Chapter Three Review

Audra Miller & Christina Geissman

VocabularyAnaerobic Respiration: a form of cellular respiration

involving the breaking down of glucose, also called fermentation

Aquatic Life Zones: divisions of the watery parts of the biosphere

Autotrophs: organisms that make their own food, also called producers

Biomass: dry weight of all organic matter contained in organisms

Biomes: large sections of the biosphere with distance climates and specific species adapted to them

Biosphere: all the earth’s ecosystems together

Carnivores: meat eatersChemosynthesis: the process of converting simple inorganic compounds into more complex nutrient compounds without sunlightCommunity: consists of all the populations of a different species that live and interact in a particular areaConsumers: get nutrients by eating something else; cannot make themDecomposers: specialized organisms that recycle nutrients in ecosystemsEcological Efficiency: the percent of usable energy from one trophic level to another

Ecology: the study of how organisms react with their environments and each otherEcosystem: a community where populations of different species interact with each other and their environment Fermentation: the same as anaerobic respirationFood Chain: a sequence of organisms in which each organism is food for the nextFood Web: many interconnected food chains

Gaia Hypothesis: earth behaves like a single self-regulating systemGross Primary Productivity (GPP): the rate at which an ecosystem’s producers convert solar energy into chemical energy as biomassHerbivores: plant eatersHumus: partially decomposed bodies of dead plants and animalsHydrosphere: consists of the world’s waterInfiltration: the downward movement of water through soilLeaching: when water in soil dissolves various organic matter in upper layers and carries them down to lower layers of the soil

Limiting Factor: one factor more important in regulating population growth than any otherLithosphere: the earth’s crust and upper mantleNatural Greenhouse Effect: as radiation interacts with molecules in the air, it increases kinetic energy, helping warm the troposphere and the earth’s surfaceNutrient (Biogeochemical) Cycles: when nutrients move in cycles through air, water, soil, rock, and living organisms

Nutrients: the elements and compounds that organisms need to live, grow, and reproduceOmnivores: organisms that live off both plants and animalsPopulation: a group of interacting individuals of the same species in a specific placePyramid of Energy Flow: illustrates the loss of energy through the food chainRange of Tolerance: the physical and chemical variations in an environmentSoil: thin covering over most land

Stratosphere: the layer above the troposphere, the layer with gaseous ozone which filters incoming ultraviolet radiationTrophic Level: a feeding levelTroposphere: the innermost layer of the atmosphere

Soil Horizons: horizontal layers of mature soilSoil Profile: a cross-sectional view of soil horizonsSoil Texture: relative amounts of different sizes of minerals found in soilSpecies: groups of organisms which resemble one another in appearance, behavior, chemistry, and genetic makeup

Objectives

• What is ecology? Ecology is the study of how organisms interact with one another and with their nonliving environment. In effect, it is a study of connections in nature—the house of Earth’s life.

• What are the major components of an ecosystem? Multitudes of a species interact in groups called populations; populations of different species living and interacting in an area form a community, and a combination of communities constitute an ecosystem. Within an organism’s habitat are biotic (living) and abiotic (nonliving) factors, that affect the overall success of the ecosystem. Examples of each are: (biotic) co-inhabitants, plants, (abiotic) climate, day-to-day weather, and food supply. These factors influence the relationships between organisms, as well as their survival.

• What happens to energy in an ecosystem? Energy in an ecosystem is neither created nor destroyed. Rather, it is passed from one trophic level to the next—10% of the usable energy from each tropic level is passed from level to level. An ecosystem survives by a combination of energy flow and matter recycling. The survival of any individual organism depends on the one-way flow of matter and energy through its body. However, an ecosystem as a whole survives primarily through a combination of matter recycling and one way energy flow. Decomposers complete the cycle of matter by breaking down organic matter into inorganic nutrients that can be reused by producers.

Energy Flow in an Ecosystem

What are soils and how are they formed?*Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth. It also helps to purify water. Soil is a thin covering over land consisting of eroded rock, mineral nutrients, decaying organic matter, water, air, and microscopic decomposers.*Soil is formed when bedrock gets broken down physically, chemically, and biologically into rock fragments. This process is called weathering. Dying lichen and other organisms in the soil add organic matter.*Infiltration and leaching bring nutrients from the upper layers of the soil to the lower layers.

The O-horizon consists of surface litter, including leaves and animal wastes

The A-horizon (topsoil) consists of clay, silt, and sand

The B-horizon is subsoil

The C-horizon is made up of parent material

Objectives, con’t.

• What happens to matter in an ecosystem? Biogeochemical cycles explain the flow of matter through an ecosystem.

Nitrogen Cycle

Carbon Cycle

Oxygen Cycle

Phosphorous Cycle

Hydrologic Cycle

• How do scientists study ecosystems? Scientists study ecosystems through observation and field research, in which samples are collected, technology is installed, and the area is monitored over time. Controlled experiments are also a method of gathering information, through creating and monitoring aquariums, tanks, greenhouses, etc. in a laboratory setting. These are often simplified forms of field research, and as such are more economical, and yield faster results. Finally, scientists can create models and computer simulations to predict an outcome, or to gain a general idea of a topic.

• What basic processes keep us and other organisms alive? Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive. Microbes, especially bacteria, help purify the water you drink by breaking down wastes. Bacteria in your intestinal tract break down the food you eat. Some microbes in your nose prevent harmful bacteria from reaching your lungs. Other bacteria are the sources of disease-fighting antibiotics, including penicillin, erythromycin, and streptomycin. Scientists are researching these bacteria not only to help humans in disease-fighting, but also to extract metals from ores, and help clean up polluted water and soils.