Unit 10: Ecology Mr. Nagel

Meade High School

Warm Up Lifestyles of the Cells and Famous…

• Outline the differences between the behaviour of the chromosomes in mitosis and meiosis.

two divisions in meiosis, only one in mitosis; meiosis results in haploid cells, mitosis in diploid cells; crossing over only occurs in meiosis; no S phase precedes meiosis II; chromosome behaviour in meiosis II and mitosis is similar / chromosome behaviour in meiosis I and mitosis is different; chiasmata only form during meiosis; homologous chromosomes move to the equator in pairs only in meiosis; Do not accept number of cells produced - it is a result not a behaviour.

IB Syllabus Statements • 5.1.1

– Define species, habitat, population, community, ecosystem and ecology. • 5.1.2

– Distinguish between autotroph and heterotroph. • 5.1.3

– Distinguish between consumers, detritivores and saprotrophs. • 5.1.4

– Describe what is meant by a food chain, giving three examples, each with at least three linkages (four organisms). • 5.1.5

– Describe what is meant by a food web. • 5.1.6

– Define trophic level. • 5.1.7

– Deduce the trophic level of organisms in a food chain and a food web. • 5.1.8

– Construct a food web containing up to 10 organisms, using appropriate information. • 5.1.9

– State that light is the initial energy source for almost all communities. • 5.1.10

– Explain the energy flow in a food chain. • 5.1.11

– State that energy transformations are never 100% efficient. • 5.1.12

– Explain reasons for the shape of pyramids of energy. • 5.1.13

– Explain that energy enters and leaves ecosystems, but nutrients must be recycled.

http://click4biology.info/c4b/5/eco5.1.htm

What is Ecology?

• Ecology is the study of the relationships between organisms and their environment. – Abiotic factors (non-living) – Biotic factors (living)

Talking Points

• Should we be trying to prevent species from becoming extinct? If so, why?

• Should emissions (carbon) be regulated? Should these regulations be a condition for developing countries to receive foreign aid?

• Are global warming and ozone loss ‘real’ issues? What role does society have in addressing them?

Essential Definitions • Producer • Consumer • Detritivores • Saprotrophs • Autotroph • Heterotroph • Decomposer • Species • Niche • Habitat • Population • Community • Ecosystem • Food Chain • Food Web • Trophic Level

Essential Definitions • Producer: an organism that is able to produce its own food from inorganic substances. (ex:

plant) • Consumer: a heterotrophic organism that feeds on other organisms in a food chain (ex:

primary, secondary, tertiary) • Detritivores: organism that uses organic waste as a food source (ex: certain insects) • Saprotrophs: organisms that consume inorganic foods • Autotroph: organism that synthesizes its organic molecules from simple inorganic

molecules • Heterotroph: organism that feeds on organic matter • Decomposer: organism that recycles nutrients (ex: fungus) • Species: organisms having common characteristics capable of mating with each other • Niche: status of an organism within its environment and community • Habitat: environment in which a species normally lives or the location of the living

organism • Population: organisms that occur in a specified habitat • Community: assemblage of two or more populations of different species occupying the

same geographical area • Ecosystem: system formed by the interaction of a community of organisms with their

physical environment • Food Chain: sequence showing the feeding relationships and energy flow between species • Food Web: complex of interrelated food chains in an ecological community • Trophic Level: group of organisms that occupy the same level of a food chain

Organisms and Relationships

Food Chains

• Create three distinctly DIFFERENT food chains, each consisting of three or more linkages (4+ organisms). – Arrows indicate energy flow, NOT what

organisms are consuming other organisms.

Food Webs

• Create a model of Terrestrial or Oceanic Food web – must contain a minimum of 10 organisms. – Arrows indicate energy flow, NOT what

organisms are consuming other organisms.

Energy Pyramids • The higher the level of organism…

– Less energy available. – More ‘lower’ levels needed to support it. – Energy enters and leaves an

ecosystem, but nutrients MUST be recycled!

IB Syllabus Statements • 5.2.1

– Draw and label a diagram of the carbon cycle to show the processes involved. • 5.2.2

– Analyse the changes in concentration of atmospheric carbon dioxide using historical records.

• 5.2.3 – Explain the relationship between rises in concentrations of atmospheric carbon

dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect. • 5.2.4

– Outline the precautionary principle. • 5.2.5

– Evaluate the precautionary principle as a justification for strong action in response to the threats posed by the enhanced greenhouse effect.

• 5.2.6 – Outline the consequences of a global temperature rise on arctic ecosystems.

http://click4biology.info/c4b/5/eco5.2.htm

Cycles of Importance

• Water Cycle • Carbon Cycle • Nitrogen Cycle

Geochemical Cycles

• All molecules contribute to the movement of nutrients through the environment.

Water Cycle

• Organisms lose water to the environment. – Evaporation – Transpiration – Perspiration

• Clouds (In/Out). – Condensation – Precipitation

• Re-entry into organisms via land.

Carbon Cycle • Atmospheric CO2

absorbed by plants. • Photosynthesis turns

CO2 to sugar. • Organisms undergo

respiration, converting sugar to CO2 gas.

• Dead organisms can become fossil fuels, which when burned, produce CO2 .

• Bodies of water can absorb CO2 .

Nitrogen Cycle • Atmospheric nitrogen is

converted by bacteria into nitrate.

• Plants use the nitrate to create protein, along with nitrogen found in animal waste products.

• Animals consume plants and produce proteins. Excess nitrogen is excreted as waste.

• Dead organisms are broken down by bacteria, converting nitrate back to nitrogen gas.

Warm Up Energy Pyramid

• The total solar energy received by a grassland is 5 × l05 kJ m–2 y–1. The net production of the grassland is 5 × 102 kJ m–2 y–1 and its gross production is 6 × l02 kJ m–2 y–1. The total energy passed on to primary consumers is 60 kJ m–2 y–1. Only 10% of this energy is passed on to the secondary consumers.

(a) Calculate the energy lost by plant respiration. (2) (b) Construct a pyramid of energy for this grassland. (3)

(a) plant respiration = gross production – net production / 6 × 102 kJ m–2 y –1 – 5 × 102 kJ m –2 y –1; = 1 × 102 / 100 kJ m–2 y –1; Units required. (b) correct pyramid shape; 6 kJ m–2 y–1 (correctly calculated as energy passed to secondary consumer); producer and primary consumer values correctly inserted; Award [2 max] if there are units omitted. Award [2 max] if a bar is included for the solar energy. Do not deduct marks if the areas of the bars are not proportional to the values, although they should get smaller going up.

IB Syllabus Statements • 5.3.1

– Outline how population size is affected by natality, immigration, mortality and emigration.

• 5.3.2 – Draw and label a graph showing a sigmoid (S-shaped)

population growth curve. • 5.3.3

– Explain the reasons for the exponential growth phase, the plateau phase and the transitional phase between these two phases.

• 5.3.4 – List three factors that set limits to population increase.

http://click4biology.info/c4b/5/eco5.3.htm

Talking Points: Populations

• What factors work to increase a population of a particular organism?

• What factors work to decrease a population of a particular organism?

Let’s Study: Populations!

What happens in each of these steps? I. Exponential Growth II. Transition Competition/Natural Selection I. Plateau

Natality + Immigration = Mortality + Emmigration

Consider the example of a bacterial

colony that has set up residence in your throat.

Consider the germination of annual

plants in the spring time.

Let’s Study: Populations!

What are some environmental forms of resistance that limit populations from growing uncontrollably?

(Hint: Think Cancer)