### Class Meeting: Monday, 17 September 2012

Announcements:
• HW6: doing your experiment turned back today.
• HW7: Grandma Johnson Due Today (9/17/12).
• Test Friday.
• Temp today 9:25am 21°C, High 23.3°C (last Thursday the high was almost 30°C, tomorrow's high=20.6°C)
• Recitation Tuesdays at 5:30pm till at least 6:30pm in the Biology Building room 1109. Come when you can and I will stay until everyone is done. Why? You will get help with ... homework, assignments, quizzes, studying for tests, and getting ideas that you didn't get in class.

### Objectives:

1. Distinguish questions that can be answered scientifically from those that cannot. Given a question or results from a "study" explain whether the results or question can or cannot be answered scientifically. chapter 1
2. Identify the pattern of scientific reasoning and investigation. Given a question/statement, create a testable hypothesis including...
• Null and alternative hypotheses
• Independent and dependent variables
Given an experimental design identify those same elements. Cane toad paper Chapter 1
3. Distinguish the difference among Observations, hypotheses, and theories. Given a statement identify whether it is an observation, hypothesis or theory. Be prepared to explain your rational Chapter 1
4. Determine whether a hypothesis has been supported through statistics using a p-value. Given a hypothesis with a p-value, state whether the hypothesis has been supported.
5. Identify the relationship between births and deaths that result in population change. given the birth rate and death rate determine whether a population is increasing or decreasing in size. determine the number of eggs surviving to reproductive age to maintain a population. chapter 36
6. Reproduce/identify exponential and logistic growth curves and all important features relative to both (including growth phases and carrying capacity). Given a population, show an expected growth curve and identify the important points in the curve. given a scenario determine whether the population is under exponential or logistic growth Chapter 36
7. Identify the intrinsic characteristics of growth (includes r vs k strategies). Given an organisms life history is it likely an r or K strategist. Given environmental conditions predict whether r or k strategists are more likely to succeed. for a given r is the population increasing, decreasing, or stable? Chapter 36
8. Distinguish between density dependent and density independent limiting factors. Given a population list a density dependent and density independent limiting factor. State whether the factor is biotic or abiotic. Explain your answer. chapter 36
9. Construct a basic carbon model of an ecosystem. Construct a basic model of an ecosystem including all major reservoirs. Predict the impact of a change in the nitrogen cycle on the carbon cycle Chapter 37
10. Follow the path of a carbon atom from a consumer to a producer. Trace the path of a carbon atom from a dead organism through a primary producer and carnivore. Be sure to show the reservoirs that the carbon atom will pass through. Chapter 37
11. Describe primary productivity and how and what factors that speed or slow productivity. Given two ecosystems, predict which system will have a higher rate of primary productivity. Chapter 37
12. Use your understanding of assimilation efficiency to determine the relative energetic cost of agricultural production. Given a choice of food items select the item that should take the least solar energy to produce a calorie of energy consumed by a human Chapter 37
13. Predict the charge of an atom based upon its neutrons, protons, and electrons. Given an element (ie AL+3) and the atomic number and atomic weight, determine the number of neutrons, protons, and electrons. Similarly, given the number of electrons and protons, give the charge of the atom. Chapter 2
14. Determine what makes an atom an isotope and what that may mean for it's radioactivity. Given some specific isotopes (ie C14) determine the number of protons, electrons and neutrons. In general terms, explain what happens when a radioactive isotope goes through radioactive decay. Chapter 2.
15. Predict whether a substance is polar or non-polar Given a chemical structure, determine whether a substance is polar or non-polar Chapter 2
16. Predict whether a substance will dissolve in a polar or non-polar substrate Given a substance predict whether the compound is likely to dissolve in oil or water Chapter 2
17. Describe the difference between covalent, ionic and hydrogen bonds. Given a specific bond in a substance identify the type of bond formed and it's relative strength (ie. is it likely to come apart when dissolved in water?) Chapter 2
18. Predict the orientation of molecules given their chemical properties. Given a compound with both a polar and non-polar potion, predict the orientation of the chemical in oil and water Chapter 2
19. Describe the special properties of water. Explain why water is both an excellent solvent and why it has water tension Chapter 2

### The Carbon Cycle

objective: 9, 10

Carbon is the backbone of all organic molecules. Aside from H2O, biological organisms are composed of mostly CARBON, hydrogen, oxygen, and nitrogen (P, S, K, Ca, Fe and other trace nutrients).
1. Name some parts of a forest ecosystem where you would find carbon.
2. Name processes that allow the carbon to flow from one component to another.

### Making box-flow models

objective: 9, 10

• Models are abstract representations of the world. box-flow models focus on how components flow through a system.
• reservoirs/compartments -
• boxes representing a portion of an system containing the compound/element/component of interest
• often lump organisms together (ie primary producers)
• arrows - represents processes that allow the compound to flow between reservoirs. Each arrow should be labeled with the specific process.
• Can be parameterized to include real rates for flows and compartment size for reservoirs.
Some points to help check your models
• Make sure that each box has arrows goiing in and going out of the box.
• What happens if arrows only point in?
• What happens if arrows only point out?
• Double check to make sure that you have included all the processes.

### Trophic levels

objective: 9, 10, 12

Ecologists classify organisms by how they acquire their carbon
• Primary Producers Plants
• Primary consumers herbivores - eat plants
• secondary consumers Carnivores and Omnivores, eat herbivores
• Detritivores/scavengers eat dead stuff and break it into small pieces
• Decomposers eat dead and convert back to CO2, mostly microbes

### The Carbon Cycle

objective: 9, 10

 Carbon is the backbone of all organic molecules. Aside from H2O, biological organisms are composed of mostly CARBON, hydrogen, oxygen, and nitrogen (P, S, K, Ca, Fe and other trace nutrients). The carbon cycle relies upon two processes Photosynthesis CO2 + H2O + light -> glucose + O2 Respiration glucose + O2 + ADP + P -> CO2 + H2O +ATP Carbon Cycle

### The Carbon Cycle

objective: 9, 10

The carbon cycle relies upon two processes
1. Photosynthesis
CO2 + H2O + light -> glucose + O2

2. Respiration
glucose + O2 + ADP + P -> CO2 + H2O +ATP
other processes
1. eating
2. death
3. waste production
4. fragmentation (breaking up into such small bits cannot see, dead to soil pool)
5. decomposition (really a special case of respiration, mediated by bacteria and fungi)
6. combustion (absent in many ecosystems, but very fast, large human influence)
7. fossilization (very slow)

### Grassland model of carbon cycle

objective: 9, 10

as a group,
Make a model of a grassland ecosystem (ie no trees),
1. Include and label all of the components we just discussed
2. Draw and label arrows indicating where the carbon can go (arrow indicates direction of flow)
Be careful, if a box only has an arrow going in or only has an arrow out, there is almost certainly something wrong.

 Components/reservoirs (boxes) Atmosphere Plant Animal Dead Soil Fossil Fuels Processes/flows (arrows, note show direction of flow) Photosynthesis Respiration eating death waste production fragmentation (breaking up into such small bits cannot see, dead to soil pool) decomposition (really a special case of respiration, mediated by bacteria and fungi) combustion (absent in many ecosystems, but very fast, large human influence) fossilization (very slow)

### Grandma Johnson problem

objective: 9, 10
What are the primary means that carbon could enter and leave
1. Grandma Johnson
2. Coyote

Box model of system

Compare to Grandma Jonson Homework

### Plants take in carbon dioxide from the air and fix the carbon into organic biomass through the process of photosynthesis.

objective: 9, 10

Primary productivity: amount of light energy converted to chemical energy (in the form of carbohydrates) by autotrophs (green plants and algae) per unit time (photosynthesis).

Net Primary Productivity (NPP): gross primary productivity minus the energy used by plants for respiration.

Secondary productivity: productivity of organisms that consume biomass (consumers).

### What factors influence primary productivity?

objective: 9, 10, 11

Abiotic:

• Temperature
• Precipitation
• Nutrient Availability in both terrestrial and aquatic ecosystems
• e.g., Green Revolution
• Disturbance over time

Biotic:

• Population Density
• Grazing density

### Ecological efficiency and Trophic pyramid

objective: 9, 10, 12

Only about 10% of Energy in food is turned into more of an organism (increased biomass)
The rest is released as respiration or waste

Joules are a measure of energy
objective: 9, 10, 12

Each level of the trophic pyramid contains about 10% of the energy below it.

### Clicker: Ecological Efficiency

objective: 9, 10, 12

Which takes more land to produce 1000 calories consumed by people?
1. Beans
2. beef
3. chicken
Note: some organisms are more efficient than others. Chickens are more efficient than cows.

See page 752 of your text.

### Quick questions

objective: 12, 13, 14

1. What makes carbon, carbon and oxygen, oxygen?
1. the number of protons
2. the number of electrons
3. the number of neutrons
4. the difference between protons and electrons
5. a different number of neutrons
1. What makes an atom an ion?
1. the number of protons
2. the number of electrons
3. the number of neutrons
4. the difference between protons and electrons
5. a different number of neutrons
1. What makes an atom an isotope?
1. the number of protons
2. the number of electrons
3. the number of neutrons
4. the difference between protons and electrons
5. a different number of neutrons

### What is matter?

objective: 12, 13, 14

• Atom = smallest unit of matter that still retains properties of the element
• Element = a substance that cannot be broken down into other substances by ordinary chemical means (ie carbon, silver, helium)
Atoms are composed of protons, neutrons and electrons
 Proton = positive charge, determines elemental properties (ie atomic number) Neutron = neutral charge, isotopes of the same element have the same number of protons but a different number of neutrons. Too many neutrons can lead to an unstable element (ie 14C radioactive vs 12C stable). Electron = negative charge, the number of electrons relative to the number of protons determines the reactivity of the element Helium atom schematic red + =proton, green = neutron, yellow - = electron (source, Wikipedia )

### Ions

objective: 12, 13, 14

The number of protons is about equal to the number of neutrons
atomic charge = difference between the number of protons and electrons (ie protons - electrons = charge)
Charge usually changes by gaining and loosing electrons, protons are only lost through radioactive decay.
• protons > electrons = positive charge positive ion
• protons = electrons = neutral charge
• protons < electrons = negative charge negative ion
Examples:
• H+ = 1 more proton than electrons (protons = 1, electrons = 0)
• Cl- = 1 more electron than proton (protons = 17, electrons = 18)
• Al3+ = 3 more protons than electrons (protons = 13, electrons = 10)
• S2- = 2 more electrons than protons (protons = 16, electrons = 18)
Compounds are ions too (nitrate = NO3-, nitrite = NO2-, Phosphate = PO43-, OH-).
objective: 12, 13, 14

element atomic number atomic weight
C 6 12
H 1 1
O 8 16
N 7 14
P 15 31
(assume neutrons and protons weigh 1 and electron weight is negligible)
The number of protons determines the element!
1. As individuals, then as a group, list the number of Neutrons, Protons, and Electrons for
1. N+
2. O-

### Isotopes

atoms with the same number of protons but with a different number of neutrons are called isotopes
• the combined number of protons and neutrons are used to indicate a specific isotope
• 12C - stable most common, 13C - stable much less common, 14C - radioactive, created by cosmic rays in atmosphere
• 235U , 238U both are radioactive
• 14N - stable
• Can be stable (not radioactive)
• unstable configuration in nucleus results in radioactive decay
• releases energy (radiation) and sometimes breaks apart into different atoms
• 235U with added neutron -> 92Kr and 141Ba and releases 3 neutrons as well as gamma radiation
• 14C -> 14N + radiation (Beta particle converts neutron to proton through loss of subatomic particles)
• Half-life = time for half of atoms to go through radioactive decay
• 14C - half life= 5730 years
• 235U - half life= 704 million years
• 238U - half life = 4.47 billion years

### Chemical Bonds

objective: 15

 covalent bond = electron shared (sometimes one atom shares better than the other resulting in a charge) [strongest] ionic bond = electron is given to the other atom (no sharing, just taking) hydrogen bond = charged ends of molecules are attracted to each other (water H=+ is attracted to O=-). Like magnets. [weakest]

### Polarity in molecules

objective: 13, 14

Polar molecules have a positive and negative part of the molecule.
This occurs when electrons are not shared equally among atoms in a molecule

Water is polar because Oxygen holds onto electrons very strongly but hydrogen atoms have much lower attraction for their electrons. The oxygen atoms are the negative end of water and the hydrogen atoms are the positive end of the water molecule.

non-polar molecules share electrons equally among the atoms. Therefore there is no charge difference along the length of the molecule.

O2 is a non-polar molecule because both oxygen atoms equally share the electrons. CO2 is another non-polar molecule.

As we shall see, most fats (including oils) are non-polar, but DNA, RNA and most proteins are polar. Carbohydrates can be either polar or non-polar.

### A special polar molecule - Water

objective: 13, 14

pH - hydrogen ion concentration in water
• the relationship between OH and H in water
• When there are an equal concentration of OH and H, pH is neutral (about 7)
• pH = negative log of H ion concentration (range 0 to 14)
• basic pH > 7 (more OH than H)
• neutral pH = 7 (H = OH concentration)
• acidic pH < 7 (more H than OH)
• buffer - a substance that helps maintain a given pH level
Note: Acids and Bases are usually reactive and release energy. What household products have you used that illustrate this reaction? (think middle school science fair)

Polarity of water
• Oxygen holds on to shared electron longer
• Excellent solvent
• water tension - water molecules attracted to each other on surface
• Water stores energy
• energy required to break hydrogen bonds (evaporation, melting)
• energy released when H bond form (condensing, freezing) moderating temp
• effects coasts (moderates temperature), used to maintain temperature in solar houses
When water freezes it is less dense than water (cool fact, maximum density of water occurs at +4 degrees C, just above freezing)

### polar and non-polar molecules don't mix

objective: 13, 14, 15

 Polar compounds are so attracted to each other that they separate from non-polar compounds. In other words, oil and water don't mix. hydrophilic = "water loving" = polar molecules and ions = water, sugar, salt, acetic acid hydrophobic = "water fearing" = non-polar molecules = fats, CO2, acetone Some compounds have portions that are polar and portions that are non-polar (from Wordpress)