Unit 1: Trophic Levels & Energy Flow (Ecology)

Study flashcards covering ecology basics, energy flow, trophic levels, and ecological pyramids as described in the lecture notes.

What is ecology?

Ecology is the study of the interactions among living things and between living things and their environment.

List the levels of organization from individual to biosphere.

Individual; Population; Community; Ecosystem; Biome; Biosphere.

Define an ecosystem.

A biological community of interacting organisms and their physical environment.

What are biotic factors?

Living components of an ecosystem, including organisms and relationships such as competition and predator–prey interactions.

What are abiotic factors?

Nonliving chemical and physical factors in an ecosystem, such as sunlight, temperature, water, wind, soil, pH, salinity, and altitude.

What are autotrophs and what is their role in ecosystems?

Autotrophs use inorganic nutrients and an external energy source to produce organic nutrients, providing energy for all other organisms.

Differentiate photoautotrophs and chemoautotrophs with examples.

Photoautotrophs use light energy to make organic nutrients (examples: plants, algae, cyanobacteria). Chemoautotrophs obtain energy from chemical bonds in inorganic molecules (examples: methanogens, nitrogen-fixing bacteria).

Who are heterotrophs?

Consumers that obtain organic nutrients from other sources to gain energy.

What are herbivores (primary consumers) and what do they eat?

Eat plants (leaves, grass, seeds, fruits, etc.); examples include cows, deer, gorillas.

What are carnivores?

Eat other animals; can be secondary consumers if they eat herbivores, or tertiary consumers if they eat other carnivores (examples: sharks, lions, wolves).

What are detritivores?

Ingest detritus (dead organic matter) and digest it internally; examples include earthworms, millipedes, and termites.

What are decomposers and saprotrophs?

Decomposers obtain nutrients by breaking down dead organic matter; saprotrophs (fungi and bacteria) release enzymes to break down matter and absorb nutrients.

What are omnivores?

Eats both plants and other animals; examples include bears, raccoons, humans, pigs, hedgehogs, ants.

What is a food chain?

A linear model of energy flow based on feeding relationships; energy moves from producer to consumer and arrows indicate the direction of transfer.

What is a food web?

An interconnected system of multiple food chains showing all possible feeding relationships in an ecosystem; includes grazing and detrital webs.

What is a grazing food web?

Energy flows from producers to herbivores to carnivores; starts with producers.

What is a detrital food web?

Energy flows from detritus through decomposers and detritivores; starts with dead organic matter.

What is a trophic level?

A step in a food chain or food web; energy flows from lower to higher levels, with less energy at higher levels.

What is the Rule of 10%?

Only 10% of the energy at one trophic level is transferred to the next; the remaining 90% is used for metabolism and lost as heat.

What is the Pyramid of Energy?

A pyramid showing the available energy at each trophic level; energy is greatest at the bottom and flows upward.

What are ecological pyramids and their types?

Pyramids of numbers, biomass, and energy; most pyramids have the greatest values at the bottom; some can be inverted.

What is the Pyramid of Numbers?

Shows the number of organisms at each trophic level; typically more producers than consumers.

What is the Pyramid of Biomass?

Shows the total mass of living matter at each trophic level; usually decreases up the chain and can be inverted in some ecosystems.

Why can energy not be recycled while nutrients can?

Energy flows in one direction and is dissipated as heat; nutrients are recycled within ecosystems.

What role do cyanobacteria play in ecosystems?

Cyanobacteria are producers, among the first to produce oxygen in the ocean and important energy sources in some ecosystems.

What are nitrogen-fixing bacteria?

Bacteria that fix atmospheric nitrogen; in notes, it is stated that they get energy from nitrogen compounds.

What is a specialist vs a generalist?

Specialists eat only one thing primarily; generalists eat a broad range of foods; generalists can have advantages and disadvantages in changing environments.

What are biosphere and biomes?

A biome is a large group of ecosystems that share similar climate and communities; the biosphere is the global zone where life exists on Earth.