems, Habitats and Ecological Niches
Check out this video lesson to understand the many complex aspects of an ecosystem. See how animals live in habitats and survive amongst their surroundings.

3. Food Chains, Trophic Levels and Energy Flow in an Ecosystem
In this lesson, you'll learn about food chains, food webs, and the different roles that organisms play in an ecosystem. You'll also learn about how energy flows through an ecosystem.

4. Interspecific Competition, Competitive Exclusion & Niche Differentiation
What happens when two similar species that consume the same resources occupy the same space? Interspecific competition, that's what! Watch our video lesson to learn about the outcomes of this ecological battle.

5. Predator/Prey Interactions, Camouflage, Mimicry & Warning Coloration
You probably know that skunks can be quite stinky, bees sting and monarch butterflies are pretty, but do you know why? This lesson will introduce you to the reasons why some animals look or act the way they do and how these things relate to the predator/prey relationship.

6. Symbiotic Relationships: Mutualism, Commensalism & Parasitism
If your cat or dog has ever had fleas, you've witnessed symbiosis in action. In this lesson, learn the many types of symbiosis in biology, and how these relationships can have a positive, negative, or neutral effect on the individual species.

7. Populations: Density, Survivorship and Life Histories
Have you ever wondered how biologists determine the populations of animals in a particular geographic area? Watch this video lesson to find out, and discover how scientists look at the survivorship and life histories of many different species.

8. Carrying Capacity, Migration & Dispersion
Have you ever wondered why some types of birds fly south in the winter or why some animals form territories? Watch this video to learn about a species' maximum growth capabilities, the way its members group themselves and why they might migrate to new locations every year.

9. Dispersal, Colonization, and Island Biogeography
Have you ever gone in your backyard and discovered a wild raspberry bush that has never been there before? How did it get there? Why is there only one bush year after year? In this lesson, you'll study how plant and animal species colonize in new areas through dispersal and immigration and how some species thrive in a new area while others fail.

10. Conservation Biology, Habitat Fragmentation, and Metapopulations
It's becoming harder to conserve large, unbroken tracts of wilderness. Is there another way for conservation biologists to ensure the survival of a species? In this lesson, you'll learn about habitat fragmentation and metapopulations.

11. Ecological Succession: From Pioneer to Climax Communities
Just as people grow and change so, too, do ecosystems. Watch this lesson to learn about ecological succession from the beginning stages of development to a community's ultimate destination, or climax.

12. How Introduced and Invasive Species Alter Ecological Balance
What happens to your block when a new neighbor moves in? Something changes, right? Now think about that on an ecological scale: what happens to an environment when a new SPECIES moves in?

13. Biomes: Desert, Tropical Rainforest, Savanna, Coral Reefs & More
Take a trip around the world and learn all about different biomes. Why can you only find certain plants and animals in specific places? What are the most fertile climates on Earth? Watch on to answer these and other questions.

14. Biomes: Tundra, Taiga, Temperate Grassland, and Coastlines
Take a trip with us in this lesson, starting in the Pacific Ocean, traveling across California through the Central Valley and up to the peaks of the Sierra Nevada mountains. We'll learn how oceans, elevation, and people can determine which types of biomes are found in different areas and check out the Earth's most massive and oldest organisms.

15. Biogeochemical Cycling and the Phosphorus Cycle
In this video lesson, we'll take a look at how elements large and small use other elements to grow. This is achieved through cycles. We'll look at macronutrients, trace elements and the biogeochemical and phosphorous cycles.

16. The Nitrogen Cycle, Acid Rain and Fossil Fuels
Do you know the difference between nitrite and nitrate? Do you have any clue how all the nitrogen in the atmosphere becomes usable? If you can't answer these questions, then you need to watch this lesson on the nitrogen cycle.

17. The Carbon Cycle and Long-Term Carbon Storage
All living organisms have a role in the carbon cycle. Do you know you understand how humans, animals and plants use carbon? This lesson will introduce you to the carbon cycle and explain how it functions on a global scale.

18. What Is IPAT? - Factors of the Human Impact on the Environment
What do the letters IPAT have to do with the environment? Learn how this four-letter equation helps explain the environmental impact of different variables, including population, affluence, and technology.

19. Deforestation, Desertification & Declining Biological Diversity
When trees are lost due to deforestation, the result can be a drier climate and desertification or the transformation of the once fertile land to desert. Learn how deforestation and desertification can lead to a decline in biological diversity.

20. Fossil Fuels, Greenhouse Gases, and Global Warming
In this video lesson, you'll learn what roles fossil fuels and greenhouse gases play in global warming, as well as what life on Earth can expect due to rising carbon dioxide levels within Earth's atmosphere.
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Other Chapters
Other chapters within the ILTS Science - Physics (116): Test Practice and Study Guide course
- Scientific Inquiry and Practices
- Cell Structure
- Heredity and Evolution
- Characteristics and Life Functions of Organisms
- Fundamentals of Thermodynamics
- The Atom & Matter
- Trends of the Periodic Table
- Chemical Bonds and Reactions
- Nuclear Processes
- Mechanics
- Waves Overview
- Magnetism & Electricity
- Land, Water, and Atmospheric Systems
- Weather and Storms
- The Universe
- Relativity
- ILTS Science - Physics Flashcards