Prelim Notes on Cell Biology PDF

All bio notes Cell basics What does the cell theory state? That all living things are composed of cells, and that all cells are produced from pre-existing cells How has humankind gained our knowledge about cells? Our knowledge of cells is due mainly to the t...

All bio notes Cell basics What does the cell theory state? That all living things are composed of cells, and that all cells are produced from pre-existing cells How has humankind gained our knowledge about cells? Our knowledge of cells is due mainly to the technology of microscopes What is resolution of a microscope? The resolution of a microscope refers to its ability to distinguish fine details. Which microscope is superior? The electron microscope is far superior in both resolution and magnification Who is credited with being the first to see cells? Robert Hook Label the diagram of a cell: Which 2 parts of a plant cell would not be found in an animal cell? Cell wall and chloroplast List 5 additional organelles normally only visible with an electron microscope. Golgi body, ribosomes, lysosomes, endoplasmic reticulum and mitochondria What is the function of the cell membrane? To stop substances from entering or leaving the cell What is the function of the endoplasmic reticulum? Divides cells into channels and compartments What is the function of the Golgi apparatus? Packages substances for storage or secretion What is the function of the mitochondria? Cellular respiration What is the function of the chloroplast? Photosynthesis What is the function of the cell wall? Ensures rigid structure/strength of the cell What are the waste products expelled from cells? Carbon dioxide, water, salt and urea Cell types Outline the major differences between eukaryotic & prokaryotic cells, including cell structures and relative cell sizes. Eukaryotic cells contain many membrane bound organelles for specialised function within the cell and the cells are relatively large Prokaryotic cells are much smaller and do NOT contain any membrane bound organelles Which type of cells are found in bacteria? Prokaryotic Which type of cells are found in fungi? Eukaryotic Which type of cells are found in plants? Eukaryotic Which type of cells are found in animals? Eukaryotic Prokaryotic vs Eukaryotic Cells Similarities - Cell membrane - Cytoplasm - Ribosomes Differences - Prokaryotes do NOT have a nucleus or membrane bound organelles - In prokaryotes, the DNA is circular but in eukaryotes it is linear - The cell size and ribosomes are much larger in eukaryotes - Prokaryotes are only unicellular while eukaryotes can be uni or multicellular  - Different kingdoms of life Prokaryotic Cells Characteristics of prokaryotic cells - No nucleus - Unicellular - Simple cell structure - Old The kingdoms of life which contain prokaryotic cells. - Bacteria (found in different shapes, rods, spears, spirals) - Archaea What is pathogenic bacteria? - A type of bacteria which causes disease Prokaryotic cells can be further sub-divided into 2 types called...? Archaea and Eubacteria Eukaryotic cells What is the nucleus referred to as? the control centre of a cell. What is the function of the nucleus? It contains the cell’s genetic information in the form of the chemical DNA arranged in structures called chromosomes. What is the function of chromosomes? Storing chemical DNA A nucleus often contains a structure. What is this called? The Nucleolus. What is the function of the nucleolus? Making RNA which is sent out as a messenger to other parts of the cell. The nuclear membrane has pores to allow RNA molecules to exit. How do RNA molecules exit the cell? Through the pores in the nuclear membrane What is the function of the mitochondria? The mitochondria are the sites of cellular respiration which use glucose and oxygen to make ATP. What is ATP? ATP is a high- energy chemical which can be used to power any & all cellular processes. Respiration enzymes control the chemical process. How does the inner membrane assist this? The inner membrane is highly folded to give greater surface area for attachment of the respiration enzymes. What is the function of chloroplasts? Chloroplasts are the site of photosynthesis in plant cells. Inside are “stacks” of membrane structures (thylakoids) containing the chemical Chlorophyll. What is the function of chlorophyll? It absorbs light energy What is the plural term of thylakoids (membrane bound compartment) within the chloroplast of plant cells? Grana What is the purpose of grana? “Grana” carry out parts of the chemical process known as the “light reaction”. Where is the light reaction completed? In the ”stoma” zone in a series of steps called the “dark reaction” because light is not needed. What is the E.R? A network of membranes throughout the cytoplasm What is the function of the E.R? It provides channels & compartments for chemicals to move & processes to occur. Where are ribosomes found? In the E.R What is the function of ribosomes? They are the sites for production of proteins. What is the Golgi Apparatus? A (usually) curved membrane structure. What is the function of the Golgi Apparatus? “Packaging” chemicals into small “vesicles” for storage or secretion. Cell Size How is the size of the cell affected by surface area to volume ratio? The shorter the distance molecules need to travel between the membrane and the inside of the cell, the faster they can get there. If the distance is too large, it will take too long for the oxygen to reach the centre of the cell and that part of the cell could run out of energy. Small cells = high SA:V ratio Large cells = low SA:V ratio How do you investigate the effect of surface area to volume ratio on cell size? The higher the SA:V ratio, the more surface area the cell has compared to its volume. This means diffusion of particles is more efficient as more particles can enter the cell at a time What is the approximate size (in micrometres) of a typical plant cell? 20-100 What is the approximate size (in micrometres) of a typical bacterial cell? 0.1-5 What is the approximate size (in micrometres) of a typical animal cell? 5-20 And so, rank the size of the typical plant, bacterial and animal cell (from largest to smallest) Plant cell, animal cell, bacterial cell 1 millimetre = how many micrometres? 1000 Microscopes *Microscopes were invented by Hans and Zacharias Janssen in 1590* Light microscope - Magnifies objects up to 1000 times - Observes cells between 1 and 100 um - Organelles that can be observed are nuclei, chloroplasts and mitochondria Resolution = the ability of a microscope to distinguish objects separated by small distances Magnification = the ability to make small objects seem larger, such as making a microscopic organism visible Electron microscope - Same concept as light microscope but replaces the beam of light with a beam of electricity - Results in high resolution and high magnification images How is the electron microscope better than the light microscope? - Achieves greater resolution (because wavelength of electrons is shorter) How is the electronic microscope worse? - More expensive  - Must be perfumed in a vacuum to keep the electrons travelling in a Beam types of electron microscopes - Scanning EM - Transmission EM What are the advantages of the scanning EM? Let’s you see the surface of any sample, faster, less restrictive, can sometimes be perfumed with limited sample preparation What are the disadvantages of the scanning EM? not as detailed as transmission EM What are the advantages of the transmission EM? Let’s you observe details as small as individual atoms and gives info about internal structure (unlike scanning em) What are the disadvantages of the transmission EM? Large and very expensive To calculate field of view: *as magnification increases, field of view decreases by the same factor 1mm=1000um To estimate cell size Divide the field of view by the number of cells that occupy the diameter Compare Optical & Electron microscopes in terms of how the image is created Optical = focused light Electron = electron beams Compare Optical & Electron microscopes in terms of how the image may be viewed. Optical = viewed by eye or photo Electron = viewed by screen of photo Compare Optical & Electron microscopes in terms of magnification Optical = 500-2000 X Electron = millions X Compare Optical & Electron microscopes in terms of resolution. Optical = 0.2 micrometres Electron = 0.0002 micrometres Compared images formed by TEMs (transmission microscopes & SEMs (scanning microscopes) in terms of how the electrons interact with the specimen being viewed. TEM: electrons pass through specimen. SEM: electrons scatter from (coated) specimen. Compared images formed by TEMs & SEMs in terms of general style & appearance of the image. TEM: flat 2-D image. SEM: 3-D surface detail image. Outline what x-ray crystallography can tell us about cell chemicals. The x-ray diffraction pattern from a pure crystal can be analysed to find the 3-D shape of the molecule. Outline, in general terms, what the “iosotopic tracer” technique is, and what it can tell us about a cell. The flow of atoms through a chemical process can be traced by introducing an isotope of one of the elements involved. Where it ends up can be detected by its radiation or mass difference. This helps understand a chain of reactions step-by-step. A plant cell via electron microscope: Cell survival requirement of cell survival - Energy sources (light/chemical) - Matter (CO2, O2 carbohydrates, amino acids…) - Wastes removed (CO2, O2, water, ions…)  The cell membrane What is the cell membrane? The cell membrane is a phospholipid bilayer made of hydrophilic phosphate heads and hydrophobic phosphate tails. The membrane contains proteins that have important functions Some proteins have sugar groups attached. What are these called and what is the function? Glycoproteins, they have important roles in cell signalling, cell recognition and adhesion If a handful of giant phospholipid molecules were thrown into water, what would happen? - The phospholipids would arrange themselves into a bilayer because phospholipids have a hydrophilic head and hydrophobic tails. - The hydrophobic tails will ‘hide’ and move inwards away from the water. - The hydrophilic heads will move to interact with the water, thus forming a bilayer with a hydrophobic region (the tails) on the inside and the hydrophilic region (the heads) on the outside. Why are membranes important in the structure and function of the cell? - The cell membrane is made up of phospholipids in a bilayer. - The centre of the bilayer is hydrophobic, and the outside is hydrophilic. - This means that the membrane only lets specific matter through, as many cannot pass through the hydrophobic core of the membrane. - The membrane also separates areas of the cell to carry out different functions - It holds the entire cell together, holding the cytosol and organelle inside Proteins found inside the cell membrane = Intrinsic Proteins found outside the cell membrane = Extrinsic Which molecules are small enough to diffuse across the membrane? Water, oxygen and carbon dioxide. How are bigger molecules (proteins, glycogen, starch) diffused through the membrane? They are broken down into smaller molecules or transported through transmembrane proteins. Function of glycoproteins - Cell adhesion - Cell receptors - Antigen for cell recognition Function of cholesterol in animal membrane cells Stabilising fluidity The cell membrane is described as fluid, what does this mean? The phospholipids can move around List the differences between organic and inorganic cell chemicals Inorganic cell chemicals are simple and small molecules (eg; H20) or ions such as phosphate and magnesium. Organic cell chemicals are more complex molecules based on carbon. They are often huge polymers of repeating units joined together. List the 4 main types of chemicals Carbohydrates, proteins, nucleic acids and lipids What are the functions of carbohydrates? Sugars and starches, energy chemicals. some structural uses (cellulose cell walls) What are the functions of proteins? Main structural chemicals for cells, hair, skin etc What is the functions of nucleic acids? DNA, RNA and genetic material What is the functions of lipids? Fats and oils. Energy storage. Main component of cell membranes. Identify the main structural unit in the membrane Phospholipid molecules Define hydrophobic in relation to membrane structure Means ‘water hating’, part of molecule repelled by water, generally fat soluble Define hydrophilic in relation to membrane structure Means ‘water loving’, part of molecule that is water soluble What other chemicals are there in the membrane? Mostly proteins, often with carbohydrates attached. Some are receptors for messenger chemicals, some are markers to identify cells as ‘self’, some help substances across the membrane. Fungal Cells Are fungal cells eukaryotic or prokaryotic? Eukaryotic. They have the same organelles as animal cells, plus a cell wall. What organelles are found in Fungal cells? nucleus, ribosomes, mitochondria, Golgi apparatus, endoplasmic reticulum, cell membrane, cytoplasm. How are fungal cells similar to plant cells? They both have a cell wall. How are they different? While the fungal cell wall is made of chitin, plant cell walls are made of cellulose. Unlike plant cells, fungal cells don’t have a large central vacuole or chloroplasts How do fungi obtain the energy needed to survive? They get nutrients by decomposing food sources (plants/dead animals) in their surroundings. The mitochondria in the fungal cells then use the glycose from the food to make ATP energy. Plant cells - are multicellular - Eukaryotic - Belong to the plantae family What is the purpose of mitochondria? Mitochondria provides energy for the cell during cellular respiration. Do both plant and animal cells have mitochondria? Yes How do plants and animals obtain glucose differently? Animals must eat food, while plants create their own glucose during photosynthesis What is the meaning of ATP? Adenosine triphosphate Compare the different functions of chloroplasts and mitochondria in plant cells - very similar - both membranes bound organelles - chloroplasts found mainly in leaf and stem cells - they use the sunlight’s energy to convert carbon dioxide and water into glucose and oxygen. This process is called photosynthesis - mitochondria are found in all plant cells - they take glucose created during photosynthesis and convert it to ATP energy. This process is called cellular respiration What do plant cells have that animal cells do not? - A vacuole - A cell wall - Chloroplasts - stronger structure plant cell diagram: Plant Cell Structure What organelles are found in plant cells? Cell membrane, chloroplast, ribosomes, vacuole, cytoplasm, mitochondrion, Golgi apparatus, cell wall, nucleus, ER Organelle Function  Cell wall Protects and supports the plant cell. Controls entry and exit of materials into Cell membrane cells. The nutrient-rich fluid in which other Cytoplasm organelles are found. Mitochondria Provide energy for the cell. Ribosomes Makes proteins. Controls and regulates the cell. This is Nucleus where DNA is found. Transports proteins and other substances Endoplasmic reticulum around the cell. Folds and packages proteins and sends Golgi apparatus them to the correct location. Stores water and nutrients, and helps Vacuole keep the cell rigid. Chloroplasts Undergo the process of photosynthesis. Food and energy for cells What is the difference between autotrophs and heterotrophs? Autotrophs are organisms which make their own food while heterotrophs eat complex, high energy compounds made by other living organisms. What is the equation of photosynthesis? Water + carbon dioxide > (chlorophyll) > glucose + oxygen Explain the process of cellular respiration - glucose reacts with oxygen, releasing energy. - This energy is in the form of a molecule called ATP In which type of cells does aerobic cellular respiration occur? in eukaryote cells (do have a nucleus) explain the difference between photosynthesis and cellular respiration in photosynthesis, plant cells make glucose. in cellular respiration, animal cells break glucose what is the equation of cellular respiration? Glucose + oxygen > carbon dioxide + water (which transfers energy to ATP) What does ATP stand for? “adenosine tri-phosphate”. In plants, photosynthesis occurs in 2 stages, in different parts of a chloroplast. Outline these 2 stages and precisely where each occurs The “light reaction” occurs in the grana structures of a chloroplast. Basically, it involves using the energy of light to tear water molecules apart. The oxygen is released. Hydrogen is “captured” for use in the “dark reaction” which occurs in the stroma part of the chloroplast. A cycle of reactions adds CO2&the captured hydrogen, to build glucose molecules. How many molecules of water & CO2are required to produce one molecule of glucose? Six of each When you look at the summary chemical equations for photosynthesis & cellular respiration, they seem to be exactly opposite processes. Comment on this statement. Overall reactants & products are exactly opposite. However, the energy absorbed by one is NOT the same energy released by the other. More significantly, the precise chemical pathways are very different and in no way opposites. Describe the ATP + ADP cycle & explain why ATP can be considered as the “energy currency” of a living cell. ATP contains a high-energy bond to a phosphate group. If the phosphate is removed (bypassing it to another chemical) the energy is released and can be used to “power” any cell process. Since any & all cell processes can be powered by ATP, it is an “energy currency”, universally accepted. With one less phosphate, ATP becomes ADP. This can return to a mitochondrion & be “re-charged” by re-attachment of a phosphate group, using energy from cellular respiration. Compare & contrast what exactly is needed to supply energy to an autotroph compared to a heterotroph (assume eukaryotic cells). Autotrophs require an energy source (usually light, but chemical energy is used by some) and a few simple, low-energy chemicals (eg CO2& H2O). From these they can manufacture their high-energy food chemicals, such as glucose. Heterotrophs must eat high-energy foods made by another living thing Leaf Structure Which type of cells produces the waxy cuticle? The upper and lower epidermal cells do, to reduce evaporation Which type of tissue carries water to the leaf? The xylem tissue (part of the vascular bundle) Which type of tissue carries food from the leaf? The phloem tissue (part of the vascular bundle) Which upper epidermal cells are modified into hairlike structures? Trichomes. the purposes of types of cells in the leaves Thin waxy cuticle prevents water loss. Epidermal cells produce the waxy cuticle. Palisade mesophyll cells contain many chloroplasts for photosynthesis and are tightly packed to capture light. Spongy mesophyll cells also contain chloroplasts to capture any remaining light, but are loosely packed, allowing movement of gases in the leaf. Vascular bundle in spongy layer transports water to the leaf and food away from the leaf. Lower epidermis includes guard cells, which control opening and closing of stomata. Photosynthesis Cellular Respiration  Passive Transport – Diffusion What is diffusion? A form of passive transport, meaning that it does not need energy to occur. It is the net movement of particles from an area of high concentration to an area of low concentration What impacts diffusion? The surface area: volume ratio What type of surface area to volume ratio would be best for effective diffusion? Why? A large ratio because as organisms increase in size and become multicellular, diffusion becomes less efficient as the surface area: volume ratio decreases. Hence cells in the middle of an organism aren’t able to expel enough waste or acquire the necessary nutrients. What factors increase diffusion? increasing temperature, moisture, surface area and concentration gradient What do multicellular organisms have which increases diffusion? They have specialised surfaces and transport systems Why do cells use diffusion? Cells use diffusion to gain useful molecules and remove waste molecules Diffusion vs Osmosis Similarities Differences Both include the movement of molecules Diffusion = movement of molecules/ from high -> low conc. particles but not solvents Both passive movements Osmosis = movement of solvents (e.g. water) only Particles continue to move down the concentration gradient until an equilibrium is achieved Passive Transport – Osmosis What is osmosis? The movement of water (solvent particles) from high to low solute concentration across a semi-permeable membrane What is tonicity? The concentration of solutions (hypotonic, isotonic, hypertonic) Hypotonic = dilute (less solute) Isotonic = equal Hypertonic = concentrated (more solute) What happens to plant cells when they lose water? They become plasmolysed (cell contents shrink) What happens to plant cells when they gain water? They become turgid (swollen) What happens to animal cells when they lose water? They shrink and may become crenated What happens to animal cells when they gain water? They swell and may burst Passive Transport – Facilitated Diffusion What is facilitated diffusion? A form of passive transport. It involves the movement of molecules or ions across a biological membrane, down a concentration gradient. Unlike simple diffusion, it requires a special carrier protein to move molecules and ions across a membrane. Describe the movement of substances across the bilayer The channel protein uses active transport to move molecules. The carrier protein uses active transport to move ions. Why is facilitated diffusion important? The plasma membrane of a cell is made of a hydrophobic lipid bilayer which means that any polar molecules will be unable to pass through the membrane unaided. Ions and large polar molecules cannot diffuse freely across the plasma membrane due to their polar nature. They require facilitated diffusion. *polar molecules have an electronegativity difference between the bonded atoms (unequal distribution of electrons) *ion = atom/molecule with a net electric charge due to the loss or gain of electrons What is the difference between passive and active transport? In passive transport, the cells do not have to use any energy however in active transport, they do. In active transport the cells use ATP to move substances across the membrane. Active Transport What is active transport? The movement of molecules across a cell membrane against the concentration gradient. The molecules move from an area of low concentration to an area of high concentration. Why is active transport important? It allows a cell to accumulate high concentration of molecules such as ions, glucose and amino acids. The process requires cellular energy in the form of ATP or from an electrochemical gradient. Endocytosis Exocytosis Meaning moving molecules into the moving molecules out of the cell cell (cells take in substances (Materials are expelled into from outside the cell by the extracellular fluid) engulfing them with its membrane to form a vesicle) How it occurs When a portion of the cell When a vesicle formed in membrane folds in on itself the Golgi Apparatus fuses to encircle extracellular fluid with the plasma membrane, and various microorganisms allowing its contents to be or molecules, to form a released outside the cell vesicle that is transported within the cell Versions Endocytosis may be Secretion (chemicals phagocytosis (moving large released for useful purposes) molecules) or pinocytosis and excretion (the removal (moving small molecules) of unwanted, likely toxic, waste materials) Similarities Active transport processes, require energy, are the bulk transport mechanisms used in eukaryotes What is an example an active transport mechanism? Sodium-Potassium Pump (Na-K Pump) which is present in all animal cells and allows the cell to maintain an ‘osmotic’ pressure which prevents it from absorbing excess water and bursting.  ENZYMES What are enzymes? Biological catalysts which speed up the rate of chemical reactions in living cells. They are globular proteins and have tertiary structure. Why do we need them? Without enzymes, the reactions in a cell would occur too slowly for the pace of metabolism. Most enzymes names end in...? ‘ase’ In a chemical reaction there is an activation energy. What is this? The amount of energy needed for the reaction to occur. What is the problem with these reactions? The activation energy needed is so high that it takes a long time. How do Enzymes help with chemical reactions? Enzymes lower the activation energy so that the reactions can happen much faster. They provide an alternative pathway, where the substrate binds to the active site of the enzyme. Substrate: substance that the enzyme acts upon Active site: the part of the enzyme where the substrate binds Activation energy: the energy needed to start a chemical reaction What are the two main models of enzyme specificity? Locke and key and induced fit Describe the Locke and key model The enzyme has an active site which specifically fits the substrate, like a key fitting a lock. If the substrate doesn't fit in the active site, then the reaction will not occur. Describe the induced fit model When the substrate interacts with the active site and alters its shape. These changes 'mould' the active site to the substrate and make the bonds between the substrate and the enzyme even stronger. Compare the two models The Locke and key model suggests that the enzyme has a rigid structure while the induced fit model is more flexible and interacts with other molecules and proteins Are enzymes used up in a reaction? – no, they can be used over and over again How do enzymes speed up a reaction? By lowering the energy barrier Why are enzymes essential to everyday life? We need reactions to happen in our body quickly and we rely on enzymes for this. STRUCTURE Describe the structure of a protein Made of molecules called amino acids Amino acid: - series of molecules that contain an amino group and a carboxylic acid group. - The chemical groups are joined at a central carbon atom and hydrogen, the final group varies from one amino acid to the next, known as the variable group - When joined together, they form a polypeptide chain through a peptide bond Peptide bond – the joining of an amino group of one amino acid onto the carboxylic group of another amino acid, through the release of water and therefore a condensation reaction Difference between polypeptide chain and peptide bond Peptide = two or more amino acids joined by the peptide bonds Polypeptide = chain of many amino acids Primary structure of a protein; the order of amino acids Secondary structure of a protein: the polypeptide chain folded. It is held together by hydrogen bonds Tertiary protein structure The secondary structure folded to form a 3D shape, known as a globular protein, held together by various bonds, important for function for enzymes. Why is protein structure important for enzymes? The enzymes tertiary protein structure gives it the 3D shape, including the active site (where the substrate binds). This then allows the activation energy to be lowered and the reaction to be sped up. FACTORS AFFECTING ENZYMES 1. Temperature 2. pH explain the relationship between enzymes and temperature increasing the temperature increases the rate of reaction to an optimum temp. After this, the rate of reaction decreases then ceases. Above the optimum temperature, the enzyme changes its shape and denatures. Explain the relationship between enzymes and pH Enzymes work best at the optimal pH so as the pH increases or decreases away from the optimal pH, the enzyme denatures and activity decreases. Explain the relationship between enzymes and substrate concentration Increasing substrate concentration also increases rate of reaction to a certain point. Once all the enzymes have bound, any substrate increase will have no effect on the rate of reaction as the available enzymes will be saturated and working at their maximum rate What are cofactors? Inorganic ions and organic molecules Purpose of coenzymes To help the enzyme catalyse a reaction Allosteric site A site on the enzyme that is not the active sight Coenzymes: Helper molecules which increase the efficiency of enzyme catalysed reactions. They are small, non-protein molecules used to carry substances to and from reactions. Coenzymes are particularly important in terms of… metabolic pathways Enzyme inhibiters are molecules which bind to… Enzymes and decrease their catalytic activity. Competitive inhibiters They bind to the active site of an enzyme, prevent the substrate from binding and slow the reaction Non-competitive inhibiters They bind to an allosteric site and change the conformation of the active site. This slows down the reaction The two type of enzyme inhibiters are… Competitive inhibiters and non-competitive inhibiters Give an example of a past experiment u did  As the pH of milk and renin solution decreased, enzyme activity increased. This was assumed as the renin enzyme is found in the stomach which Is known to have acidic conditions  The effect of the ph on the rennin enzyme activity was investigated. As the pH decreased below neutral, there was a steady increase peaking at 3.5 before a steady decrease occurred. Therefore, as Ph increased above neutral, enzyme activity steadily decreased.  Outside of optimum pH range, the enzyme denatures (3D structure changes and active site is no longer the correct shape)  Hence as the enzyme and substrate no longer have a complimentary shape no more enzyme catalysed reactions occur. Describe the link between pH, acidity and enzymes - Lower pH=more acidity - Slight decrease in pH can have a major impact on cell function - Enzymes require specific pH environments to function and a change in pH can lead to a decrease in cellular respiration Evaluate a graph about substrate concentration  - As the substrate concentration increases (to saturation point), the rate of the reaction will increase because more enzyme is available to catalyse the reaction. - At higher substrate concentrations the rate of reaction will plateau because no more enzyme is available. - All active sites have been filled. Organisation of cells Unicellular organisms - So small their SA:V ratio allows them to rely on simple diffusion to supply requitements such as oxygen for cellular respiration and to remove waste products such as carbon dioxide, urine and other metabolic wastes. An example of a unicellular organism Paramecium – swims using cilia (tiny beating hairs), is eukaryotic and asexual Multicellular organisms - bigger in size - the total surface area to volume ratio is smaller colonial organisms - The link between unicellular and multicellular - all the individual cells can carry out all functions necessary for life examples of colonial organisms mats and biofilms, slime moulds, a colonial alga (volvox) and sponges Complexity - multicellular organisms need specialised organ systems - all the life process is in a unicellular Organism take place in that one cell - multicellular organisms need organ systems to carry out functions such as o communication between cells like the nervous system and circulatory system o supplying the cells with nutrients like the digestive system o controlling exchanges with the environment like the respiratory system and exoskeletal system Why do multicellular organisms need the nervous system and circulatory system? - for communication between cells Why do multicellular organisms need the digestive system? - For supplying the cells with nutrients Why do multicellular organisms need the respiratory and exoskeletal systems? - For controlling exchanges with the environment Tissue a group of cells that are simple in structure and work together to carry out a common function What are the levels of organisations within an Organism, from largest to smallest? - multicellular organisms (eg; humans/animals/plants) - systems - organs - tissues - cells - organelles - atoms Why is a large, unicellular organism not possible? A large single cell has a lower SA/Vol ratio. It becomes impossible to absorb enough nutrients How do the main systems of the body (digestive, respiratory, circulatory) serve the needs of cells? All cells require nutrients, water, oxygen & the removal of wastes. In a multicellular life-form many of the cells are buried deep within the body & must be supplied with their requirements. The digestive system breaks foods down into a form a cell can absorb, then the circulatory system carries the nutrients to every cell. Similarly, the respiratory system carries out gas exchange & the circulatory system carries gases to/from the cells. Explain if biofilm can be considered a multicellular organism? No, the cells are individual and are not specialised within an organism Explain if a sponge can be considered a multicellular organism? Yes. Although there are no true organs or systems, there are certainly specialised cells (even perhaps tissues) living together as a single organism. Explain if volvox can be considered a multicellular organism? Yes, but at about the lowest possible level of multicellularity. Volvox has 2 or 3 types of specialist cells & some ability to co-ordinate its activities. Explain if a slime mould can be considered a multicellular organism? Probably not. Usually, the cells live as individuals. They only clump together under certain environmental conditions. (When stressed) It is arguable that they exhibit some cell specialisation for a short time only. Explain cell differentiation in multicellular organisms Not all the cells in a multicellular organism are the same. They are differentiated into many shapes and sizes. Each cell type does a different “job” in the body, and has the shape, size and ability to match that function. What are the 4 types of tissue? Connective, epithelial, muscle, nerve (colds explode my nose) The function of connective tissue Gives the body structure and support Examples of connective tissue Fat, bone, blood The function of epithelial tissue Covers and protects the body Examples of epithelial tissue Skin, lining of internal cavities The function of muscle tissue Movement Examples of connective tissue Skeletal, smooth and cardiac muscles The function of nerve tissue Control and communication Examples of nerve tissue Nerves in brain and spinal cord What is an organ? An organ is a structure that contains more than one type of tissue working together. The organ can then perform a specific function. The stomach is an organ. Explain this. The stomach is lined by epithelial tissue, which protects it. Smooth muscle tissue helps it to churn the food, and nervous tissue transmits signals that coordinate the muscle contractions. Connective tissue holds all the other tissues together. The circulatory system in animals What is the role of the circulatory system? - To transport gasses, nutrients, waste products, hor____ and antibodies/antigens - To maintain a connected internal environment - To remove tonics and pathogens What is the structure of arteries in relation to their function? - They carry blood away from the heat under high pressure and so must have a structure that can withstand the pressure - They have thick? but elastic walls made up of three tissue layers o Endothelium as a lining o Smooth muscle o Connective tissue True or false, arteries pump blood? False Identify 2 features of red blood cells in relation to function - Contain millions of haemoglobin molecules that are strongly attracted to oxygen, allowing the red blood cells to carry large numbers of oxygen molecules - They have a biconcave shape that allows the maximum amount of oxygen to join to haemoglobin on both and outer and inner surfaces of the cell - Both these allow them to transport large amounts of oxygen across the body Describe the structure of capillaries in relation to their function They have walls only 1 cell thick as they have to allow diffusion of materials through their wall to reach the cells found in the tissues where the capillary is located Describe the structure of veins in relation to their function - They carry blood back towards the heart - They carry the same quantity of blood as the arteries but not at the same high pressure - Like arteries, they have 3 tissue layers o Endothelium as a lining o Smooth muscle o Connective tissue - They also contain valves which prevent the backflow of blood Differentiate between arteries and veins Arteries Veins Structure arteries have a thick wall of the layers in the walls of muscular, elastic and veins are thinner connective tissue Blood flow arteries have a narrow while veins have a wide lumen lumen blood in arteries is pumped (because of the low under pressure pressure) veins have valves to prevent the back flow of blood Direction of flow arteries take blood away veins take blood back to the from the heart heart  Oxygenation arteries transport veins transport oxygenated blood, except deoxygenated blood, except for the pulmonary artery for the pulmonary vein Explain the changes that occur in the thorax as a person breathes in - the ribs move upwards and outwards - the diaphragm flattens - with the increase in volume in the thorax, the air pressure is lowered - the pressure is now lower than the air pressure - so air moves into the lungs passively describe the digestion of starch in the body - starch digestion begins in the mouth - the enzyme, amylase that is released is contained in saliva - amylase catalyses the breakdown of starch into maltose - in the duodenum, pancreatic amylase contains enzymes that continue the digestion of starch and maltose - starch digestion is completed by enzymes in the ileum (these are actually in the wall of the ileum) - human amylases work best around neutral/slightly alkaline pHs and these are created by the secretion of sodium hydrogen carbonate The main changes in chemical composition of blood as it moves around the body Which systems in the body does the blood circulate through? 1) The pulmonary system 2) The systemic system Describe the flow of blood in the pulmonary system 1. Blood flows from the heart to the lungs then back to the heart 2. It travels in the pulmonary artery from the right ventricle to the left where CO2 is released into the al…? of the lungs 3. It is released out of the body 4. Oxygen is picked up from the alveoli and diffuses into the red blood cells to then be taken back to the heart Via the pulmonary system, are CO2 and O2 increased or decreased? CO2 is decreased and O2 levels are increased. Describe the blood flow of the systemic system 1. Blood flows from the heart to the rest of the body except the lungs then returns 2. The left ventricle? Pumps oxygen Blood to the rest of the body and as this blood circulates in cap…. Oxygen is delivered to the c…. and carbon dioxide is picked up 3. Waste products (eg; urine) are also picked up from the li… and transported in the blood to the kidney  4. Blood flowing to the small intestines collects the products of digestion and transports them to the li… 5. Glucose is circulated in the blood stream to all cells in the body for respiration 6. Deoxygenation blood returns to the heart via the inferior and superior v… c… Open vs closed circulatory systems Open systems Closed systems Blood is pumped by the heart through Blood is pumped by the heart through a large vessels into body cavities called closed network of vessels sinuses Body tissues are in direct contact with Body tissues not in direct contact with blood blood Blood flows at low pressure, thus is a Blood flows at high pressure, is faster, slower and less efficient system of more efficient system of circulation circulation Flow of blood is not regulated through Flow of blood can be regulated by valves tissues and organs System is present in anthropoids System is present in annelids (leeches, (primates, eg; apes) and molluscs (eg; worms), echinoderms (star fish, sea snails, clams etc) urchins) and vertebrates (birds, mammals) Small blood vessels Extensive blood vessels Digestion in a mammal Physical digestion The physical cutting and mashing of the food, mainly achieved by the chewing of food in the mouth. Breaking the food into smaller fragments increases the surface area available for chemical attack by digestive enzymes Chemical digestion Involves digestive enzymes Absorption of nutrients, minerals and water - Occurs mainly in the intestines - Water soluble nutrients are absorbed into the blood stream and flow directly to the liver - The liver sorts out the mixture and some nutrients are placed into storage, and some are chemically processed. Any undesirable chemicals are de-toxified Elimination of solid waste - Regular elimination and bowel health are dependent on consuming a lot of indigestible fibre. This materials adds bulk to the solid waste (faeces) which accumulate in the rectum and stimulates the process of elimination on a daily basis - There is growing evidence that keeping these “gut bacteria” happy improves many aspects of health, including weight control, resistance to disease and general well- being. Digestive enzymes – agents of chemical digestion (ends in -ase) Protease - A “protease” is a digestive enzyme which attacks proteins. - Most proteases attack a protein chain only at the location of a specific amino acid. - There are a variety of proteases, each with its own “target” amino acid. - The enzyme latches on to its “target” (lock-and-key idea) and breaks the connecting bond between amino acids. - Later in the digestive process, other protease enzymes (called “peptidases”) will attack these peptide fragments and eventually chop them up into individual amino acids. - Produced in the stomach and pancreas Lipase - Attack lipids - Break lipids into individual fatty acids and glycerol  - A fat molecule is first emulsified into water solution through gall bladder secretions then digested by lipase - Found in the pancreas Amylase - Attacks amylose, a type of starch (polymer of sugar molecules) - Dextrins (variable-length short chains) & disaccharide sugars are attacked by specialist enzymes until everything is broken down into the simplest sugar molecules. For example, sucrose (table sugar) is attacked by “sucrase”, lactose (milk sugar) is attacked by “lactase”, and so on. - Found in salivary glands + pancreas Absorption of digested nutrients Intestinal villi - Look like fingers - Greatly increase surface area of intestinal lining available for absorption of digested nutrients - Surface layer of 1 villus is only 1 cell thick so digested nutrients can easily be absorbed and carried to the blood capillary network inside - Water soluble nutrients (amino acids/sugars) are carried into the blood street - fatty acids + chemicals are carried into a lacteal tube and this lymph fluid eventually drains into the blood stream near the heart so the fatty nutrients circulate around the body - Waters/minerals/vitamins is reabsorbed from the gut by osmosis Gas exchange in animals how does respiration help animals? - allows an animal to inhale, exhale and involves using muscles and the skeletal system - helps to increase the amount of gas exchange that can occur what is gas exchange? - physical process in living organisms - gases move by diffusion often across the respiratory surface what is the purpose of gas exchange? To give living cells a constant supply of oxygen and remove carbon dioxide What are the requirements of gas exchange? - A large surface area over which the gases can be exchanged between the environment & the animal’s body. - A moist gas exchange membrane between the environment & the animal’s body. (Gases must dissolve in water before diffusing.) - Close contact between the gas exchange membrane & the animal’s blood supply. (Because diffusion is only efficient over a short range.) How do mammal lungs reflect the requirements? - total surface area is approx. size of tennis court - moist inside surface, each alveolus is in intimate contact with a blood capillary to transport the gasses to and from the body cells Mammalian Respiratory System, Structure + Function - trachea o flexible, cannot kink, stays open when head moves o made of soft tissue with rings of cartilage - sponge like lungs o millions of alveoli o increases surface area for gas exchange - alveoli and blood o each alveolus has a blood capillary wrapped around the thin wall o allows oxygen and carbon dioxide to move easily o alveoli always moist so gasses are dissolved in water before moving across membrane similarities and differences in gas exchange Organism: Mammal Insect Fish Frog Where gas Sponge like No lungs or gills. Gills Small lungs exchange Lungs occurs? Each alveolus is Series of holes Fish gills are Carries out gas in intimate on body exposed but exchange in contact with a (spiracles) which shielded by a gill mouth, throat, blood capillary allow air to cover. cavity and skin to transport the move through (all are lined gasses to and trachea with blood from the body vessels + moist) cells How gas Lungs transfer Series of holes Each gill plate small lungs and exchange gasses to and on body consists of not many alveoli occurs from the (spiracles) which 1000s of circulatory allow air to filaments cold blooded so system move through packed with tiny does not need to trachea which blood capillaries carry out cellular infiltrates the respiration to whole body make body heat (mammals do) Gasses are so less oxygen is transferred needed through diffusion to a less developed system of gas  exchange How this total surface as animal grows Lower level of Less oxygen is relates to area is approx. as SA:V ratio oxygen under needed which surface area size of tennis decreases (why water so gills means less and court bugs are always have to be surface area and efficiency small) ** highly efficient efficiency ** how are C02 levels controlled in mammals? - Carbon dioxide is carried mainly in the blood plasma of a mammal then travels to the alveoli of the lungs where it diffuses out of the capillaries into the air sacs where it is breathed out - Through continuous blood flow and removal of gas from the lungs, a rapid rate of gas exchange is maintained and so the carbon dioxide is cleared out - Haemoglobin changes its affinity for oxygen in the presence of carbon dioxide to realise oxygen in the tissues and increase the pick up of oxygen in the lungs Plant structure/function + gas exchange What are the main systems of a plant? Leaves (main site for photosynthesis) Stem, trunk and branch (hold leaves up for light, conduits for transport of water (transpiration) and food (translocation) around plant) Roots (anchors plant into soil, stores food, absorbs water and minerals from soil) flowers (reproductive organs) buds (growth point for new leaves/roots/flowers) Discuss the relationship between structure and function shown by the leaf cell layers known as the “palisade layer” & the “spongy layer”. Palisade layer: composed of cells neatly and tightly packed together under the upper epidermis where there is maximum light. Each cell is packed with chloroplasts. These features all help the palisade layer carry out maximum photosynthesis. Spongy layer: composed of cells that are very loosely packed. This allows spaces for water & gases to more easily diffuse to/from stomates & veins and so helps supply photosynthesising cells. Soil minerals such as nitrates, phosphates and sulphates are essential to a plant for which purpose? To make proteins from glucose. Transport systems in plants - In plants larger than Moss and algae special tissues have developed for transport o vascular tissues  xylem  phloem - Explain the process of the xylem and phloem cells: - Water and dissolved nutrients move from the soil into the roots o (Through the root epidermal cells) o most of the uptake is in the region of the root hair - Water then moves across the root tissues from the outer epidermal layout to the transport tissue in the centre of the root and into the Xylem tissue - Xylem vessels form continuous tubes for the transport of water - When cells specialise to becomes xylem vessels their transverse walls break down, so the cells stacked on top of each other become continuous tubes - Cell contents die leaving hollow vessels for the easy flood of water and dissolved mineral salts - the walls of Xylem are reinforced with lignin thickenings which prevent the vessels from colliding and help the easy movement of water and dissolved substances - Movement of water up the Xylem vessels occurs mainly as a result of transpiration stream that develops: o as water evaporates through the stem of leaves o it sets up a concentration gradient across the leaf creating a suction pull on the water and dissolved minerals in the Xylem tissue  o this force or transport stream shows the upwards movement of ascending sap in the Xylem What is the function of the Xylem? - to transport water and dissolved inorganic nutrients from the roots of the plants to the leaves The transpiration-cohesion-tension theory - current theory which accounts the movement of water from the right to left through the Xylem vessels - the SAP is mainly pulled up by transpiration rather than pushed by root pressure - cohesion o the attraction between water molecules o in this way water molecules form a continuous stream of molecules extending from the left down to the right - Adhesion o the attraction between two types of molecules o water molecules adhere to the cell molecules in the walls of the Xylem o as water molecules are removed by transpiration in the leaf, the next molecule moves upwards to take its place, pulling the stream of molecules continuously along o this is passive transport Phloem vessels - a specialised tissue that transports sunlight from the leaves to the rest of the plant feeding cells o unlike Xylem vessels sieve tube elements are cells with living contents but they do not have a nucleus or any other organelles besides mitochondria Companion cells - Small - Associated with each sieve tube element - organic nutrients such as sugars produced by photosynthesis move down or up the plant to the sieve tube elements (translocation) - The sap flows from 1 cell to the next through perforated transverse walls known as sieve plate - The function is providing ATP for active transport of sugars gas exchange in plants - leaves contain open air spaces formed by the irregular placement of the spongy mesophyll which allows the gasses to move freely due to high surface area - most gas exchange occurs through the stomata and lenticels heterotrophs - obtain organic compounds by consuming autotrophs or other heterotrophs - are known as consumers autotrophs - Plants - also known as producers - make their own organic compounds using energy and inorganic compounds from the environment for synthetic oil drives use light energy to manufacture their food by photosynthesis - chemosynthetic autotrophs use chemical energy (eg; some bacteria) nutrient and gas requirements for autotrophs and heterotrophs: NUTRIENT REQUIREMENTS GAS REQUIREMENTS AUTOTROPHS water, phosphate, carbon dioxide and nitrate oxygen HETEROTROPHS carbs, lipids, proteins, (Take in oxygen, water excrete carbon dioxide) oxygen SIMILARITIES Both undertake respiration, 2. In detail, explain the process of photosynthesis The process of photosynthesis can be summarised as carbon dioxide + water = glucose + oxygen. Photosynthesis occurs in the chloroplasts (organelle) in plant cells. The green pigment chlorophyll absorbs light energy for the process. This energy is stored as chemical energy in the glucose molecules produced. Thousands of glucose molecules can be joined together by the process of polymerisation to form starch (used for storage) or cellulose which is used to build cell walls. Glucose can also be chemically converted into lipids. To convert sugar to amino acids, the plant needs a supply of minerals. Amino acids can then be joined together to form proteins. Briefly describe how “isotopic tracers” have been used to understand biological processes, such as photosynthesis. Different isotopes of an element react chemically the same but can be detected by their mass differences or radiations emitted. Therefore, when introduced into a biological pathway, the isotopes can be detected later in the pathway products or intermediate stages. For example, if a heavy isotope of oxygen in water molecules is made available to a plant, it is later found in the “excreted” oxygen gas, but not in the glucose or starch from photosynthesis. This shows that the O2 released is from the splitting of water molecules, not from the CO2. Such studies allow details of chemical pathways to be unravelled. Diversity Genetic diversity – the variety of genes within a species. What is a species made up of? Individuals that have their own particular genetic composition. Species diversity – the variety of species within a habitat or region How are species grouped together? They are grouped into families according to shared characteristics Ecosystem diversity – the variety of ecosystems in a given place. Define megadiversity: a country with a high level of diversity How do we conserve biodiversity? By saving habitats and ecosystems rather than a single species. Effects of the environment on organisms Abiotic factors – non-living factors of the environment Biotic factors – living factors of the environment Give two examples of abiotic factors: Climate, light. Give two examples of biotic factors: Sources of food, number of predators What do abiotic and biotic factors determine? The distribution, diversity and abundance of organisms Ecosystems Define ecosystem all the living and non-living factors in a defined area that interact and exchange materials Define community a group of different species living together and interacting in a particular habitat What do all ecosystems have? The sun, nutrients and organisms There are three types of organisms. What are these? The producers, the consumers and the decomposers Define producers organisms which make or produce their own food using simple substances and energy from the sun. Another name for producers is…? Autotrophs Define consumers organisms which depend on other organisms for food. Another name of consumers is….? Heterotrophs *Think: heterosexual: different partners, hence heterotrophs: different food sources* Define decomposers Organisms which break down waste products and dead bodies of other organisms, hence releasing simple chemical substances into the environment. Can decomposers be recycled by other organisms? Yes Give two examples of decomposers Fungi and bacteria Symbiotic Relationships When organisms interact with each other in an environment, different relationships are formed. These are: Predator prey An interaction wherein an organism acts as a predator feeding on an organism of a different species (eg: dolphins eating fish) Competition (interspecific) Different species competing for the same resources (eg: grey and red squirrels fighting over habitat) Competition (intraspecific) Same species members competing for the same resources (eg: monkeys competing for food) Allelopathy One organism producing a chemical which harms another (eg: skunks on maple pine) Parasitism One organism benefits, one is harmed (eg: tick) Commensalism One organism benefits, the other unharmed (eg: barnacles on whale) Mutualism Both organisms benefit (eg: bee and flower) Antibiotic resistance in bacteria Antibiotic a chemical that produces harm to bacteria. This chemical may be produced naturally or synthetically Penicillin An example of an antibiotic Pathogen A disease-causing organism Mutation A change in DNA which may be beneficial or harmful to the organism it occurs within Microflora Microorganisms (eg; bacteria) found on the surface of the human body (eg; on the skin) which are beneficial to human health. What are the four steps of bacteria developing resistance to antibiotics through the process of natural selection? 1. Variation 2. Selection pressure 3. Inheritance 4. Gradual changes in population Natural and Sexual selection How does natural selection occur? It occurs when a selection pressure favours the survival of a particular variation in a species. Members of the population with this favourable variation are more likely to survive to reproduce, allowing their offspring to inherit the advantageous trait. Sexual selection is a form of natural selection. Explain how this works The selection pressure is finding a mate with whom to reproduce. In most species, particular traits make an individual more likely to be chosen as a mating partner (eg; male bowerbirds build nuptial bowls and dance). In each case, the traits that increase the likelihood to be chosen as a mating partner are more likely to be inherited by offspring, leading to gradual change in the population over time. Convergent and divergent evolution Convergent evolution occurs when… two or more unrelated species evolve to develop similar adaptations as a result of being subject to similar selection pressures. Give an example of a convergent evolution - Both humans and octopuses have camera-like eyes with an iris, a lens and a retina (however octupus’ do not have blind spots due to the unique wiring) - And both bats and birds have wings. (bird wings are more similar to arms, bat wings, are similar to hands) o These are all analogous features Does convergent evolution occur in analogous or homologous structures? Analogous. Analogous … Analogous structures share a common function, but do not share a common ancestry Divergent evolution occurs when… From a common ancestor, two or more species arise due to different ecological niches, usually by a way of allopatric speciation Give an example of a divergent evolution - Darwin discovered that different Galapagos finch species share a common ancestor (varying diets, reflects different beaks) What is allopatric speciation? The process where new species are formed from one common ancestor while in different geological locations. Does divergent evolution occur in analogous or homologous structures? Homologous Homologous Homologous structures share a common ancestry, but not necessarily a common function. A type of divergent evolution is adaptive radiation. What is this? It is a process in which organisms change rapidly from an ancestral species into an abundance of new forms. It is a rapid speciation. What is adaptive radiation likely to occur? After an extinction event (a species goes extinct) which creates many vacant ecological niches. What is a selection pressure? An environmental factor which may reduce reproductive success. What is an example of a selection pressure? Disease or predation Adaptations Give an example of a structural adaptation - In plants: leaves on spinifex frass reduce water loss - In animals: a platypus has webbed feet which allows it to swim fast Give an example of a behavioural adaptation - In plants: the Venus Fly Trap has adapted to live in nitrogen-poor soils. It can act quickly when a small insect alights on it as part of the plant is able to snap shut when the insect touches delicate sensory hairs. They then secrete digestive enzymes onto the insect and nutrients are absorbed by the plant as the insect is digested - In animals: puffer fish are able to pump air into their stomachs and blow up to twice their size to frighten predators Give an example of a physiological adaptation - In plants: plant cells found in the growing tips of stems are sensitive to the hormone auxin which causes them to grow towards light - In animals: the intertidal marsh crabs has gills and kidneys that function to concentrate ad excrete excess salt Darwin’s theory of evolution Who was Charles Darwin? A scientist who theorised that all species evolved from a common ancestor and that they became a new species through the theory of evolution. What is evolution? The process of genetic change of a species over many generations through genetic inheritance which sometimes forms a new species. What is natural selection? The increase or decrease in the frequency of certain alleles within a population due to abiotic or biotic pressures. Microevolutionary change mechanisms What is microevolutionary change? The change in allele (gene) frequencies that occurs over time within a population. What are the four different processes that microevolutionary change is due to? Mutation, selection (natural and artificial), gene flow and genetic drift. What is a mutation? A change in an organisms DNA What happens if a mutation causes the protein they code for to change? There will be a change in the organisms phenotype What is the source of new alleles? Mutations in gametes (sex cells) Mutations create _______ which allows evolution to occur Genetic diversity What is gene flow? The addition or removal of alleles from a gene pool through immigration and emigration. What is the difference between immigration and emigration? Immigration is when new organisms join a population and emigration is when members of a population leave. What is genetic drift? The random change in the allele frequency of a population which occurs through either random patterns of mating or after a catastrophic event. Evidence for evolution What are the 6 evidences for evolution? Comparative anatomy, comparative embryology, selective breeding, biogeography, the fossil record and DNA hybridisation How does comparative anatomy provide evidence for evolution? It shows that if two organisms have similar anatomical features, they are relatively closely related evolutionary and likely share a common ancestor. How does comparative embryology provide evidence for evolution? If two different species have similar embryos it is likely they share a common ancestor even if their adult forms look nothing alike. *Diagrams show all vertebrates share a common ancestor How does selective breeding provide evidence for evolution? Selective breeding leads to future generations of selectively bred plants and animals, all sharing very similar alleles which will reduce variation in the species. This way the species will grow to be vastly different from their actual wild ancestors and can be beneficial to humans. *Relative vs absolute dating* What is selective breeding? When humans breed plants and animals to selectively develop particular phenotypic traits by choosing which animal or plant male and females will reproduce. How does biogeography provide evidence for evolution? The geographic distribution of organisms on Earth follows patterns that are best explained by evolution, in combination with the movement of tectonic plates over geological time. Give an example of a way biogeography provides evidence for evolution? Broad groupings of organisms that had already evolved before the breakup of the supercontinent Pangaea (about 200 million years ago) tend to be distributed worldwide. What is biogeography? The study of the geographical distribution of organisms How does the fossil record provide evidence for evolution? Fossils are contained in rocks that build up in layers called strata. This strata provides a timeline with the layers at the top being older and vice versa. They therefore document the existence of now-extinct species, showing that different organisms have lived on Earth during different periods of the planet's history. How does DNA hybridisation provide evidence for evolution? Evolution deals with heritable changes in populations over time. Because DNA is the molecule of heredity, evolutionary changes will be reflected in changes in the base pairs in DNA. Two species that have evolved from a common ancestor will have DNA that has very similar base pair sequences. What is DNA Hybridisation? The process of combining two complementary single-stranded DNA or RNA molecules and allowing them to form a single double-stranded molecule through base pairing What is DNA The genetic material that an organisms inherits from it’s parents. It is double stranded and each strand has a sugar-phosphate backbone as well as DNA bases which can bond in specific pairs with each other (A and T, G and C). By applying heat, these bonds break and result in single stranded DNA If asked to find the approximate age of a fossil using radio-carbonating - Know that when an organism dies, it stops taking in carbon atoms (as carbon ones in the forms c12 and c14). Carbon 14 decays to nitrogen 14, a stable isotope and then carbon 14 decays by 50% for every half-life which is 5730 years - To calculate how many half-lives: o After 5730 years, 50% of carbon 14 will remain o Another 5730, 25% o Another 5730, 12.5%  (Keep going until u get an answer using the percent of carbon 14 given in question)  5730 x number of half lives Analyse palaeontological (study of fossils) and geological (Earth’s structure and substance) evidence that can be used to provide evidence for past changes in ecosystems including aboriginal rock paintings, rock structure and formation and ice core drilling - Aboriginal rock paintings show evidence of past ecosystems and species (eg; the thylacine which was believed to be alive at least 200, 000 years ago) - Marine animal fossils have been found in outback Australia around 65-140 million years ago providing evidence that an inland ocean covered these parts of the outback Australia during these times. - The east coast of Australia has volcanic rock deposits that dating reveals are around 35 million years old providing evidence that Australia previously has active volcanoes that erupted around this time - The Sydney basin has numerous black coal deposits, alongside fossils of plants from the Permian period. - The Bass Strait lies between Tasmania and mainland Australia. This ocean is relatively shallow providing evidence that Tasmania has been connected to Australia by land during the past ice ages, displaying how this would have drastically lowered the world’s sea levels. - Many fossilised pollen grains from rainforest species of plants have been found in the sediment of arid areas and dated at over 76,000 years old providing evidence that arid parts of Australia where these pollen grains have been found were cooler and wetter around that period of time. - There is a marked increase in the number of fossilised pollen grains of dry forest species found in sediment throughout Australia that have been dated to the last 27,000 years providing evidence that Australia’s climate has shifted to be warmer and drier in more recent years, favouring the survival of populations of dry forest species. Analyse evidence that present-day organisms have evolved from organisms in the past, for example, small mammals and sclerophyll plant - Comparative anatomy for example displays that whales, bats, horses and humans all come from a common ancestor as a result of their forelimbs, which are pentadactyl  limbs. Although they form and appear in different ways their forelimbs all consist of five bones which was inherited from a common ancestor - Embryology: For example, all vertebrate embryos have gill slits and tails, - Biogeography: splitting of Pangea, This can be seen in the differences between old world monkeys, those that live in the eastern hemisphere, and new world monkeys, those that live in the western hemisphere - Hyper diverse sclerophyll flora existed under high-rainfall, summer-wet climates in south-eastern Australia therefore it must have suffered subsequent extinctions to result in its currently low diversity what effect can 1 species have on others in the community? - Evident through the trophic cascade (an ecological process which starts at the top of a food chain) - Example: the reintroduction of the grey wolf to Yellowstone National Park in 1995 o When grey wolves were removed from Yellowstone Park the nature of the river dramatically changed. o The vegetation diminished as the deer population started to graze this vegetation due to the lack of predation which was worsened by their increased population size. o By reintroducing the wolf, the behaviour of the deer was changed. They began avoiding certain areas of the park in fear of the wolves o This allowed the vegetation to regenerate, with tree heights quintupling in six years. o This led to an increase in migration of songbirds and beavers o The beavers constructed dams which served as habitats for other species (eg; otters) o The wolves also increased the population of hawks, weasels, foxes and badges as they preyed on coyotes which were eating all the rabbits and mice o The reintroduction of the wolf led to less soil erosion due to the deer and the narrowing of water channels. Also, more wildlife habitats were formed such as small pools. Human impact on ecosystems Issue Description Example Effect on flora and How to restore fauna Introduced Thick infestations The prickly pear can The prickly pear stops As the prickly pear is plant species of invasive be found over much the growth and bad for the introduced plant of the desert regeneration of native environment, an idea species, for example southwest from plant species, destroys is to not have them in the prickly pear, central Texas the habitat of native the environment due  impede on the through inland fauna, and provides to them damaging the growth and southern California. shelter for other ecosystem. This can regeneration of introduced pests, such be fixed by planting native plant species, In Australia, the as rabbits and foxes, more native plants that and can provide prickly pear can be which prey on native can restore the shelter for pests found along coastal animals. Some species ecosystem. such as rabbits and parts of NSW of the prickly pear have foxes. The prickly rendered over 40,000 pear was introduced square km of farming to Australia by land unproductive, due colonisers in 1788. to its destruction of the natural habitats and Another example of native flora. an invasive plant species is the bitou bush, which invades natural grasslands, woodlands and forests. It destroys native plants and habitats for native animals Introduced Cane toads became Large cane toad Their toxins can kill Cane toads are linked animal pests after being populations are other species that eat to the large decline as species introduced into based currently frogs or frog eggs well as extinction of Australia in 1935 to across Queensland, including birds, frogs, several native predator control beetles that the Northern reptiles and mammals. species in which live were destroying territory and into The Native Quoll in the Northern sugarcane crops in NSW and beginning population is at high Territory and Queensland. But the to invade Western risk of extinction as Queensland. numbers of them Australia. they would eat almost Strategies and soon became out of everything including a practices in which can control and they Some scientist Cane Toad if it help restore damaged began to spread believes that there encountered one. ecosystems include: across Australia, are over 200 million They breed quickly Repairing and poisoning predators cane toads around which allows them to replanting wetlands, that try to eat them Australia, and they rapidly colonise and creek beds, forestland, and have been are still expanding dominate a particular and other habitats | killing many native across Australia. area. Eradicating invasive species, such as the They have a large species | Replacing northern quoll. appetite and eat a turf grass with native variety of things which species | Planting rain depletes the other gardens to absorb animals in the same rainwater running off area of food and roofs or asphalt | nutrients. Monitoring pond and They a big competitor lake habitats and when it comes to preparing reports on finding food and habitat findings to space government  authorities Pesticides The problem with Since pesticides and There are various ways Household: and pesticides is that fertilisers are used that the impacts of Regularly inspect Fertilisers they are mobile to keep pests away pesticides can be linked pesticide containers within the from crops and to the extinction of for leaks | keep environment. They fertilised used to wildlife, this both pesticides out of can therefore travel help plants grow. through direct and waters/ water areas | through air as well They are normally indirect application. when using outdoors, as water and soil. found in soil. But This occurring through apply at at night (most This causes harm to since plants are out instances such as are toxic to bees) the environment, in the open, being pesticide drift, animals and watered and grow secondary poisoning Farmers: humans. They also throughout the soil, occurring through Be aware of geology disrupt the balance the pesticides and runoff into local water of area, clean spills of an ecosystem by fertilising are bodies or groundwater immediately, educate causing harm to becoming a type of contamination. There is self organisms that are pollution. The use the possibility of direct not pests. of these pollutants spraying upon some can harm animals, however Contamination of waterways, rain can others consume plants water with nitrates wash the pesticides or prey that have been and phosphates is and fertilisers off exposed. the main problem the plant and into with fertilizers. The the soil and into Crop physiology is nitrogen from water ways. This impacted through fertilizers and pollutes not only various disruptions of manures are water ways but also pesticides. Such as converted by the soil making it perturbation in the bacteria after some hard to use after the development of the time in the soil to crop has been reproductive organs, nitrates.... High harvested. They growth reduction, and nitrate levels in also harm plants alteration of the carbon drinking water are and animals like and/or nitrogen said to be dangerous soil microorganism metabolism, this all to human health. and insects to other leading to a lower types of plants, nutrient availability for birds and fish. The plant growth, stunting pollutants can their growth and poison these possibly shortening animals and plants their life span. when they had no intention to. The pollution is coming from land used for agriculture and any land used to grow plants without pests, like gardens. But it is then going into  waterways, the air and the soil around. Land Land degradation is Asia, Africa and Effect on Fauna In order to bring degradation a process in which South America (animals) degraded ecosystems the value of the currently suffer the Land degradation back to life, strategies biophysical most from land causes destruction of need to be environment is degradation. In Asia species habitat and implemented into our affected by a deforestation is the biodiversity. Land environment. By combination of most dominant degradation leads to giving the human-induced reason for land reduction of population environment time and processes. It is degradation, size and abundance, space to recover viewed as any however, change of genetic without any human change or agricultural diversity and extinction activity can allow the disturbance to the activities and over- of wildlife. Clearing ecosystem to restore land perceived to be grazing are also removes habitats, itself, increasing their harmful or causes for the leading to losses of benefit to society and undesirable. Some degradation in Asia. millions of animals biodiversity. More of the main factors Africa is affected by every year. As habitats strategies include site that are responsible land degradation become increasingly stabilisation where the for land degradation from mining, poor fragmented, populations degraded land should is extreme weather farming practices become more be stabilised by conditions, and illegal logging. vulnerable to the other implementing actions deforestation, over- South America is threats, such as to remove the key grazing by currently most predation by feral influences of livestock, bio- affected by species and destructive degradation. Through industrial activities deforestation, fires and lose the ability the removal of these and pollution that is erosion and over- to recolonise suitable influences this will degrading the grazing, and in habitat from which help reduce the rate of quality of soils and places such as they’re lost. decline in the land utility. Bolivia, Chile, condition of the land Ecuador and Peru Effect of Flora and can initiate they are facing (plants) immediate desertification. Land degradation can improvement. After result in loss of soil removing the key fertility and soil influences and erosion. The soil loses stabilising the land, the ability to support environmental plants and ultimately reconstruction is the keep them alive. It next step. Strategies of reduces water storage, restoring agricultural making soil less land can include crop permeable to plant management, inter- roots. Land degradation cropping, crop puts a large toll on selection and rotation, native plant species. strip cropping and The invasive species shelter belts. pose as a thread to Strategies to improve native biodiversity the land and soil which results in many include applying  native plant extinctions. organic manures and Land clearance is mineral fertilisers, another factor of land mulching, Agro- degradation that has forestry, contour had a huge impact on farming practises and native flora. Land physical soil clearance greatly conservation impacts on the health of measures. Also, the rivers and coastal implementation of ecosystems. It increases cut-off drains and erosion and runoff of retention ditches can sediment, nutrients and help restore the other pollutants into degraded land. coastal waters, causing damage to coral reefs More strategies and other marine include improved ecosystems such as water and rice seagrass beds. management, set- asides, land use change and improved livestock and manure management. Mining Mining and overuse Adani – the Adani FLORA – Mining Reintroduction of of natural resourced mine is a Carmicle operation can species that have been can significantly coal mine located in contaminate the soil extinct within that affect the natural the northern part of with toxic metals and particular area. This is environment in loss central Queensland. acids. Acids can lower as well as establishing of habitat for Currently 75% of pH of the soil; this laws and policies that animals and plant Australia’s energy prevents the make it harder harder species. Through comes from coal microorganisms from for mining companies overuse of the land, sourcing – thus thriving, and various to destroy land and there is extreme directly relating to mineral in the soil can especially scared sites. impacts on the mining. In 2019 this react. Minerals, such as For example, Adani fertility of the land mine was approved calcium and placing a 388km and can impact by the Australian magnesium, are railway through water sources government. required by plants. Aboriginal sacred significantly. Negatives sites and bombed associated with this FAUNA – Mining Aboriginal caves with specific example destroys many animals sacred rock paintings include habitat ecological habitats. in order to produce destruction through Runoff from mines can this railroad in central introduction of a also contaminate local Queensland. 388 km railroad to water supplies (e.g., Soil and capping support the industry rivers, creeks and material assessment and the site lakes). This causes are a critical covering 44 700 ha death of wildlife and/or component of rehab of land while 28 genetic mutations in planning. This 000 ha of this being offspring. Adani Cole includes soil actively mined. This mine is severely assessment activities  land will likely impacting the Great to be conducted at never recover, Barrier Reef and its appropriate intervals. species in the area organisms. Water management -- no longer possess It is important to that habitat, and as a ensure water result the whole management at ecosystems in the mining sites in order area have collapsed. to achieve a long-term rehabilitation process. For example – large Revegetation --A environmental revegetation land must impacts on the purpose activities at Gailee Basin will establish elf- resultant from waste sustaining vegetation and output from the communities that are mine contributed to appropriate for the loss of productivity intended area. of the land and Tailing storage degradation of the facilities -- contain groundwater. some of the most hazardous materials on the mine site and may represent significant long-term risk to environmental