Chapter 55 Flashcards
Ecosystem
The basic units of ecology, made up of individual communities and their abiotic environments
earth’s largest ecosystem is the
biosphere
Energy enters an ecosystem as
radiant energy (sunlight)
___ is trapped and used by producers for photosynthesis
less than 1%
as work is accomplished,
energy dissipates into the environment as heat
Primary producers
capture the sun’s energy through photosynthesis and incorporate the chemicals they manufacture into their own biomass
consumers
extract energy from organic molecules produced by other organisms
Herbivores
consumers that eat plants
Carnivores
eat herbivores or other animals
Omnivores
eat a variety of organisms, both plant and animal
Detritivores
eat detritus
Decomposers
break down organic remains and release simple inorganic molecules used by producers
trophic level
in a food web influences other trophic levels to which it is not directly linked
biomass is reduced by an average of ___ at each trophic level
90%
Pyramids of Biomass
shows the amount of living material at each trophic level, which indicates the amount of fixed energy at a particular time
Energy pyramids always have
large bases and get progressively smaller through succeeding trophic levels
showing that most energy dissipates into the environment when there is a transition from one trophic level to the next
Tropical rain forest
have the highest productivity
the least productive terrestrial ecosystem are
tundra and desert
wetlands connect ___ and ___ environments and are extremely productive
wetlands connect terrestrial and aquatic environments and are extremely productive
The most productive aquatic ecosystems are
algal beds, coral reefs, and estuaries
The Carbon Cycle
The global movement of carbon between the abiotic environment and organisms
Major processes that move carbon from the abiotic environment into organisms include
photosynthesis and the productin of shells by marine organisms
Carbon is returned to the environments by
cellular respiration, decomposition, and combustion of wood or fossil fuels
Carbon is stored for long periods in
wood, fossil fuels, and marine sediments
The Nitrogen Cycle Steps
- Nitrogen fixation
- Nitrification
- Assimilation
- Ammonification
- Denitrification
Earths atmosphere is ___% N2 which does not readily combine with other elements
78% N2
Nitrogen fixation
Converts n2 Gas to ammonia
nitrogen fixing bacteria use nitrogenase to break up molecular nitrogen
Rhizobium form
nodules on roots of legumes
Nitrification
converts ammonia or ammonium to Nitrate (NO3-)
assimilation
the incorporation of nitrogen compounds by plants or animals into their own proteins and nucleic acids
Ammonification
converts organic nitrogen compounds into ammonia and ammonium
ammonifying bacteria perform ammonification in both
the soil and aquatic environments
Denitrification
The reduction of NO3- to N2
Denitrifying bacteria are
anaerobic
The hydrolytic Cycle
Water continuously moves from the ocean to the atmosphere, to land, and back to the ocean
transpiration
loss of water vapor from land plants
runoff
movement of surface water from land to the ocean
watershed
the area of land drained by runoff
Groundwater eventually supplies water to
soil, streams and rivers, plants, and the ocean
___ and ___ are the two abiotic factors that affect organisms in ecosystems the most
water and temperature
The sun makes life on Earth possible
- Warms the earth
- Primary determinant of climate
- photosynthesis
- most fuels represent solar energy captured by photosynthetic organisms
Rays strike almost ___ near the equator
vertically
near the poles, the suns’s rays strike ___ and are spread over a larger surface area
obliquely
March 21 to September 22
Earths Northern Hemisphere tilts toward the sun
Higher concentration of sunlight, longer days
September 22 to March 21
The Northern Hemisphere tilts away from the sun
Lower concentration of sunlight, shorter days
Earth’s atmosphere
Nitrogen 78% and Oxygen 21% make up 99% of dry air
Other gases in earth’s atmosphere
Argon, carbon dioxide, neon, and helium
The atmosphere performs essential ecological functions
- Supplies organisms with oxygen
- CO2
- Protects Earth’s surface from most of the sun’s UV radiation and X-rays, and from cosmic rays from space
- Interacts with solar energy to create weather and climate
Four Global Oceans
Pacific, Atlantic, Indian, and Arctic Oceans
Ocean currents
Prevailing winds blowing over the ocean produce movements of surface ocean waters
surface ocean currents and winds tend to move
in the same direction
Wildfires have several effects on organisms:
- Combustion frees minerals locked in dry organic matter
- Fire removes plant cover and exposes soil, stimulating seed germination and encouraging shade-intolerant plants
- Removing plant cover leaves soil more vulnerable to wind and water, increasing soil erosion
