Environmental Biology Chapter 2

Ecology

Study of how organisms live in their natural environments.

Trophic Level

Feeding level. A classification of organisms based on what they are eating or using as sources of energy and material-but note that many animals feed at more than one trophic level. (herbivore, carnivore, producers.) [2.2.1]

Food Chain

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Food Web

A diagram identifying what each species in an ecosystem eats and is eaten by. (E.g., Fig. 2-3, 7-5.) [2.2.1]

Producer

An organism that takes energy from the sun and materials as simple compounds (carbon dioxide and minerals) from the air and soil. Sometimes simply called producers. (E.g., plants, algae, phytoplankton.) (Contrast consumers.) [2.2.1]

Herbivore

An animal eating plants or other primary producer. (E.g., a catepillar eating a leaf; a human eating a salad.) (herb-of plants, vore to eat) [2.2.1, Fig. 2-1]

Carnivore

An animal eating live animals (predator) or dead meat (scavenger). (E.g., spiders, brown tree snakes.) (carni-meat, -vore to eat) [2.2.1; Figs. 2-1, 2-2]

Decomposer

"Recycler" of nutrients sch as bacteria or fungil. Strictly speaking, only fungi and bacteria that breakdown organic matter (from dead organisms) into smaller molecules (less complex organic matter and simple inorganic molecules). Sometimes used to include the whole community or organisms that feed on dead organic matter, including detritivores and scavengers. [2.2.1; Fig. 2-3]

Biomass

Mass of all living and dead organisms in an ecosystem. The total dry weight of a group of organisms (most often used with referenceto a trophic level, e.g., the biomass of herbivores). [2.2.1]

Energy

"The ability to do work," whether that work is converting one chemical into another or moving a muscle. Energy for organisms is available from food or the sun. Energy from the sun is stored in food through through the process of photosynthesis. Energy for humans also include fuel and electricity. [2.2.2, 9.5.1; Table 2-1]

Plant Nutrients

Fertilizer. Minerals necessary for plant growth but not for supplying energy; often used to include only the material plants get out of soil, but may also include carbon (obtained as carbon dioxide from the air). May be supplied by gardeners or farmers as fertilizer. (E.g., nitrogen, phosphorus.) [2.2.3, 4.2.1]

Photosynthesis

The pathways by which plants trap energy from the sun and make sugars from carbon dioxide. Occurs only in pigmented cells of primary producers and only in light. Carbon dioxide is taken up and oxygen is released. [2.2.2]

Respiration

Pathways by which organisms release energy from fuel (food) molecules such as sugar. Occurs all the time in all organisms that live where there s oxygen. Oxygen is absorbed and carbon dioxide is released. [2.2.2]

Symbiosis

Close physical relationship between 2 species where at least one benefits. Symbiosis means living together and the partners are called symbionts. Often the partnership is a nutritional one, and depending on which partner(s) benefit(s), the relationship may be classified as mutualism, commensalism, or parasitism. (E.g., coral polyps + zooxanthekkae, trees + mycorrhizae.) [2.3]

Parasitism

A type of symbiosis in which one partner (the parasite) obtains nourishment from the other (the host). Usually implies that the parasite lives in or on the host. (E.g., flies, intestinal worms.) [2.3]

Mutualism

A type of symbiosis in which both partners benefit; often one provides primarily food or nutrients, the other shelter. (E.g., coral polyps + zooxanthellae; trees + mycorrhizae.) [2.3.1, 2.3.2; Fig. 2-18; Table 2-2, 2-3]

Primary Succession

Succession starting from bare surface, such as recent lava flow, a boat hull, or the surfaces tree trunks and leaves. [2.1.1]

Secondary Succession

Succession starting from disturbed community, such as regrowth of forest on abandoned farmland or recovery of a forest after a typhoon. (Compare primary succession.) [2.4.2]

Pioneer Species

A plant or animal that moves in quickly during primary or secondary succession, able to take advantage of the new conditions but not usually persisting to later stages. (E.g., lichens in primary succession, papaya in secondary succession. [2.4]

Forest Canopy

The layer formed by the tree crowns (the leaves and branches at the tops of the trees). Tall forests may have an upper canopy formed by the tall trees and a lower canopy formed by shorter trees. [4.3.3; Fig. 4-12]

Environmental Gradient (of some abiotic factor such as light)

A change in an abiotic factor from one place to another. (E.g., change in salinity along an estuary, change in amount of light from a clearing into the forest.) [3.1.2; Figs. 2-15, 3.10]

Classification (of living organisms based on similar characteristics)

Arrangement of things into groups depending on shared characteristics; higher categories(taxa) have fewer characyers in common than lower taxa. (Contrast biological organization). [2.2.4, 4.3.2, 5.3.3; Figs. 2-10, 4-10, 4-11, 5-12]

Biological Species

All organisms that can interbreed to produce fertile offsprings.

Population (of a single species)

All of the individuals of a given species, either in some defined area or the total in the world. (E.g., all the fiddler crabs in a mangrove swamp; all the koa haole on O'ahu; all the remaining Guam rails.) [2.2.4; Fig. 2-9]

Community (of many species)

All the species populations living together in a habitat and their interactions. (E.g., all the epiphytes on a tree and the organisms living on and among them; all the plants, animals, fungi and bacteria in a pond.) [2.2.4; Fig. 2-9]

How primary producers make food from sunlight via photosynthesis.

Leaves of plants use light from the sun to turn the air people breathe out and water into glucose and oxygen. Glucose is a type of sugar that plants use for food help them grow. Oxygen is the gas that people breathe in. So not only do plants make their own food, but they make the air that we breathe in!

How consumers burn energy via respiration.

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Why is energy is lost as it moves up the food chain.

At each level of the food chain, about 90% of the energy is lost in the form of heat. The total energy passed from one level to the next is only about one-tenth of the energy received from the previous organism. This means that an animal eating a plant will only get about ten percent of the energy that the plant gets from the sun. The remainder of the plant's energy is unusable as energy by the animal. Therefore, as you move up the food chain, there is less energy available.

Why classification is useful in science.

Scientists use classification systems to help them make sense of the world around them. They use classification to organize information and objects. When things are sorted into groups it makes them easier to understand and it makes it easier to see the relationships between them.

Some types of symbiosis (and which species in the symbiosis benefits).

Mutual Relationships

Mutual relationships between plants and fungi are common. The fungus invades and lives in the cells of the host's roots. The fungus then helps the host plant absorb minerals from the soil.

Commensal Relationships

Commensal means "at the table together." A common example of a commensal relationship is that of barnacles to other marine life. One tyep of barnical attaches itself to the the the jaws of whales. Without the whale they could not live, but the whale is not hurt by their presences. Another example is the bacteria that live in our large intestines. It is harmless, but it lives off of the food in our gut.

Parasitic Relationships

Animals and plants can have parasites. Some may be living and others (like viruses) can be nonliving. A parasite is an organism that lives on or in the body of another organism, from whose tissues it gets its nourishment, and to whom it does some damage. Parasites can damage their host by either causing tissue damage or delivering toxins.

How succession leads to the replacement of one community by other communities over time.

Succession takes place over time when one community creates conditions (habitats) that are better for species oof later stages than for themselves. Primary succession begins on bare surfaces and leads to a climax community; disturbance of an existing ecosystem initiates secondary succession, again tending toward a climax community.