Chapter 3Biology One

The Biosphere

6/5/2016

I. EcologyA. What is the biosphere?

*1. all life on Earth & all parts of Earth in which life exists

a. incl: land, water, atmosphere1) extends 8 km above land to 11 km below ocean surface

b. incl: every organism

B. What is ecology? Greek: oikos = house; logos = study

*1. scientific study of interactions among organisms, & between organisms and their physical environment

2. organisms are interdependent w/ their environmentsa. respond to & change each otherb. creates a dynamic biosphere

C. Levels of Organization1. Organism – individual living thing2. Species – group of similar organisms that can interbreed &

produce fertile offspring3. Population – group of individuals of the same species living in the same area4. Community – different populations living together in a

defined area5. Ecosystem – communities plus their physical

environments6. Biome – group of ecosystems sharing similar climates &

typical organisms7. Biosphere – entire planet, w/ all organisms & biomes

D. Biotic & Abiotic Factors1. Biotic = biological influences on an organism

a. other organismsb. incl: animals, plants, fungi, bacteria

2. Abiotic = physical components of an ecosystema. nonliving factorsb. ex: sunlight, temperature, precipitation, soil

type, wind, water3. Abiotic & biotic factors together form

dynamic environments

II. Energy, Producers & ConsumersA. Primary Producers

*1. the 1st producers of energy-rich compounds later used by other organisms2. a.k.a. autotrophs Greek: auto = by itself; trophikos = to feed

3. algae, plants, some bacteria4. use solar or chemical energy to produce

complex organic compounds a. use these to feed themselves & store energy

in forms that other organisms can also use

5. Some use photosynthesis a. capturing light energy & using its power to

convert CO2 & water into sugars & starchesb. removes CO2 from environment, and adds O2 back

to the atmosphere6. Others use chemosynthesis

a. chemical energy, such as CO2, H2S & O2, is used to produce carbohydrates

b. occurs in areas sun doesn’t reach1) ex: deep ocean waters, hot springs2) sulfur compounds are a byproduct

B. Consumers*1. organisms that rely on other organisms for energy &

nutrients2. a.k.a. heterotrophs3. animals, fungi, protozoa, many bacteria4. classifications

a. carnivores – kill and eat animalsb. herbivores – eat plant matterc. omnivores – eat a variety of foodsd. detritivores – eat decomposers & detrituse. decomposers – chemically break down organic

matterf. scavengers – eat already dead animals

III. Energy Flow in EcosystemsA. Food Chains

*1. series of steps in which organisms transfer energy by eating & being eaten

2. 1-way, from primary producers to various consumersa. vary in # of steps in the chainb. consumers rarely eat just 1 type of food

B. Food Webs * 1. networks of complex interactions formed by the

feeding relationships among various organisms in an ecosystem

Food Web

C. Trophic Levels & Ecological Pyramids1. Trophic level = each step of a food chain or food web

a. 1st level = primary producerb. all other levels = various consumers

2. Ecological pyramid = show relative amount of energy or matter contained w/in each trophic levela. 3 types: energy, biomass, numbersb. Energy = show relative amount of energy

available at each trophic level1) on avg., about 10% of available energy is

transferred on to next level

c. Biomass - show relative amount of living organic matter available at each trophic level1) measured in grams of organic matter per unit

aread. Numbers - show relative number of individual

organisms at each trophic level

IV. Cycles of MatterA. Recycling in the biosphere

1. matter isn’t created or destroyed – it’s recycled w/in & between ecosystemsa. it passes through biogeochemical cycles

1) biological processes – activities performed by organismsa) ex: breathing, eliminating waste

2) geological processes a) ex: volcanic eruption, erosion

3) chemical & physical processes a) ex: cloud formation, water flow

4) human activitya) ex: mining, farming, burning fossil fuels

B. The Water Cycle1. water moves between oceans, the

atmosphere & landa. may be within organisms or outside themb. incl: evaporation, precipitation, runoff,

absorption, transpiration, water flow, etc.

C. Nutrient Cycles1. nutrients = substances needed to sustain life functions & build tissues2. 3 main pathways

a. Carbon Cycle1) carbon = main element in organic

compounds, living tissues & ecosystems2) found as CO2 in air & oceans, in

organisms, rocks, soil, coal, petroleum, as calcium carbonate, & in carbohydrates made by producers

b. Nitrogen Cycle1) organisms require nitrogen to make amino acids,

proteins & nucleic acids2) N2 gas = 78% of Earth’s atmosphere

a) nitrogen is also found in soil, wastes, dead & decaying organic matter & in large bodies of water

3) some bacteria convert nitrogen gas into ammonia, nitrates or nitrites by nitrogen fixationa) producers use those to form proteins, nucleic acids

4) others convert nitrates into nitrogen gas by denitrification

c. Phosphorous Cycle1) important for forming vital molecules

a) ex: DNA, RNA2) not abundant in biosphere

a) doesn’t really enter atmosphereb) inorganic phosphate is found in rocks, soil

minerals & as dissolved phosphate in oceansc) released by erosion, absorbed by plant roots or

marine organisms

D. Nutrient Limitation1. primary productivity in an ecosystem is

limited by availability of nutrientsa. limiting nutrient = that nutrient causing

productivity to be limited2. in the soil, fertilizers help provide adequate nutrient supplies3. water has fewer nutrients than land

a. marine water is usually low in nitrogenb. fresh water is usually low in phosphorusc. ground water runoff can disrupt nutrient

& producer-consumer balances