Grade 10 Lessons

 

 

EXOTIC SPECIES

 

//An exotic organism is one that is not native to an ecosystem. It can migrate into the system naturally or as a result of man’s movements. When it enters an ecosystem it competes with other species that occupy the same niche it has. Because it has few natural predators, it usually out-competes these species, and severely limits their populations and can lead to extinction of local species in these niches.

 

An example of this is the Zebra Mussel

The zebra mussel entered Lake Erie in the early 1990’s. This bivalve came from the Caspian Sea and entered the lakes from bilge water discharged from ships. By 1991 there were extensive colonies in Lake Ontario. By 1995 it was found as far as the Gulf of Mexico.

The mussel blocks water intake pipes from the great lakes, choking hydroelectric plants and freshwater supplies. It has out-competed the pearly mussel that used to occupy its niche. Zebra mussels actually attach to the shells of pearly mussels that form hard surfaces on the mud. Mussels are filter feeders, taking in bacteria and protista and clearing the water of food for other species. This also allows ultraviolet light to filter down to the bottom of the lakes, heating the water and thereby reducing oxygen and  adversily affecting fish like trout that need more oxygen.

 

On the other hand they provide food for ducks and other aquatic birds. Their shells are habitats for snails, aquatic insects, small crustaceans and water mites. Their larvae are the source of food for hydra. Fish that eat the crustaceans also benefit. The mussel clears the ever increasing algae blooms. They remove pollutants from the water. However, the organisms that eat the mussels bioaccumulate these pollutants.

 

The Goby fish, another exotic from the Black Sea, also found its way into the lakes via ballast water. These eat zebra mussels. However, being an exotic, they chase other fish from spawning grounds and eat the eggs of native fish like walleye, perch and small-mouth bass.

 

Another example is the purple loosestrife in marshes in Canada.

There are over 6 billion humans on the planet today. This is largely due to the decline in death rate as a result of better health care, improved sanitation and increased food production. We use plants and animals for many things other than food e.g clothing, tobacco, pets, ornamentation, housing, furniture, paper, technology.

Humans also affect ecosystems indirectly – we burn forests, drain wetlands, pave cities, highways, golf courses, parks, flood land for dams, overgraze and plant monocultures. All this has reduced diversity, reduced the plant biomass, created deserts. Our consumption decreases the amount of energy available for other organisms. Human use, conversion and diversion of the earth’s biomass exceeds 20%.

 

 

CANADIAN BIOMES AND THE PLANTS THAT ADAPT TO THEM

 

 

Plants need the right abiotic or physical conditions to grow:

·       Water/rain or precipitation

·       Sunlight

·       suitable temperatures

·       minerals from the soil.

Plants, however, have adapted to a wide variety of abiotic conditions: huge natural areas which present a specific set of abiotic factors that cause certain plants to grow are called biomes.

 

Canada has 5 major biomes

 

CLIMAX COMMUNITY	CLIMATE	ADAPTATIONS
ARCTIC TUNDRA Lichen, moss, grass, herb. Perennials (grow for several seasons)	·        Long cold winters (-32C) ·        Short cool summers (5C) ·        Permafrost and no drainage together with the low temps prevents decomposition of organics and results in a soil of low nutrient density. ·        Low precipitation (<25cm/yr)	·        Low growing plants that are buried in snow in winter. ·        Perennials (live many seasons) that store nutrients in underground stems ·        Evergreens (don’t need to grow new leaves each season) ·        Compact form protects delicate growing tips from cold winds ·        Disc-shaped flowers that orient toward the sun and can have higher temps that attract pollinators.
BOREAL FOREST Coniferous forest of Spruce, Fir and Pine	·        Long cold winters ·        Short warm summers (4 months) 15C. ·        Permafrost and so again little organic decomposition. Many nutrients trapped in mosses. Soil nutrient poor. ·        More precipitation (25-50cm/yr)	·        Evergreens that have needles which can live up to 15 yrs and can photosynthesise over a wide range of temps.  Also needles have thick cuticles, reduced surface area and sunken stomata that reduce water loss. ·        Jack pine cones only open to release seeds after the heat of a fire. The seedling grows on the more nutrient dense soil that occurs after a fire. ·        Birches and poplars can sprout from a burnt stump.
TEMPERATE FOREST Deciduous trees like Maple, Beech, Birch Hemlock (drop leaves), conifers and shrubs, vines, mosses, ferns	·        Shorter winters ·        Warmer summers of 6 months (20C) ·        Still more precipitation (50-75cm/yr) ·        Leaf litter decomposes resulting in rich nutrient dense soils	·        Hardwoods in the north avoid harsh winters by being deciduous (winter dormant). ·        Spring ephemerals sprout from underground stems, and go through their cycles in a short time. They grow in early spring before the trees have foliage that blocks their light.
PRAIRIE GRASSLAND Grasses and mixed herbaceous plants	·        Cold winters and warm, dry summers ·        Soils are deep, and rich in nutrients ·        Frequent fires prevent the growth of trees and favour the grasses.	·        prairie grasses get nitrogen from legumes that have nitrogen-fixing bacteria ·        many grasses are perennials that survive as underground rhizomes in winter ·        leaves and stems are covered in a thick cuticle that reduces evaporation losses ·        leaves can roll into a tube that protects the stomata on the inside ·        roots are high to absorb rainwater quickly before runoff. ·        Leaves and stems grow from the base not the tip of the plant – preventing die-off from grazing animals. ·        Laves have silica grains or bitter phenolic compounds to reduce grazing.
DESERT Succulents, desert ephemerals – desert grasses and daises	·        Less than 20cm of rain a year ·        Hot days, cold nights ·        Unpredictable rainfall ·        Low humidity ·        Sparse vegetation results in little organic matter, dry, rocky land with little soil prone to erosion                                               ·        The rain leaches the abscisic acid, so inhibition stops. ·	·        Leafless succulents that hold water in their stems. Stems adapted for photosynthesis. Thick cuticles and reduced surface areas prevent water loss. ·        Shallow, spreading roots catch water after brief rains ·        Cacti have spines and a bitter taste to stop animals taking their water. ·        Stomata stay closed during the day to prevent water loss. At night, they open and take carbon dioxide from the air and store it in organic acids. In the day, when photosynthesis occurs the carbon can be used. ·        Annual desert ephemerals spend most of the year as dormant seeds. After the rains, they germinate and grow quickly. The seed coats contain the hormone abscisic acid which inhibits growth.

 

 

COMPETITION

 

Competition takes place among species sharing resources. Individual organisms struggle for access to limited resources. The closer the niche is of two different species, the more they will compete for similar resources. No two species can share exactly the same niche. Within a species, the individuals also compete with each other for the same resources. Competition prevents population growth.

 

INTERSPECIFIC COMPETITION: is competition between species. They usually occupy the same trophic level.

INTRASPECIFIC COMPETITION: is competition among species of the same species.

 

POPULATION STUDIES

 

Population:// a group of organisms of the same species that exist in the same place at the same time. A species consists of organisms so similar that they can mate and produce fertile offspring.

 

Carrying Capacity: //the largest population of a species that an environment can support.

 

FACTORS THAT DETERMINE AND LIMIT THE SIZE OF THE CARRYING CAPACITY

 

1. Density-independent factors:

//regardless of numbers of a species, the presence of this factor will limit the population. These are abiotic factors that initially set up the populations of species that will exist in an area.

Examples are climate and weather, temperature, drought, ‘acts of God’, fires and floods, loss of habitat, pollution of air, water and soil.

 

2. Density-dependent factors:

//factors that become significant as the population grows.

1. Materials and energy: the supply of water, carbon, essential materials and energy caps the size of a population.
2. Availability of habitat and shelter
3. Parasites and diseases
4. Number of predators and predation.  

 

Percentage Population change: // [number of births] – [number of deaths] + [number of immigrants] – [number of emigrants] / total population >< 100.

In an open ecosystem, all four mechanisms are operating.

In a closed ecosystem, there is no immigration and emigration.

 

A typical population growth is sigmoidal.

See graphs.

 

Biotic Potential: //the maximum number of offspring a species can produce, if resources were unlimited. It depends on gestation and litter size. Any resource that is in short supply is a limiting factor to this biotic potential. 

 

Population explosion:// extremely fast growth. It can occur when a new species is introduced into an ecosystem in which there are few predators, a plentiful food supply and abundant space. Exotic species often do this.

See typical population explosion graph (exponential)

 

VECTOR DIAGRAMS

//are the combining of vectors head to tail to draw the resultant vector Dd_R

 

The Scale Diagram Method

 

A.  COLLINEAR VECTORS: vectors on one plane:

1. State the direction which is positive and which is negative.
2. State the scale you will use.
3. Scale each vector and then draw them by connecting the head of one with the tail of the next.
4. Find the resultant vector by drawing an arrow from the tail of the first to the head of the last vector.
5. Measure the size and direction of the resultant vector. Convert it back to the actual size using the scale.

 

B. TWO DIMENSIONAL VECTORS:

vectors at angles to each other.

 

1. Choose a scale. Calculate the scaled length of each of the vectors.

2. Draw the compass symbol on the page.

3. Draw the vectors, head to tail. Use a protractor to work out the

    angle on the compass for each vector. Note the convention: e.g 30⁰

     E of S means you start at S and go E by 30⁰

1. Draw the resultant displacement as an arrow from the tail of the first vector to the head of the last. Label this the resultant displacement Dd_R
2. Work out its angle from the compass direction using a protractor.
3. State the resultant displacement to size and with direction.

 

Adding collinear vectors algebraically

(cannot be done for vectors at an angle).

Note: it is a number line system for adding displacements

 

1. Indicate which direction is positive and which is negative. Always state which convention you are using viz: the initial direction is taken as positive, or N and E are taken as positive.
2. List the givens and indicate which variable is being solved.
3. Write the equation for adding the vectors:

                            Dd_R = Dd₁ + Dd₂ + …..  Dd_n

4. Substitute the displacements, with their correct signs, into the equation, and solve.
5. Write a concluding statement.

 

 

THE VECTOR QUANTITY: VELOCITY

 

1.  Recall average speed: v_av = the change in distance divided by the change in time.

2.  Velocity is the rate of change of position or the rate of displacement. It is basically speed with a direction.

3.  Average velocity: V_av = Dd_R/Dt.

   The direction of the velocity is the same as the direction of the displacement.

       It is the resultant displacement divided by the time interval over which the displacement occurred.

   Note: if the resultant displacement is zero, then the velocity is zero. This may be quite different from the speed. 

4.  Constant velocity: is constant speed in a constant direction.

 

 

 

NOTE

The resultant displacement can be worked out without measuring it, if a right angled triangle is created:

1. To find the angle of displacement: sine j = o/h; cos j = a/h; and tan j = o/a (“ossie has a hat on again”)

 

So find tan j = 0/a then arc-tan gives the angle.

 

2. Pythagoras’ theorem will give the resultant displacement: the hypotenuse of a right-angled triangle is equal to the square root of the sum of the squares of the other 2 sides: Dd_R = Dd₁ and Dd₂ squared, then square rooted.

 

 

 

 

 

WRITING A LAB REPORT

 

1. Title Page:

State the following on a cover page:

• the title of the investigation
• your name and the instructor’s name
• the course code and the due date.

 

2. Purpose:

In a sentence or two, make a brief statement about why you did the investigation.

 

3. Hypothesis:

Make an educated guess about the outcome of the investigation.

It must take the following form:

If ….(I do this manipulation/the independent variable), then ….(I expect this outcome/the dependent variable).

 

4. Materials:

Make a detailed list of materials you used. Be specific about sizes and quantities.

 

5. Procedure:

Write the procedure in detail, in the correct order in which it was done. It must be listed in point form.

 

6. Results:

Record the outcome in sentences, tables, charts, labeled diagrams or graphs. Do not discuss or explain the results.

 

7. Discussion:

Explain the results. Use theory or give a theory to support or interpret your results. If you were assigned questions, answer them in this section.

Include sources of error in this section. In other words, explain why your experiment may be inaccurate. All experiments and observations have some degree of error.

There are different types of error:

1. Instrument error: measuring devices can be malfunctioning or calibrated incorrectly. All measuring devices have limitations with respect to the accuracy of the measurements which can be attained from them, and so the number of significant digits that can be quoted is also limited.
2. Uncontrollables: In real life there are always many interfering variables that can affect the outcome of an experiment or piece of research that is trying to establish a relationship between the independent and dependent variables. As much as possible these other variables should be controlled, but it is hard to control all of them. Any interfering variables should be identified and discussed here.
3. Human error: Any known human error should be included here.

 

8. Conclusion: Accept or reject your hypothesis and briefly say why.

 

 

THE PERIODIC TABLE

 

1. Elements are arranged in increasing atomic number.
2. Periods run horizontally, and groups run vertically.
3. Metals are on the left, non-metals on the right.
4. Each new period represents the filling of a new outer orbit, called a valence orbit. For example: period 1 is filling orbit one; period 2 is filling outer orbit two.
5. Each group has the same number of electrons in the outer shell, called valence electrons. This gives each member of the same group the same chemical properties. The number of valence electrons enable us to predict the formation of compounds.
6. Each valence orbit reaches stability when it has 8 electrons in it, called valence electrons.
7. Because the Noble gases always have 8 valence electrons they are stable and unreactive (inert).
8. All other groups on the periodic table want 8 valence electrons. This is the only reason they are reactive. They will react with each other to form bonds that enable them to achieve 8 valence electrons. This is the reason for chemical reactions.

 

 

THE OCTET LAW

All elements, except the noble gases, react with other elements in order to have 8 electrons in their outer, or valence, shell/orbit.

 

 

REACTIVITY OF THE GROUPS

 

      GROUP ONE:  has one valence electron, which it wants to lose to fall back on an inner full orbit of 8. Oxidation number is +1. Very reactive.

 

      GROUP TWO:  has two valence electrons, which it wants to lose to obey the octet law. Oxidation number is +2. Less reactive than group 1.

 

      GROUP THREE: has three valence electrons which it loses to obey the octet law. Oxidation number is +3. Less reactive than groups 1 and 2.

 

      GROUP FOUR: has four valence electrons which it shares with other atoms to reach the 8 valence electrons. Least reactive group.

 

      GROUP FIVE: has five valence electrons which means it acquires 3 electrons to obey the octet law. Oxidation number of -3. Not very reactive.

 

      GROUP SIX: has six valence electrons which means it acquires 2 electrons to reach 8. Oxidation number is -2. More reactive than group five.

 

      GROUP SEVEN: has seven valence electrons which means it need 1 electron to obey the octet law. Oxidation number is -1. It is very reactive.

 

 

VALENCY

 

// the number of electrons an element must either give/take/share in reactions in order to obey the octet law.

Group 1: 1                                      Group 5: 3

Group 2: 2                                       Group 6: 2

Group 3: 3                                       Group 7: 1

Group 4: 4                                       Group 8: 0

 

 

 

 

OXIDATION

Bonding of substance to oxygen

      Loss of electrons

      Increase in oxidation number (becomes positive – because electrons are lost)

      Loss of hydrogen ions

 

 

REDUCTION

      Loss of oxygen

      Gain of electrons

      Decrease in oxidation number (becomes negative – because electrons are gained)

      Gain of hydrogen ions

 

 

THE STABLE ION of an atom is the atom with either the addition of electrons (anion) or loss of electrons (cation) that it would go through within a chemical reaction in order to satisfy its need to obey the octet law. The Bohr-Rutherford is drawn with these electron changes and hence the atom will have a charge.

 

 

CONTROLLING CHEMICAL REACTIONS

 

All reactions take place at different speeds. The RATE OF THE REACTION is the speed at which a reaction takes place.

 

Some reactions occur quickly e.g. a match burning.

Others take time e.g. a car rusting.

 

Reactions occur when molecules collide with each other. If the collision is hard enough (an effective collision) and fast enough, the molecules will come apart and atoms will combine to form new molecules.

 

COLLISION MODEL:  the rate of a reaction is affected by the number of effective collisions that occur between the reactants.

 

FACTORS AFFECTING CHEMICAL REACTIONS

 

There are three factors:

1.     TEMPERATURE: Most reactions occur at higher temperatures. The higher the temperatures the greater the kinetic energy or movement speed of the molecules. The reason for this is explained by Kinetic molecular theory: particles are always moving and they move faster at higher temperatures.

As molecules move faster, they collide more often. There is more chance for reactions to occurs.

 

2.     CONCENTRATION: Increasing the concentration of a reactant increases the rate of the reaction. This happens because when more molecules are packed into a smaller space, there will be more collisions with other molecules. Increased collisions means increased rates of reaction.

 

3.     SURFACE AREA: surface area is the amount of area that is able to react. For example the surface area of a whole orange is the outer peel. Cutting it in half increases the surface area to the peel and the cut surface. Decreasing the size of the pieces of a reactant increases the surface area for contact and increases the rate of the reaction. Increasing the number of particles that are able to react allows more collisions to occur. Increasing collisions increases the rate of the reaction.

 

 

LAW OF THE CONSERVATION OF MASS

 

//A chemical equation: summarises what happens to substances during a chemical reaction.

 

There are two very important scientists work done at the turn of the 19^th century:

ANTOINE LAVOISIER’S LAW OF THE CONSERVATION OF MASS

//during a chemical reaction the total mass of the reacting substances (reactants) is always equal to the total mass of the resulting substances (products).

 

DALTON’S ATOMIC THEORY:

1. All matter is made up of small particles called atoms
2. Atoms cannot be created nor destroyed, or divided into smaller particles.
3. All atoms of the same element are identical in mass and size and are different in mass and size from the atoms of another element.
4. Compounds are formed when atoms of different elements combine in fixed/definite proportions.

 

 

BALANCING CHEMICAL EQUATIONS

 

The number of atoms is conserved. This is not the same as saying that the concentration of the reactants is equal to the concentration of the products - even when there is chemical equilibrium (the rate of the forward reaction equals the rate of the reverse reaction).

 

1.      Write the word equation for the reaction

Iron + oxygen à magnetic iron oxide

2.      Write the skeleton equation by replacing each name with a correct formula

Fe + O₂ à Fe₃O₄

3.      Count the number of atoms of each type in reactants and products and record in a table

Type of atom	reactants	products
Fe	1	3
O	2	4

4.      Multiply each of the formulae by the appropriate coefficients to balance the number of atoms. Balance polyatomic ions first. Then balance all atoms other than oxygen and hydrogen. Balance oxygen. Then balance hydrogen.

3Fe + 2O₂ à Fe₃O₄

 

THERMODYNAMICS

EXOTHERMIC AND ENDOTHERMIC REACTIONS

 

//exothermic: energy is released in the reaction. This refers to the release of bonding energy or enthalpy (-DH). Enthalpy is the total potential energy in the environment and is mainly bond energy.The reactants contain more energy than the products.  Example: burning fuel, rusting iron, and explosion, firework releasing light and sound.

 

//endothermic:  reaction requires the addition of energy to cause a chemical change. It again refers to bond energy or enthalpy (+DH). The reactants contain less energy than the products. Example: electrolysis.

 

NOTE: A change of state (physical change) can also be exothermic or endothermic e.g vapourisation of water is endothermic, condensation is exothermic.

 

//Activation energy: the amount of energy needed to start a reaction. Molecules need a specific amount of kinetic energy to react, whether it is an exothermic or endothermic reaction (see www.blinn.edu )

 

//First law of thermodynamics/law of the conservation of energy: the mass of energy in the universe is constant. Energy cannot be created or destroyed, only converted from one form to another or borrowed. This could be chemical bond energy.

Energy is needed to break bonds, and energy is also released when new bonds form. The difference between the energy absorbed in breaking bonds and the released energy of new bonds determines whether the reaction is exothermic or endothermic.

Most chemical reactions are exothermic.

 

CLASSIFICATION OF REACTIONS

 

There are five types of reactions: synthesis, decomposition, single-displacement, double-displacement, and combustion reactions.

 

Read through the notes on this: p139-140 course pack.

 

1. Synthesis Reaction (combination or addition reactions)

·        Two or more reactants combine to form a new product

·        A general equation can represent this synthesis reaction

X + Y à XY

·        Reactants are usually elements

·        Example: 2H₂(g) + O₂(g) à 2H₂O(l)      -DH

(exothermic – energy from chemical bonds)

·        Atmospheric pollution: N₂(g) + O₂(g) à 2NO(g)  +DH

(endothermic. Car engines provide the heat for the reaction to form the nitric oxide). This is then followed by another synthesis reaction:

2NO(g) + O₂(g) à 2NO₂(g) nitrous oxide, a reactive brown gas that forms a smelly brown haze over cities in summer.

 

2. Decomposition reaction

·        A compound breaks down into two or more simpler compounds or elements

·        Opposite of a synthesis reaction

·        A general equation can represent this decomposition reaction

XY à X + Y

·        Example: electrolysis of water: 2H₂O(l) à 2H₂(g) + O₂(g)  +DH

(endothermic: requires high temps, but photosynthesis achieves this through the use of enzymes)

·        The fizz of carbonated drinks is created by dissolving CO₂(g) in H₂O(l) to form aqueous carbonic acid: CO₂(g) + H₂O(l) àH₂CO₃(aq)

When the bottle is opened, the decreased pressure above the liquid causes a decomposition reaction in which the CO₂ leaves the liquid as bubbles:

H₂CO₃(aq) à CO₂(g) + H₂O(l)

·        Sodium bicarbonate is used to make biscuits rise in the following decomposition reaction:

2NaHCO₃(s) à Na₂CO₃(s) + CO₂(g) + H₂O(g). The gas makes the biscuits rise.

 

3. Single Displacement/Replacement Reactions

·        One element takes the place of /displaces another element in a compound

·        Two general forms:

A + BX à AX + B

AX + Y à AY + X

·        All the alkali metals can displace hydrogen in water in an exothermic reaction:

2K(s) + 2H₂O(l) à 2KOH(aq) + H₂   -DH

·        Alkali earth metals can displace H from an acid, although they are not reactive enough to displace H from water:

Mg(s) + 2HCl(aq) à MgCl_2(aq) + H₂(g)

·        Silver can be recovered from a compound in solution by using copper:

2AgNO₃(aq) + Cu(s) à Cu(NO₃)₂(aq) + 2Ag(s)

·        Single displacement reactions can help to ascertain the reactivity of metals. This is listed in the ACTIVITY SERIES of metals (p87 course pack)

 

4. Double Displacement/Replacement Reactions

 

A double displacement reaction: lead(II)nitrate(aq) and KI combined will produce potassium nitrate and a bright yellow precipitate lead(II)iodide:

Pb(NO₃)₂(aq) + 2KI(aq) à 2KNO₃(aq) + PbI₂(s)

 

In a double displacement, the cations of two different compounds exchange places, forming two new compounds.

 

In a double displacement precipitation reaction, two metals salts dissolved in water react and form a precipitate. For example, when barium hydroxide and sodium sulphate, both colourless, are mixed, a white barium sulphate precipitate is formed, and sodium hydroxide remains dissolved in a clear solution: Ba(OH₂)(aq) + Na₂SO₄(aq) à BaSO₄(s) + 2NaOH(aq)

 

In a double replacement neutralisation reaction, an acid and a base neutralize each other to form a salt and water. For example, sodium hydroxide (drain cleaner)  and hydrochloric acid neutralize each other:

NaOH(aq) + HCl(aq) à NaCl(aq) + H₂O(l)

 

Acids react with carbonates to produce carbon dioxide:

Na₂CO₃(aq) + 2HCl(aq) à  2NaCl(aq) + H₂CO₃(aq) (double displacement)

The carbonic acid decomposes to CO₂ + H₂O

 

Fifth type of reaction: Combustion Reactions

Hydrocarbons and introduction to organic chemistry

 

//Combustion is the rapid reaction of a substance with oxygen to produce oxide compounds. Energy is released in the form of heat and light.

We use mainly fuels in the form of hydrocarbons in these reactions. Gasoline, natural gas, kerosene, and candle wax are examples.

 

What fuels are found in the head of a match?

The head is first dipped in paraffin wax, then a mixture of glue,colouring, a fuel (sulphur)and potassium chlorate, which is a source of oxygen (KClO₃). The tip/striking surface is dipped intoa mixture of glue, a fuel tetraphosphorus trisulphide (P₄S₃) and powdered glass.

When the tip is rubbed on a surface, the friction with the ground glass provides heat that ignites the P₄S₃ which reacts with oxygen in the air:

P₄S₃ + 6O₂ à P₄O₆ + 3SO₂     -DH

This heat causes the KClO₃  to decompose:

2KClO₃ à 2KCl + 3O₂

The heat and oxygen causes the sulphur to catch fire:

S + O₂ à SO₂    -DH

The heat ignites the paraffin wax and combusts it:

Hydrocarbons + O₂ à CO₂ + H₂O   -DH

And this heat combusts the wood of the match.

Most matches today are safety matches which means combustion only occurs if the head of the match is struck on the matchbox cover. The striking surface consists of red phosphorus, powdered glass and glue. Striking the surface converts the red phosphorus to white phosphorus, which can ignite and combust in oxygen.

 

Organic chemistry

Organic chemistry is the study of carbon-containing compounds and their properties. Some carbon containing compounds are not considered organic i.e. CO₂, CO and ionic carbonates. Before synthesis in labs, these were substances made by living organisms. Organically grown today means something completely different: grown without pesticides, composting, no NPK fertilizers, no antibiotics and no steroids.

A hydrocarbon contains only hydrogen and carbon.

 

Number of carbons	prefix	Suffix –ane means only single bonds	Suffix –ene means double bond	Suffix –yne means triple bond	Formula for -anes
1	Meth	Methane	-	-	CH4
2	Eth	Ethane	Ethane	Ethyne	C2H6
3	Prop	propane	Prop-1-ene	propyne	C3H8
4	But		But -2,3-diene		C4H10
5	Pent				CXH2X+2
6	Hex
7	Hept
8	Oct
9	Non
10	dec

 

 

 

 

CANADIAN BIOMES AND THE PLANTS THAT ADAPT TO THEM

 

 

Plants need the right abiotic or physical conditions to grow:

·       Water/rain or precipitation

·       Sunlight

·       suitable temperatures

·       minerals from the soil.

Plants, however, have adapted to a wide variety of abiotic conditions: huge natural areas which present a specific set of abiotic factors that cause certain plants to grow are called biomes.

 

Canada has 5 major biomes

 

CLIMAX COMMUNITY	CLIMATE	ADAPTATIONS
ARCTIC TUNDRA Lichen, moss, grass, herb. Perennials (grow for several seasons)	·        Long cold winters (-32C) ·        Short cool summers (5C) ·        Permafrost and no drainage together with the low temps prevents decomposition of organics and results in a soil of low nutrient density. ·        Low precipitation (<25cm/yr)	·        Low growing plants that are buried in snow in winter. ·        Perennials (live many seasons) that store nutrients in underground stems ·        Evergreens (don’t need to grow new leaves each season) ·        Compact form protects delicate growing tips from cold winds ·        Disc-shaped flowers that orient toward the sun and can have higher temps that attract pollinators.
BOREAL FOREST Coniferous forest of Spruce, Fir and Pine	·        Long cold winters ·        Short warm summers (4 months) 15C. ·        Permafrost and so again little organic decomposition. Many nutrients trapped in mosses. Soil nutrient poor. ·        More precipitation (25-50cm/yr)	·        Evergreens that have needles which can live up to 15 yrs and can photosynthesise over a wide range of temps.  Also needles have thick cuticles, reduced surface area and sunken stomata that reduce water loss. ·        Jack pine cones only open to release seeds after the heat of a fire. The seedling grows on the more nutrient dense soil that occurs after a fire. ·        Birches and poplars can sprout from a burnt stump.
TEMPERATE FOREST Deciduous trees like Maple, Beech, Birch Hemlock (drop leaves), conifers and shrubs, vines, mosses, ferns	·        Shorter winters ·        Warmer summers of 6 months (20C) ·        Still more precipitation (50-75cm/yr) ·        Leaf litter decomposes resulting in rich nutrient dense soils	·        Hardwoods in the north avoid harsh winters by being deciduous (winter dormant). ·        Spring ephemerals sprout from underground stems, and go through their cycles in a short time. They grow in early spring before the trees have foliage that blocks their light.
PRAIRIE GRASSLAND Grasses and mixed herbaceous plants	·        Cold winters and warm, dry summers ·        Soils are deep, and rich in nutrients ·        Frequent fires prevent the growth of trees and favour the grasses.	·        prairie grasses get nitrogen from legumes that have nitrogen-fixing bacteria ·        many grasses are perennials that survive as underground rhizomes in winter ·        leaves and stems are covered in a thick cuticle that reduces evaporation losses ·        leaves can roll into a tube that protects the stomata on the inside ·        roots are high to absorb rainwater quickly before runoff. ·        Leaves and stems grow from the base not the tip of the plant – preventing die-off from grazing animals. ·        Laves have silica grains or bitter phenolic compounds to reduce grazing.
DESERT Succulents, desert ephemerals – desert grasses and daises	·        Less than 20cm of rain a year ·        Hot days, cold nights ·        Unpredictable rainfall ·        Low humidity ·        Sparse vegetation results in little organic matter, dry, rocky land with little soil prone to erosion                                               ·        The rain leaches the abscisic acid, so inhibition stops. ·	·        Leafless succulents that hold water in their stems. Stems adapted for photosynthesis. Thick cuticles and reduced surface areas prevent water loss. ·        Shallow, spreading roots catch water after brief rains ·        Cacti have spines and a bitter taste to stop animals taking their water. ·        Stomata stay closed during the day to prevent water loss. At night, they open and take carbon dioxide from the air and store it in organic acids. In the day, when photosynthesis occurs the carbon can be used. ·        Annual desert ephemerals spend most of the year as dormant seeds. After the rains, they germinate and grow quickly. The seed coats contain the hormone abscisic acid which inhibits growth.

 

 

COMPETITION

 

Competition takes place among species sharing resources. Individual organisms struggle for access to limited resources. The closer the niche is of two different species, the more they will compete for similar resources. No two species can share exactly the same niche. Within a species, the individuals also compete with each other for the same resources. Competition is one (density-dependant) factor preventing population growth.

 

INTERSPECIFIC COMPETITION: is competition between species.

INTRASPECIFIC COMPETITION: is competition among species of the same species.

 

Examples of these limited resources are water, food, space/habitat, mates (intraspecific).

 

ACTIVITY: complete p36-37 of course pack.

 

POPULATION STUDIES

 

Population:// a group of organisms of the same species that exist in the same place at the same time. A species consists of organisms so similar that they can mate and produce fertile offspring.

Changes in population occurs in response to changes in environmental factors such as resources (food, water, habitat), climate, competition, predation and disease.

 

Carrying Capacity: //the largest population of a species that an environment can support.

 

FACTORS THAT DETERMINE AND LIMIT THE SIZE OF THE CARRYING CAPACITY

 

1. Density-dependent factors:

//factors that become significant as the population grows

1. Materials and energy: the supply of water, carbon, essential materials and energy caps the size of a population.
2. Food chains: any population is limited by the biomass in all the trophic levels below it (food supply) and by the trophic levels above it (predation).

ACTIVITY: Read p40-41 and p43 of the course pack on the wolf and summarise the effect changing wolf population size has on the other trophic levels.

3. Competition: the demand for resources like food, water, mates and space for organisms in a similar niche results in interspecific competition (between species) and intraspecific competition (amongst members of the same species).
4. Population density: the need for space varies with species – naked mole rats need to be very dense to stay warm, whilst grizzly bears need territory and live far apart. But for any organism, there comes a point where the density will cause stress, the spread of disease, aggression, decreased fertility and neglect of offspring. Death and birth rates will rise.

 

2. Density-independent factors:

//regardless of numbers of a species, the presence of this factor will limit the population

Examples are climate and weather, temperature, drought, ‘acts of God’, fires and floods, loss of habitat, pollution of air, water and soil.

 

See page 47 course pack

 

Population growth: // [number of births] – [number of deaths] + [number of immigrants] – [number of emigrants] / total population.

In an open ecosystem, all four mechanisms are operating.

In a closed ecosystem, there is no immigration and emigration.

 

A typical population growth is sigmoidal.

See graphs.

 

Biotic Potential: //the maximum number of offspring a species can produce, if resources were unlimited. It depends on gestation and litter size. Any resource that is in short supply is a limiting factor to this biotic potential. 

 

Population explosion:// extremely fast growth. It can occur when a new species is introduced into an ecosystem in which there are few predators, a plentiful food supply and abundant space. Exotic species often do this.

See typical population explosion graph (exponential)

 

Activity:

Complete p 48 of course pack.

 

EXOTIC SPECIES

 

//An exotic organism is one that is not native to an ecosystem. It can migrate into the system naturally or as a result of man’s movements. When it enters an ecosystem it competes with other species that occupy the same niche it has. Because it has few natural predators, it usually out-competes these species, and severely limits their populations and can lead to extinction of local species in these niches.

 

An example of this is the Zebra Mussel

The zebra mussel entered Lake Erie in the early 1990’s. This bivalve came from the Caspian Sea and entered the lakes from bilge water discharged from ships. By 1991 there were extensive colonies in Lake Ontario. By 1995 it was found as far as the Gulf of Mexico.

The mussel blocks water intake pipes from the great lakes, choking hydroelectric plants and freshwater supplies. It has out-competed the pearly mussel that used to occupy its niche. Zebra mussels actually attach to the shells of pearly mussels that form hard surfaces on the mud. Mussels are filter feeders, taking in bacteria and protista and clearing the water of food for other species. This also allows ultraviolet light to filter down to the bottom of the lakes, heating the water and thereby reducing oxygen and  adversily affecting fish like trout that need more oxygen.

 

On the other hand they provide food for ducks and other aquatic birds. Their shells are habitats for snails, aquatic insects, small crustaceans and water mites. Their larvae are the source of food for hydra. Fish that eat the crustaceans also benefit. The mussel clears the ever increasing algae blooms. They remove pollutants from the water. However, the organisms that eat the mussels bioaccumulate these pollutants.

 

The Goby fish, another exotic from the Black Sea, also found its way into the lakes via ballast water. These eat zebra mussels. However, being an exotic, they chase other fish from spawning grounds and eat the eggs of native fish like walleye, perch and small-mouth bass.

 

Another example is the purple loosestrife in marshes in Canada.

There are over 6 billion humans on the planet today. This is largely due to the decline in death rate as a result of better health care, improved sanitation and increased food production. We use plants and animals for many things other than food e.g clothing, tobacco, pets, ornamentation, housing, furniture, paper, technology.

Humans also affect ecosystems indirectly – we burn forests, drain wetlands, pave cities, highways, golf courses, parks, flood land for dams, overgraze and plant monocultures. All this has reduced diversity, reduced the plant biomass, created deserts. Our consumption decreases the amount of energy available for other organisms. Human use, conversion and diversion of the earth’s biomass exceeds 20%.

 

HOMEWORK:

p37 McGH #14-15

P34 McGH #1-7

 

 

 

 

THE SCIENTIFIC METHOD

 

1. The independent variable is the factor in the experiment that is manipulated by the researcher.

 

2. The dependent variable is the factor in the experiment that changes in response to the independent variable. It is the outcome or effect.

 

Remember that

·        both the independent and the dependent variables have to be measurable variables i.e. the variables in an experiment have to be testable.

·        A hypothesis is a testable prediction or educated guess on the outcome of the experiment. It really doesn’t matter if this is the final outcome of the experiment – a rejection of a hypothesis does not mean the experiment has failed. The outcome is valid in its own right – the hypothesis was just a guess.

 

3. The interfering variables are all the factors that could effect the relationship between the independent and dependent variable. Because we are trying to measure the relationship between these latter two variables, it is important to control the interfering variables.

 

• Interfering variables are controlled in two ways:

(i)                  By inclusion and exclusion criteria. These are choices made right at the start as to who/what will be accepted into a study and who/what will not. These choices are based on the interfering variables identified, which then become part of what is excluded from the study.

(ii)                By using study and control groups. A study group is the group that gets the manipulation and the control is the group that does not. The initial sample subset taken from the population is randomly assigned to one or the other group. In this way it is hoped that the two groups will be the same, and that the same interfering variables are present to the same extent in both groups. If this is achieved there should be no measurable differences between the two. The manipulation is then applied only to the study group. If the two groups are compared with each other, it is logical to assume that any measurable differences between them would have to be due to the manipulation and none of the interfering variables. In this way, the interfering variables have been controlled in that they do not affect the outcome.

 

REMEMBER: We are trying to measure the relationship between the independent and dependent variable, and keep any other variables from getting in the way of this.

 

4.There are many inherent weaknesses in study design:

(i)                  We cannot control all variables. Many times we don’t know all these variables. We cannot screen them all out, and if we use control and study groups we can never be sure if they are the same in all respects and that some bias hasn’t crept into the experiment.

(ii)                The more we control the variables, the less like life it becomes. This becomes a problem when we extrapolate our findings back to the entire population. However, the more we control variables, the more confident we are in any association we see between the independent and dependent variable. This is the catch-22 of research.

(iii)               All experimentation is ultimately subjective. It is also influenced by the society and the age within which that work was done.