1. Ecology Unit:
Biology Chapter 13.2 – 13.6

2. 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

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

4. 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)

5. 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

6. 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

7. 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)

8. 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)

9. Trophic Levels

10. Cycling of Matter
Hydrologic Cycle

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

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

13. 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

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

17. 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

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

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

20. THE END