Experimental Design

Propose experimental designs by which the rate of enzyme function can be measured and studied.

The rate of enzyme function can be measured and studied by having an enzyme catalyze reactions in different temperatures, in different pH, in different concentrations of substrates, etc. to see how the enzyme functions if one variable is changed slightly. These are all variable that impact an enzyme’s productivity, so picking any one of these variables ]or some other variable that impacts enzyme functioning] and modifying it slightly as you measure the change in productivity can help study the rate at which an enzyme functions. Depending on the enzyme and variable used/ manipulated, different equipment will be needed for the experiment. If I were measuring the rate of enzymatic activity in different pH, I would need to add acid or base to an enzyme in it’s natural environment, then measure the change in time, or change in production of the product.

Demented PAC-MAN and Competitive Interactions

Describe how enzyme-mediated reactions can be controlled through competitive and noncompetitive interactions.

The following is a helpful little video that explains competitive and noncompetitive interactions through animation:

Enzymes are Serial Huggers

Describe the relationship between the structure and function of enzymes.

Substrates are reactants that attach to enzymes, and detach as a product of the reactants. The structure of an enzyme dictates what reactants it can help catalyze. When reactants enter and bond with an enzyme, the enzyme will reshape itself slightly around the substrate, to create a more snug hold. This allows the reactants to be in very close proximity, forcing the reaction to run faster.

Traffic Jam on Metabolic Lane

Explain how enzymes accomplish biological catalysis.  Provide examples.

Enzymes are reusable catalysts that speed up metabolic reactions. Without enzymes, metabolic reactions would take so long that an organism would not receive the needed substances fast enough. There would be a build up of reactions waiting to occur because the amount of time and energy needed to reach the activation point wouldn't be available. Imagine having to wait hours for painkillers to kick in when you have a raging headache. Sounds fun! Enzymes speed up chemical reactions by lowering the activation energy needed for products to form. This allows molecules involved in the reaction to absorb more energy in lower temperatures, causing the reaction to again enough energy to form products more quickly. Take a look at the figure below: it shows how substrates and enzymes work to lower the activation energy.

Mastering Biology | Pearson; Campbell Biology

Enzyme Environmental Conditions

Analyze data showing how changes in enzyme structure, substrate concentration, and environmental conditions (pH, temperature, salinity, etc.) affect enzymatic activity - ie. include a graph of each example and predict the effects when one of the parameters is further changed.

Justify and explain your predictions.

Enzymes have ideal states of pH and temperature in which they have optimal enzymatic activity. If an enzyme is placed in an environment in which the pH or temperature is not ideal, the rate at which it functions will be altered. Take a look at the graphs below. If a typical human enzyme was placed in a thermophilic bacteria, the human enzyme would be inactive and possible become denatured. Why? Because the optimal temperature for the enzyme to activate is around 37 degrees, anything past 50 degrees is too high and the enzyme can become damaged because it is not in an environment in which it can survive. Same goes for pH with pepsin and trypsin. They cannot exchange locations and be expected to function because they are only stable and functioning in their own environment.

Mastering Biology | Pearson; Campbell Biology

Energy Coupling Reactions

Explain the key role of ATP in energy coupling reactions. Provide a model showing energy before and after phosphorylation of the reactants.

Energy coupling is the process of using the energy released from exergonic reactions to drive endergonic reactions. ATP is not only a cell’s main source of power, but also responsible for energy coupling reactions. Energy is stored in the bond between the third and second phosphate in ATP, and when this bond is broken by hydrolysis [catabolic reaction], energy is released. This energy could be used to facilitate all sorts of cellular work, such as stimulate a potassium-pump to run[anabolic reaction].

Exergonic and Endergonic Reactions

Compare and contrast Exergonic and Endergonic reactions - include a model of each showing the change in free energy from reactants and products.

Exergonic - Catabolic reactions. They break down substances and require no energy, so they are able to occur spontaneously. The change in free energy in these reactions are negative because the reactions break DOWN to create products.

Endergonic - Anabolic reactions. They build up substances and require energy to do so. As a result, these reactions can only occur when energy is available. The change in free energy in these reactions are positive because reactants work UP to create a product.

Lil' Plant Cell

Create a visual representation/model (ie. graph or diagram) to make predictions about the exchange of molecules between an organism and its environment, the use of these molecules (ie. CHNOPS and incorporation into carbohydrates, proteins, lipids, nucleic acids, membrane structure, genetic information, etc.), and consequences to the organism if these molecules cannot be obtained.

Take a plant cell and put it in an isotonic solution. Take an animal cell and put it in the same isotonic solution. Which one is happier? The animal cell! [Take a look at ‘-tonic’ under Ch 7 yo understand why] With this in mind, understand that the plant cell is somewhat soft and limp because it is not in the ideal state of absorbing water and water soluble molecules, such as carbohydrates. The plant cell is not retaining the full amount of molecules it needs to be efficient at providing energy and structure to the whole plant. If this continues, and the solution changes to become a hypertonic solution, there will be no water retained in the plant cell, and it will become very limp and quite squishy. As a result, it will have a hard time creating energy and providing structure to the plant. If all plant cells end up like this within a plant, the plant may rot and die from lack of water.

Endo- and Exo- -cytosis

Describe the processes of endocytosis and exocytosis. Propose a model illustrating each process.

Endocytosis is the process of a cell taking in macromolecules by forming a vesicle around the substance with its own cell membrane. Exocytosis is the expulsion of material as a vesicle within a cell travels outwards and fuses with the membrane, opening up and ejecting the substances it was carrying.

http://ibbiology.wikifoundry.com/page/Explain+how+vesicles+transport+materials+within+a+cell

Active Transport

Describe active transport. Propose a model illustrating this process.

Active transport is the opposite of passive transport, in the way that active uses ATP to transfer material through a membrane whereas passive does not. This is the movement against the concentration gradient. Because substances are moving against the grain, they need extra help, an extra push. Proteins studded throughout the membrane facilitate this process. This is an important process because it helps cells work towards equilibrium, even when the surrounding environment is not the proper tonicity for a cell to maintain equilibrium. Please see ‘Glucose and Na+/K+ Transport’ under Ch 7 for an explanation of the sodium-potassium pump which is depicted below.

http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ce/m3/s5/

Glucose and Na+/K+ Transport

Explain how membrane proteins play a role in facilitated diffusion of charged and polar molecules in general and in relation to the specific molecules below.

Glucose transport: These transport proteins are integral membrane proteins that allow glucose to pass through the hydrophobic [glucose is a hydrophilic polar molecule] regions of a cell membrane by creating a polar pathway for the molecule to pass through.

Na+/K+ transport: The sodium-potassium pump is activated by ATP and pumps two K+ ions into the cell as three Na+ ions leave the cell. The following link will take you to a very helpful and informative animation that is followed up with a mini quiz.

http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html

Passive Transport

Describe passive transport and explain its role in cellular systems

Passive transport is the movement of substances across a membrane without the expenditure of energy. Diffusion, facilitated diffusion, filtration, and osmosis are examples of passive transport. In cellular systems this is a very important action, because all ATP created by a cell is very precious, the more it can reserve and use for other purposes, the better. Essential substances such as lipids, water, oxygen, and small monosaccharides can pass through via passive transport and give the cell the materials it needs, without causing it to work overtime for it. Water, for example, is a very important substance in all cells. [See ‘-tonic’ under Ch 7 for more details on the importance of water in cells] Because water can diffuse in and out of cells passively, a cell is able to maintain its internal environment without exerting too much energy.

-tonic

Explain the terms: hypotonic, hypertonic or isotonic in relationship to the internal environments of cells. Illustrate each environment with a model and explain which environment is best for plant and animal cells. Justify and explain your model with evidence.

Hypotonic - Cells expand in this environment, because there is less solute outside the cell than there is inside. In an attempt to reach equilibrium, the fluid outside the cell will enter the cell to even out the solute-to-volume ration. This causes cells to swell because there is more fluid within the cell than there usually would be, there is more volume. This can cause animal cells to burst, [lysed] as they do not have cell walls to provide a hard casing. Plant cells love hypotonic solutions because they are able to fill up their vacuoles and internal environments with water and other substances. This gives plants structure and rigidity [turgid].

Hypertonic Solution - Cells shrivel up in this environment, because there is more solute outside the cell than there is inside. In an attempt to reach equilibrium, the fluid within the cell will exit and flow outside, to even out the solute-to-solution ratio. This causes cells the shrivel up because there the fluid that once gave the cell structure is now gone. In animal cells, this is called a shriveled cell. In plant cells, this is called a plasmolyzed cell.

Isotonic - Cells are at a normal state, the amount of solute outside and inside the cell is even. Animal cells and plant cells are both gaining and losing water in this state. This is the ideal state for animal cells; a constant exchange with the environment. But, this is not the ideal state for plant cells. Plant cells do not want to have a constant exchange of water, they want to retain water. If they are unable to retain water, plants will be limp.

Mastering Biology | Pearson; Campbell Biology

Chloroplasts and Mitochondria

Explain the structure and function relationships between chloroplasts and mitochondria

Chloroplast converts sunlight into energy, and mitochondria break this energy into cell-friendly ‘food’. Chloroplasts are harvesters, mitochondria are utilizers.

Relate structural and functional evidence in chloroplasts and mitochondria to the endosymbiotic theory of their origins.

Structural Evidence: Both have their own DNA, and have a double membrane

Functional Evidence: They can move on their own without instruction from the nucleus, and also divide on their own without instruction.

Conclusion: These organelles were once prokaryotic cells that were engulfed by a eukaryote. The eukaryote decided to utilise their functions to help itself and let them be.

To learn more about these two topics, watch this video that has an strange robotic-male voice over. Truly though, this is a very informational video.

Teamwork

Explain how several internal membrane-bound organelles and other structural features (e.g., ER, ribosomes) work together to provide a specific function for the cell (e.g., synthesis of protein for export) and contribute to efficiency (e.g., increasing surface area for reactions, localization of processes).

The endomembrane system consists of the movement of material between the membranous vesicles of a cell. [Nuclear envelope, smooth and rough ER, Golgi, lysosomes, vesicles, and vacuoles]Here, the rough ER and its ribosomes work together to synthesize proteins. The information to create these proteins comes from the nucleus via the nuclear envelope. The rough ER sends these proteins to the golgi, where they are packaged and sent to various locations within the cell to be digested [lysosome], stored [vacuoles], or function within the cell membrane.

https://en.wikipedia.org/wiki/Endomembrane_system

Basic Structure and Functions of Key Organelles

Describe the basic structure and functions of key cell organelles (nucleus, Golgi, ER, mitochondria, chloroplast, vacuoles, plasma membrane).

Nucleus - Houses the genetic information [DNA] of the cell. This is a circular structure usually located in the center of a cell, it is made of chromatin [tightly wound up DNA]

Golgi Apparatus - Modifies, stores, and reroutes materials sent over from the ER. This is a sort of wavy structure (which is located near the ER and nucleus) that is made of membranous sacs stacked up on top of eachother.

Endoplasmic Reticulum - Two kinds:

Smooth ER - Synthesizes lipids, metabolizes carbs, detoxifies drugs/poisons, and stores calcium ions [in Lumen]. It is more tubular than the rough ER and located throughout the cytoplasm.

Rough ER - Folds [in Lumen], assesses the quality of [also in lumen], and packages/reroutes proteins. This is a convoluted flat sac that is continuous with the nuclear membrane. Most of these are located around the nucleus as a result.

http://www.buzzle.com/articles/smooth-endoplasmic-reticulum-function.html

Mitochondria - Generates ATP and is the main power provider of a cell. This organelle has a double membrane, the inner membrane has many folds called cristae which function to produce ATP.Fun Fact: Mitochondria can trigger cell death by releasing certain enzymes.

Chloroplast - Double membraned plastid cell; this organelle is only found in plant cells and is the site of photosynthesis. It converts light energy into ATP. These organelles are green in color because of the green chlorophyll they contain, and have stacks of thylakoids that capture sunlight and convert it into usable power.

http://www.nature.com/scitable/topicpage/plant-cells-chloroplasts-and-cell-walls-14053956

Vacuoles - These organelles are mostly storage units. They store wastes [and also dispose of wastes], excess material, proteins, pigment, and also defensive compounds. They are usually bubble-like structurally and larger in plant cells than in animal cells, to provide structure and rigidity.

Plasma Membrane - A semipermeable membrane that functions as a barrier between the inside and outside of a cell. This regulates what enters and exits the cell.

SA:V Again!

Represent graphically and explain the relationship between surface area to volume ratios as it relates to the efficiency of cellular work.

Please see ‘SA:V and its Impact’ under 2.A.3 for more details on surface area to volume ratios.
This lab information may further explain the relationship between surface area to volume ratios.

"Why don't Cells Grow Indefinitely?" Lab

[from left to right] cell with length of 4, 2, or 1 unit(s) filled with sand to measure the mass of this cell, AND to calculate the surface area

Prokaryotic v Eukaryotic

Compare and contrast the structure of Prokaryotic and Eukaryotic cells - be sure to include a discussion regarding the cellular organization of each.

Prokaryotic cells are single-celled organisms such as bacteria. Eukaryotic cells typically make up multicellular organisms, such as plants and animals, but can also be single-celled organisms like algae. The main difference between the two is that how a prokaryotic cell stores its genetic information and its “organelles”. Eukaryotic cells have a cell membrane, membrane bound organelles, and linear DNA. Prokaryotic cells have a cell membrane, but the similarities stop there. There are no membrane bound organelles and the DNA is of the circular variety. While both cells have genetic material, this material is stored differently. Eukaryotic cells have a nucleus covered by a double membrane [nuclear envelope] that regulates the movement of material in and out of the nucleus. Prokaryotic cells only have a nucleoid, a region in which all the DNA clumps together. Prokaryotic cells also lack certain organelles that only eukaryotic cells have, such as mitochondria, lysosomes, peroxisomes, endoplasmic reticulum, and Golgi Apparatus. There are more cellular structures that are not found or rarely found within prokaryotic cells. Overall, the cellular organization of prokaryotic cells are more primitive and simplified than that of eukaryotic cells.

https://www.thinglink.com/scene/507555562901209089

Structure Imparts Function

Justify how structure imparts function for key biological molecules (DNA, RNA, lipids, carbohydrates, proteins, ATP) and cell organelles (nucleus, Golgi, ER, mitochondria, plasma membrane chloroplasts, vacuoles) and describe how they interact in key biological processes.

DNA - allows for genetic information to be passed on

RNA - carries out instructions found in DNA

Lipids - protects, provides structure, stores energy

Carbohydrates - stores energy, provides structure

Proteins - storage, transportation, identification, communication, structural support,

ATP - energy to drive reactions

Nucleus: Housing for DNA; allows RNA to come and go as it gathers instructions from DNA

Golgi Apparatus: Processes and packages lipids, carbs, and proteins

Endoplasmic Reticulum: Protein and lipid synthesis within cells; studded with ribosomes [Protein manufacturing bits that read code off of mRNA]

Mitochondria: Powerhouse of the cell, uses carbs to produce ATP

Plasma Membrane Chloroplasts: Convert sunlight into ATP or carbs

Vacuoles: Stores extra material, mostly water; gives plant cells structure and support

http://biology.tutorvista.com/animal-and-plant-cells.html

http://biology.tutorvista.com/animal-and-plant-cells.html

Basic Structure and Functions of Key Biological Polymers

Describe the basic structure and functions of key biological polymers (DNA, RNA, lipids, carbohydrates, proteins).
Okie dokie! I have covered all this material, but it is scattered throughout 4.A.1 
Please take a look at ALL the previous posts under this tag.

Directionality

Explain how directionality influences structure and function of the following polymer:

Nucleic acids - Sugar phospate backbone with a 3' end and 5' end. This is the "backbone" of DNA and RNA

Protein - side chain R group determines structure, and this forms the protein

Carbohydrates - See ‘Really Tiny and Cool Legos ’. Carbohydrates are made up of polysaccharides.

Starch v Cellulose

Why is starch easily digested by animals, while cellulose isn’t?

Starch is made of alpha glycosidic linkages [Helices], whereas cellulose is made of beta glycosidic linkages [Pleated sheets]. Animals digest sugars such as starch through hydrolysis [see ‘Magical Water’], but cellulose is an insoluble fiber. Animal bodies do not have the enzyme to break down cellulose, so herbivores such as cows use microbes to break down this fiber.

https://www.studyblue.com/notes/note/n/biology-unit-one/deck/1133991

Lipids

Explain how the structure of lipids determines the polarity of the molecule. If the chemistry of water occurs in aqueous solution, why are lipids useful in biological systems?
Lipids are made up of hydrocarbons. Hydrocarbons form nonpolar covalent bonds, so as a result lipids have little love for H20. So, this makes lipids nonpolar. Water does not mix with lipids because water is nonpolar, and lipids are polar. Only like mixes with like. But, Lipids are still very useful because they protect organs and add cushioning to the body. Lipids also give cells structure and shape. And most importantly, lipids can store energy.

Denaturation of Proteins

Explain how the conditions of the environment that a protein is in effect the structure and function of that protein.

Physical conditions, chemical conditions, pH, salt concentration, temperature, and various other environmental factors can cause the denaturation of a protein. Denaturation is the loss of a protein's structure, as it has unraveled from the shape it should be in. Chaperonin refold denatured proteins[polypeptide] by creating a hydrophobic environment.

http://image.slidesharecdn.com/ch-5-proteinsandnucleicacids-120908140021-phpapp02/95/ch5-proteins-and-nucleic-acids-25-728.jpg?cb=1347112945

Protein Structure

Explain how the sequence of amino acids in a protein determines each level of that protein’s structure.
See proteins under ‘Really Tiny and Cool Legos’ Primary structure is what influences and determines the complexity of a protein, because primary structure is what all the other structures build upon. [side note, the source I got this picture from seems really shady.. but I really liked the picture. If you try to go to the source, use caution]

http://www.mhhe.com/biosci/pae/botany/uno/graphics/uno01pob/vrl/

RNA: Single and Ready to Mingle

How do the differences in the structure of DNA and RNA contribute to the difference in the functions of those molecules?
The main difference between DNA and RNA is that DNA is double stranded, and RNA is single and can twist to connect to itself. Also, RNA replaces thymine with uracil [see ‘Nitrogen’s Purpose’ under 2.A.3]. The difference in their functions are explained in ‘Really Tiny and Cool Legos’.

More DNA

Why is DNA a good molecule for information storage?
DNA can be wound up to be very, very, VERY, compact. As a result, it can hold an enormous amount of information. Through the use of nitrogenous bases [see ‘Nitrogen’s Purpose’ under 2.A.3], the code written in DNA can be detailed and precise; one DNA molecule includes many genes. DNA also provides instruction for its own replication, so this allows for information to be duplicated as well as stored.

DNA

How does the structure of DNA contribute to its roles in protein synthesis and heritability?
The linear nucleotide sequence in DNA is passed down from parent to progeny. Offspring will typically have 50% of each parent’s DNA.The more closely related species are, the more similar their DNA is. For more information on DNA see Nucleic Acids under ‘Really Tiny and Cool Legos’.

Krill-pocalypse

Predict the effect of a change in one of the components on the interactions within the community and matter and energy flow.
Taking a look at this very crisscrossed food web, I’m going to take a wild guess here and say that krill is a very important part of it. 

Everything is very centered around krill, and it is near the bottom, so it is very important in the trophic level. If humans suddenly began to consume krill in mass quantities, large scale krill fishing could deplete this ecosystem’s supply of krill. This would negatively impact every consumer preying after krill [or preying after something that preys after krill, etc.], because their food source is suddenly gone. It could imbalance the ecosystem, or even lead to mass extinction.

http://theliquidearth.org/2013/10/page/2/

Really Tiny and Cool Legos

How does the structure of [polysaccharides, proteins, nucleic acids] influence the function of those molecules?

Polysaccharides - Structure and function is determined by the position of glycosidic linkages within the macromolecule, and the monomers that are present. Polysaccharides function as a means of sugar storage, or are used as building material. A storage polysaccharide would be starch, which can be found in foods like potatoes, bread, and pasta. A structural polysaccharide would be cellulose, which is fiber. Fiber can be found in many vegetables, it helps plant cells keep their rigid shape.

Proteins - There are four structures proteins can form: Primary structure is the sequence of amino acids in DNA, secondary structure forms hydrogen bonds, tertiary deals with hydrophobic interactions, and quaternary forms a transport protein like hemoglobin. There is a vast diversity of protein structures, so proteins have various functions. Protein functions include storage, transportation, identification, communication, structural support, defense against foreign substances, and more. Membrane proteins [cellular adhesion molecules] can determine how a cell will interact with others. This is what helps white blood cells move to an injury site within the body.

Nucleic Acids - There are two types of nucleic acids; deoxyribonucleic acid [DNA], and ribonucleic acid [RNA]. DNA provides instructions for its own replication. It’s like a blueprint for proteins that need to be made to create an organism. DNA is a double stranded double helix, and RNA is a single strand. DNA holds the information, while RNA actually carries out the instructions.

If you think about it, all of this stuff is just a bunch of tiny building blocks. A bunch of very tiny legos.

The Mitochondria is the Powerhouse of the Cell

Where does the energy needed to drive the synthesis of biological macromolecules come from?
The mitochondria is the powerhouse of the cell. This powerhouse generates ATP [adenosine triphosphate] which is used as energy to drive the synthesis of forming macromolecules.

http://hyperphysics.phy-astr.gsu.edu/hbase/biology/mitochondria.html

Magical Water

Compare the synthesis and decomposition of biological macromolecules.

Dehydration Synthesis - subtraction of a water molecule when two monomers come together to form a bond [synthesis of a polymer]

Hydrolysis - addition of a water molecule to break apart a polymer into two monomers [decomposition of a polymer]

Destructive Human Activities

Provide examples to demonstrate how human activities have impacted ecosystems on local, regional, and global scales. Describe the causes, and effects of these impacts, and discuss possible avenues of mitigating these impacts.

Humans have caused chaos and wrecked havoc over the minuscule amount of time we have inhabited Earth. We have destroyed forests, polluted bodies of waters, driven animals to extinction, created massive amounts of imperishable trash, and more. This is all from our production of various products and having no regard for the safety of the environment we live in. We overuse paper packaging and kill thousands of trees in the process. We add chemicals and microbeads to beauty products that will later pollute oceans. We pump chemicals into the air from massive factories to make sure the supply of products keeps up with the demand. Take a look at China, the amount of pollution the country produces is visible from space.

http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=84530&eocn=home&eoci=nh

The air is so toxic, in many parts of China people wear face masks in an attempt to filter the air. If humans are having difficulty breathing and processing this adulterated air, just image how vegetation is fairing in such an environment. This image shows vegetation that has been infected by chemicals from a nearby factory.

http://www.theguardian.com/world/2014/feb/25/china-toxic-air-pollution-nuclear-winter-scientists

What can be done to mitigate these impacts is not very simple, nor is it very easy. As a world, we must collectively work to be more environmentally friendly and use renewable resources for energy, such as wind power. Pollution can be reduced by using electrically powered devices and weaning off of the use of fossil fuels and coal. We must also dispose of toxic chemicals and matters properly, so we do not infect the environment with poisonous substances.

The Dead and The Gone

Provide examples of species that have been driven to extinction by human activities.
West African Black Rhinoceros - 2011
Poaching and hunting killed off this species. Their horns were coveted pieces from which ornaments, jewelry, and so called medicines were made from.

http://earthfirstjournal.org/newswire/2013/05/07/western-black-rhino-declared-extinct/

Tasmanian Tiger - 1936 
Died off because their land was taken away from them by settlers, and they were hunted and sold for quite a bit of money.

http://animalstime.com/tasmanian-tiger-facts-tasmanian-tiger-habitat-diet/

Guam Flying Fox - 2008

Hunted to extinction because they were considered a delicacy.

http://www.petermaas.nl/extinct/speciesinfo/guamflyingfox.htm

Trophic Structure

Explain how modeling of the trophic structure of an ecosystem can be used to make predictions about the effects of changes in biotic and abiotic factors on that ecosystem.

Trophic structure shows the transfer of energy from organism to organism ‘Movement of Energy and Matter’ has a trophic chart that shows the transfer of energy in a food chain. Monitoring a trophic structure, ecologists can predict changes by observing minute alterations in the transference of material/energy from abiotic factors to biotic factors, as well as the transference of energy between primary consumers and onwards.

Herbivores: Predators of Vegetation?

Describe the major interactions among organisms in a food web.
Major interactions in food webs are those of omnivores, carnivores, herbivores, etc. each of these consumers is a predator [if you think about herbivores as predictors of vegetation, although vegetation cannot really be preyed upon] and sometimes also prey. The main interactions would be who eats who, and where. Because food webs are so complex and crisscrossed, it is important to understand how major interactions play out, such as the order in which consumers consume or are consumed.

Geometry and Food Webs and Food Chains - Oh my!

Compare food chains and food webs.
In a geometry class, you may have heard of the phrase “A rectangle is a square, but a square is not a rectangle” This concept applies to food chains and food webs. A food web is really just a mass of food changes organized together. So a food web includes many food chains, but a food chain is very simple. This visual aid may help better clarify the difference between the two.

http://www.majordifferences.com/2013/02/difference-between-food-chain-and-food.html#.Vg29zflViko

A food chain is a linear process, showing how energy is transferred down the line. A food web is more helter-skelter showing different possible paths of energy transfer. 

Rain Forest in Antarctica

Explain how changes in climate can influence primary productivity in an ecosystem.

The main climate factors that influence primary productivity in an ecosystem are temperature and moisture. So if we were to take a look at the primary producers of a rain forest, it would be easy to conclude that these plants thrive on moisture and heat. Now if we were to take away those factors, and say, drop this rain forest in an arctic tundra, the plants are no longer in the climate they require for full production. This will result in low productivity as plans begin to die off, and eventually all the plants will die because rain forest vegetation cannot survive frigid conditions. Essentially, the important thing to know about climate change and primary productivity is that any changes that pull away from the normal climate, will usually have a negative impact on the primary productivity since the vegetation is not receiving the right amount of heat or moisture.

Movement of Energy and Matter

Describe how ecosystems provide organisms with their energetic and matter requirements.

Energy enters the ecosystem through sunlight. Plants (Primary producers) absorb 10% of sunlight, and from there on, 10% of the energy is transferred to the next consumers. So in this example, sunlight is 1,000,000 J and the energy/matter passed on decreases the higher up a consumer is.

Mastering Biology | Pearson; Campbell Biology

Energy, unlike matter, is not recycled and as a result much energy is lost the further up a food chain you go. To see how matter is recycled, see 'Key Building Blocks and Wastes' under 2.A.3