Science 20 Unit D:

Changes in Living Systems

The Biosphere of LifeThe Biosphere of Life

POS Checklist:•investigate and analyze an aquatic or a terrestrial local ecosystem, distinguish between biotic and abiotic factors, describe how these factors affect population size and

infer the abiotic effects on life. infer biotic interactions. infer the influence of biota on the local environment.

It is the narrow zone around the earth where life exists.

The biosphere is made up of three parts:

Atmosphere

Hydrosphere

Lithosphere

There are two factors that affect any part of the biosphere:

1.Biotic Factors: living organisms (life forms).

2.Abiotic Factors: nonliving components (geological and physical factors).

Question: what are some biotic and abiotic factors in a lake?

When we study living systems, we will be looking at the following:

1. Organism (the individual).

2. Population (group of individuals).

3. Community (one or more populations).

4. Ecosystem (community and abiotic factors that interact).

*Using the Prairies, give examples of each of the 4 parts of a living system.

Habitat

• Water is the most important abiotic factor of an ecosystem.

• The habitat of an organism determines the amount of water, sunlight and temperature for growth and survival.

*What is your ideal habitat? Why?

Habitat: abiotic and biotic factors that encourage survival.

Nutrients• One component of habitat is

chemical nutrients.• Nutrients are needed

compounds/elements used by organisms to grow and reproduce.

• Gardeners use fertilizers to give all the needed nutrients to the plants.

• The run-off from fertilizers can cause problems with lakes and

algal blooms.

Fertilizers

Manure: contains N which is ammonified first in the soil, then nitrified to provide useful nitrates.

Commercial Fertilizers: 3 numbers:• The first number is the % nitrogen (by weight)• The second number is the % phosphorus (by

weight)• The third number is the % potassium (by

weight)

- chemicals that contain nitrogen and phosphorus natural fertilizer.

This fertilizer contains 34% ___________ and 64% filler.

This fertilizer contains 25% _________ , 3% _________ and 5% __________.

This diagram shows some of the major, minor and micro nutrients a plant needs.

Note that K, N and P are all major nutrients.

Adding fertilizers to crops has been good for society:

What are some advantages of using fertilizers?

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However, there have alsobeen negative side effects.

While fertilizers help our crops grow, they also increase the growth of some unwanted plant life.

Often, fertilizers run off into lakes, creating high concentrations of chemicals.

The natural algae in these lakes start to grow uncontrollably: resulting in a lake full of algae.

This process is called eutrophication:

- a process in which nutrient runoff from agricultural lands or livestock operations causes photosynthetic organisms in ponds and lakes to multiply rapidly

Human-caused eutrophication wiped out fisheries in Lake Erie in the 1950s and 1960s.

High levels of P and N containing compounds (fertilizers/ detergents)

High levels of P and N containing compounds (fertilizers/ detergents)

Algal Bloom(rapid growth of algae)

Algal Bloom(rapid growth of algae)

LAKE EUTROPHICATIONLAKE EUTROPHICATIONAlgae die food for decomposers population grows

Algae die food for decomposers population grows

Decomposers (bacteria) break down material and use up oxygen in lakeDecomposers (bacteria) break down material and use up oxygen in lake

Low oxygen other organisms die outLow oxygen other organisms die out

•Water in which oxygen becomes too low to support animal life is called eutrophic water.

•To protect Canadian lakes, ponds, and streams from becoming eutrophic, some states no longer allow the sale of detergents containing phosphorus compounds.

A surplus or lack of oxygen does occur in lakes naturally as well.

Oligotrophic lake: Nutrient-poor, photosynthesis-limited, clear water, O2 rich.

Eutrophic lake: Nutrient-rich, high photosynthesis, murky water, O2 poor.

Hydrological (water) Cycle

• Water plays a critical role by:– Maintaining global heat balance.– Acting as a solvent in reactions.

• Movement of water through environment: from atmosphere to Earth.

• Volume of water remains constant, specific amounts vary in phases; water continuously cycles.

The Hydrologic Cycle

The Hydrologic Cycle II

Biotic FactorsWe have looked at some abiotic factors so far, now we will look at some biotic factors that affect ecosystems:

Symbiosis = “living together”

Long lasting relationship that benefits at least one organism of two different species.

Types of symbiosis:

–Mutualism: both species benefit.

Read the paragraph on page 416 to determine the mutualism between prairie dogs and bison.

- Commensalism: one organism benefits, the other is unaffected/unharmed.

Read the paragraph on page 417 to determine the mutualism between cowbirds and bison.

- Parasitism: one organism (parasite) benefits by harming the other (host).

Read the paragraph on page 417 to determine the mutualism between cowbirds and the yellow-rumped warbler.

Predator-Prey Interactions• This is NOT symbiosis; the two

organisms do not live together and it is a short interaction.

• Predation: one organism (predator) kills the other (prey).

– Mostly benefits the predator BUT the prey community is left with fit individuals.

Some predator-prey relationship examples.

• Competition is where two or more organisms compete for the same resource.

• All organisms involved are harmed; no one benefits.

• This is NOT symbiosis.

Competition

Assignment

• Please complete the following:– Read and highlight the important

points on “biomes and habitats” and “animal partnerships”.

– Complete #2,3 and 4 on page 412.– Complete the Symbiosis Fact sheet.– Complete #2,3,5 on page 422.