HL Biology: Global Issues and Ecology

Contains Stability and change, climate change, transfers of energy and matter

What are greenhouse gases?

Gases in Earth's atmosphere that trap heat from the sun.

Name some examples of greenhouse gases.

Includes CO2, Methane, nitrous oxide, water vapor.

Greenhouse effect

Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

Climate

The long-term average weather condition at a particular location

Weather

the day-today variations in air temperature precipitation, cloud cover, and winder

Climate change

A long term change in global or regional climate patterns, caused by natural or human factors

What are the anthropogenic causes of climate change

Primarily attributed to increased levels of atmospheric greenhouse gases. Methane and carbon dioxide emissions being a primary concern.

How is carbon dioxide emitted? Through what?

Cellular respiration, combustion of fossil fuels, etc.

How methane is released

Released due to human activities such as extractions of fossil fuels, agricultural practices

Positive feedback cycles in global warming

1. O - increase of co2 from deep ocean
2. S - an increase absorption of solar radiation due to loss of reflection snow -> causing more heat melting more snow
3. D - an increase in decomposition of peat which release co2 -> causing rapid decomp
4. M - increase of methane from warm temps melting permafrost areas -> causing more greenhouse gases & heat
5. increase in droughts and fires -> causing more co2

tipping points in climate change

Boreal forests, polar habitat change, changes in ocean currents, range shift of temperate species

Boreal forests

- Play a crucial in absorbing CO2 from the atmosphere to use for photosynthesis
- Warmer temperatures and reduced winter snowfall contribute to drought conditions which result in water loss and increases forest fire conditions

Polar habitat change

Melting of polar ice leads to habitat loss
- Due to breakage of landfast and sea ice

Nutrient upwelling

When deep, nutrient-rich water rises to the surface of the ocean, supporting marine ecosystems.

How can warmer surface water affect nutrient upwelling?

It can prevent nutrient upwelling to the surface

What is the impact of decreased nutrient availability?

Organisms that rely on nutrients may face a decrease in their availability

Temperate species

Organisms that are adapted to inhabiting temperate regions which are characterised by moderate climates with distinct seasons. As global temperatures rise, temperate species are moving into regions they couldn't previously inhibit.

Coral reefs

Vibrant underwater ecosystems built by tiny coral animals
Aka the "rainforests of the sea"

Carbon sequestration

the process of capturing and storing atmospheric carbon dioxide

Afforestation

Planting trees on previously non-forested land
- Effective method of carbon sequestration

Phenology

the timing of seasonal events (biological events) and their relationship with season and environmental factors

What influences the timing of biological events?

Photoperiods and temperature patterns

Photoperiod

Day length (# of sunlight hours)

Seasonal temperatures can be affected by....

climate change

Budburst

When leaf buds swell, unfold, burst into leaves or flowers

Migration

Seasonal journeys of different animals across great distances

Photosynthesis

When producers convert light energy (from sunlight) to chemical energy through the absorption of CO2 and water, and release oxygen and glucose

Ecology

The study of the relationships between organisms and their environment.

Specieis

Groups of organisms that can potentially interbreed to produce offspring

Population

Includes all individuals of a species that live in the same area at the same time

Community (hows it formed)

Formed by populations of different species living together and interacting with eachother

Ecosystems

A community of organisms and their surroundings

What type of system are ecosystems

They are open systems

Types of biological systems and what they are

Open -> allows both energy and matter to be exchanged with its surroundings
Closed systems -> allows for exchange of energy with surrounding environment but restricts the flow of matter
isolated systems -> niether energy nor matter are exchanged with their surroundings

What is the primary source of energy that sustains most ecosystems?

Sunlight

Other sources of energy

H2S, which is an energy source in hydrothermal vent ecosystems

How is energy transferred through the food chain?

By feeding interactions

Explain the energy pyramid/transfer of energy

Herbivores consume plants, carnivores consume herbivores

Food chains and food webs

As organisms eat other organisms, they get energy. Food chains and food webs show us how that energy moves from one organism to another in an ecosystem.
- Arrows indicate the direction of energy flow

What does biomass refer to?

Total dry mass of organisms in an ecosystem

How is biomass created by organisms?

Chemical energy (aka food) is used by organisms to create biomass

Decomposers

breaks down dead organisms and organic matter
- examples: bacteria, fungi, invertebrates

What are Saprotrophs

Heterotrophs that obtain organic nutrients from dead organic matter by external digestion

Detritivores (Scavengers)

Heterotrophs that obtain nutrients from Detritus by internal digestion
- Directly ingest and consume dead organic matter, internally breaking it down using digestive enzymes

Autotrophs vs. Heterotrophs

Autotrophs - "self feeders" that produce organic compounds (key example - glucose) (producers)

Heterotrophs - organisms who must obtain their energy source by ingesting or absorbing nutrients from other living things (consumers)

Photoautotrophs

Derives their energy through photosynthesis, which involves converting sunlight, CO2, & water into glucose & oxygen gas

Chemoautotrophs

Obtain energy through oxidization of inorganic compounds (iron, sulfur, mg)
example: iron-oxidising bacteria

Explain trophic levels

Represents an organisms position in food chain/web

Explain the energy flow in a food chain (energy pyramids)

- Energy decreases as it moves up the pyramid due to inefficiencies like heat loss
- Only about 10% of the heat is transferred to the next, 90% is lost
- When biomass is consumed, energy is transferred from the food source to the consumer

Factors of energy losses between trophic levels

Incomplete consumption
Inefficient digestion
Inefficient energy conversion & storage
Used in metabolic processes
Heat dissipation

Majority of energy is lost as heat

Primary production

The rate at which producers accumulate carbon compounds in their biomass
- Measured in units of mass per unit area per unit time (gm^-2yr^-1)

Gross primary Productivity (GPP)

Rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time.
- The amount of energy captured as biomass by primary producers
ie. rate of photosynthesis

Net primary production

The remaining energy after losses to cellular respiration(R)
- Represents the energy available to consumers at higher trophic levels
NPP = GPP - R

Secondary production

The rate at which consumers accumulate carbon compounds as part of their biomass
- Heterotrophs also experience biomass loss during cell respiration

Cell respiration (R)

The process where cell derives energy from glucose
glucose+oxygen --> CO2 + H2O + ATP

Gross secondary production (GSP_

The total biomass assimilated by heterotrophs in an ecosystem
- Determined by measuring the mass of food eaten by consumers subtracted mass lost from poopp
GSP = food eaten - fecal loss

Net secondary productivity

Biomass that remains after accounting for respiration losses
- Represents energy available to sustain higher trophic levels

Carbon sinks

absorb more carbon than they release

Carbon sources

Locations or processes that release more carbon into the atmosphere than they absorb

How are photosynthesis and respiration linked together?

Photosynthesis uses CO2 released by cellular respiration, aerobic respiration relies on oxygen released by photosynthesis

Biodiversity

The variet of living organisms including plants, animals, microorganisms

Genetic biodiversity

Variations in species are caused by genetics

Stability

The ability to maintain the ecosystem’s structure and function over time, despite changes or disturbances

If disturbance affects structure or function, then what should a stable ecosystem do?

It should be able to restore itself back to its original state

What are some examples of stable ecosystems?

Tropical rainforests, coral reefs, boreal forests, Sonoran desserts

An ecosystem requires ____ and ____ to maintain its stability over time

Resistance and resilience

Resistance

The ability of an ecosystem to remain stable in the face of disturbances

Resilience

The ability of an ecosystem to recover after a disturbance

Factors contributing to the stability of an ecosystem

Supply of energy, recycling of nutrients, biodiversity, climatic factors

Tipping points

The critical threshold of a change that results in a significant and irreversible change in an ecosystems structure, function, composition

Transpiration

The loss of water vapor from plant leaves

Causes of deforestation

Farming, logging, mining, road building, energy development, settlement, population growth

Keystone species

A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

• They help define an entire ecosystem
  

Sustainability

The ability to be maintained at a certain rate or level

Agriculture

The practice of cultivating plants and livestock

Soil erosion

A process that involves the detachment, movement, transportation of soil particles from one location to another

Agrochemicals

Chemicals used in agriculture

Leaching

Occurs when water-soluble minerals in soil are washed away by rain

Carbon footprint

The amount of CO2 released into atmosphere

Eutrophication

Algae overgrowth — A process which water bodies are enriched with excessive nutrients (nitrogen and phosphorus) leading to overgrowth of algae and other aquatic plants

Bioaccumulation

The gradual buildup of chemical substances in tissues of organisms over time

Biomagnification

The tendency of pollutants to concentrate as they move up the food chain

Microplastics

Small plastic pieces or fragments, measure less than 5mm in size

Rewilding

Reintroducing and restoring natural processes and biodiversity to ecosystems that have been degraded/altered by human activities

Ecological succession

Sequences of changes that progressively transforms ecosystems

Primary succession

The formation of an ecosystem in an environment devoid of vegetation and lacking soil

Secondary succession

Ecological change in an area that previously had life but was destroyed

Cyclic succession

Community composition changes rapidly, continuous cycle of change and regeneration, can be seasonal

Climax community

A stable and mature ecological community, remains unchanged for a long period of time

Arrested succession

Disruption/interruption in normal progression of ecological succession

Examples of keystone species

Beavers, elephants, wolves, bees