Environmental Science Chpt. 3.1, 3.2, 3.3, 3.4 - Lauren Antonacci

What is an ecosystem?

A community of organisms and their abiotic (non-living) environment.

What are the three categories of ecosystems? Give some information about them.

1) Freshwater - Least common ecosystem, comprises of lakes, rivers, streams, and springs.

2) Marine - Most common ecosystem, comprises of three basic types of ecosystem: shallow ocean, deep ocean, and deep ocean bottom.

3) Terrestrial - Are grouped into large categories called biomes.

• A biome is a large-scale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions.

• Examples of biomes include tropical rainforests, savannas, deserts, grasslands, temperate forests, and tundras

What is a food chain?

A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another.

• Divided into levels: Producers, primary consumers, higher-level consumers, and decomposers

Give an Example of a Food Chain Using the Proper Names:

Grey Wolf - Tertiary (Apex) Consumer

Hare - Secondary Consumer

Grasshopper - Primary Consumer

Grass - Producer

How is energy moved between trophic levels?

Energy is lost at each trophic level and between trophic levels as heat, and in the transfer to decomposers.

• After a limited number of trophic energy transfers, the amount of energy remaining in the food chain may not be great enough to support viable populations at higher trophic levels.

What is a food web?

A food web is a concept that accounts for the multiple trophic (feeding) interactions between each species.

There are Two Types of Food Webs:

• A grazing food web has plants or other photosynthetic organisms at its base, followed by herbivores and various carnivores.

• A detrital food web consists of a base of organisms that feed on decaying organic matter (dead organisms), including decomposers (which break down dead and decaying organisms) and detritivores

What are photoautotrophs? What are chemoautotrophs?

Photoautotrophs: Use sunlight as an energy source.

Chemoautotrophs: Use inorganic molecules as an energy source.

What is Gross Primary Productivity (GPP)?

GPP is the rate at which photosynthetic producers incorporate energy from the Sun.

What is Net Primary Productivity (NPP)?

NPP is the energy that remains in the producers after accounting for these organism’s metabolism and heat loss.

What is biomagnification?

Biomagnification is the increasing concentration of persistent, toxic substances in organisms at each successive trophic level. (Think of fish containing high mercury - the larger tertiary/secondary consumers have more mercury because of eating primary consumers - the toxic substances add up).

What are Biogeochemical Cycles?

It is the recycling of inorganic matter between living organisms and their nonliving environment.

• Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during energy transformation between trophic levels.

What is the hydrosphere?

The hydropshere is the area of Earth where water movement and storage occurs.

What is the water cycle?

The water cycle is driven by the Sun’s energy as it warms the oceans and other surface waters.

• This leads to evaporation (liquid water to water vapor) of liquid surface water and sublimation (ice to water vapor) of frozen water, thus moving large amounts of water into the atmosphere as water vapor.

• Over time, this water vapor condenses into clouds as liquid or frozen droplets and eventually leads to precipitation (rain, snow, hail), which returns water to Earth’s surface.

• Rain reaching Earth’s surface may evaporate again, flow over the surface, or percolate into the ground. Most easily observed is surface runoff: the flow of freshwater over land either from rain or melting ice. Runoff can make its way through streams and lakes to the oceans.

What is transpiration and evapotranspiration?

Transpiration: water enters the vascular system of plants through the roots and evaporates, or transpires, through the stomata (small microscope openings) of the leaves. Ecologists combine transpiration and evaporation into a single term that describes water returned to the atmosphere: evapotranspiration

What is the Carbon Cycle?

The carbon cycle is most easily studied as two interconnected subcycles: one dealing with rapid carbon exchange among living organisms and the other dealing with the long-term cycling of carbon through geologic processes.

• Carbon dioxide gas exists in the atmosphere and is dissolved in water.

• Photosynthesis converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas.

• Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized.

What is respiration? What does it have to do with the Carbon Cycle?

Respiration is a process in which organic molecules are broken down to release energy by other organisms. As these organic molecules are broken down, carbon is removed from food molecules to form CO2, a gas that enters the atmosphere. CO2 is a byproduct of respiration.

What is the Nitrogen Cycle?

• Nitrogen enters the living world from the atmosphere via nitrogen-fixing bacteria.

• This nitrogen and nitrogenous waste from animals is then processed back into gaseous nitrogen by soil bacteria, which also supply terrestrial food webs with the organic nitrogen they need.

What is the Phosphorus Cycle?

• Weathering of rocks and volcanic activity releases phosphate into the soil, water, and air, where it becomes available to terrestrial food webs.

• Phosphate enters the oceans in surface runoff, groundwater flow, and river flow.

• Phosphate dissolved in ocean water cycles into marine food webs. Some phosphate from the marine food webs falls to the ocean floor, where it forms sediment.

What is a Dead Zone?

A dead zone is an area in lakes and oceans near the mouths of rivers where large areas are periodically depleted of their normal flora and fauna. These zones are caused bu eutrophication coupled with other factors like oil spills/ dumping toxic waste.

What is the Sulfur Cycle?

• Sulfur dioxide from the atmosphere becomes available to terrestrial and marine ecosystems when it is dissolved in precipitation as weak sulfuric acid or when it falls directly to Earth as fallout.

• Weathering of rocks also makes sulfates available to terrestrial ecosystems.

• Decomposition of living organisms returns sulfates to the ocean, soil, and atmosphere.

Human activity has played a major role in altering the sulfur cycle, causing Acid rain - a corrosive rain caused by rainwater falling to the ground through sulfur dioxide gas, turning it into weak sulfuric acid, which causes damage to aquatic ecosystems.