Honors Biology KEY

Chemistry of Ecology

Ecology the scientific study of interactions among organisms and between organisms and their physical environment

3.1 What is Ecology

There is interdependence between organisms and the environments in which they live. Organisms respond to their environment and can also change their environments, therefore the biosphere is dynamic.

Ecological Levels of Organization

There are 6 ecological levels of organization presented in circular representations on pages 64-65 of your textbook. Start on the bottom left of page 64 and count #1-6 as you move to the right side of page 65.

What is the difference between an organism and a species? An organism is one single living thing, where as a species is a group of the same organism

What is the difference between a population and a community? The individuals in a population all belong to the same species but the individuals in a community are

members of more than one species

What is the difference between a community and ecosystem?

A community is an assemblage of populations in a given area, an ecosystem is not only the group of

different populations but also their physical environment (abiotic factors).

How are the terms ecosystems and biomes related?

A biome is a group of ecosystems that share similar climates and organisms.

The biosphere consists of all areas on Earth in which life exits, including land (lithosphere), water_(hydrosphere), and atmosphere

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1._Individual Organism/Species

2. Population

3. Community

4. Ecosystem

5. Biome

6. Biosphere

The word environment refers to all conditions or factors surrounding an organism. These factors can be living or nonliving.

Any living part of the environment with which an organism might interact is known as a biotic factor, while the physical (nonliving) parts of ecosystems are called abiotic factors.

Which of the 6 levels of organization include abiotic factors?

Ecosystem, Biome, Biosphere

Fill in theBlanks In the Diagram.

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Individual organism

population

community

ecosystem

biome

biosphere

Chapter 3: The Biosphere3.2 – Energy, Producers and Consumers

At the core of every organism’s interaction with the environment is its need for energy to power life’s processes. You may wonder where energy in living systems comes from and how it is transferred from one organism to another.

Materials and energy move between the living (biotic) and nonliving (abiotic) parts of ecosystems. Materials (atoms, molecules) must be recycled but energy is NOT - therefore a constant supply of energy must enter every ecosystem (usually from the sun).

Organisms must be able to: a) produce or obtain nutrients; b) convert the nutrients into usable forms of chemical energy (making ATP through cellular respiration); and c) use these forms of energy to power their life processes.

For most life on earth, the sun is the ultimate energy source.

There are different types of autotrophy: ____photosynthesis____ and __chemosynthesis____________,

which differ in terms of the energy they harness (solar or chemical) to produce carbohydrates.

Autotroph: capture energy from sunlight or chemicals and convert it into forms that living cells can use

Autotrophs are also called primary producers because they are they store energy in forms that make it available to other organisms that eat them. So, they are the first producers of energy-rich compounds that are later used by other organisms.

Autotrophs are essential for the flow of energy through the biosphere because they are the first producers of energy-rich compounds that are later used by other organisms.

Photosynthesis: capture energy from sunlight or chemicals and convert it into forms that living cells can use; this process adds oxygen to the atmosphere and removes carbon dioxide.Examples of photosynthetic organisms: plants, algae, and cyanobacteria.

Chemosynthesis chemical energy is used to produce carbohydrates; harness chemical energy from inorganic molecules such as hydrogen sulfide . Examples of chemosynthetic organisms: deep in the ocean, or bacteria in volcanoes/hot springs, tidal marshes

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Heterotroph: must acquire energy from other organisms—by ingesting them in one way or another

Heterotrophs are also called _consumers because they rely on other organisms for energy and nutrients and cannot produce it for themselves. There are a variety of ways that consumers can acquire energy and nutrients.

There are 6 categories of consumers listed in your book on page 71. Use the diagrams and descriptions provided to fill in the information below. Write in your own words!

Examples include: Snakes, dogs, cats, lions

Examples include: vultures, hyena

Examples include: bacteria, fungi (mushroom)

Examples include: Cows, caterpillars, deer, rabbits

Examples include: Humans, bears, pigs

Examples include: Mites, shrimp, earthworms, crabs

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1. Carnivores – kill and eat other animals

2. Scavengers – are animals that consume the carcasses of other animals that have been killed by predators or have died of other causes.

3.Decomposers_”feed” by chemically breaking down organic matter – the decay caused by decomposers is part of the process that PRODUCES detritus (small pieces of dead/decaying plant and animal remains)_

4.Herbivores_obtain energy and nutients by eating plant leaves, roots, seeds, fruits

5.Omnivores – diets include a variety of different foods- including both plant and animals.

6.Detrivores_feed on detritus particles, often chewing or grinding them into smaller pieces.

3.3 – Energy Flow in Ecosystems

In every ecosystem, primary producers and consumers are linked through feeding relationships. Though there is a wide variety of feeding relationships in various ecosystems, energy flows through an ecosystem in a one-way stream, from primary producers to various consumers.

The ultimate source of energy is the sun and energy flows through ecosystems in a one-way stream from producers to various levels of consumers.

A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Food chains vary in length, or in the number of steps depending on the specific ecosystem.

Feeding relationships are complicated and don’t occur as simple isolatedfood chains. Food webs consist of interconnected food chains, and show networks of feeding interactions.

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What is the difference between a food chain and a food web? A food chain shows only one possible feeding relationship, whereas the food web is more complicated. Because many animals eat more than one kind of food, a single, simple food chain is usually insufficient to describe the complicated feeding relationships typically found in an ecosystem. Therefore studying a food web may be more appropriate when trying to understand the flow of energy and materials in a complex ecosystem.

What is the importance of decomposers and detritivores in a food web? RECYCLE! Decomposers break down dead and decaying matter into detritus, the detritivores feed on that. This matter is recycled back into the environment so that the compounds can be reused!

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*We will complete this flow chart together in class*

Trophic Level: each step in a food chain or a food web

Which trophic level always includes primary producers? First Trophic Level

Which type of organism occupies all the other trophic levels? Heterotrophs (herbivores, carnivores, omnivores)

Ecological Pyramids show the relative amounts of energy or biomass (in terms of living matter or numbers of individuals) contained in each trophic level in a given food chain or food web.

What are the three types of ecological pyramids? Pyramid of energy/biomass/numbers

A Pyramid of Energy shows: the relative amount of energy available at each trophic level of a food chain or food web

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Energy is lost due to :a) * Some use for daily activities (Cell Work)

b) * Some released (lost) as heat to the environment

c) * Some is never consumed or undigested waste (used by decomposers)

On average, about 10% percent of the energy available within one trophic level is transferred to the next trophic level.

THINK!! The diagram shows that a large amount of energy is released from each step as “heat”. Which essential metabolic process creates this heat? Cellular Respiration

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Gross vs. Net Productivity

* Gross Primary Productivity : all the energy (glucose) the plant ever produced from sunlight

* Net Primary Productivity : gross primary productivity minus all energy used in cellular respiration and eventually heat. This is what is available to the next trophic level. Also known as biomass (all organic compounds minus water)

A Pyramid of Biomass shows: the relative amount of living organic matter available at each trophic level in an ecosystem .

Biomass: The total amount of living tissue within a given trophic level

Biomass is usually measured in grams if organic matter per unit area.

The amount of biomass a given trophic level can support is determined, in part, by the amount of energy available.

A Pyramid of Numbers shows: the relative number of individual organisms at each trophic level in an ecosystem .

In most ecosystems, the shape of the pyramid of numbers is similar to the shape of the pyramid of biomass for the same ecosystem. In this shape, the numbers of individuals on each level decrease from the level below it.

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Describe an example in which a pyramid of numbers may be turned upside whereas the corresponding pyramid of biomass would have the normal orientation. One tree fed upon by thousands of insects. Or countless mosquitos can feed off a few deer.

Chapter 4: Ecosystems and Communities4.2 – Niches and Community Interactions

Niche: is the range of physical and biological conditions in which a species lives and the way the species obtains what it needs to survive and reproduce

Niche refers to the range of physical and biological conditions in which a species lives and way species obtain what they need to survive and reproduce. Niche describes where an organism lives, what it does, and how it interacts with biotic and abiotic factors in the environment. Niche refers to an organisms total way of life.

Define the following terms:

Tolerance the ability to survive and reproduce under a range of environmental circumstances,

Habitat the general place where an organism lives. “address”

Resource: any necessity of life – water, nutrients, light, food, space

How is a niche like a profession? In ecological terms, describe your niche and be sure to include resources, physical, and biological aspects of your niche. A niche is an organism’s “role” in the environment, including all its biotic and abiotic interactions – how its presence affects that ecosystem. As a human you drink water, breathe air, live in a house which is built on soil/rocks, you pull weeds form your garden, mow your lawn, apply pesticides/fertilizers on your grass to prevent certain plants/insects, go to school, drive a car which is made of metal and produces emissions, you make waste, you are a consumer (omnivore) which eats plants and animals, you interact with various other organisms like mosquitos, squirrels, deer, etc……get it? Watch this niche video (about 15 mins) for some examples of other organisms’ niches: http://video.nhptv.org/video/1491210214/

CompetitionCompetition occurs when organisms attempt to use the same limited ecological resource in the same place at the same time.

What is the difference between intraspecific competition and interspecific competition?*INTRASPECIFIC – competition between members of the SAME species.

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INTERSPECIFIC – competition between members of DIFFERENT species Competitive Exclusion Principle: that no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time. If two species attempt to occupy the same niche, one species will be better at competing for limited resources and will eventually exclude the other species.

What is the result if two species do attempt to occupy the same niche? One species will be better for competing for limited resources and will eventually exclude the other species. Therefore, usually niches don’t overlap significantly in natural communities .

Instead of competing for similar resources, species usually divide them. Give an example of this: 3 species of NA Warblers – same trees, feed on insects – they divide high/med/low parts of tree, therefore each species has its own niche which reduces competition

Therefore competition helps determine the number and kinds of species in a community and the niche each species occupies.

Predator-Prey RelationshipsPredation:An interaction in which one animal (the predator) captures and feeds on another animal (the prey).

Predators can affect the size of prey populations in a community and determine the places prey can live and feed.

THINK! Give an example of a predator-prey relationship that you may see in your own local ecosystem.fox – rabbit

Using the above diagram, why do the oscillations of the lynx population follow those of the hare population? *When producer levels are high (ex – mild winters) prey numbers rise due to abundance of food. When prey numbers rise, predator levels rise because they have more food. As predators eat prey, prey levels drop and there is a following drop in predator numbers. The reduction in predators is followed

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by a rise in prey numbers. Thus predator /prey interactions cycle and limit each other ( density dependent – we will look at this in the next portion of the unit) Here’s a nice simulation of the predator-prey (graph) interactions: http://www.phschool.com/atschool/phbio/active_art/predator_prey_simulation/index.html

Herbivore-Plant RelationshipsHerbivory:An interaction in which one animal (the herbivore) feeds on

producers (such as plants)

Herbivores can affect both the size and distribution of plant populations in a

community and determine the places that certain plants can survive and

grow

THINK! Give an example of herbivory you may see in your own local ecosystem. Deer – plant

SYMBIOSESSymbiosis: any relationship in which 2 species live closely together

Three main types of symbiotic relationships in nature:

1) Mutualism: a relationship between 2 organisms in which BOTH benefit. Who benefits? Both organisms Who is harmed? None Example(s): Sea anemone and Clownfish – clowfish live among the sea anemones tentacles and protect the sea anemone by chasing away attackers. The sea anemone in turn protects the clownfish from their predators.

2) Parasitism: One organism feeds/lives on or in another organism and harms it Who benefits? Parasite Who is harmed? Host Example(s): Fleas, ticks, lice, leeches, tapeworms

3) Commensalism:A relationship in which one organism benefits and the other is neither helped nor harmed. Who benefits? One organism Who is harmed? None Example(s): Barnacles attached to whales skin – The barnacles perform no known servce to the whale, nor do they harm it. Yet the barnacles benefit from the constant movement of water (full of food particles) past the swimming whale!

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