AHSGE Review J. Pollock Spring 2007 Ecology

Describe levels of organization in the biosphere.  The ecosystem is all living and nonliving things in the environment.  Within the ecosystem, there are food webs (interrelated chains of organisms that depend on each other for food).  The aspects of an animal’s lifestyle are referred to as niche.  The habitat is the physical surroundings in which an organism lives.

Describe levels of organization in the biosphere.  The biosphere is the part of the earth where life exists. It is composed of air, land, and water.  Large regions that are identifiable by the types of plants and animals living there are biomes.

How does energy flow through the trophic levels of the ecosystem?  Food webs are interrelated cahins of organisms that depend on each other for food.  Producers are the green plants that make their own food.  Consumers are the animals that rely on other organisms for food.  Scavengers feed on dead organisms.  Decomposers are organisms that break down dead organic matter.

Consumers  Consumers can be primary, secondary, or tertiary.  Primary consumers are herbivores, or plants eaters.  Secondary consumers are carnivores, or flesh eaters.  Tertiary consumers are omnivores, which eat both plants and animals.  With each increasing level of the food web, energy is lost when it is consumed.

Food Web

What are biotic factors?  Biotic factors are living things.  Plants  Animals  Parasitism  Disease  predation

What are abiotic factors?  Abiotic factors are nonliving things.  Light intensity  Temperature range  Type of soil or rock  pH level  Water availability  Dissolved gases  Level of pollutant

Compare autotrophs and heterotrophs.  Autotrophs – Obtains energy from sunlight or chemicals – Undergo photosynthesis  Heterotrophs – Cannot make own food – Undergo cellular respiration

What is the niche of decomposers?  Decomposers break down dead organic matter.  They produce the raw materials used for photosynthesis.  They prevent the buildup of dead matter and insure that nutrients are available for producers.

What is the ten percent law, and how does it relate to energy flow through tropic levels?  Only a small amount of energy is available for transfer from one trophic level to the next.  Most of the energy is lost to the surroundings as waste heat.  According to the ten percent law, only about 10% of the energy in a trophic level is transferred to the next trophic level.

What are biomes?  Biomes are regions of the earth that are identified by the types of plants and animals that live there.  There are 8 biomes.

What are the biomes of Earth and their characteristics? BIOMEREGIONSFLORAFAUNACHARAC- TERISTICS PolarNorth and south poles Moss and lichenPolar bears, penguinsPermafrost TundraArctic/Antarctic regions Grass and wildflowers Reindeer, caribouThin soil, permafrost TaigaNorthern forestsStunted conifersWolves, rabbitsLong,cold winters Deciduous forestNE/mid-eastern US, W. Europe Deciduous treesDeer, birds, small animals Mod. Precipitation, warm summers, cold winters GrasslandsMid-western US, Eurasia, Africa GrassesPrairie dogs, ferrets, snakes Hot summers, cold winters, rainfall unpredictable DesertW. US, N. and SW Africa Cacti, succulentsJackrabbits, lizards, rats Arid, extreme daily temperatures Tropical rainforestSouth AmericaDiverse plantsMonkeys, leopardsHigh rainfall and temperatures Temperate rainforestNW USGiant conifersBear, deer, birdsMoist soil, high rainfall, moderate temperatures

What are limiting factors in an ecosystem?  A limiting factor is one that controls a process, such as organism growth or species population size or distribution.  They can biotic or abiotic.  Food  Shelter  Water  predation

What is the water cycle?  The water cycle is Earth’s system of recycling water.  About 70% of Earth’s surface is covered with water.  In the water cycle, water evaporates from oceans, lakes, and rivers and rises into the atmosphere. The water condenses to form droplets in clouds. The droplets become heavy, and water falls back to Earth as precipitation. Runoff collects back into oceans, lakes, and rivers, and the process is repeated.

Water Cycle

What is the carbon cycle?  The carbon cycle is a model that describes how carbon molecules move between the living and nonliving world.  Producers remove carbon dioxide from the air during photosynthesis. They use photosynthesis to produce energy-rich molecules. This energy is released during cellular respiration. Cellular respiration releases carbon dioxide.

Carbon Cycle

What is the oxygen cycle?  The oxygen cycle describes the movement of oxygen within the atmosphere, the biosphere, and the lithosphere.  It is driven by photosynthesis.  It works closely with the carbon cycle.

Oxygen Cycle

What is the nitrogen cycle?  The nitrogen cycle is a model describing how nitrogen moves from the atmosphere to the soil, to living organisms, and then back to the atmosphere.  Nitrogen is essential to creation of proteins, which are required by the cells of all organisms.  Plants and animals cannot directly absorb nitrogen from the soil or atmosphere, so nitrogen- fixing bacteria are necessary for the process.

Nitrogen Cycle

What events affect the equilibrium of ecosystems?  Weather  Global warming  Introduction of non-native species  Strip mining  Agriculture  Burning fossil fuels  Acid rain  Ozone depletion  Construction  Waste disposal

How do humans affect the equilibrium of ecosystems?  Humans consume large amounts of natural resources, destroying much of the environment and natural habitats.  We also produce ever-increasing amounts of waste.  We mine fossil fuels and minerals, damaging the environment in the process.  The greenhouse effect is being magnified by our use of fossil fuels and acid rain is being created.

What is ecological succession?  Ecological succession is the change in dominant species in an area.  A pioneer community is a plant species that colonizes an area. It is a hardy species, and it makes the habitat hospitable for other organisms.  Different species become dominant until a climax community is reached.  A climax community is the final stage of ecological succession. There are many types of plants, and it is very stable. It changes little.