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Science 20 Unit D: Changes in Living Systems

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Presentation on theme: "Science 20 Unit D: Changes in Living Systems"— Presentation transcript:

1 Science 20 Unit D: Changes in Living Systems

2 The Biosphere of Life

3 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.

4 It is the narrow zone around the earth where life exists.
Atmosphere The biosphere is made up of three parts: Hydrosphere Lithosphere

5 There are two factors that affect any part of the biosphere:
Biotic Factors: living organisms (life forms). Abiotic Factors: nonliving components (geological and physical factors). Question: what are some biotic and abiotic factors in a lake?

6 When we study living systems, we will be looking at the following:
Organism (the individual). Population (group of individuals). Community (one or more populations). Ecosystem (community and abiotic factors that interact). *Using the Prairies, give examples of each of the 4 parts of a living system.

7 Habitat Habitat: abiotic and biotic factors that encourage survival.
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?

8 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.

9 Fertilizers - chemicals that contain nitrogen and phosphorus natural fertilizer. 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)

10 This fertilizer contains 34% ___________ and 64% filler.

11 This diagram shows some of the major, minor and micro nutrients a plant needs.
Note that K, N and P are all major nutrients.

12 Adding fertilizers to crops has been good for society:
What are some advantages of using fertilizers? - However, there have also been negative side effects.

13 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.

14 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.

15 LAKE EUTROPHICATION Algae die  food for decomposers  population grows High levels of P and N containing compounds (fertilizers/ detergents) Algal Bloom (rapid growth of algae) Low oxygen  other organisms die out Decomposers (bacteria) break down material and use up oxygen in lake Organisms living in this part of the lake also feed on decaying plant and animal remains that wash into the water from the land Freshwater biomes located near areas with human populations often contain high concentrations of phosphorus and nitrogen compounds These compounds come from fertilizers and detergents used by people Phosphorus and nitrogen compounds that enter lakes, ponds, and streams serve as nutrients for algae and plants But if too many nutrients are present, algae and plants may grow out of control These large populations eventually begin to die and decay As decomposing bacteria break down the remains, they use up much of the oxygen dissolved in the water The resulting oxygen-poor water becomes uninhabitable for protozoa, fish, and other small animals Water in which oxygen becomes too low to support animal life is called eutrophic water. 15

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

17 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.


19 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.

20 The Hydrologic Cycle The Hydrologic Cycle II



23 Biotic Factors We 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.

24 Types of symbiosis: Mutualism: both species benefit.
Read the paragraph on page 416 to determine the mutualism between prairie dogs and bison.

25 - Commensalism: one organism benefits, the other is unaffected/unharmed.
Read the paragraph on page 417 to determine the mutualism between cowbirds and bison.

26 - 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.

27 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.

28 Some predator-prey relationship examples.

29 Competition Competition is where two or more organisms compete for the same resource. All organisms involved are harmed; no one benefits. This is NOT symbiosis.


31 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.

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