4.1 Species, communities and ecosystems: The continued survival of living organisms including humans depends on sustainable communities.

Nature of science: Looking for patterns, trends and discrepancies—plants and algae are mostly autotrophic but some are not.

Understandings: Species are groups of organisms that can potentially interbreed

to produce fertile offspring. Members of a species may be reproductively isolated in

separate populations. Species have either an autotrophic or heterotrophic method of

nutrition (a few species have both methods). Consumers are heterotrophs that feed on living organisms by

ingestion. Detritivores are heterotrophs that obtain organic nutrients from

detritus by internal digestion. Saprotrophs are heterotrophs that obtain organic nutrients

from dead organisms by external digestion. A community is formed by populations of different species living

together and interacting with each other. A community forms an ecosystem by its interactions with the

abiotic environment. Autotrophs obtain inorganic nutrients from the abiotic

environment. The supply of inorganic nutrients is maintained by nutrient

cycling. Ecosystems have the potential to be sustainable over long

periods of time.

Applications and skills: Skill: Classifying species as autotrophs, consumers,

detritivores or saprotrophs from a knowledge of their mode of nutrition.

Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. To obtain data for the chi-squared test, an ecosystem should be chosen in which one or more factors affecting the distribution of the chosen species varies. Sampling should be based on random numbers. In each quadrat the presence or absence of the chosen species should be recorded.

Skill: Recognizing and interpreting statistical significance.

PRACTICALSetting up sealed mesocosms to try to establish sustainability. Mesocosms can be set up in open tanks, but sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones.

International-mindedness: The need for sustainability in human activities could be discussed and the methods needed to promote this.

Topic 4: Ecology (12 hours)

4.2 Energy flow: Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.

Nature of science: Use theories to explain natural phenomena—the concept of energy flow explains the limited length of food chains.

Understandings: Most ecosystems rely on a supply of energy from sunlight. There is a continuous but

variable supply of energy in the form of sunlight but that the supply of nutrients in an ecosystem is finite and limited and must be cycled.

Light energy is converted to chemical energy in carbon compounds by photosynthesis. Chemical energy in carbon compounds flows through food chains by means of feeding. Energy released from carbon compounds by respiration is used in living organisms and

converted to heat. Living organisms cannot convert heat to other forms of energy. Heat is lost from ecosystems. Energy losses between trophic levels restrict the length of food chains and the biomass

of higher trophic levels. Biomass in terrestrial ecosystems diminishes with energy along food chains due to loss of carbon dioxide, water and other waste products, such as urea.

Pyramids of energy should be drawn to scale and should be stepped, not triangular. The terms producer, first consumer and second consumer and so on should be used, rather than first trophic level, second trophic level and so on.

Applications and skills: Skill:

Quantitative representations of energy flow using pyramids of energy.

International-mindedness: The energetics of food chains is a factor in the efficiency of food production for the alleviation of world hunger.

Topic 4: Ecology (12 hours)

4.3 Carbon cycling: Continued availability of carbon in ecosystems depends on carbon cycling.

Nature of science: Making accurate, quantitative measurements—it is important to obtain reliable data on the concentration of carbon dioxide and methane in the atmosphere.

Understandings: Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds. In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen

carbonate ions. Carbon dioxide diffuses from the atmosphere or water into autotrophs. Carbon dioxide is produced by respiration and diffuses out of organisms into water

or the atmosphere. Methane is produced from organic matter in anaerobic conditions by methanogenic

archaeans and some diffuses into the atmosphere or accumulates in the ground. Methane is oxidized to carbon dioxide and water in the atmosphere. Peat forms when organic matter is not fully decomposed because of acidic and/or

anaerobic conditions in waterlogged soils. Partially decomposed organic matter from past geological eras was converted either

into coal or into oil and gas that accumulate in porous rocks. Carbon dioxide is produced by the combustion of biomass and fossilized organic

matter. Animals such as reef-building corals and mollusca have hard parts that are composed

of calcium carbonate and can become fossilized in limestone.

Applications and skills: Application:

Estimation of carbon fluxes (measured in gigatons) due to processes in the carbon cycle.

Application: Analysis of data from air monitoring stations to explain annual fluctuations.

Skill: Construct a diagram of the carbon cycle.

Aims: The ethical implications of diverting crops such as maize from a food to a fuel crop could be considered.

Topic 4: Ecology (12 hours)

4.4 Climate change: Concentrations of gases in the atmosphere affect climates experienced at the Earth’s surface.

Nature of science: Assessing claims—assessment of the claims that human activities are producing climate change.

Understandings: Carbon dioxide and water vapour are the most significant greenhouse gases. Other gases including methane and nitrogen oxides have less impact. The impact of a gas depends on its ability to absorb long wave radiation as well as

on its concentration in the atmosphere. The warmed Earth emits longer wavelength radiation (heat). Longer wave radiation is absorbed by greenhouse gases that retain the heat in the

atmosphere. Global temperatures and climate patterns are influenced by concentrations of

greenhouse gases. There is a correlation between rising atmospheric concentrations of carbon

dioxide since the start of the industrial revolution 200 years ago and average global temperatures.

Ozone depletion ≠ enhanced greenhouse effect Recent increases in atmospheric carbon dioxide are largely due to increases in the

combustion of fossilized organic matter.

Applications and skills: Application: Threats to coral

reefs from increasing concentrations of dissolved carbon dioxide.

Application: Correlations between global temperatures and carbon dioxide concentrations on Earth. Databases can be used to analyse concentrations of greenhouse gases.

Application: Evaluating claims that human activities are not causing climate change.

International-mindedness: Release of greenhouse gases occurs locally but has a global impact, so international cooperation to reduce emissions is essential.

Theory of knowledge: The precautionary principle is meant to guide decision-making in conditions where a lack of certainty exists. Is certainty ever possible in the natural sciences?

Aims: There are interesting parallels between humans that are unwilling to reduce their carbon footprint and cheating in social animals. When the level of cheating rises above a certain level, social behaviour breaks down.

Topic 4: Ecology (12 hours)

Perceived Causes of Climate Change in USA

Science Journal 3/23/2015

What do you think most Americans base their beliefs on?

Do any of these statics surprise you?

How could these statics be biased?

International Climate Change Concern Survey

Biology Journal 4/15/2015

This graphic shows movements of carbon, called carbon flux, on the Earth. Answer these questions.

1. Where is most of the carbon on Earth found? How much (include units)?

2. How much carbon is stored as plant material on Earth?

3. What amount of carbon dioxide gets added by humans every year?

4. Does all of the photosynthesis balance out all of the cellular respiration?

EcologyWhiteboard Review!

What are the 3 fossil fuels?Oil, coal, and natural gas

What is the difference between an autotroph and a heterotroph?

Autotrophs make their own food through photosynthesis (usually) and heterotrophs do not make their own food, they must eat another living thing.

How is a population defined?A population is organisms of the same species that live in the same area and can interbreed.

What tool can be used to estimate a population size?A quadrat is used to measure the population of a small area, and then multiplied to estimate a larger area.

What does an ecosystem include, that a community does not

include?

An ecosystem include the abiotic factors of a system, such as temperature, H2O,

and nutrients.

A community is limited to all of the living things.

H2O + CO2 → O2 + C6H12O6

Write out the chemical reaction for photosynthesis.

Write it using out the formulas (like “H2O”) Below the formulas, write out the words (like “water”)

sugar(or glucose)

plus yields(or turns into)

carbondioxide

pluswater oxygen

Photosynthesis

Cellular Respiration

Diffusion

Deposition (becomes fossil fuels over a long time

Burning (combustion)

Decomposition

2

3

6

1

5

4

CO2 (in atmosphere)

CO2 (in ocean as carbonic acid)

What would each of these processes be called?

If the first consumers of a square kilometer of temperate forest ecosystem have a biomass of 1,490 kilograms, what is the biomass of the third level consumers?

You don’t start here!

1490 kg

x 0.1 (which is 10%)

149 kg

14.9 kgx 0.1

(which is 10%)

Answer!

Compare and contrast saprotrphs and detritovores in a Venn diagram.

Saprotroph Both Detritovore

Compare and contrast saprotrphs and detritovores in a Venn diagram.

Saprotroph Both Detritovore

• Digests its food externally, then absorbs it

• Fungi

• Decomposers• Important for

recycling matter (not energy!)

• Consumes its food the breaks it down and absorbs it.

• Bacteria, earthworms

Here is a graph of atmospheric CO2 concentration at Mauna Loa, Hawaii over 60 years.

Positive correlation. CO2 concentration increases as time increases.

1. Summarize the trend.

2. Explain why CO2 concentration “zig-zags.”

Photosynthesis (mostly) can’t happen in the winter. Why not?

CO2 + H2O → C6H12O6 + O2

Water is frozen, and thus inaccessible

The sunlight is dim, and days are short

When it is summer (in the Northern hemisphere) plants do more photosynthesis, reducing CO2; when it is winter (in the Northern hemisphere) plants do less photosynthesis, and CO2 builds up.

C6H12O6 + O2 → CO2 + H2O

Write out the formula for cellular respiration.

Write it using out the formulas (like “H2O”) Below the formulas, write out the words (like “water”)

sugar(or glucose)

plus oxygen yields(or turns into)

carbondioxide

plus water

Explain the greenhouse effect

The sun causes infrared rays to hit the Earth. Some of these rays bounce off, and don’t heat the earth. Some rays are absorbed in the atmosphere by greenhouse gasses, warming the Earth.

On this food web, name all of the…1. Producers2. 2nd consumers3. Decomposers4. Autotrophs5. Heterotrophs

Bladderwrack, microscopic algaeCrab, lobster, seal, herring gullNone are shown!

Bladderwrack, microscopic algaeEverything except the autotrophs

How long does it take for fossil fuels to form?

300,000,000 yearsPrehistoric Fern Plants fossilized in coal samples

Name at least 4 greenhouse gasses found in the atmosphere

H2O (water) CO2 (carbon dioxide) CH4 (methane or “natural gas”) O3 (ozone) N2O (nitrous oxide) CFCs (chlorofluorocarbons)

Greenhouse Gasses

These are the most significant!

What happens to the energy in a food web? What happens to the matter?

The energy is continually lost. Only 10% of energy is passed from any organism when it is eaten. The matter is never lost. It is recycled by decomposers and by other processes.

What do these 2 have in common?

A coal power plant

Weightlifting

Create CO2

Create H2O Consume O2

Burn calories Consume / release energy Break down organic (carbon-based) molecules to

get energy The energy for these molecules at one point came

from the sun (either food or fossil fuels)

Both of these…

True or False?Write out the numbers 1 through 6. Then, write “true” or “false” for each one.

1. Plants do photosynthesis. 2. Plants do cellular respiration.3. Plants create O2.4. Plants remove CO2 from the air.5. Plants cause global warming.6.Plants get the energy for photosynthesis

from water.

True or False?

1. Plants do photosynthesis. True! 2. Plants do cellular respiration. True!3. Plants create O2. True!4. Plants remove CO2 from the air. True!5. Plants cause global warming. False!6.Plants get the energy for photosynthesis

from water. False!

True or False?

Write out the numbers 1 through 4. Then, write “true” or “false” for each one.

1. Animals do photosynthesis. 2. Animals do cellular respiration.3. Animals depend on plants as a source of O2

and a source of energy.4. Animals create CO2.

1. Animals do photosynthesis. False!2. Animals do cellular respiration. True!3. Animals depend on plants as a source of O2

and a source of energy. True!4. Animals create CO2. True!

True or False?

Where does the energy to build the food molecules in photosynthesis come from?

The Sun

Apollo, god of the sun and Greek restaurants