Tropism- response of a plant to an environmental stimulus. 1.Phototropism - is the tendency of a plant to grow toward a source of light. 2.Gravitropism - response to gravity. This assures that roots grow down and stems grow up. m1USHlQY

Tropism Thigmotropism-Response to touch. May be used for venus fly trap, to capture insects, or allow a plant to grow on a surface for support. Tendril U3eZsYkhttps:// U3eZsYk R6eQEhttps:// R6eQE

UNIT 4 – INTRODUCTION TO ECOLOGY (pp. 63, 64, )

A. Introduction Ecology is the study of interactions between organisms and their environment Includes biotic, or living factors And abiotic or non - living factors Biotic factors and abiotic factors determine the health of an ecosystem and its inhabitants

B. Levels of Organization a. Species b. Population c. Community d. Ecosystem e. Biome

II. ENERGY IN AN ECOSYSTEM (pp ) The ultimate source of energy for most life on earth is the sun. A. Autotrophs – –Self – feeders –also known as producers. –Most producers capture energy from the sun in a process called photosynthesis.

B. Heterotrophs Have to obtain food Also known as consumers. There are several categories of consumers: 1. Herbivores – Eat producers (plants) 2. Carnivores – Eat other consumers (animals) 3. Omnivores – Eat Producers and Consumers 4. Decomposers – Break down organic matter. Most are found in Kingdom Eubacteria or Fungi.

C. Energy in a Cell All producers and consumers must convert chemical (potential) energy present in glucose into usable energy. This is known as metabolism. The end-product is known as ATP. Most ATP is produced through the process of cellular respiration. The equation for cellular respiration is C 6H12O6 + O2 → CO2 + H2O + ATP

III.ENERGYFLOW–A COMPARISON OF PHOTOSYNTHESIS CELLULARRESPIRATION (p. 232) Process PHOTOSYNTHESISCELLULAR RESPIRATION Function Use energy from sun to make glucose Release energy from glucose to make ATP Cell Location ChloroplastsMitochondria Occurs In AutotrophsHeterotrophs AND Autotrophs Reactants CO 2 + H 2 O + energyC 6 H 12 O 6 + O 2 Products C 6 H 12 O 6 + O 2 CO 2 + H 2 O + energy Overall Reaction CO 2 + H 2 O + energy → C 6 H 12 O 6 + O 2 C 6 H 12 O 6 + O 2 → CO 2 + H 2 O + energy

IV ENERGY FLOW – A COMPARISON OF PHOTOSYNTHESIS & CELLULAR RESPIRATION (p. 232)

IV. Energy Flow in an Ecosystem Energy flows in one direction CANNOT be recycled Energy is captured by producers and converted to glucose in photosynthesis, which is then used by the plants or eaten by consumers to make ATP.

A. Trophic Levels Step in the pathway of energy The first trophic level is always a producer. The 2 nd trophic level is known as the primary (1 st ) consumer and may be an herbivore or omnivore. The last step is always a decomposer. Energy (sun) → Producer →1 Consumer (herbivore or omnivore) → 2 Consumer (carnivore or omnivore) → Decomposer

T R O P H I C LEVELSLEVELS

B. Tracing Energy Flow 1. Food Chains illustrates how energy is transferred by showing feeding relationships. The arrows show the direction of energy transfer – means “is eaten by” consist of only 3 or 4 trophic levels

Food Chains  Which organism acts as secondary consumer?  According to this food chain, which organism could be described as an herbivore?  Which organism is the producer?  What are two terms that could be used to describe the hawk?

2. Food Webs are more complex than a food chain Most organisms eat & and are eaten by a variety of organisms interconnected pathways are shown in a food web

Food Web How many different producers are there? Is the grasshopper a producer, primary, or secondary consumer? Is the grasshopper an herbivore, carnivore, or omnivore? What organism(s) acts as the decomposer? Give an example of an organism in this food web that acts as secondary and tertiary consumer. If all the squirrels in the community perished, would the hawk be able to survive? Explain. If the grass was destroyed, which organism would be most directly affected? Explain.

3. Ecological Pyramids 10% of the energy stored in an organism is passed to the next trophic level. 90% of the energy is either used by the organism to maintain homeostasis or lost as heat to the environment Used to represent amount of energy or matter at each trophic level

3 Types of Ecological Pyramids

V. ECOSYSTEM INTERACTIONS (pp ) A. The Niche –The role an organism plays in its __________ –comprised of _______ and ______ factors –example: the type of food it eats how it obtains its food the way it is food for other organisms how & when it reproduces its physical living requirements to survive community bioticabiotic

B. Interactions Within a Community 1. Competition –organisms are attempting to use the same _____________ at the same time 2. Predation –_________ killing and eating _______ 3. Symbiosis –A relationship in which two organisms _____________________________ resources predator prey live very closely together

3. Symbiosis 1. Mutualism- Both organisms ________ example, clown fish (Nemo) & sea anemone 2. Commensalism one organism benefits, the other organism _______________________ example: barnacles on whales 3. Parasitism one benefits and the other is ________ example: ____________________________ benefit in not helped nor harmed harmed tapeworms, hookworms, ticks, lice

VII. POPULATIONS WITHIN AN ECOSYSTEM (pp )  ___________- conditions that have an impact on population size A.Density-Dependent Limiting Factors –depend on population size –example: ___________ and availability of _________, _________, __________ limiting factors competition food, water, and sunlight

VII. POPULATIONS WITHIN AN ECOSYSTEM B. Density-Independent Limiting Factors –affect all populations the same way, regardless of size –Examples: ____________, _____________ and human activities: ____________________________________ C. Climax Community –a ______ community with very little population growth or decline –_______________, a certain number of organisms that can exist _____________ –carrying capacity is exceeded, resources become a ____________, and population numbers ________ unusual weathernatural disasters cutting down trees, damming rivers, etc stable carrying capacity successfully limiting factor decline

VII. Ecological Succession Succession- a series of changes in a community in which new populations of organisms gradually replace existing ones

Primary succession- colonization of new sites by communities of organisms – takes place on bare rock

Primary succession- New bare rock comes from 2 sources: –1. volcanic lava flow cools and forms rock

Primary succession- New bare rock comes from 2 sources: –2. Glaciers retreat and expose rock

Pioneer organisms- the first organisms to colonize a new site –Ex: lichens are the first to colonize lava rocks

Primary Succession- Rock

Climax community- a stable, mature community that undergoes little or no succession

Climax community- Is also called a Biome

Primary succession-

Secondary succession- sequence of community changes that takes place when a community is disrupted by natural disaster or human actions – takes place on existing soil

Secondary succession- Ex: – A fire levels portions of a forest

Secondary succession- Ex: –A farmer plows his field

Secondary succession-

Pond Succession

VIII. NUTRIENTS IN AN ECOSYSTEM (pp ) only available to an ecosystem in specific quantities and must be _______ Nutrients may become a ____________ when depleted. require nutrients to ____________________________________ recycled limiting factor build macromolecules, cells, tissues, etc.

A. Carbon Cycle make __________, ______, ________, and _________________ taken up by ________ and ________ for _____________ _______ is a waste product of cellular respiration Erosion, burning of ____________, and ______________ recycle carbon carbohydrates, lipids proteins nucleic acids plants algae photosynthesis CO2 fossil fuels decomposition

A. Carbon Cycle

B. Nitrogen Cycle require nitrogen to build ____________ and _____________ _____________ is mostly nitrogen only _________ can convert nitrogen from the atmosphere to a useable form, known as ______________ absorbed by _______ and used to make ________ & _______________ other organisms ______________________ can re-use the nitrogen to build their own _______ and ______________ ______________ return the nitrogen to the soil proteins nucleic acids atmosphere bacteria nitrogen fixation plants proteins nucleic acids eat plants & algae proteins nucleic acids decomposers

B. Nitrogen Cycle

C. Water Cycle Precipitation Evaporation Transpiration Condensation