CP Biology Name 2015-2016

UNIT 2A: Introduction to Ecology

Science is a body of knowledge and skills acquired through systematic experimentation and observation to describe natural

phenomena; or, more simply, it is a “way of knowing”. The process of science helps biologists investigate how nature works at all

levels, from the molecules in cells to the biosphere.

3.1 What is Ecology?

Biosphere: all life on earth and all parts of earth in which life exists including land, water and air or atmosphere.

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

Interactions within the biosphere produce a web of interde-pendence between organisms and the environments in which they live. Organisms respond to their environments and can also change their environments; therefore, biosphere is dy-namic and ever-changing.

How is economics linked with ecology?

The existence of life on Earth depends on interactions among organisms and between organisms and their environment. There is a great diversity

among living organisms yet there are similar characteristics that all organisms share.

Where is the biosphere located AND what does it include?__ It extends from 8km above the Earth’s surface to as far as 11km below the surface of the oceans.____________

How is economics linked with ecology? Humans live within the biosphere and depend on ecological processes to provide such essentials as food and drinkable water that can be bought and sold or traded.______________

Levels of Organization in the biosphere : (use #s to label from USG)

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*Practice Task:In the space below, fill in the blanks with the

appropriate levels of organization using the word bank below.

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Word Bank

Biome Population EcosystemCommunity Biosphere Organism

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Environment: all conditions or factors surrounding an organism

**Environmental conditions include both biotic and abiotic factors**

Biotic Factors _____ Biological (living) influences on an organism____________________________________________________________Pick any organism and name 4 biotic factors relating to it:

Organism: __deer____________1. ___grass___________________________2. ___wolves__________________________3. ___trees__________________________4. ___squirrel________________________

Abiotic Factors _____ Physical components of an ecosystem______________________________________________________________Using the same organism you picked earlier, name 4 abiotic factors relating to it

1. ___water___________________________2. ____climate / weather______________3. ____rocks__________________________4. ____oxygen_________________________

Abiotic and Biotic factors are closely linked. Many physical (abiotic) factors can be strongly influenced by the activities of organisms. The dynamic mix of biotic and abiotic factors shapes every environment.

Is a mucky shoreline around a pond strictly part of the physical

(abiotic) environment? Explain.

_____No, there are living organisms within the muck/mud (i.e.,

bacteria, algae, snails, etc.)_______________________

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3.2 Energy, Producers, and Consumers

Energy is needed to power life's processes (including growth, reproduction, metabolism, etc.). No organism can "create" energy. Organisms can only use energy from other sources. You may have wondered where this energy comes from and how it is transferred from one organism to another.

For most life on Earth, sunlight is the ultimate energy source. However, for some organisms, chemical energy stored in inorganic chemical compounds serves as the ultimate energy source for life processes.

The following are the only organisms that can capture energy from sunlight or chemicals and convert it into forms that living cells can use, therefore they are essential to the flow of energy through the biosphere. They store energy in forms that make it available to other organisms that eat them.

Autotrophs: organism that is capable of capturing energy from sunlight or chemicals and use to produce its own food from inorganic compounds;

Also Known As: Producers

The next process is how the best-known and most common primary producers harness solar energy

Photosynthesis : captures light energy and uses it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches

What would happen to the amount of oxygen in our atmosphere without the presence of photosynthetic producers?___ the amount of oxygen would decrease (it is a byproduct of photosynthesis) to such a low level that heterotrophs could not undergo cellular respiration!._______________

Name three examples of organisms which are autotrophs (primary producers):

1. __plants_____________________

2. __some protists – like algae

3. __cyanobacteria (formerly, blue-green algae)

Photosynthesis

Chemosynthesis: Chemosynthetic autotrophs do not need sunlight. Often they may be found in extreme environments such as tidal marshes along the coast, or around hot springs or volcanic vents on the ocean floor. Here they utilize the energy stored in chemical bonds of inorganic molecules such as hydrogen sulfide to make energy-rich carbohydrates.

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Consumers are organisms that cannot directly harness energy from the environment as autotrophs do.

Heterotrophs: organism that obtains its energy by consuming other organisms

Also Known As: Consumers

Name three examples of organisms which are heterotrophs (consumers).

1. __all animals________________

2. __all fungi__________________

3. ___some bacteria, some protists

Consumers are classified by the specific ways in which they acquire energy and nutrients from other organisms.

The type of "food" eaten may vary widely from one type of consumer to another.

Realize, however, that organisms in nature often do not stay inside the tidy categories in which ecologists place them.

For example, some animals often described as carnivores will scavenge if they get a chance.

Herbivores: organisms that obtain energy by eating plant leaves, roots, seeds, and or fruits

Carnivores: organisms that obtain energy by eating animals

Omnivores: organisms that obtain energy by eating both plants and animals

Decomposers: organisms that break down and obtain energy from dead organic matter

Detritivores: organisms that feed on detritus which are the small pieces of dead and decaying plant and animal remains

Scavengers: animals that consume the carcasses of other animals

Examples of:Herbivores: _deer, cows, squirrels____________________________________________________________________

Carnivores: __lions, snakes, dogs____________

___________________________________________________

Omnivores: _humans, bears, pigs____________________

___________________________________________________

Decomposers: _bacteria and fungi___________________

___________________________________________________

Detritivores: __earthworms, snails, shrimp, mites, crabs

___________________________________________________

Scavengers: _vulture, hyena________________________

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3.3 Food Chains and Food Webs

Energy flows through an ecosystem in a one-way stream, from primary producers to various consumers.

You can think of energy as passing through an ecosystem along a food chain. Some food chains are simple, being composed of only two steps, while others can be longer with as many as 5 or 6 steps!

Food chain: a series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

A common type of primary producer found at the base of many aquatic food chains is a mixture of floating algae called phytoplankton and attached algae.

Partially 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.

Food Web: network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem; a food web can also be defined as a series of interconnected food chains 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

Example of a Food Chain

Construct a 4-step food chain below:

grass __grasshopper___ ___snake______ ___hawk_____

What do you think would happen to the ecosystem above if the

algae were killed off?___Since algae are the primary producers in

this ecosystem, providing the energy necessary for life processes

in this ecosystem, life in this ecosystem would not continue if

algae were killed off _______________________________________

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All of the animals in the food web shown to the right, ultimately depend on krill. If the marine algae population is disturbed, then there may be changes in all of the populations connected in this food web.

Killer whales indirectly depend on krill for survival.

The food web shows that killer whales depend directly on blue whales and leopard seals to obtain energy. Blue whales consume krill for energy; therefore, since killer whales consume blue whales, killer whales indirectly depend on the krill population for energy. Leopard seals consume Adelie penguins which in turn consume krill, so again, killer whales depend on krill for energy, indirectly. In addition, krill are the only herbivores in this web, so they are the only organisms that consume the primary producers of this web.

Primary producers are always at the first trophic level of a food chain or food web.

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

Food chains and food webs cannot go on forever; in other words they cannot have an unlimited number of trophic levels. Why do you think this is true? _ Only a small portion of the energy available at each level of the food web or chain is transferred to the next level (on average, 10 %). Eventually, as we move up the energy pyramid, the amount of energy transferred will not be enough to support the life processes of another trophic level.

Some might make an analogy of decomposers being like earth's "recycling center". Summarize the importance of decomposers and detritivores in food webs.Decomposers break down any dead organisms that have not been consumed into detritus. Detritivores breakdown both decomposers and the detritus that they produce to obtain energy. Without decomposers, nutrients would be locked forever in dead organisms. Instead, these nutrients re-enter the food web through primary producers; they are recycled .

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