apes unit 2 (kortum)

Ecosystem

All living organisms and nonliving components interacting in an area (plants, animals, soil, water, climate).

Community

All the different species living and interacting in the same area.

Population

A group of the same species living in one area at the same time.

Autotroph (Producer)

Organism that makes its own food using sunlight or chemicals.
Examples: plants, algae, phytoplankton.

Heterotroph (Consumer)

Organism that gets energy by eating other organisms.

Producers

plants, algae (make food through photosynthesis)

Primary consumers

herbivores that eat plants

Secondary consumers

carnivores that eat herbivores

Tertiary consumers

carnivores that eat other carnivores

Quaternary consumers

apex predators

Herbivore

eats only plants

Carnivore

Eats only animals

Omnivore

Eats plants and animals

Decomposer

Breaks down dead organisms chemically

Detritivore

Eats dead organic matter physically

10% Rule

Only ~10% of energy transfers from one trophic level to the next.

Energy is lost as heat through respiration.

Gross Primary Productivity (GPP)

Total energy captured by producers through photosynthesis. NPP = GPP − Respiration

Net Primary Productivity (NPP)

Energy available to consumers after producers use some energy for respiration. NPP = GPP − Respiration

Photosynthesis

CO₂ + H₂O + sunlight → glucose + O₂

Occurs in plants and algae.

Cellular Respiration

glucose + O₂ → CO₂ + H₂O + energy

Occurs in all organisms.

Fast Carbon Cycle

plants absorb carbon dioxide→ carbon is quickly returned to the atmosphere through respiration and decomposition →

Slow Carbon Cycle

carbon from dead organisms is buried underground and stored for millions of years as fossil fuels or carbonate rocks → fossil fuels are burned through combustion→ carbon dioxide is released back into the atmosphere, returning carbon from the long to the short cycle

Nitrogen Cycle: Nitrogen Fixation

N₂ → NH₃ / NH₄⁺

Driven by

• nitrogen-fixing bacteria

• lightning

• industrial fertilizer production

Occurs in

• soil

• root nodules of legumes

Carbon Sinks

Places that store carbon.

Human Impacts:

• Burning fossil fuels

• Deforestation

• Cement production

Result: increased atmospheric CO₂ → climate change

Nitrogen Cycle: Nitrification

NH₄⁺ → NO₂⁻ → NO₃⁻

Done by nitrifying bacteria in soil.

Produces nitrate, which plants can absorb.

Assimilation

Plants absorb NO₃⁻ or NH₄⁺ and incorporate nitrogen into tissues.

Animals get nitrogen by eating plants or other animals.

Nitrogen Cycle: Ammonification

Decomposers convert organic nitrogen → NH₄⁺.

Occurs during decomposition.

Nitrogen Cycle: Denitrification

NO₃⁻ → N₂ gas

Performed by denitrifying bacteria in anaerobic soils or wetlands.

Returns nitrogen to the atmosphere.

Phosphorus Cycle

Key facts

• Main source is weathering of rocks

Steps

Rock weathering releases phosphate → Plants absorb phosphate → Animals eat plants → Decomposition returns phosphorus to soil →Some becomes sediment and rock again

Human impact

• fertilizer runoff

• causes eutrophication

Sulfur Cycle (Basics)

weathering of rocks releases sulfur into soil and water → sulfur int the atmosphere reacts with oxygen and water to form sulfates which fall back to earth through rain or dry fallout → plants and microorganisms absorb inorganic sulfates from the soil or water for bio molecules → animals consumer plants and when they dies the waste gets decomposed which converts sulfur back into sulfate

Water Cycle

evaporation → transpiration → condensation → precipitation → infiltration → percolation → runoff → aquifers

Resistance

Ability of an ecosystem to remain unchanged after disturbance

Resilience

Ability to recover after disturbance.

Genetic diversity

variation of genes within a species

Species diversity

number of species in an area

Ecosystem diversity

variety of ecosystems

Species richness

Number of species in an area.

Species evenness

How evenly individuals are distributed among species.

Genotype

Genetic makeup (DNA).

Phenotype

Physical traits expressed from genes.

Natural Selection

Environment favors traits that increase survival and reproduction.

Artificial Selection

Humans choose traits to breed.

Fitness

Ability to survive and reproduce.

Adaptation

Inherited trait that improves survival.

Evolution

Change in genetic traits of a population over generations.

Mutation

Random DNA change creating new traits.

Genetic Drift

Random change in gene frequency in small populations.

Bottleneck Effect

Large population suddenly reduced → genetic diversity drops.

Example
Natural disasters.

Founder Effect

Small group starts a new population → limited gene pool.

Example
Colonization of islands.

Allopatric Speciation

Species separated by geographic barrier.

Sympatric Speciation

Species evolve in same geographic area.

Fundamental Niche

Full range of conditions a species could live in.

Realized Niche

Actual conditions where species lives due to competition and predators.

Niche Specialist

• narrow niche

• specific habitat or diet

• more vulnerable to extinction

Niche Generalist

• broad niche

• adaptable diet/habitat

GMO

Organism whose DNA has been altered using genetic engineering.

Pros

• higher crop yields

• less pesticide use

• improved nutrition

Cons

• possible ecosystem impacts

• gene transfer to wild species