ANSWERSKEYSTONE REVIEW PACKET ANCHOR 8: ECOLOGY

LEARNING OBJECTIVES: Describe the ecological levels of organization in the biosphere

o Describe the levels of ecological organization (i.e., organism, population, community, ecosystem, biome, biosphere)

o Describe characteristic biotic and abiotic components of aquatic and terrestrial ecosystems. Describe interactions and relationships in an ecosystem.

o Describe how energy flows through an ecosystem (e.g., food chains, food webs, energy pyramids). o Describe biotic interactions in an ecosystem (e.g., competition, predation, symbiosis). o Describe how matter recycles through an ecosystem (i.e., water cycle, carbon cycle, oxygen cycle, and

nitrogen cycle). o Describe how ecosystems change in response to natural and human disturbances (e.g., climate

changes, introduction of nonnative species, pollution, fires). o Describe the effects of limiting factors on population dynamics and potential species extinction.

Vocabulary:

Concepts To Know:

Abiotic Community Endemic species Food Web SuccessionAquatic Competition Endosymbiosis Habitat Limiting Factor SymbiosisBiogeochemical Cycle Consumer Energy Pyramid Nonnative Species SystemBiome Decomposer Energy Transformation Population TerrestrialBiosphere Ecology Environment Population Dynamics Trophic LevelBiotic Ecosystem Food Chain Producer

Main Idea #1: Levels of Biological Organization

There are many different levels of organization in living things. The diagram to the right shows all of the different levels.

Ecology is the study of how organisms interact with their environment and therefore is concerned with the higher levels on the diagram (Organism Biosphere)

1. Using the headings from the diagram on the previous page, label the missing levels of ecological organization on the diagram below:

Main Idea #2: Abiotic vs Abiotic Factors

Ecosystems have both living components (biotic factors such as the trees, birds, and fish) and nonliving components (abiotic factors such as how much rain or sun an area gets).

Biome

Biosphere

Ecosystem

Community

Population

Organism

2. Looking at the diagram to the right, categorize each labeled item as either biotic or abiotic:

Main Idea #3: Flow of Energy in an Ecosystem

All ecosystems need energy, and the most basic form of energy comes from the sun. Producers (also known as autotrophs or “self-feeders”) are able to make their own food. Producers are eaten by consumers (also known as heterotrophs or “other feeders”). We can track the flow of energy linearly using a food chain or look at a more detailed flow of energy using a food web. An organisms trophic level is its position with in these.

Within an ecosystem, we can track the number of organisms, the amount of energy available and amount of biomass (relative amount of organic matter). In all ecosystems, the amount of these three will decrease as you move up through the trophic levels, therefore they take on the shape of a pyramid. Below are examples of each of these pyramids.

Wind, soil, water

Sun rocks

Trees deer fish

Duck butterfly

3. What is a trophic level? List and describe different trophic levels in ecosystems.

Trophic level is the position of an organism in a food chain or web, can be a producer, consumer (primary, secondary, etc) or decomposer.

4. How do producers and consumers differ in how they obtain energy?

Producers make their own food (ex/plants via photosynthesis), consumers have to eat (consume) their food. Consumers can eat plant material (herbivores), meat (carnivores), or both (omnivores).

5. What happens to energy as it moves through the trophic levels of an ecosystem?

The amount of usable energy decreases as you move through a food chain/web’s trophic levels. Only about 10% of the energy from the previous trophic level moves on to the next.

6. What happens to biomass and numbers of organisms as you move through trophic levels of an ecosystem?

These also decrease, since there is less and less energy available at each higher trophic level, an ecosystem cannot support as many organisms in higher levels.

7. What is the ultimate source of all energy on earth? The SUN

Main Idea #4: Interactions Between Living Things in an Ecosystem

Organisms can interact with each other in many different ways. Symbiosis is the general term for organisms that closely interact with each other.

8. Using information in the chart to the right, list which type of relationship is being described in each situation below:

___MUTUALISM_____ a. Cleaner fish eat parasites and dead cells from other fish, such as grouper. The cleaner fish get food, and the grouper avoid disease

__COMMENSALISM_____ b. Some mites attach to flies for transportation. The mites are able to move from one place to another, and the flies are not affected.

__PARASITISM___ c. Fleas feed on the blood of dogs. The fleas get food, but the dogs experience itching and discomfort.

__PREDATION____ d. A wolf hunts and kills a sheep

_COMPETITION____ e. Plant species grow taller to reach more sunlight

NICHE vs HABITAT –

Habitat = where an organism lives Niche = that organism’s role in it’s habitat (what it eats,

how it interacts with other organisms, when it reproduces, etc)

NO TWO SPECIES CAN OCCUPY THE SAME NICHE AT THE SAME TIME (OR COMPETITION RESULTS) Species can divide up a niche to make smaller niches – see warblers to right.

Main Idea #5: Cycles of Matter

Nutrient CyclesImportant nutrients such as carbon, nitrogen, phosphorus, and water are cycled through living things and the environment through biogeochemical cycles. The following pictures are overviews of the carbon, phosphorus, and nitrogen cycles.

Carbon Cycle Nitrogen Cycle

9. How is the movement of matter in an ecosystem different than the movement of energy?

Matter is recycled, energy does not get recycled

10. What processes add water to the atmosphere? What process removes water from the atmosphere?

Add: Transpiration & evaporation

Removes: Precipitation

11. What process adds carbon to the atmosphere? What process removes it?

Adds: Cellular respiration (all organisms release carbon dioxide gas)

Removes: Photosynthesis (plants/algae consume carbon dioxide gas)

12. What process makes nitrogen available to living things? Who does this process?

Nitrogen fixation converts nitrogen gas to usable compounds for plants. This is done by bacteria living in the soil.

Main Idea #6: Responses to Natural and Human Disturbances

Succession: The orderly process by which an ecosystem changes over time. First species to arrive are called pioneer species, which get replaced systematically over time, eventually ending with a stable climax community. Succession occurs in one of two patterns – primary or secondary.

Primary Succession Secondary SuccessionBegins with a surface that did not previously support life (bare rock)

Begins in an area that previously supported life, but has been removed or been abandoned

No soil present Soil presentLichen (can break down rock) and moss come first Grasses & annuals come firstOccurs more slowly Occurs more quickly

Impact of Invasive Species: Invasive (nonnative) species live outside of their normal range and compete with native (endemic) species. They may be introduced by shipping or as discarded pets. Populations of invasive species grow rapidly because:

They have fewer predators or no predators in their new ecosystem They use more of the ecosystem’s resources or use available resources more effectively They may reduce other endemic populations directly through predation

13. A tornado completely destroys a cornfield on a farm. The farmer decides to not re-plant his crops, and instead sells the farm. Describe what type of succession would follow if no one buys the farm for 20 years.

Secondary succession, because soil was already present and life had previously been supported on the farm.

14. You decide it would be cool to buy a couple of piranhas and add them to your fish tank. After they have killed all of your fish, you decide to throw them into the large lake behind your house. Why would this be a bad idea?

The piranhas would be a non-native, or invasive species to the lake. They would have few or no predators, could & could quickly reproduce and start to impact the native (endemic) fish species already in the lake. This could upset the whole lake ecosystem. Human Impact on the Environment:

A) Agricultural Runoff and Eutrophication

Agricultural runoff – when fertilizers added to crops dissolve in rain and get carried to nearby bodies of water.

Eutrophication - demonstrates how changing nutrient levels affect the organisms in an ecosystem. Eutrophication occurs in stages:

1. Increase of nutrients (usually nitrogen and phosphorus because they are limiting nutrients) in body of water due to runoff.

2. Photosynthesis increases (sometimes called an algal bloom because the algae covers the top of the body of water)

3. As these producers die, the decomposers come in to feed off of them. 4. These decomposers are going through respiration and lower the oxygen available to all organisms that can cause

many to die.

B) Atmospheric and Climate Change

Greenhouse gases: trap heat energy in the atmosphere EX/ water vapor, carbon dioxide, nitrous oxide, methane

Many human activities raise greenhouse gases in the atmosphere (burning fossil fuels, deforestation)

Greenhouse effect: natural process in which certain gases in the atmosphere retain heat radiating from Earth’s surface

Global warming: an increase in average temperatures worldwide; contributes to climate change

Increasing average temps even a few degrees will have large effects on ecosystems (EX/melting ice caps causing sea levels to rise – flooding coastal areas)

Ozone layer: region of the upper atmosphere in which high concentrations of ozone gas absorb much of the sun’s UV radiation

Holes in the ozone layer are caused by CFC’s (commonly used in cooling agents) – can destroy ozone Holes increase amount of UV radiation reaching Earth’s surface (can harm crops and marine organisms like

plankton)

C) Habitat Destruction

Habitat destruction is the leading cause of extinction of endangered species Habitat destruction decreases the amount of biodiversity (variety of life forms) in an area

Pollution: addition of substances, objects or other factors that cause harmful changes to an ecosystem

Deforestation: clearing of all trees from an area; can greatly affect organisms in an ecosystem

15. Briefly describe one impact that humans have on the environment:

Answer: summary of one of the areas listed above: Agricultural runoff, atmospheric and climate change, or habitat destruction

Main Idea #7: Limiting Factors on Population Dynamics

Population Dynamics: Study of the changes in population size.

Factors that increase population size: births, immigration Factors that decrease population size: deaths, emigration

A limiting factor is some sort of factor (biotic or abiotic) that is going to limit the population’s growth. It could be an important nutrient that is cycled through the ecosystem (such as water, nitrogen, carbon, or phosphorus), or it could be a food source or predator. A great example of limiting factors are predator-prey graphs. It is easy to see how the size of the population is affected.

Here, the size of the populations depends on the number or prey and predators. The predator population peaks after the prey population because of the lag time in reproduction. When the predator population is at its highest, the prey is at its lowest. With limited food, the population size of the predator decreases. This allows the prey population to increase, and the cycle continues again…

Carrying Capacity is the maximum population size an ecosystem can support, and is determined by the effects of different limiting factors.

Growth curves: exponential (growth under ideal conditions) vs logistic (growth with limiting factors):

PRACTICE QUESTIONS:

1. Which of the following is a biotic-biotic interaction?a. A snake warming on a sunny rock

b. A rainstorm washing nutrients from the soilc. A human shivering because of cold weatherd. A squirrel gathering acorns from an oak tree

2. Which statement correctly describes a part of an ecosystem?a. A community consists of both biotic and abiotic factorsb. A community is made up of different types of organismsc. A population is an abiotic factor affecting the ecosystemd. A population consists of different species living in an area

3. Which piece of evidence best supports the following statement? “In an ecosystem, the total amount of matter remains constant, even though its form and location change”

a. Producers capture energy from sunlightb. Most food chains have three levels or fewerc. Decomposers return nutrients to the environmentd. Multiple food chains can be combined into a food web

4. Small birds eat insects from the backs of rhinoceroses. The birds obtain food, and the rhinoceroses eliminate biting insects from their skins. Which ecological relationship is not represented by this situation?

a. Commensalismb. Mutualism (birds get food, rhinos get rid of bugs)c. Parasitism (insects biting rhinos)d. Predation (birds hunting insects)

5. Which trophic level is generally the smallest in a terrestrial ecosystem?a. Producerb. Primary consumerc. Secondary consumerd. Tertiary consumer

6. Which statement describes the function of producers in Earth’s biogeochemical cycle?a. Producers add nitrogen to the atmosphere and remove oxygen from the atmosphereb. Producers remove carbon dioxide from the atmosphere and add oxygen to the atmospherec. Producers add carbon dioxide to the atmosphere and remove oxygen from the atmosphered. Producers remove nitrogen from the atmosphere and add carbon dioxide to the atmosphere

7. The carbon dioxide in the atmosphere is an inorganic form of carbon. Organic compounds contain both carbon (C) and hydrogen (H). Which process in the carbon cycle changes carbon to an organic form?

a. Respirationb. Photosynthesisc. Burning of fossil fuelsd. Burial of dead organisms

8. A multicellular consumer can obtain nitrogen for use by its cells in which of the following forms?a. Nitrites (plants get from soil)b. Nitrates (plants get from soil)

c. Amino acids (consumers get from eating plants or animals)d. Nitrogen gas (bacteria get from atmosphere)

9. Forests of American beech and sugar maple trees are a type of climax community found in parts of western Pennsylvania. Which statement is most likely true concerning these plant species?

a. Their roots change environments of bare rock to fertile soilb. Their seeds grow best in bare soil with little other plant lifec. They reduce the ecosystem’s carrying capacity for grasses and shrubsd. They alter the ecosystem so that it is better suited for other plant species

10. Flooding can impact aquatic ecosystems by increasing turbidity. Turbidity refers to the amount of solid material suspended in water. Turbid water appears cloudy or muddy. What is the most likely effect of increased turbidity on an aquatic ecosystem?

a. The water contains less dissolved oxygen (bc not as much light – so not as much photosynthesis)b. Large fish are able to take in more energyc. The water contains fewer dissolved nutrientsd. Small fish are more easily caught by predators