Ecology Flashcards Preview

SAT Biology > Ecology > Flashcards

Flashcards in Ecology Deck (38)
Loading flashcards...

Levels of organization in ecology

Cell, Tissue, Organ, Organism, Population, Community, Ecosystem, Biome, Biosphere.


What is population?

1. A group of individuals in a particular area that interbreed and therefore share the same gene pool.
2. Like a subset of a species, will interbreed due to close location.
3. Evolution is seen at this level as individuals and their offspring have changing genotypes and phenotypes.


Exponential growth

Growth occurs exponentially until it can no longer sustain that rate, and it stabilizes.


Carrying capacity

Max population size an environment can sustain. Can change if an environment changes (damaged food source, etc). Predators affect the carrying capacity of an environment.


What is a community?

Group of populations that live in a particular environment. Members of the same community are members of the same ecosystem.



The way an organism lives in its environment (type of food it eats, where it hunts).If 2 populations have the same niche, there will be a lot of competition, and the losing population will usually evolve to survive.



When one organism eats another. The organism eating is the predator, but the organism that is eaten doesn't always die. For example, leaves.



The prey evolves to escape the predator, then the predator evolves to better hunt the prey.


The food chain

1. Starts with primary producers. Photosynthetic, usually plants. Highest amount of species here.
2. Primary consumers- herbivores that eat the primary producers.
3. Secondary consumers- omnivores
4. Tertiary consumers- carnivores



Break down dead bodies. Bacteria and fungi.



Eat the waste and remains of dead organisms. Vultures, worms.


How does a food web work?

Arrows show who feeds who.


The 10% rule

There is more energy available at the bottom of the pyramid than at the top. Only 10% of energy is transferred from one level to the next, because most of the energy is used to power the prey.


Ecological Succession

Gradual change in a community over time. Each new community coexists with the previous one. Lichen is first to colonize barren rock. The final community would be deciduous trees.


Pioneer organisms

First to arrive in the area. Other organisms arrive as they are attracted by the first.


Climax community

Permanent group that is the last to arrive. Shows that succession is finished.


How is ecological succession different from evolution?

Time frame is shorter, and it consists of continuous change with predictable changes.



A community together with the environment it lives in.


The water cycle

1. Recycles water
2. Water is taken into clouds by evaporation and transpiration (water escaping from leaves). It returns to bodies of water through precipitation, and from the soil to the ocean through runoff.


The carbon cycle

1. Carbon is mostly found as carbon dioxide in the atmosphere
2. Is used by plants to form organic molecules (sugars) which are then eaten by animals.
3. The carbon is recycled to the atmosphere by respiration.


The nitrogen cycle

1. Most nitrogen is taken from the soil by plants as nitrate and incorporated into protein
2. The proteins are consumed by animals and recycled to the soil when the animals die.


What is a biome?

Large areas classified by the ecosystems they contain.



Animal life



Plant life



All biomes together (planet Earth).


Terrestrial Biomes

1. The Tundra- frozen topsoil, some shrubs, a few mammals such as wolves.
2. The Taiga- contains many evergreen trees. Moose, bears, wolves.
3. Deciduous Forests- lots of rain, hot and cold seasons, trees that drop leaves in winter. Deer, foxes
4. Grasslands/savanna- scattered trees limited by drought. Tropical- zebras, kangaroo, Temperate- horses, bison.
5. Tropical Rain Forests- high rain fall, tall trees, many plants, birds, monkeys, lizards
6. The Desert- very dry. Cacti, birds, lizards, small rodents


Marine Aquatic Biomes

1. Interdial Zone- where land and water meet, periods of submersion with tides. Clams, crabs.
2. Neritic Zone- from shore to edge of continental shelf. Kelp, seaweed, reefs in warm water
3. Oceanic Zone- open water, marine mammals. Divided into open water (pelagic) and ocean bottom (benthic) zones.


Freshwater Aquatic Biomes

1. Littoral Zone- shore of a lake, many plants, insects, snails.
2. Limnetic Zone- extends downward as far as light will penetrate. Photosynthetic organisms and primary consumers.
3. Profundal Zone- aphotic region. Nutrients float down to support primary consumers, which support secondary consumers.


Aphotic Region

No light at all.


Greenhouse effect

1. Increased concentrations of carbon dioxide through burning fossil fuels causes increased temperatures.
2. Effects- flooding, changes in plant and animal populations, detrimental changes in agriculture, changes in precipitation patterns.