Ecology Unit: Biology Chapter 13.2 – 13.6

13.2 Biotic & Abiotic Factors An ecosystem contains living (biotic) and nonliving (abiotic) components Biotic: plants, animals, fungi, bacteria Abiotic: water, atmospheric gases (O2, CO2, etc.), soil, sunlight

Biodiversity refers to number of different biotic components of ecosystem Keystone species essential to ecosystem…main contributory species

13.3: Energy in Ecosystem Producers: (autotrophs)—get energy from abiotic sources (light or chemical) Consumers: (heterotrophs)—get their energy from other sources (autotrophs & other consumers)

Nearly all producers use sun as source of energy Extremophiles found in hostile conditions like hydrothermal vents chemicals (hydrogen or iron sulfide, hydrogen, methane) as their energy source via chemosynthesis rather than photosynthesis

13.4: Food Chains & Food Webs Sequence that connects producer & single chain of consumers Food Web Complex network of feeding relationships & flow of energy within ecosystem

Energy enters ecosystem via producer level & consumers exist at different levels: Herbivores: rabbits, cattle, sheep, horses, etc. (vegetarians) Carnivores: eat consumers (hawks, snakes, lions, etc.) Omnivores: eat producers and consumers (humans, rats, bears, raccoons) Detritivores: eat dead organic matter (millipedes, dung beetles, earthworms, fiddler crabs and sea cucumbers) Decomposers: break down organic matter into simple compounds & return it to soil (bacteria, worms, fungi)

Specialists: consumers that eat one specific organism (e. g Specialists: consumers that eat one specific organism (e.g. Koala, Panda, Snail Kite) Generalists: consumers that has variety in diet (e.g. wolf, lion, snake)

Trophic Levels

Cycling of Matter Hydrologic Cycle

Oxygen Cycle: Plants release O2 as a waste product Animals take O2 in during respiration CO2 released as a waste product of respiration

Carbon Cycle: Exists in abiotic & biotic forms…found in all living things Carbon Sinks (storage): Oceans Land Atmosphere

Nitrogen Cycle: 78% of atmosphere is N2 gas but not usable to plants, must be “fixed” first Nitrogen fixation: conversion of N2 to NH3 (ammonia) or ammonium (NH4+) by bacteria mainly in soil & nodes on plants Nitrates good for plants

Phosphorous Cycle: Only biogeochemical cycle that does NOT include atmosphere Weathering of rocks begins cycle Moves through producers & consumers Returns to soil by decomposers

13.6: Pyramid Models Biomass Pyramid (total dry mass of organisms in a given area) is greatest at producer level & decreases as one moves up the energy pyramid

Energy Pyramid: 90% of energy lost, only 10% of energy is transferred – 10% Rule

Pyramid of Numbers: Shows comparison of #s of individual organisms that make up each trophic level

THE END