Ecology EOC Review

Biotic vs. Abiotic Factors

– Biotic = living (plants, animals, bacteria, fungus, protists)

– Abiotic = non-living (temp, water, soil, weather, rocks, sunlight, etc)

Ecological Organization

– Organism ~ one member of one species– Population ~ all members of one species in a given

area– Community ~ all populations in a given area– Ecosystem ~ all members of community plus

abiotic factors in the area– Biome ~ group of ecosystems with same climate

and organisms

The Water Cycle

The Carbon Cycle

The Nitrogen Cycle

Succession– Primary Succession = colonization of NEW land by

pioneer species until a climax community is reached. • Lava flow lichens mosses grasses shrubs

trees– Secondary Succession = existing community is

destroyed and a new one begins to form• Occurs more quickly than primary succession because

soil is already present and seeds were left behind• Forest Fire mosses grasses shrubs trees

Ecosystem Relationships– Niche vs. Habitat

• If an organism’s habitat is its address, its niche is its occupation.

– Competition• Organisms of same or different species try to use same

resource at same place during same time.• Competition can be reduced by developing different niches.• Ex. 3 species can easily live in same tree if one eats leaves,

one eats bark and another eats the flowers.– Predator-Prey

• Organism doing killing = predator• Organism being killed = prey

Symbiosis• Mutualism – both species benefit from the relationship–Flowers may feed on insects, which may in turn

disperse pollen to other flowers• Commensalism – one species benefits and the other is

unaffected by the relationship–Barnacles attach to the skin of a whale to catch more

food particles• Parasitism – one species benefits and the other is

harmed by the relationship–Tapeworms live inside a human intestine and feed

from the human

Energy Flow– Producers (autotrophs)• Use sunlight to make their food and energy through

photosynthesis or chemosynthesis• Only plants and some bacteria/algae are autotrophic

– Consumers (heterotrophs)• Must acquire their energy from other organisms• Herbivores = eat plants only• Carnivores = eat animals only• Omnivores = eat both plants and animals• Scavengers = eat dead or decaying plants and animals• Decomposers = break down dead or decaying plants or

animals

Feeding Relationships

• Food Chains = series of steps in which organisms transfer energy by eating and being eaten–Arrow shows the direction of energy transfer in

the food chain–Ex. Grass Grasshopper Mouse Snake

Hawk

Feeding Relationships• Food web = links all food chains together in an ecosystem

Trophic Levels

–Producers – get energy from sun & use some for own metabolism–Primary Consumers – get 10% of original energy from

producers and use some for own metabolism–Secondary Consumers – get 10% of energy from

primary consumers and use some for own metabolism–Tertiary Consumers – get 10% of energy from

secondary consumers and use some for own metabolism

Ecological Pyramids

Populations

– Population Growth• If birth rate is larger than death rate = growing• If birth rate is smaller than death rate =

shrinking• Immigration = movement into a population• Emigration = movement out of a population

Populations

– Exponential Growth (J-shaped Curve)• Occurs when individuals reproduce at a

constant rate (ex. every individual has 2 kids)• Will occur under ideal conditions with

unlimited resources

Populations– Carrying Capacity (S-shaped Curve)• A population’s growth slows or stops following

a period of exponential growth• Carrying capacity = largest number of

individuals that a given environment can support

Populations– Limiting Factors• A factor that causes a population’s growth to

decrease• Competition, predation, disease, climate extremes,

human disturbance– Density-dependent vs. Density-independent• Density-dependent = limit a population according to

population size–Competition, predation

• Density-independent = affects all populations the same, regardless of size–Natural disasters

Human Environmental Impacts

– Human population is growing exponentially with no slowing in sight because of technological advances in medicine.

– Humans are clearing habitats of plants and animals to have more room for cities & suburbs as well as space to grow more food for the growing populations.

Human Environmental Impacts

• Ozone depletion–Ozone protects us from harmful UV

radiation from the sun–Chlorofluorocarbons (CFCs) destroy the

ozone layer–CFCs are banned, but their affects are lasting

as the ozone layer slowly heals itself

Human Environmental Impacts

• Global Warming–Burning of fossil fuels adds excess carbon

dioxide in the atmosphere–Carbon dioxide is an insulator and traps heat

in the atmosphere causing the global temperature to slowly rise.–Higher global temperatures could have

devastating effects such as melting of glaciers and changes in weather patterns.

Human Environmental Impacts• Pesticide Use–DDT and other pesticides are dangerous because they

can contaminate groundwater and other water sources.–Biological magnification – concentrations of a

harmful substance increase in organisms at higher trophic levels in a food web or a food chain.»Ex. algae pick up toxin from water they live in –

plankton eat much algae to survive – small fish eat the plankton – large fish eat the large fish there is much more DDT in the large fish than the plankton because it has concentrated up the food chain.

Practice Questions1. Which situation would result in the greatest

increase in the human population?

A. decreased birth rate and increased death rate

B. increased infant mortality and decreased death rate

C. decreased death rate and increased birth rate

D. increased birth rate and increased infant mortality

2. In a forest ecosystem, which is an abiotic

factor?

E. the amount of rainfallF. the size of the deerG. the type of treesH. the number of birds

3. In the carbon cycle, atmospheric carbon dioxide is converted into organic material by which process?

A. cellular respirationB. decompositionC. photosynthesisD. transpiration

4. Why do ecosystems rarely contain more

than a few trophic levels?

E. Energy transfer efficiency is high.F. Energy transfer efficiency is low.G. Energy amounts remain constant.H. Energy cannot flow through levels.

Practice Questions5. Recent climate data suggests a global

warming trend. The most likely cause could be an increase in which gas?

A. oxygenB. carbon dioxideC. nitrogenD. hydrogen sulfide

6. Silt and nutrients from eroding farmland

flow into a lake. As a result, which will most likely increase first?

E. fish populationF. shore vegetationG. algae growthH. dissolved oxygen

7. A community is studied and several interactions are observed and recorded.

Which type of interaction could illustrate the process of mutualism?

A. interaction AB. interaction BC. interaction CD. interaction D