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Fossil Fuels: Any combustible hydrocarbon deposit formed from the remains of prehistoric organisms. Examples are petroleum, coal, and natural gas.

The Carbon Cycle

JoVE 10933

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle. All living things are composed of organic molecules that contain atoms of the element carbon. Carbon exists in the atmosphere as carbon dioxide gas, which reacts with water to form bicarbonate. During photosynthesis, primary producers (or autotrophs) convert carbon dioxide and bicarbonate into organic carbon-containing compounds, such as glucose, to provide energy for growth, maintenance and other processes. Heterotrophs receive organic carbon for growth and maintenance by consuming autotrophs. Through the process of cellular respiration, these organic molecules are broken down to release the energy stored within them. The byproducts of this process are water and carbon dioxide, which is released into the atmosphere through respiration, continuing the cycle. Carbon can also return to the environment as animal waste or as decaying material from dead organisms. Decomposers, such as bact

 Core: Ecosystems

Proton Exchange Membrane Fuel Cells

JoVE 10022

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

The United States consumes a large amount of energy – the current rate is around 97.5 quadrillion BTUs annually. The vast majority (90%) of this energy comes from non-renewable fuel sources. This energy is used for electricity (39%), transportation (28%),…

 Environmental Science

The Sulfur Cycle

JoVE 10936

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the atmosphere as sulfur dioxide (SO2), sulfur is released by decaying organisms, weathered rocks, geothermal vents, volcanos, and burning fossil fuels. It is deposited into the ecosystem, cycled through the biotic community, and either released back into the atmosphere as gas or deposited in marine sediment for long-term storage and eventual release back into the soil and atmosphere. Sulfur is essential to biological systems and is a component of certain amino acids, such as cysteine, which plays an important role in the structure of proteins. Sulfur is distributed to terrestrial (i.e., land) ecosystems by the precipitation of weak sulfuric acid, direct fallout from the atmosphere, weathering of sulfur-containing rocks, and geothermal vents. From the soil, it is taken up by microorganisms and plants and converted into organic forms that can be used by consumers in the ecosystem. When organisms die, decomposers break the organic sulfur compounds down into gases, such as hydrogen sulfide, which is oxidized in the atmosphere to form sulfur dioxide. Additionally, some chemoautotrophs use sulfur as a biological energy source and recycle sulfur molecules directly through ecosystems. Sulfur

 Core: Ecosystems

Photosynthesis- Concept

JoVE 10565


Almost all living organisms on Earth depend on photosynthesis, which is the process that converts sunlight energy into a simple sugar called glucose. This molecule can be used as a short-term energy source or to build more complex carbohydrates like starches for long-term energy storage. Autotrophs are organisms that capture light energy using photosynthesis. Also known …

 Lab Bio

What is Conservation Biology?

JoVE 10994

Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the human population. Humans require properly functioning ecosystems to maintain our supply of natural resources, including food, medicines, and building materials.

Ecosystems also perform critical services, such as purifying our air and water. A large body of evidence indicates that such ecosystem services depend on biodiversity. Furthermore, the importance of conservation extends beyond the material needs of the current human population. Many philosophical and religious traditions argue that we bear the responsibility of preserving healthy environments for future generations of people and that non-human species have an inherent right to exist. Human activities are the primary threat to biodiversity and ecosystem health. These activities include deforestation, pollution, overharvesting of wild species, the introduction of non-native species, and global climate change caused by the burning of fossil fuels. To mitigate these threats, conservation biology combines genetics, climatology, ecology, social sciences, and many other disciplines to both identify and prevent the loss of biodiversity.

 Core: Biological Diversity

Dye-sensitized Solar Cells

JoVE 10328

Source: Tamara M. Powers, Department of Chemistry, Texas A&M University

Today's modern world requires the use of a large amount of energy. While we harness energy from fossil fuels such as coal and oil, these sources are nonrenewable and thus the supply is limited. To maintain our global lifestyle, we must extract energy from…

 Inorganic Chemistry

Sustainable Development

JoVE 10995

As the human population continues to grow and use resources, we must be mindful of our planet’s natural limits. Sustainable development provides a pathway to maintain and improve human life now while also ensuring that future generations will have the resources that they need. The long-term success of sustainability efforts rests on understanding the interplay between human actions and ecological systems. The oceans are one important focus of global conservation efforts. Overfishing, pollution, and effects of climate change, such as ocean acidification and rising sea levels, are just a few of the major concerns that must be addressed in order to protect the world’s oceans. In addition to providing vast amounts of food for humans, the oceans are an important source of atmospheric oxygen and provide a carbon sink for CO2 gas. They also help regulate the climate and influence weather patterns all over the globe. One major focus of sustainable development is ocean fishing. Modern fishing methods allow the collection of large numbers of fish at once, which is efficient in the short term but also causes local depletion of fish populations, which can have effects across the ocean food web. Current large-scale fishing methods also result in the deaths of other animals, such as dolphins and sea birds, which are caught in nets along with the int

 Core: Biological Diversity

Biofuels: Producing Ethanol from Cellulosic Material

JoVE 10014

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

In this experiment, cellulosic material (such as corn stalks, leaves, grasses, etc.) will be used as a feedstock for the production of ethanol. The cellulosic material is first pretreated (ground and heated), digested with enzymes, and then fermented with…

 Environmental Science


JoVE 10350

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA

This experiment will demonstrate the hydrogenation of chalcone as an example of an alkene hydrogenation reaction (Figure 1). In this experiment, palladium on carbon (Pd/C) will be used as a heterogeneous catalyst for the…

 Organic Chemistry II

Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol

1Bioenergy Research Unit, National Center for Agricultural Utilization Research, 2Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, 3Chemical Engineering and Material Science, Great Lakes Bioenergy Center, Michigan State University

JoVE 54227


Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids (BPCA)

1Department of Geography, University of Zurich, 2Department of Earth and Ocean Sciences, University of South Carolina, 3Department of Earth Sciences, ETH Zurich, 4Laboratory of Ion Beam Physics, ETH Zurich, 5Department of Geological Sciences, Stockholm University

JoVE 53922

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