ESS Unit 2 - ecology

Question 1

How are ecosystems sustained?

Answer 1

Ecosystems are sustained by supplies of energy and matter.

Question 2

What does the first law of thermodynamics state?

Answer 2

Energy cannot be created or destroyed, but can change from one form to another

Question 3

What processes transform energy and matter in ecosystems?

Answer 3

Photosynthesis and cellular respiration transform energy and matter in ecosystems.

Question 4

What is photosynthesis?

Answer 4

Photosynthesis is the conversion of water and CO2 to glucose and oxygen some of which can be stored as biomass by autotrophs.

Question 5

What is the role of producers in a food chain?

Answer 5

Producers form the first trophic level in a food chain. They make their own food and provide energy and habitats to other organisms, supply nutrients to the soil and slows soil erosion.

Question 6

What does cellular respiration do?

Answer 6

Cellular respiration releases energy from glucose by converting it into a chemical form that can easily be used in carrying out active processes within living cells.

Question 7

What happens to some chemical energy during cellular respiration?

Answer 7

Some of the chemical energy released during cellular respiration is transformed into heat.

Question 8

What does the second law of thermodynamics state?

Answer 8

When energy is converted from one form to another, some of it is degraded to heat (thus lost). Heat is highly entropic (disorganized) → increase in entropy as energy flows to the next trophic level in the food web.

Question 9

How do consumers obtain chemical energy?

Answer 9

Consumers gain chemical energy from carbon (organic) compounds obtained from other organisms.

Question 10

What is the significance of trophic levels?

Answer 10

Carbon compounds and the energy they contain are passed from one organism to the next in a food chain. The stages in a food chain are called trophic levels.

Question 11

What is gross productivity (GP) and net productivity (NP)?

Answer 11

Gross productivity (GP) is the total gain in biomass by an organism. Net productivity (NP) is the amount remaining after losses due to cellular respiration.

Question 12

Why are there limited trophic levels in ecosystems?

Answer 12

The number of trophic levels in ecosystems is limited due to energy losses.

Question 13

What do food webs represent?

Answer 13

Food webs show the complexity of trophic relationships in communities.

Question 14

How can biomass of a trophic level be measured?

Answer 14

Biomass of a trophic level can be measured by collecting and drying samples.

Question 15

What are ecological pyramids used for?

Answer 15

Ecological pyramids are used to represent relative numbers, biomass or energy of trophic levels in an ecosystem.

Question 16

What are non-biodegradable pollutants?

Answer 16

Pollutants that are non-biodegradable, such as polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT) and mercury, cause changes to ecosystems through the processes of bioaccumulation and biomagnification.

Question 17

How do human activities affect ecosystems?

Answer 17

Human activities, such as burning fossil fuels, deforestation, urbanization and agriculture, have impacts on flows of energy and transfers of matter in ecosystems.

Question 18

What is the 10% rule in energy transfer?

Answer 18

Typically 10% or less of the energy flowing to a trophic level is available to the next level, limiting the length of food chains.

Question 19

What is an ecosystem?

Answer 19

An ecosystem is defined as a mass or area.

Question 20

What does productivity refer to in an ecosystem?

Answer 20

Productivity refers to the flow of energy in an ecosystem over a period of time (energy/area/yr).

Question 21

What does a pyramid of numbers represent?

Answer 21

A pyramid of numbers shows the number of organisms at each trophic level in a food chain at one time - the standing crop. (# / unit area)

Question 22

How do ecologists estimate the total number of organisms in an ecosystem?

Answer 22

Ecologists sample numbers of organisms in a species in a measured area, then multiply (extrapolate) the results to estimate the total number of the target organisms in the whole ecosystem.

Question 23

What is a pyramid of biomass?

Answer 23

A pyramid of biomass represents an estimate of the total biomass of all organisms at each trophic level in an ecosystem.

Question 24

How is biomass calculated?

Answer 24

Biomass is calculated using the formula: biomass = individual biomass x number of organisms / area.

Question 25

What assumptions are made when using pyramids of biomass?

Answer 25

Assumptions include that all individuals at that trophic level are the same and that the sample accurately represents the entire habitat.

Question 26

What can cause a pyramid of biomass to be inverted?

Answer 26

A pyramid of biomass can be inverted in aquatic ecosystems when growth is rapid and seasonal.

Question 27

What do pyramids of energy show?

Answer 27

Pyramids of energy show the amount of energy flowing to each trophic level per unit area and per unit time (usually kJ m-2 year-1).

Question 28

What is bioaccumulation?

Answer 28

Bioaccumulation refers to the increasing concentration of non-biodegradable pollutants in organisms or trophic levels over time.

Question 29

What is biomagnification?

Answer 29

Biomagnification refers to the increasing concentration of non-biodegradable pollutants along a food chain.

Question 30

What are persistent organic pollutants (POP)?

Answer 30

Persistent organic pollutants are chemicals like DDT, PCB, and heavy metals that do not break down or break down slowly in the environment.

Question 31

What is the difference between gross productivity (GP) and net productivity (NP)?

Answer 31

Gross productivity (GP) is the total gain in biomass by an organism, while net productivity (NP) is the amount remaining after losses due to cellular respiration.

Question 32

What is maximum sustainable yield?

Answer 32

Maximum sustainable yield is the amount of biomass that may be removed from an ecosystem without diminishing the natural income produced by that system each year.

Question 33

What is the formula for net primary productivity (NPP)?

Answer 33

NPP = GPP - R, where R = respiratory loss.

Question 34

What is optimal sustainable yield?

Answer 34

Optimal sustainable yield is generally 50% of maximum yield to account for unknown factors affecting populations.

Question 35

What is biomass?

Answer 35

The mass of organic material in an organism or ecosystem. Usually expressed by dry weight per unit area.

Question 36

What is a biogeochemical cycle?

Answer 36

Cycles of chemicals between biological and geological storages. This happens in closed storages and ensures that essential elements like carbon, nitrogen and phosphorus are being recycled and made available to organisms. They have storages sinks and sources.

Question 37

What do storages, sinks and sources do?

Answer 37

Storages remain in equilibrium with the environment, sinks indicate a net accumulation of the element and sources indicate a net release of the element.

Question 38

What is the role of carbon in the ecosystem?

Answer 38

All living things are made of carbon based molecules like proteins, fats, etc. Organisms use carbon compounds for energy storage and it is the main component of fossil fuels.

Question 39

What is a fast carbon cycle?

Answer 39

A rapid interchange between the ocean, atmosphere, and top layer of soil and biomass in the biosphere. This could take from days to a decade.

Question 40

What is a slow carbon cycle?

Answer 40

This only involves the inorganic stores of carbo through a series of chemical reactions and tectonic activities. This could take a up to a hundred million years.

Question 41

What is a carbon budget?

Answer 41

This is a concept used in climate policy to help set emission reduction targets in a fair and effective way. It examines the amount of cumulative net global anthropogenic CO2 emissions that would result in limiting GW to a given level.

Question 42

What are the causes of ocean acidification?

Answer 42

Carbonate ions are not very soluble, therefore the concentration in seawater is low. Dissolved CO2 decreases the carbonate concentration further.

Question 43

What are the effects of ocean acidification?

Answer 43

At risk: Marine calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.*
Need to absorb carbonate ions from seawater to make the calcium carbonate in their skeletons.
Benefit: Photosynthetic algae and sea grasses
Low CO2 is a limiting factor for photosynthesis

Question 44

What is carbon sequestration?

Answer 44

The process of capturing gaseous and atmospheric CO2 and storing it in a solid or liquid form

Question 45

What are the major types of biomes?

Answer 45

Aquatic - freshwater, marine
Forest—tropical, temperate and boreal (taiga).
Grassland—tropical, savanna and temperate.
Chaparral - hot and dry coastal (with woody shrubs)
Desert—hot and cold.
Tundra—arctic and alpine.

Question 46

What are the main abiotic factors determining terrestrial biome distribution?

Answer 46

Insolation: It is measured by the amount of solar energy received per square centimetre per minute.
Precipitation: Water can exist in three states (ice, liquid, vapour) → has a role in absorbing or releasing heat energy as it changes in state
Temperature (°C): temperature is hotter near the equator and tends to become cooler towards the poles.
Latitude: Distance north and south from the equator
Altitude: Height above sea level
Ocean Currents and Winds: Winds cause ocean currents. The ocean absorbs solar radiation and ocean currents distributes heat around the world.

Question 47

What are the types of cells on earth?

Answer 47

Polar Cell: near Earth’s poles; circulates cold air.
Ferrel Cell: mild latitudes; typically circulate air with moderate temperature
Hadley Cell: near the equator; typically circulate hot or warm air.

Question 48

Facts on atmospheric circulation

Answer 48

• Hot air contains the most energy and therefore can hold more water vapor than cold air
• Latent heat of condensation: energy released when water vapour turns into liquid
• Coriolis force: air is deflected to the right in the northern hemisphere, and to the left in the southern hemisphere due to earth rotating on its axis.
• Intertropical convergence zone (ITCZ): a band of low pressure, clouds and usually thunderstorms near the equator.

Question 49

What are hotspots and some examples?

Answer 49

Areas predicted to have a high turnover of species due to climate change. Examples include:
The Himalayas – species can move no higher than the land mass.
Equatorial Eastern Africa – with a very drought-sensitive climate.
The Mediterranean Region(s) – drought, high temp.
Madagascar – more extreme weather events.

Question 50

What are limiting factors of each biome?

Answer 50

Aquatic: water absorbs light and limits PS, deep oceans have no light for PS, freshwater may freeze in cool temperatures
Forest: nutrients locked in biomass, high rainfall leaches nutrients from soils, thin soils, cold and dry winters in temp, forests
Grassland: less precipitation than forests but more than deserts, temp. extremes limit productivity and low decomp and nutrient cycling
Desert: low prec., high evap., extreme day/night temperature difference, PS limited: low H2O
Tundra: short days and frozen water limit PS, slow nutrient cycles

Question 51

What is succession?

Answer 51

the process of change over time in an ecosystem involving pioneer, intermediate and climax communities. This takes place over a long period of time and caused by progressive changes through time

Question 52

What is zonation?

Answer 52

the change in community along an environmental gradient due to factors like changes in altitude, latitude, etc. It is caused by an abiotic gradient.

Question 53

Examples of biotic and abiotic factors influencing a mountain zonation?

Answer 53

Temperature – decreases with increasing altitude and latitude.
Precipitation—Higher up on mountains, the air is too dry and cold for trees. Most rainfall is in the middle altitudes where deciduous trees grow.
Solar insolation—more intense at higher altitudes and plants have adapted to this.
Soil type—in warmer zones, decomposition is faster so soils are deeper and more fertile. Higher up, decomposition is slow with acidic soils.
Species interactions—competition may crowd out some species and grazing may alter plant composition. Mycorrhizal fungi may play an important role in tree growth.

Question 54

What is a transect?

Answer 54

a line or corridor through a section of an ecosystem along an environmental gradient. A continuous one is placed in the direction of the gradient and measures the presence or absence of species. An interrupted one is in the direction of the gradient and samples are taken at fixed distances

Question 55

What is a kite graph used for?

Answer 55

To display the results from a transect investigation and shows the distribution and abundance of each species along an environmental gradient

Question 56

What is primary succession?

Answer 56

occurs on a bare inorganic surface and involves the colonization of newly created or uncovered land by organisms

Question 57

What are the stages of primary succession?

Answer 57

Bare inorganic surface: Lifeless abiotic environment becomes available for colonization by pioneer plant, animal and lichen species. Soil is a little more than mineral particles, nutrient is poor and has an erratic water supply.
Stage 1 Colonization: First species to colonize are pioneer species adapted to extreme conditions. Pioneer species are typically r-selected species showing small size, short life cycles, rapid growth and production of many offspring or seeds. Simple soil starts from windblown dust and mineral particles.
Stage 2 Establishment: Species diversity increases. Invertebrates (no backbone) begin to visit and live in the soil, increasing humus (organic material) content and water-holding capacity. Weathering of rock enriches soil with nutrients.
Stage 3 Competition: Microclimate continues to change as new species colonize. Larger plants increase cover and provide shelter, enabling k-selected species to become established. Temperature, sun and wind are less extreme. Earlier pioneer r-species are unable to compete with K species for space, nutrients or light and are lost from the community.
Stage 4 Stabilization: Fewer new species colonize as late colonizers become established shading out early colonizers. Complex food webs develop. K-selected species are specialists with narrower niches. They are generally larger and less productive (slower growing) with longer life cycles and delayed reproduction.
The final stage or Climax community is stable and self-perpetuating. It exists in a steady-state dynamic equilibrium. The climax represents the maximum possible development that a community can reach under the prevailing environmental conditions of temperature, light and rainfall.

Question 58

What is secondary succession?

Answer 58

When an already established community is suddenly disturbed or destroyed

Question 59

What can happen in a seral community during succession?

Answer 59

The size of the organisms increases with trees* → create a more hospitable environment.
Energy flow pathways becomes more complex as simple food chains become complex food webs.
Soil depth, humus, water-holding capacity, mineral content, and rate of nutrient cycling all increase.
Biodiversity increases because more niches appear, then falls as the climax community is reached.