Science section 2: Community ecology -> Biogeochemical cycles

Question 1

Mutualism

Answer 1

a symbiosis in which both partners benefit

Question 2

Predation

Answer 2

One species uses another species as a resource. This includes herbivory and parasitism.

Question 3

Competition

Answer 3

occurs when the demand for an ecological resource exceeds its
limited supply, causing organisms to interfere with each other

Question 4

limiting resource

Answer 4

an environmental resource that
is the primary restriction on the productivity of
autotrophs in an ecosystem

Question 5

Georgy Gause

Answer 5

led a very famous experiment: begins with two species of bacteria, P. Aurelia and P. Caudatum., and cultivates them in two separate laboratories. When grown separately, both species thrived. However, when Gause put the two species together, P. Aurelia thrived much as it had before while most of the P. Caudatum died off.

Question 6

community

Answer 6

the populations that live in a certain area. Made up of multiple species

Question 7

limiting resource

Answer 7

an environmental resource that
is the primary restriction on the productivity of autotrophs in an ecosystem

Question 8

competitive exclusion principle

Answer 8

If a resource limits the growth and reproduction of multiple species, it cannot be shared: one species will succeed, and
the other will go extinct. This is a principle known as competitive exclusion.

Question 9

niche

Answer 9

the role of an organism within a community

Question 10

parasitism

Answer 10

An example of predation, in which animals, plants, fungi, or bacteria feed on or use another organism as a habitat,
causing injury but usually not death

Question 11

numerical response

Answer 11

when prey density increases, so will predator density

Question 12

functional response

Answer 12

when prey populations decrease, individual
predators change their behavior and switch from low-density to high-density prey.

Question 13

food webs

Answer 13

summarizes the species that make up a community and the ways they are linked by various predator-prey interactions to form pathways of energy flow.

Question 14

keystone species

Answer 14

a dominant species in a
community, usually a predator, with an influence on structure and function that is highly
disproportionate to its biomass

Question 15

Pisaster star fish

Answer 15

The Pisaster starfish is a key predator that keeps other species in balance. If you remove it from the ecosystem, mussels (specifically, mytilus) end up consuming pretty much everything because there’s no species left to eat them.

Question 16

In what way are beavers keystone species?

Answer 16

Beavers transform streams into ponds. If you remove them from the ecosystem, pond-animals/plants won’t have anywhere to live.

Question 17

In what way are mycorrhizal fungi keystone species?

Answer 17

Mycorrhizal fungi live on the roots of many trees. They are critical for the growth process of the tree. If the fungi is removed, many tree habitats are lost.

Question 18

In what way are old world fruit bats keystone species?

Answer 18

Old world fruit bats are the sole pollinators for hundreds of tropical plant species.

Question 19

Primary succession

Answer 19

• begins with an event that leaves behind bare rock (e.g. glacial retreat, or volcanic eruption)
• early successional species are usually lichens and mosses. These organisms die and contribute organic matter to the soil
• later successional species are adapted to exploiting open, sunny areas with poor soil nutrients

Question 20

Secondary succession

Answer 20

• begins on an area of land that is covered with bare soil, usually after an event like a wildfire or hurricane
• after that, it is basically the same process as primary succession

Question 21

climax forest

Answer 21

outdated term for the plants in the “last” stage of succession. It is now recognized that because natural disturbances are a regular part of most forests, a late-successional stage is always a temporary, rather than a final
phenomenon, so the term climax is no longer used.

Question 22

decomposers

Answer 22

a heterotroph that feeds on dead organic matter

Question 23

Where is Organ Cave?

Answer 23

The southern Appalachia of West Virginia

Question 24

What are the four “full-time residents” of Organ Cave?

Answer 24

A small distant relative of shrimp, crayfish, isopods, and amphipods

Question 25

How has warming climate impacted organisms in Organ Cave?

Answer 25

Surface waters in the cave became too hot for many organisms during summer, so they became isolated in the consistently cold waters.

Question 26

What resource do organisms in Organ Cave compete for?

Answer 26

proper sized rocks so they can avoid being washed downstream

Question 27

Describe the energy flow in Organ Cave.

Answer 27

water flow brings in energy and nutrients, species competition regulates the use of this energy, and water flow takes out unused energy

Question 28

Laws of thermodynamics

Answer 28

physical principles that govern all transformations of energy

Question 29

first law of thermodynamics

Answer 29

energy can never be created or destroyed, but it can undergo transformation. The energy content of the universe remains constant

Question 30

second law of thermodynamics

Answer 30

when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes

Question 31

what is the primary source of energy on Earth?

Answer 31

the sun

Question 32

primary producer

Answer 32

an organism that uses the energy from the Sun to produce usable forms of energy

Question 33

photosynthesis

Answer 33

the process by which producers use solar energy to convert carbon dioxide and water
into glucose.

Question 34

equation for photosynthesis

Answer 34

CO2+H2O+energy from the sun —> CH2O+O2

Question 35

primary productivity

Answer 35

productivity by primary
producers, such as plants or algae; often measured
as biomass accumulated over a unit of time, or
sometimes by the amount of carbon fixed

Question 36

Gross primary productivity

Answer 36

The total amount of solar energy converted to chemical energy by photosynthesis.

Question 36

respiration

Answer 36

physiological process that is the opposite of photosynthesis. Cells use carbohydrates and oxygen to create carbon dioxide and water.

Question 36

Equation for respiration

Answer 36

CH2O+O2—>H2O+energy(heat)

Question 37

Net primary productivity

Answer 37

the gross primary productivity minus the energy that is expended during respiration

Question 38

Net primary productivity equation

Answer 38

NPP=GPP-respiration

Question 39

Approximately what percent of solar energy is converted to biomass?

Answer 39

1%

Question 40

What is the average transfer efficiency of energy in an ecosystem?

Answer 40

10% efficiency (so primary consumers will have 10% the energy that primary producers have, etc)

Question 41

secondary consumers

Answer 41

a carnivore that feeds on
primary consumers (or herbivores)

Question 42

ecological pyramids

Answer 42

a model of the trophic structure
of an ecosystem, organized with plant productivity
on the bottom, that of herbivores above, and
carnivores above the herbivores

Question 43

detritivores

Answer 43

organisms that feed on dead organic matter. E.g. bacteria, fungi, dung beetles, and earthworms

Question 44

ecosystems

Answer 44

a general term used to describe one or more communities that are interacting with their
environment as a defined unit; ecosystems range
from small units occurring in microhabitats to
larger units such as landscapes and seascapes, and
even the biosphere.

Question 45

what kind of ecosystems have easily defined boundaries?

Answer 45

Caves, as well as many aquatic ecosystems because their boundary is just where land meets water

Question 46

How do environmental scientists usually define the boundary of ecosystems?

Answer 46

Ecosystem boundaries are often defined based on how Populations of organisms are distributed. However, sometimes boundaries are set according to administrative rather than scientific criteria (e.g. national parks and reserves)

Question 47

Biotic

Answer 47

the living parts of an ecosystem

Question 48

Abiotic

Answer 48

non-living parts of an ecosystem, including temperature, water, salinity, soil structure, and mineral nutrients

Question 49

disturbance

Answer 49

an episode of destruction of some part of a community or ecosystem

Question 50

perturbation

Answer 50

a much broader term that refers to any kind of change to the norm of an ecosystem

Question 51

Resilience

Answer 51

the ability of a system to recover from disturbance

Question 52

Intermediate distribution hypothesis

Answer 52

in ecosystems with no disturbances, competitive exclusion will lead to the dominance of one species. On the other hand, if there is too much disturbance, most species will go extinct. Therefore, an intermediate level of disturbance is ideal

Question 53

Restoration ecology

Answer 53

activities undertaken by
ecologists to repair ecological damage, such
as establishing vegetation on degraded habitat,
increasing the populations of endangered species,
and decreasing the area of threatened ecosystems

Question 54

biome

Answer 54

a geographically extensive ecosystem,
occurring throughout the world wherever
environmental conditions are suitable

Question 55

solar energy flux

Answer 55

Some places on Earth receive more direct sunlight than others

Question 56

Hadley cell

Answer 56

The air at the equator receives the most direct sunlight out of any location on Earth. This causes it to ascend and release moisture over the equator as it does so. After that, the air is cool and dry because it has lost all its moisture. It descends around 30 N and 30 S, creating desert ecosystems at these latitudes

Question 57

Coriolis effect

Answer 57

due to the Earth’s constant rotation, winds in the Northern
Hemisphere deflect to the right and those in the
Southern Hemisphere deflect to the left

Question 58

How do ocean currents effect the distrubution of biomes?

Answer 58

warm currents flowing away from the equator bring heat to northern latitudes. Also, water tends to heat up more slowly in summer and cool off more slowly in winter, helping to moderate the temperature changes of adjacent land masses.

Question 59

tropical rainforest

Answer 59

Wet and warm
High plant and animal diversity
High productivity
Soil is poor in nutrients

Question 60

Tropical dry (seasonal) forest

Answer 60

Pronounced dry season
Deciduous trees drop their leaves during the dry season
Basically a less productive and less diverse version of the tropical rainforest

Question 60

Temperate rainforest

Answer 60

Mild winters
Rainy and foggy
Massive coniferous trees (think of the redwoods)
Mid productivity
Soil is rich in organic matter

Question 61

Temperate broadleaf forest

Answer 61

Somewhat similar to the temperate seasonal rainforest, but instead of pine trees, we have trees with actual leaves.
Productivity is also mid
Nutrient rich soil (because of all the leaves decomposing)
Low plant and animal diversity

Question 62

Boreal forest

Answer 62

Coniferous trees
Large mammals
Nutrient poor soil (due to low temperatures and a lack of “leaf litter”)
Dramatic variations in seed production each year, causing dramatic fluctuations in birds and other populations.

Question 63

Temperate grassland

Answer 63

Not enough precipitation to support a forests
Productivity is about ⅓ of what you would find in a tropical rainforest
Decomposition is slow, so organic matter accumulates, resulting in rich land that can be used for agriculture.

Question 64

Tropical scrub forest/Savannah

Answer 64

Plant life is limited to scrub vegetation because of limited soil nutrients and a short growing season
Migrating herbivores follow the rain
Fires and grazing keep the region almost bare
Low productivity and species diversity

Question 65

Desert

Answer 65

Less than 25 cm of rain per year
The key element here is the lack of precipitation, not heat. There are cold deserts (e.g. Antarctica is technically classified as a desert)
Shrubs and grasses
Very low productivity
Animals and vegetation are adapted to the lack of moisture

Question 66

Mediterranean/chaparral

Answer 66

Woody shrubs and small trees
Vegetation has adapted to conserve moisture with small, waxy leaves
Vegetation is adapted to wildfires with fire-resistant bark
Animal life: jackrabbits, mule deer, kangaroo rats, and several lizards

Question 67

Tundra

Answer 67

Tundras occur beyond the tree line, or the upper limit of tree growth at high latitudes.
Sedges, lichens, and dwarf trees
Layer of permafrost in the soil is frozen year round
Low productivity
Bird species in the summer, but they migrate south during winter
Rodents are abundant but their populations fluctuate dramatically

Question 68

Freshwater systems

Answer 68

• Not salty
• Can be flowing (rivers & streams) or standing (lakes and ponds)

Question 69

transpiration

Answer 69

the evaporation of water from plant leaves (stomata)

Question 70

evapotranspiration

Answer 70

water losses from a landscape
due to evaporation AND transpiration

Question 71

Infiltration

Answer 71

the process where rainwater sinks into the soil and percolates downward

Question 72

groundwater

Answer 72

water stored underground in soil and in rocks

Question 73

runoff

Answer 73

water that doesn’t sink into the soil – it just flows over the surface of Earth

Question 74

what is the largest reservoir of water on Earth?

Answer 74

The ocean

Question 75

what is the main energy source that drives the water cycle?

Answer 75

the sun

Question 76

Equation for the water cycle/hydrologic cycle

Answer 76

PRECIP = ET + I + RO

*Precip= precipitation
ET= evapotranspiration
I= infiltration
RO= runoff

Question 77

Mean Residence Time for the ocean (around how many years does water remain in the ocean?)

Answer 77

2,650 years

Question 78

Mean Residence Time for terrestrial water (around how many years does water remain on terrestrial landscapes?)

Answer 78

403 years

Question 79

Mean Residence Time for the atmosphere (around how many years does water remain in the atmosphere?)

Answer 79

8 days

Question 80

carbon fixation

Answer 80

CO2 is pulled out of the atmosphere (by terrestrial plants) and from the ocean (by phytoplankton) via photosynthesis.

Question 81

Respiration

Answer 81

All living things, including plants and phytoplankton themselves, respirate. In doing so, they release CO2 back into the atmosphere.

Question 82

Decomposition

Answer 82

Organisms die and the organic carbon that was within them is released to the soil or ocean

Question 83

Sedimentation

Answer 83

a very small minority of dead organisms don’t decompose before they are buried in sediments. When this happens, the dead organism becomes a fossil. The fossil can later turn to oil, coal, or natural gas, hence why these compounds are called fossil fuels.

Question 84

Combustion

Answer 84

occurs in forest fires or during the burning of fossil fuels. Chemically, it is an identical process to respiration and decomposition:
CH2O + O2 —> CO2 +H2O + energy

Question 85

sedimentary rock

Answer 85

rock formed from precipitated
minerals such as calcite, or from lithified particles
weathered and eroded from other rocks