Bio 107 Quiz 4

ecology

relationships of living organisms and their environment

Ecological system / Ecosystem

the abiotic (nonliving) and biotic (living) components and their
interactions

Ex of abiotic factors

sunlight, temperature, humidity, soil

Why do we have seasons?

The tilt of the Earth’s axis of rotation: The Earth is tilted at this slight angle [23.5] (can be tilted towards/ away from the sun)
→ responsible for various climate patterns in Earth

- Earth's orbit around the sun is circular

The equator receives the most solar
radiation compared to North and
South poles

→ highest amount of solar radiation in equator. Less solar radiation as move apart from the equator

Input of solar energy generates atmospheric circulation patterns

a. Solar radiation heats up the land
b. Warm air rises
c. As the warm air rises, it cools
d. Cool air loses the ability to retain moisture and it rains
e. The dry air moves north or south and descends at 30° N or 30° S

Atmospheric circulation patterns + Earth’s rotation → Prevailing winds

The combination of the Earth’s rotation and the movement of atmospheric air circulation

- Large scale atmospheric patterns of movement of air = prevailing winds
Air flows east or west in predictable patterns

The direction of prevailing winds at Earth’s surface is determined by …?

A. Cyclic movements of air masses
B. Rise of warm air mass that results from latitudinal gradients in solar energy input
C. The rotation of Earth on its axis

Prevailing winds → Ocean currents (upwelling)

Upwelling: vertical currents create variations in temperature and nutrients along coasts
a. Cooler water + nutrients move up towards surface

Ocean gyre

large scale currents of water generated by prevailing winds

Levels of Biological Organization

Biosphere
Ecosystems / landscape
Community
Population
Organism
Organ systems
Tissue
Cell
Organelle
Molecule (DNA, RNA, proteins)

Micro climates are...

Regional and local variations from global
climate patterns

Ex: Rain shadows
- As winds push air over the coast, it rises then cools and
loses its moisture (loses ability to retain water), leading
to rain
- Because of the deflection of the air, we see that there
are usually wet areas on the coast and dry areas inland
- The Columbia Basin has a microclimate due to the rain shadow

Anthropogenic Influences on Microclimates

Microclimates due to anthropogenic changes (deforestation, agriculture, and urbanization) can lead to changes in temperature and precipitation rates

Biomes

An ecosystem (ecological system) characterized by ecological similarities (in terms of climate, temperature, precipitation, and the organisms present)

Across biomes, we can have the same selective pressures, but a
different evolutionary history of the organisms living there

We often see convergent evolution within the biomes (e.g.
Euphorbia (native to Africa), and Cactus (native to the
Americas))

Boreal forest

Spans the entire northern hemisphere (around 60ºN) – e.g. the
Taiga
- Very cold in the winter, and very hot in the summer

The temperate seasonal forest

OUR biome! --> Fairly stable temperatures (-8 to 20ºC)
- Average amount of rainfall (85 cm annually)
- Deciduous trees that lose their leaves every year

Subtropical deserts

- Found around 30ºN and 30ºS (with variation due to other structures in ocean circulation and prevailing winds)

- A lot of radiant heat from the sun, driving moisture away from the surface → creation of deserts

- Cold ocean currents cool the air above it → dense and cool, stable layer of air → warm air cannot mix with it to form rain

- Prevailing winds go from west to east

Right at the equator (0º), we have the tropical rainforest

High levels of precipitation
- Very high temperatures all year around (very stable)
- The equator sees the most solar radiation in comparison to the northern
and southern hemispheres

Ecosystem function

Primary producers capture the input of energy (solar radiation)
into the ecosystem --> Energy is then consumed by the other levels in the ecosystem, and then eventually lost

Role of solar radiation in ecosystem processes

Solar energy enters ecosystems via plants

- Take energy contained in solar radiation and convert it into another form

Gross Primary Productivity (GPP)

Rate at which primary producers in a community convert solar energy into stored chemical energy through photosynthesis (total energy produced)

Net Primary Production (NPP)

The amount of primary producer biomass (weight
of organic matter) available for consumption by
other organisms in other trophic levels

- Highest NPP at the equator – as we move north
or south, NPP decreases

- Biomes and energetics define each other
** The tropical rainforest biome has the highest NPP

NPP = GPP - R (respiration)

Cellular respiration is the sum total of ALL biochemical processes, *not only breathing*

Limits on Terrestrial NPP

Temperature
- NPP shows the same pattern as latitudinal gradients in solar energy
- NPP increases with increasing temperature

Precipitation
- Low NPP at 30ºN and 30ºS (desert regions)
– very arid, low precipitation → low NPP
- NPP increases with increasing precipitation,
but only up to a certain point

Too much water is detrimental to plant health; oxygen levels can be depleted, roots can start rotting, etc.

Oceans and Limits on Aquatic Systems

Depends on nutrient availability and light

- Photosynthesis is restricted to surface waters – light cannot reach the deepest parts of the ocean

Low NPP in the open ocean
- Nutrients are limited (phytoplankton take them up quickly)
- NPP is highest where nutrients are most abundant – in near - shore areas and upwellings (coastlines)

- Upwelling brings nutrients from the deep ocean
to the shallows near our coast

Energetics of The Earth

There are aquatic systems that far outproduce terrestrial
systems

- The tropical rainforest is the most productive biome,
capturing the most energy and converting it at the highest
rate

The Earth --> open or closed system?

Open system with respect to energy (there is a constant input of solar energy from the sun to our
global ecosystem)

Closed system with respect to matter (materials on the planet are fixed; they are neither created nor destroyed, but are moved around)

Photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2

Energy from the sun drives this overall process of capturing carbon and converting it into a usable form

Laws of Thermodynamics

1) Energy is changed from one form to another, but it cannot be created or destroyed

a) Plants are not creating energy
i) Converting solar energy into the energy in a carbon-carbon bond (chemical bond energy)


2) In all energy exchanges, if no energy enters or leaves the system, the potential energy of the system will always be less than that of the initial state — entropy (a measure of disorder) always increases

a) As energy is transferred from one organism to another, much of it is lost as heat

b) Loss in energy = entropy increasing; energy that is not available for use
i) When an energy transformation occurs, there is an increase in entropy

Question: The second law of thermodynamics states that in every energy exchange, some energy
becomes unavailable for further use. And yet energy-expensive life continues. How can we reconcile
these two facts?

Primary producers convert solar energy into a chemical bond energy

The Nitrogen cycle

1. N2 gas makes up 78 percent of the atmosphere
a. Most organisms can’t use nitrogen in this form

2. Nitrogen fixation: conversion of N2 from inorganic to organic form (usable by plants)
a. Process carried out by many microorganisms (called diazotrophs)
i. Conversion of N2 → ammonium (NH4)

3. Denitrification: returning N2 to the atmosphere
a. Reverse process of nitrogen fixation

Question: Human activities, such as deforestation, alter local microclimates. How are these
microclimates related to the water cycle?

The amount of precipitation in the deforested area is reduced
a. True → deforestation results in dry land (= less precipitation)

Upwelling

Nutrient rich (+nitrogen) water coming back to the surface of water
⇒ high NPP along our coast due to higher plant growth from the nutrient rich water uprising

What is the relationship between the processes of nitrogen fixation and denitrification?

Nitrogen fixation takes nitrogen from the air and makes it usable by plants; denitrification reverses this process

How do human activities affect the nitrogen cycle?

Burning fossil fuels, rice cultivation, and raising livestock releases nitrogen to atmosphere

a. contributes to smog and acid rain (NH3 and HNO3/nitric acid)
b. N2O is a greenhouse gas and contributes to global warming

Nitrogen is REQUIRED for growth

Can fertilize more land from industrial processes of nitrogen
fixation ⇒ can get high yield of crops!

Eutrophication

The over-fertilization of bodies of water and the results that follow

a. High levels of N2 ultimately leads to low level of O in the body of water
i. called the “dead zone”

In comparing the water and nitrogen cycles, which statement is true?

a. The water cycle has no chemical conversion of a molecule of water
i. Just change states
b. Nitrogen cycle relies on chemical conversions

Biogeochemical cycles

The movement of elements through compartments by biological, geological, and chemical processes
a. Water
b. Nitrogen
c. Carbon

The Water Cycle

a. Solar-powered evaporation moves water from ocean and land surfaces into the
atmosphere
b. Movement of heat and materials around planet
i. 2 main processes
1. Precipitation: atmosphere to land
2. Erosion: land to water

Patterns

1. Largest pool is in the ocean
a. 97% of all of the water in the global water system is in the ocean
b. Salt water in ocean = cannot be used

2. Transpiration : evapor-transformation of water
i. Once an area is deforested, leads to greater run off in the area
1. Leads to a dryer climate because of the increased runoff and decreased transpiration

3. Ice/snow
a. As our planet warms, the ice/snow pool will melt
i. Melting pool will change the dynamics of the overall water cycle
1. Change the evaporation rates from the sea

4. Ground water = sink of water
a. We are now drilling out the ground water to capture usable water
i. Pull it up into accessible space for its use in our industry and agriculture

how is a "dead zone" created

The Global Carbon Cycle

Movement of carbon is linked to energy flow
through the ecosystems
- Photosynthesis moves inorganic C from the
atmosphere to the organic compartment
(“carbon fixation”)
- Total carbon fixation = GPP
- Carbon is moved from accessible
inorganic to accessible organic
- Cellular respiration reverses this flux

Fossil Fuels

- The burial of animals in anaerobic environments – organic molecules were not broken down by
detritivores, but accumulated millions of years ago!
- Organic, inaccessible
- When an atom of C is captured in fossil fuels, it is pulled out of the immediate carbon cycle, and
can sit in the fossil fuel space for millions of years; they are preserved rather than being returned
to the atmosphere
- C–C bonds in fossil fuels represent a source of energy: oil, coal, and natural gas are the fossil
fuels we have on the surface of the planet

Greenhouse Gasses

- Solar radiation hits the surface of our planet,
warming it
- Some of the radiation is absorbed by
atmosphere, and the rest is reflected back
- Greenhouse gasses are transparent to sunlight, but
trap heat
- Accumulation of greenhouse gasses in
atmosphere serve as a block to outwards
radiation
- Increased greenhouse gasses have led to our
planet having a warmer surface

The Keeling curve

a common way of analyzing patterns in carbon dioxide
concentrations

Climate

Different biomes can be analyzed and classified based on the climate (temperature and precipitation) of that area
- If we define our biomes based on physical parameters, what will happen as those climate measures (temperature and precipitation) change?
- Our biome is defined by a very specific (and fairly large) range of temperature and precipitation

- How will the area around change as temperature and precipitation change?