Copy of Sammy's Yr 9 Biology Notes PDF

GRUNDINATOR’S CLASS Links and Extras Remember that when you have 3 variables remember you are changing the minutes and measuring the temperature of 2 different concentrations Quizlet All Topic flashcards Quizlet Topic 10 flashcards Quizlet Topic 9 flashcards Quizlet Topic 8 flashcards Quizlet Topic...

GRUNDINATOR’S CLASS Links and Extras Remember that when you have 3 variables remember you are changing the minutes and measuring the temperature of 2 different concentrations Quizlet All Topic flashcards Quizlet Topic 10 flashcards Quizlet Topic 9 flashcards Quizlet Topic 8 flashcards Quizlet Topic 7 flashcards Quizlet Topic 6 flashcards Quizlet Topic 5 flashcards All Cambridge Past Papers Extra Notes + Resources Practice Questions Cambridge Syllabus Topic I : Classification of living organisms Topic 1 - Outcomes Class Slides Topic 1 MRS GREN Movement is an action by an organism or part of an organism causing a change of position or place (ie. human walking, fish swimming) without environmental interference (ie. wind) Respiration is the chemical reaction in cells that breaks down nutrient molecules and releases energy for metabolism (there are two types aerobic/ with oxygen and anareboic/ without oxygen ) Sensitivity is the ability to detect and respond to changes in the internal and external environment. (ie. increased heat = sweat) Growth as a permanent increase in size and dry mass (new cells being added to body) Reproduction is the processes that make more of the same kind of organism  Excretion is the removal of the waste products of metabolism and substances in excess of requirements Nutrition is taking in materials for energy, growth and development Blooket Link for Mrs.Gren Linnaean Classification Scientist Carl Linnaeus realised in his career that the classification system used at the time was not working. Scientists would create a long unique description for each new species found. So he grouped organisms into Kingdom, Phylum, Class, Order, Family, Genus and Species. Ie. the scientific name for a tomato plant was Solanum caule inerme herbaceo foliis pinnatis incisis racemis simplicibus. Binomial Naming Binomial = Two Names = Genus species (Genus written with capital letter species with lowercase afterwards) ‘Bi’ meaning two ‘nomial’ meaning names Only the Genus and Species names are used for the name of the organism. The binomial system of naming species is an internationally agreed system. Classifying How do we classify? things Organisms can be classified into groups by the features they share. These features must not change with the seasons or age of the organism. Ie. number of body segments, number of wings, number of legs Why’s it important to classify? ⤷ Conservation: Identifying different organisms in habitats which are being managed and in breeding programs. ⤷ Understanding evolutionary relationships: Organisms which have many of the same features are normally descended from common ancestors. The more features they share the more recently they separated from one another during evolution. Ie. we share 98% of our DNA with apes In the past organisms were grouped together based on morphology (shape/ form) and anatomy (parts of inside of their body). Morphology Anatomy DNA structure: Closely-related organisms have very similar base sequences in their DNA because there has been less ‘evolutionary time’ for mutations to change this sequence. Therefore organisms which share a more recent ancestor have base sequences in DNA that are more similar than those that share only a distant ancestor. Dichotomous A way of identifying an organism by Keys Working through pairs of opposite statements There are two types of dichotomous keys a. Written in a and b choices b. Or making a physical table Species A species is a group of organisms that can reproduce to produce fertile offspring. In order to differentiate between organisms we need an internationally recognised means of identification using the BINOMIAL NOMENCLATURE. Kingdoms  Plant Kingdom Animal Kingdom Members of the animal kingdom can be divided into vertebrates and invertebrates. Vertebrates have a backbone. Invertebrates do not have a backbone. Phylum Arthropods are a phylum of invertebrates can be distributed into: Classes Fish: lose wet scales on their skin, have gills, have soft eggs Amphibian: smooth moist skin, adult live on land, have loose legs Reptile: dry fixed scales, lay eggs with rubbery shells on land, have lungs Bird: skin covered with feathers, wings and two legs Mammal: have hair or fur, have a placenta, young feed on milk from mammary glands, external ears visible, give birth to live young, endothermic You can identify them through their: limbs [appendages (fins,wings, leg, horns)] body coverings [smooth skin, scales, feathers, hair] Temperature regulations, ectothermic (outside of body, reptiles, amphibians, fish)endothermic(heat comes from the inside of their body) breathing mechanism (gills or lungs) Viruses They do not show the typical features of living things. Unless they are inside a host cell they do not undergo respiration, nutrition or reproduction. Do they belong in a sixth kingdom? Great variation between different viruses although all have a protein coat and genetic materia (can be DNA or RNA or both). Topic 2 : Organisation of an organism Topic 2 - Outcomes Class slides Topic 2 Animal Cell Cell membrane Structure: Double-layered membrane made of proteins and fats Where it is found: Around the entire cell Function: Holds cell contents in shape Controls the movement of substances into and out of the cell. It is selective in the molecules that can pass and those that cannot. This is called ‘selective permeability’. Cytoplasm Structure and location: Jelly-like substance that fills spaces within the cell. The cytoplasm is mostly water, with a variety of chemical substances dissolved in it (salts, sugars enzymes). Function: The fluid of the cytoplasm allows many chemical reactions to take place inside the cell. Nucleus Structure: Large, spherical structure in cytoplasm Colourless, transparent Most organisms have one nucleus per cell Where it is found in cell: Surrounded by cytoplasm and organelles Function: The control centre of cell contains chromosomes (DNA) - genetic information; controls cell reproduction; controls protein synthesis e.g. enzyme production Rough endoplasmic Reticulum Structure: Network of flattened, interconnected membranes Ribosomes are attached to it. Function: Connects cell membrane with cytoplasm Ribosomes are attached. Endoplasmic Reticulum Where it is found: Throughout the cytoplasm Ribosomes Function: Site of protein synthesis (link amino acids together in correct sequence) Newly synthesised proteins pass from ribosomes to ER where folding occurs Produces proteins Mitochondria Where it is found: In the cytoplasm Function: Aerobic respiration occurs here. Cells with high rates of metabolism require large amounts of mitochondria to provide sufficient energy. Vesicles Vesicles are membrane-bound sacs that function in storage and transport. The membrane of a vesicle can fuse with the membranes of other cellular components. Plant Cell Chloroplast Where it is found: In the chloroplast of plant cells, photosynthesis occurs. Function: Site of photosynthesis May serve as organelle for storing starch Cell Wall Structure: Made up of cellulose (little elasticity) Some are thickened with chemicals such as lignin (for strength ) Where it is found: Around the entire cell in plant cells and fungi Function: Provides support and strength Not selective like the cell membrane. Vacuole Structure  Large, fluid (sap) filled sac surrounded by a membrane (tonoplast) Where it is found: In the cytoplasm (large vacuoles more common in plant cells). Function: Storage → Contains substances such as mineral salts, sugars and amino acids dissolved in water. Can also contain dissolved pigments. Support → Pushes outward on cytoplasm making cell firm or turgid Magnification Calculation Magnification = Image Actual Size You may be given the value of magnification only and then asked to calculate the actual size. In this case, you will need to measure the drawing (across its widest length) on the paper itself to get a value for the image size. Cells are often measured in micrometres (µm [1mm is 1000 µm]). Specialised Cells Specialised cells are dedicated to one particular function in an organism. The shape of these cells suits their function. There are specialised cells in all multicellular organisms. All specialised cells start from the same stem cell before being assigned a ‘job’ Ciliated Cells Has a layer of tiny hairs (cilia) which can move and push mucus in the trachea and bronchi. The mucus can transport trapped dust and microbes when the cilia push it. Root Hair Cells In plants, root hair cells absorb water and minerals from the soil and store it until it can be passed into the vascular system. The root hair cell has a large extension (the root hair) to give it a large surface area for absorption and a large vacuole for storing the water. Xylem Vessels Transports water and supports the plant The cell has no cytoplasm (so water can freely pass) no end wall (so many cell can form a continuous tube) and walls strengthened with a waterproof substance called lignin. Palisade mesophyll cells In the middle of the plant leaf Tall, thin cells arranged in columns and separated by very narrow air spaces. Cells contain many chloroplasts, and densely packed cells allow for the absorption of the maximum amount of light energy. Nerve Cells Nerve cells conduct nerve impulses The cell has a long fibre called an axon along which impulses travel, a fatty sheath which gives electrical insulation and a many-branched ending which can connect to other cells. Red Blood Cells RBCs transport oxygen. The cells have no nucleus, leaving more space for haemoglobin (a pigment which carries oxygen). They are very flexible, meaning they can be forced through narrow blood vessels. RBCs have a large surface area to ensure the efficient uptake of oxygen. When blood goes through capillaries it goes to a single-file large surface to take in oxygen. Sperm and egg Sperm: They are motile, and have flagellum that beat to move towards the ovum. Small Egg: Much larger Do not move, have a large food store. Level of Organisation Organs An organ is a structure made up of a group of tissues, working together to perform specific functions. Tissues A tissue is a group of cells with similar structures, working together to perform a shared function. [ie skin is a tissue working to keep you covered] There are four types of tissue in the human body: nervous, muscle, connective, and epithelial tissues. Topic 3 : Movement in and out of cells Topic 3 - Outcomes Class slidesTopic 3 Movement in and out of cells Solute and Diffusion can be seen when a drop of ink (the solute) is placed in a jar Solvent of still water (the solvent). Solute: A substance dissolved in a fluid (the solvent) Solvent: a fluid in which the substance (the solute) is dissolved. Diffusion Diffusion is the net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement. - Does not require energy input → passive Diffusion is a passive process - Diffusion is a passive process, it does not require an input of energy. - The energy for diffusion comes from the kinetic energy of random movement of molecules and ions. The importance of diffusion of solutes Diffusion is the main process by which substances move over short distances in living organisms. Examples of diffusion of solutes: The importance of diffusion of gases Most living things require oxygen for respiration. This moves into the organism by diffusion down a concentration gradient. Carbon dioxide produced leaves the cells via diffusion following a concentration gradient. Example of biological diffusion Factors affecting diffusion Distance : The smaller the distance molecules have to travel the faster transport will occur This is why blood capillaries and alveoli have walls which are only one cell thick, ensure the rate of diffusion across them is as fast as possible One cell thick meaning diffusion is easy Temperature: The higher the temperature, the faster molecules move as they have more energy. This means more collisions against the cell membrane and therefore a faster rate of diffusion/movement across them Surface area: Surface area is the amount of space covering the outside of a three-dimensional shape. - If 100 molecules diffuse through 1mm2 of a membrane in 1 minute, it is reasonable to suppose that an area of 2mm2 will allow twice as many through in the same time. - Therefore the rate of diffusion into a cell will depend on the cell’s surface area. - The greater the surface area, the greater the total diffusion. - Cells that are involved in rapid absorption (eg. kidney or intestine) often have a ‘free’ surface membrane formed into hundreds of tiny projections which increase the surface area.  Concentration gradient: The greater the difference in concentration on either side of the membrane, the faster movement across it will occur. This is because on the side with the higher concentration, more random collisions against the membrane will occur. Osmosis The diffusion of water molecules from a region of high water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane Does not require energy input ⤷ Water moves in and out of cells by osmosis through the cell membrane. ⤷ Water cannot move directly through the cell membrane but must instead go through channels called aquaporins. If a more concentrated solution and a more dilute solution are separated by a semipermeable membrane, the net diffusion of water molecules will occur from the dilute solution to the concentrated solution until the concentration is equal on both sides Hypertonic: A solution that has a greater concentration of solutes compared to another solution or inside normal body cells. Isotonic: A solution that has an equal concentration of solutes compared to another solution or inside normal body cells. Hypotonic: A solution that has a lower concentration of solutes compared to another solution or inside normal body cells. 0 - turgid Water potential The water potential of a solution is a measure of whether it is likely to lose or gain water molecules from another solution. A dilute solution, with its high proportion of free water molecules, is said to have a higher water potential than a concentrated solution because water will flow from the dilute to the concentrated solution (from a high potential to a low potential).  Pure water has the highest possible water potential because water molecules will flow from it to any other aqueous solution, no matter how dilute. Osmosis and plant turgidity/flaccidity If vacuoles lose water, the cells will lose their turgor and become flaccid. If a plant has flaccid cells, the leaves will be limp and the stem will droop. This plant is said to be wilting. A plant with a vacuole pushing out on the cell wall is said to be turgid and the vacuole is exerting turgor pressure on the inelastic cell wall. If all the cells in a stem and leaf are turgid, the stem will be firm and upright and the leaves held out straight. Plasmolisis Water from inside the cell dries it out ripping the membrane of the wall After plant cells become flaccid, if the conditions continue plant cells become plasmolysed. Plasmolysis: 1. When the solution outside the cell is more concentrated than the cell sap. 2. Water diffused out of the vacuole.  3. The vacuole shrinks, pulling the cytoplasm away from the cell wall, and leaving the cell flaccid. The cell becomes plasmolysed when the cell membrane is ripped from the cell wall killing the cell. Osmosis potato experiment - Potatoes become softer when they lose water and harder when they gain water example : if the sucrose solution is more dilute this means it has lower sucrose concentration and higher water potential. Therefore if the solution's water potential is higher than the water potential of the submerged potato sticks, the water will move from the higher to lower water potential in this case from the sucrose solution into the potato. Active transport - The movement of particles through the cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration. (the opposite of diffusion and osmosis) - moves up the concentration gradient - Requires the input of energy and a carrier or channel protein that spans the membrane Example of active transport is when: mineral ions move from the soil into the root hair cell; blood and amino acids are reabsorbed into the kidneys so they arent lost in urine.  Carrier proteins embedded in the cell membrane to pick up specific molecules and take them through the cell membrane against their concentration gradient: 1. Substance combines with carrier protein molecule in the cell membrane 2. A carrier transports substances across the membrane using energy from respiration to give them the kinetic energy needed to change shape and move the substance through the cell membrane 3. A substance released into the cell Topic 4 : Biological Molecules Topic 4 - Outcomes Class slides Topic 4 DNA Deoxyribonucleic Acid In nucleus is Present in all living organisms. The genetic material that encodes for ALL proteins that allow a cell to function Where? In the nucleus of Eukaryotic organisms In the nucleoid of Prokaryotic organisms The double helix Very long molecule, made of 2 parallel strands that coil around each other forming a double helix. Each strand contains chemicals called bases. The bases always pair up in the same way A to T and G to C Crosslinks between the strands are formed by pairs of bases.  Nucleotide A molecule consisting of a sugar, a nitrogenous base and a phosphate group. Smaller molecules join together to make larger molecules. Nucleotides join together to form larger nucleic acids like DNA and RNA RNA vs DNA U replaces T in RNA Rna is single-stranded - one helix Has a different type of sugar Carbohydrates Sucrose = glucose + fructose Lactose = galactose + glucose Maltose = glucose + glucose Glycogen, sucrose and cellulose = multiple glucose molecules chemically bound in different branching patterns. Monosaccharides: One sugar ring A simple sugar ie. glucose  A glucose molecule contains six carbon atoms, twelve hydrogen atoms and six oxygen atoms. (C6H12O6) Simple sugars are very small, dissolve in water (are soluble) and taste sweet. Disaccharides Two sugar rings Two simple sugars join together and form a larger complex sugar called a disaccharide. Two examples are sucrose and maltose. They are also soluble in water and taste sweet. Polysaccharides Simple sugars join together and make a polysaccharide. Some contain thousands of sugar molecules Cellulose which makes up plant cell walls is an example of this Plants store excess sugars as starch Animals store excess sugars as glycogen Most polysaccharides are insoluble and do not taste sweet Function of carbohydrates: Needed for energy. The carbohydrate needed for respiration is glucose. (Oxygen+Glucose = Water + Oxygen (ATP energy)) Animals transport carbohydrates around their bodies as glucose and store it as glycogen. Plants transport carbohydrates around as sucrose and the cells change the sucrose to glucose when they use it: They store sugar as starch. How to test for starch: 1. Put food samples into a test tube.  2. Add a few drops of iodine solution to the sample 3. If starch is present, the solution turns from brown to blue-black. How to test for carbohydrates: Benedict's solution 1. Add Benedict’s solution and Heat 2. If the food contains a reducing sugar then a brick-red colour will be produced. The mixture will change from blue, to green/ yellow, orange and then brick red. Proteins Contains carbon, hydrogen, oxygen and nitrogen Large molecules made from smaller units of amino acids Examples of animal proteins (don’t need to know) Shape of proteins There are 20 different amino acids in animal proteins.  A small protein molecule might be made up of a hundred amino acids. Each type of protein has its amino acids arranged in a particular sequence. The chain of amino acids in a protein takes a particular 3D shape due to cross-linkages between amino acids. 3d structure gives proteins its function Function of protein Structural proteins: proteins contributing to the structure of the cells, eg. to the cell membranes, the mitochondria, ribosomes and chromosomes. Enzymes: control the chemical reactions that keep the cell alive. Present in the membrane systems, in the mitochondria, in special vacuoles and the fluid part of the cytoplasm. …although many other proteins are important in living things. Tests for protein: biuret test 1. add a few drops of Biuret’s reagent (sodium hydroxide and copper (II) sulphate) to the sample in a test tube. 2. Wait for a few minutes for reaction to occur. 3. If protein is present, the solution turns from blue to purple. Dangers: burns skin, immediate blinding Antibodies and proteins Antibodies are proteins produced by white blood cells called lymphocytes. Each antibody has a binding site, which can lock onto pathogens such as bacteria.  This destroys the pathogen directly or marks it so that it can be detected by other white blood cells called phagocytes. Each pathogen has antigens on its surface that are a particular shape, so specific antibodies with complementary shapes to the antigen are needed Enzymes and proteins Enzymes are proteins that catalyse metabolic chemical reactions (stimulate chemical reactions involved in metabolism.). The shape of the enzyme molecule is very important. Enzymes have an ‘active site’, which is complementary to the substrate on which it acts. (locks together) Lipids [fats] Intro Also known as fats Contains carbon, hydrogen and oxygen. A fat molecule is made of four smaller subunits joined together. A glycerol and three long molecules called fatty acids. Insoluble in water. If they are liquid at room temperature they are called oils. Function of lipids Can be used to release energy (twice as much as carbohydrates) Useful for storage of energy. Most cells will use carbohydrates first for energy and then use lipids after these have been used up. Mammals store fats and oils underneath the skin in cells. These stores can be used to release energy when needed. This layer of cells (adipose tissue) helps to insulate the body and keep it warm. Plants store oils in their seeds to use for energy in germination. Lipids are also structural as they form all cell membranes. Test for lipids: emulsion test 1. Add a few cm3 of ethanol to the sample.  2. Pour this mixture into a test tube of equal volumes of distilled water. 3. If lipids are present, a white emulsion is formed in the mixture (tiny droplets suspended -not dissolved- in the water). Testing for vitamin C 1. Add 1cm3 of DCPIP solution to a test tube 2. Add a small amount of food sample (as a solution)(juice) 3. A positive test will show the blue colour of the dye disappearing Water: important Water is important as a solvent in the following situations within solvent organisms: Dissolved substances can be easily transported around organisms - eg. xylem and phloem of plants and dissolved food molecules in the blood Digested food molecules are in the alimentary canal but need to be moved to cells all over the body - without water as a solvent this would not be able to happen Toxic substances such as urea and substances in excess of requirements such as salts can dissolve in water which makes them easy to remove from the body in urine Water is also an important part of the cytoplasm and plays a role in ensuring metabolic reactions can happen as necessary in cells Overall notes Large molecules are made of smaller molecules What elements are in each ‘food’ Carbon, hydrogen, oxygen, nitrogen, phosphorous Joining smaller molecules together Glucose is a monosaccharide, which means it is a single sugar molecule. Glucose molecules can join together to form starch, glycogen and cellulose Amino Acids are small molecules and they join together to form larger molecules known as proteins. Fatty acids along with Glycerol join together to form larger molecules known as fats and oils Topic 5 : Enzymes Topic 5 - Outcomes Class slides Topic 5 Enzymes are A catalyst is a substance that increases the rate of a chemical catalysts reaction and is not changed by the reaction. An enzyme is a protein that functions as a biological catalyst. Part of an Enzyme Action of Enzymes can build larger molecules and enzymes can break down Enzymes molecules into smaller molecules. [can join and break nucleotides,] Enzymes ‘recognise’ their substrates like a ‘lock and key’. Each enzyme is specific for its substrate. (it can only perform one job)  Lock and key model Enzymes are These reactions may have occurred without the enzymes being important to all present, but they would have done so extremely slowly, too slowly to sustain life. living organisms The enzyme brings the substances closer together and makes the reaction happen much more rapidly. Enzymes are Each different type of enzyme will usually act on only one substrate(s) specific to catalyse a biological reaction. Enzymes are specific because different enzymes have differently shaped active sites. They fit together like a lock and key The shap  e of the active site of an enzyme is complementary to the shape of its specific substrate. This means they are the correct shapes to fit together. Ie. sucrase can only break down sucrose Enzyme Names Enzymes that were discovered early were given general names which are still used as pepsin, trypsin, cathepsin, emulsin, etc…Now a suffix (ase) is added to indicate enzyme. The prefix may be: Name indicating the general nature of substrate e.g.: protease, lipase (in the name you can mostly guess what it breaks down) The real name of the substrate: urease, lactase, sucrase. Type of reaction catalysed e.g.: dehydrogenase (if they end in, in or ase think about enzymes) Enzyme activity As the temperature increases in a chemical reaction, the rate of and temperature reaction increases due to the increased rate of collisions and higher kinetic energy of particles. → They hit each other more when temperature has increased. This happens up to a certain point (optimal temperature). After this, the rate of reaction decreases because the enzyme denatures (changes shape→ they change shape and can’t lock into a substrate, you can’t reverse this process) Once the enzymes have denatured they disappear  At extreme levels of temperature, enzymes change their 3D shape, they denature. This renders them inactive. They cannot perform their function, because they are unable to for a lock and key structure. You can freeze them then heat them to bring them back but when heated too far they change shape and can’t lock and key to break down and build up molecules. Optimal Temperature Every enzyme has an optimal temperature at which it works best, eg. the fastest rate of reaction, our optimal temperature [humans] is about 360C Enzymes have different optimal temperatures Acidity and pH What's pH? pH is the measure of the amount of acidity or alkalinity that is in a solution. The pH scale describes the relative acidity or alkalinity of a solution. What's an Acid? Acids are a group of chemical compounds with similar properties. - Sour taste - Produce a prickling or burning sensation on skin - Contain at least one hydrogen atom e.g: HCl: Hydrochloric acid - Tend to react with many metals What's a Base? The chemical opposites of acids - Bitter - Feel slippery or soapy to touch A base that dissolves in water is called an alkali and solutions that are formed by these soluble bases are described as alkaline solutions. Ie. Baking soda (sodium hyrdoixde) Enzyme activity and pH The pH of the solution where the enzyme acts, affects the enzyme’s rate of reaction. Every enzyme has an optimal pH at which it works best; it’s fastest rate of reaction Every enzyme has its own particular optimal pH, Eg. pepsin: pHopt 2.0 and trypsin: pHopt=8.0 pH and Enzyme shape At extreme levels of pH, the enzymes change their 3D configuration, it changes shape. This is called denaturation.  When an enzyme is denatured, it stops working. The reaction cannot proceed because the active site is no longer in the right shape to fit its substrate. (its 3D shape changes) Normal Denatured Topic 6 : Plant Nutrition Topic 6 - Outcomes Class slides Topic 6 Plants need food Plants require raw materials for building tissues and as a source of energy. They manufacture everything they need out of simple ions and compounds available in the environment. They build up more complex molecules from simpler ones using enzymes. Photosynthesis The process by which plants manufacture carbohydrates from raw materials using energy from light. or… Photosynthesis is the process in which light energy, trapped by chlorophyll, is used to convert carbon dioxide and water into glucose and oxygen. Plants, algae and some bacteria (Cyanobacteria) make their own food in a process called photosynthesis. Almost all life on Earth depends upon this process. Photosynthesis is also important in maintaining the levels of oxygen and carbon dioxide in the atmosphere. Glucose use Some glucose is used for cellular respiration by the plant’s cells. Some glucose is stored as starch for later use. This starch can be turned back into glucose again later for use (for at night when photosynthesis doesn’t occur) What can be made from glucose? Plants make all the molecules from glucose and nitrates from the soil (they have different enzymes to do this) Absorbing light Photosynthesis takes place inside plant cells in organelles called chloroplasts. Chloroplasts contain a green substance called chlorophyll. This absorbs the light energy needed to make photosynthesis happen. Chlorophyll Chlorophyll is a large molecule whose job is to trap light. It absorbs (traps) red and blue light and reflects green, hence we see it as a green-coloured pigment (that's why we see plants green) Once chlorophyll traps light, a series of chemical reactions (where enzymes are involved) transform the light energy into chemical energy in molecules. The end product is the synthesis of glucose. How to draw a leaf cross-section Generally, only draw a section of the leaf Stomata Stomata can open and close depending on environmental conditions. If the vacuoles in the guard cells are full they are turgid and held open. If the vacuoles are empty the guard cells become flaccid and close Limiting factors What a limiting factor of A condition that when in shortage slows down a reaction photosynthesis Factors that affect the rate of photosynthesis Light intensity Carbon dioxide concentration Temperature Amount of chlorophyll Light intensity Without enough light, a plant cannot photosynthesise very quickly - even if there is plenty of water and carbon dioxide and a suitable temperature. Increasing the light intensity increases the rate of photosynthesis until some other factor - a limiting factor - becomes in short supply. Carbon dioxide concentration Carbon dioxide is one of the reactants in photosynthesis. If the concentration of carbon dioxide increases, the photosynthesis rate will increase. At some point, a different factor may become limiting. Beyond this concentration, further increases in the concentration of carbon dioxide will not result in a faster rate of photosynthesis. The level of carbon dioxide in the atmosphere is rising because of greenhouse gas emissions. It is currently at around 0.04 per cent. This concentration is still very low in terms of being the optimum for photosynthesis. Carbon dioxide concentration is therefore an important limiting factor for photosynthesis. Temperature Enzymes control the chemical reactions of photosynthesis. As with any other enzyme-controlled reaction, the rate of photosynthesis is affected by temperature. At low temperatures, the rate of photosynthesis is limited by the number of molecular collisions between enzymes and substrates. At high temperatures, enzymes are denatured, chemical reactions stop and so does the rate of photosynthesis. It is then possible to control conditions in colder countries so that they are photosynthesising as fast as possible. This is done in a glass house/greenhouse CO2 Enrichment CO2 concentration can be controlled. CO2 is often a limiting factor for photosynthesis because its natural concentration in the air is so very low (0.04%). In a closed glasshouse, it is possible to provide extra CO2 for the plants, e.g. by burning fossil fuels or releasing pure CO2 from a gas cylinder. Optimal Light Light also can be controlled. In cloudy or dark conditions, extra artificial lighting can be provided, so that light is not limiting the rate of photosynthesis. The kind of lights that are used can be chosen carefully so that they provide just the right wavelengths that the plants need. Optimal Temperature The temperature can be raised by using a heating system. If fossil fuels are burned, there is also a benefit from the CO2 produced.  Gas exchange in light and dark Plants are respiring all the time so plant cells take in oxygen and release carbon dioxide as a result of aerobic respiration Plants also photosynthesise during daylight hours, for which they need to take in carbon dioxide and release the oxygen made in photosynthesis At night, plants do not photosynthesise but they continue to respire, meaning they take in oxygen and give out carbon dioxide The The previous graphs have been plotted with the rate of compensation photosynthesis against the factor under investigation. If O2 production or CO2 uptake is used as a measure of photosynthetic point rate, the line does not go through the origin. This is because O2 production or CO2 uptake are affected by respiration as well as photosynthesis. If a graph is plotted of CO2 uptake against light intensity: The compensation point is the light intensity at which the rate of photosynthesis is equal to the respiration rate. A similar graph will be obtained if oxygen production is plotted against light intensity. Gas exchange in Plants are respiring all the time so plant cells take in oxygen and light and dark release carbon dioxide as a result of aerobic respiration Plants also photosynthesise during daylight hours, for which they need to take in carbon dioxide and release the oxygen made in photosynthesis At night, plants do not photosynthesise but they continue to respire, meaning they take in oxygen and give out carbon dioxide Respiration (spongy mesophyll) Oxygen+glucose carbon dioxide+water (ATP energy) Photosynthesis (palisade mesophyll) Carbon dioxide+ water→ glucose+oxygen During the day, especially when the sun is bright, plants are photosynthesising at a faster rate than they are respiring, so there is a net intake of carbon dioxide and a net output of oxygen We can investigate the effect of light on the net gas exchange in an aquatic plant using a pH indicator such as hydrogencarbonate indicator This is possible because carbon dioxide is an acidic gas when dissolved in water Hydrogencarbonate indicator shows the carbon dioxide concentration in solution The table below shows the colour that the indicator turns at different levels of carbon dioxide concentration  Hydrogen Carbonate indicator Gause lets light through at a slower rate Structure of An autotroph is an organism which produces its own food using light, Autotrophs water, carbon dioxide and other chemicals. The majority of autotrophs are plants. We often do not think of the different parts of a plant as organs, however the leaf for example is a very complex organ that can conduct gas exchange and produce glucose for the plant. Leaf model: Leaves Functions of a leaf: Photosynthesis: the process by which plants use sunlight, water, and carbon dioxide to create oxygen and glucose Transpiration: loss of water through the stomata Gas exchange: intake of carbon dioxide and release of oxygen. Adaptations of leaves Lenticels Lenticels are pores through which the woody parts of plants (such as the trunk and branches) can exchange gas with the atmosphere  Minerals in Plants need many minerals to live healthily. plants These may be needed to make certain chemicals or for reactions to work properly. Plants absorb these minerals from the soil via the roots when water is absorbed. (root hair cells ) Plants absorb minerals in their ionic (charged) form. For example: nitrate (NO3−), phosphate (HPO4−), potassium (K+) ions When not dissolved in water, these form mineral salts. Magnesium and nitrogen Plants need nitrate ions (NO3−) to make amino acids. Amino acids are important because they are joined together to make proteins, needed to form the enzymes and cytoplasm of the cell. Magnesium ions (Mg2+) are needed to form chlorophyll, the photosynthetic pigment in chloroplasts. This metallic element is also obtained in salts from the soil. Other minerals in plants Topic 7 :Human Nutrition Outcomes Topic 7 - Human nutrition Topic 7: Human Nutrition Parts 1, 2 and 3 Whats a balanced Enough carbohydrates and fats to meet our energy needs. diet? Enough protein to provide the essential amino acids to make new cells and tissues for growth or repair. The diet must also contain vitamins and mineral salts, plant fibre (roughage) and water Difference Females tend to have lower energy requirements than males. between gender, Two reasons for this are: Females have, on average, a lower body mass than males, which age and activity has a lower demand on energy intake. There are also different physical demands made on boys and girls. However, an active female may well have higher energy requirements  Age As children grow, the energy requirement increases because of the energy demands of the growth process and the extra energy associated with maintaining their body temperature. Metabolism, and therefore energy demands, tends to slow down with age once we become adults due to a progressive loss of muscle tissue. Pregnancy A pregnant woman who is already receiving an adequate diet needs no extra food. Her body’s metabolism will adapt to the demands of the growing baby although the demand for energy and protein does increase. If her diet is deficient in protein, calcium, iron, vitamin D or folic acid, she will need to increase her intake of these substances to meet the needs of the baby. The baby needs protein for making its tissues, calcium and vitamin D are needed for bone development, and iron is used to make the haemoglobin in its blood. Lactation ‘Lactation’ means the production of breast milk for feeding the baby. The production of milk, rich in proteins and minerals, makes a large demand on the mother’s resources. If her diet is already adequate, her metabolism will adjust to these demands. Otherwise, she may need to increase her intake of proteins, vitamins and calcium to produce milk of adequate quality and quantity. Malnutrition Malnutrition literally means ‘bad feeling’: Eating too much of all foods. Having too little food. Eating foods in the wrong proportions. WHO definition: Malnutrition refers to deficiencies, excesses, or imbalances in a person’s intake of energy and/or nutrients starvation = Undernutrition. It causes: Wasting: low weight for height Stunting: low height for age - holds children back from reaching their physical and cognitive potential Underweight: low weight for age Deficiencies in vitamins and minerals. Undernutrition makes children in particular much more vulnerable to disease and death. In developing countries, many people have diets which are neither adequate nor balanced. They often have shortages of iron (anaemic), vitamin C (scurvy) and more. The most obvious signs of malnutrition in these people is a deficiency of protein. Two extremes of protein deficiency are kwashiorkor and marasmus. Rickets Cause: A lack of vitamin D in children. Vitamin D is needed to absorb calcium in the digestive system. Calcium is required for healthy bones. Effect: Softening of the bones and bowed legs. Iron deficiency: Anameia Cause: Too little iron in the diet, loss of blood, pregnancy Effects: Not enough iron leads to deficient haemoglobin. Haemoglobin is a protein that carries oxygen in red blood cells. Not enough healthy red blood cells. Less iron means less oxygen in cells → tiredness, exhaustion Pale skin, dizziness, lightheadedness Treatment includes iron supplements. Constipation Caused by too little fibre in the diet and lack of water intake. Faeces can’t be passed regularly. Bacteria may be trapped in the faeces and release chemicals that may cause colon cancer. Coronary Heart Disease Caused by a diet with too much-saturated fat and cholesterol. These cause blockage in blood vessels, especially in vessels that supply the heart (‘coronary arteries) Consequence: heart failure Obesity May be caused by an excessive consumption of foods, especially fats. The body stores the excess fat. Body Mass Index (BMI) in obesity surpasses 30.  This puts the person at risk of developing Type 2 diabetes, breathing difficulties, atherosclerosis (narrowing of blood vessels) and arthritis. Scurvy Nutritional disease caused by deficiency of vitamin C. Symptoms (effects) include: Gum disease Loosening of teeth Rough skin Small bruises on the skin Poor wound healing Emotional changes Fatigue Muscle weakness The alimentary The alimentary canal is a muscular tube, which extends from the mouth canal to the anus. Food moves through the alimentary canal using muscular contractions called peristalsis. Food goes through the alimentary canal only and not through the accessory organs. These provide digestive enzymes that are ‘poured’ into the canal usually through ducts. The main organs of the alimentary canal are shown on the diagram. You need to learn these. Definitions pancreas An organ that produces enzymes that digest starch, protein and fat absorption The movement of nutrient molecules and ions through the wall of the intestine into the blood enamel The outer, very hard layer of the tooth duodenum The part of the alimentary canal into which bile and pancreatic juice flow amylase An enzyme that digests starch to reducing sugars lipase An enzyme that breaks down its substrate to fatty acid and glycerol stomach An organ that secretes a juice containing hydrochloric acid digestion The breakdown of food into small molecules so that they can move from the intestine in the blood Processes of Ingestion: The taking of substances, e.g. food and drink, into the body consumption through the mouth. Digestion: Mechanical digestion: The breakdown of food into smaller pieces without chemical change to the food molecules. Teeth, stomach churning. Chemical digestion: The breakdown of large, insoluble molecules into small, soluble molecules. Through enzymes. Absorption: The movement of small food molecules and ions through the wall of the intestine into the blood Assimilation: The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells  Egestion: The passing out of food that has not been digested or absorbed, as faeces, through the anus Human Teeth Human teeth are the hardest substance in the body There are 32 adult teeth, 16 in the upper jaw and 16 in the lower jaws. Of these: 4 incisors, 2 canine, 4 premolars and 6 molars in each jaw Teeth are involved in the mechanical digestion of food. Teeth break down food into smaller pieces without altering its chemical composition. Chewing of the food by the teeth increases its surface area so that it can be exposed to saliva and other digestive enzymes that carry out chemical digestion. Different teeth have different shapes that are suited to different functions: Tooth Shape Function Incisors chisel Biting and cutting pointed Tearing, holding Canine and biting Large, flat surface with Chewing and Molar ridges on the edges grinding  Structure of a tooth: Part of Description tooth Enamel The hardest tissue in the body. Resistant to wear. Dentine Forms the major part of the tooth. Harder than bone. Provides support to enamel. Pulp Contains tooth-producing cells, blood vessels and nerve endings which can detect pain. A tooth connects to the circulatory system via the pulp cavity. Nerves Detect pain if a tooth is injured and pressure during chewing and biting. Cement/ Helps anchor the tooth to the jaw. cementum Gums Soft tissue that covers the junction between enamel and cement. Gums recede with age. Tooth decay What is it? Tooth decay is a common dental problem caused by the breakdown of tooth structure due to acids produced by bacteria in the mouth. Bacteria present in the mouth feed on sugar and starch from the food left on the other as they metabolise sugar they produce acid as a byproduct - this erodes the enamel. If left untreated it continues to break down to tooth causing pain and sensitivity.  How to keep teeth healthy Diet - limit sugary and acidic food and drinks. Consume foods rich in calcium, phosphates and vitamins essential for dental health (vitamins d and c) Hygiene - brushing teeth twice a day, toothpaste consists of minerals and fluoride that help fortify the enamel Chemical The purpose of digestion is to break down large, insoluble molecules Digestion (carbohydrates, proteins and lipids) into small, soluble molecules that can be absorbed into the bloodstream Food is partially digested mechanically (by chewing, churning and emulsification) in order to break large pieces of food into smaller pieces of food which increases the surface area for enzymes to work on Digestion mainly takes place chemically, where bonds holding the large molecules together are broken to make smaller and smaller molecules Chemical digestion is controlled by enzymes which are produced in different areas of the digestive system There are three main types of digestive enzymes - carbohydrases, proteases and lipases Different enzymes Amylase Amylase breaks down starch into simpler sugars Amylase is secreted into the alimentary canal in the mouth and the duodenum (from the pancreas) and digests starch to maltose (a disaccharide) Maltose is digested by the enzyme maltase into glucose on the membranes of the epithelium lining the small intestine Protease Proteases are a group of enzymes that break down proteins into amino acids in the stomach and small intestine (with the enzymes in the small intestine having been produced in the pancreas). Protein digestion takes place in the stomach and duodenum with two main enzymes produced:  Pepsin is produced in the stomach- Trypsin is produced in the pancreas and secreted into the small intestine (duodenum). Lipase Lipases digest lipids into fatty acids and glycerol Lipase enzymes are produced in the pancreas and secreted into the duodenum The stomach The stomach produces several fluids which together are known as gastric juice (one includes hydrochloric acid) This kills bacteria in food and gives an acid pH for the enzyme pepsin to work in the stomach The stomach is very acidic with a pH of 2 Low pH of the stomach The low pH kills bacteria in food that we have ingested as it denatures the enzymes in their cells, meaning they cannot carry out any cell reactions to maintain life. Pepsin, produced in the stomach, is an example of an enzyme which has a very low optimum pH - around pH 2 The hydrochloric acid produced in the stomach ensures that conditions in the stomach remain within the optimum range for pepsin to work at its fastest rate. The Liver The liver produces bile which is then stored in the gallbladder Bile It is alkaline to neutralise the hydrochloric acid which comes from the stomach The enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach It breaks down large drops of fat into smaller ones. This is known as emulsification. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster. NB: emulsification is mechanical digestion not chemical digestion! Absorption Villi The internal wall of the small intestine(ileum) is covered with tiny projections called villi. These villi increase the surface area of the intestine allowing for optimal absorption for faster absorption of nutrients. The wall of the villus is one cell thick meaning that there is only a short distance for absorption to happen by diffusion and active transport. Well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood. Lacteal runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine in the lymph. Water absorption Water is absorbed in both the small intestine and the colon, but most absorption of water (about 90%) happens in the small intestine. The colon absorbs any remaining water as it prepares the undigested materials for egestion.  Diarrhoea Diarrhoea is the loss of watery faeces. If it is severe and continues for a long time, it can lead to death Severe diarrhoea can cause the loss of significant amounts of water, causing the tissues and organs to stop working properly It can be treated through oral rehydration therapy This is a drink with a small amount of salt and sugar dissolved in it There are many causes of diarrhoea, one of which is infection with Vibrio cholerae bacteria, which causes the disease cholera Cholera is an acute diarrhoeal infection caused by eating or drinking food or water that is contaminated with the bacterium Vibrio cholerae (often present in dirty water). How does it cause illness? 1. Bacteria latch embed and release toxins which irritate the intestine wall. They multiply in the intestine and invade epithelial cells 2. They produce a toxin. The toxin stimulates the cells lining the intestine to release chloride ions from inside the cells into the lumen of the intestine 3. The chloride ions accumulate in the lumen of the small intestine and lower the water potential 4. Once the water potential is lower than that of the cells lining the intestine, water starts to move out of the cells into the intestine (by osmosis) 5. Large quantities of water are lost from the body in watery faeces 6. The blood contains too little chloride ions and water Topic 8 :Transport in Plants Class Slides Topic 8 Topic 8 - outcomes Transport in plants All living organisms need to obtain substances from the environment For plants, these substances include carbon dioxide and water as well as many other nutrients  The product of photosynthesis in all plants is glucose. Glucose is produced in green tissues, mostly on the leaves of all plants. Minerals and water are required for the production of glucose. These are taken from the soil and transported to the leaves and shoot. The glucose produced is then transported to the rest of the plant for all cells to carry out cellular respiration. Xylem The xylem is a specialised tissue for the transport of water and dissolved mineral ions from the roots to the leaves. Xylem are made up of hollow, dead cells joined end to end. They contain no cytoplasm or nuclei. Their cell walls are lignified meaning they have been converted to wood. They are cells stacked on top of each other but the cells have disintegrated and exist as one continuous tube from the roots to the leaves They have lignin making the cells impermeable or waterproof Xylem are dead Phloem Plants have a second transport system made of tissue called phloem. The phloem Carry glucose made on the leaves to the rest of the plant. Vascular bundles in Vascular bundles of non-woody dicots have different distributions in diocots different plant parts: root, stem and leaf. Vascular bundles are the entire xylem and phloem group whereas vascular tissue is the individual xylem or phloem - Vascular bundles in non-woody plants are arranged near to the outside of the stem  - Mono and Diocots Flowering plants (angiosperms) can be divided into Monocots and Dicots. Each has different features → In terms of the vascular system: Monocots: Vascular bundles with both xylem and phloem are scattered through all the stem Dicots: vascular bundles are organised in a ring on the stem. Non-woody dicots = herbs Root hair cells The Function of root hair cells are absorption of water and mineral ions from the soil. Root hair cells are: Long and thin cells allowing for easy penetration between soil particles. Large surface area: better absorption of water and minerals. Water passes from the soil water to the root hair cell's cytoplasm by osmosis. The soil water has a higher water potential than the root hair cell cytoplasm (more water than the cytoplasm). Mineral salts pass from soil to root cells via active transport. The cells use energy to pump minerals against their concentration gradient (more concentrated inside the cell). This helps keep the lower water potential inside the cell and draws more water in.  This ensures osmosis and the transpiration stream continues. Water moves in through osmosis Pass through the cortex of the roots and into the xylem Water passage from root to leaves Root hair cell→ root cortex cells→xylem vessel→mesophyll cells How it moves through the plant 1. Transpiration - water evaporates from leaves and lowers the water potential in the leaf tissues. 2. Water moves from the xylem to enter leaf tissues down the water potential gradient. 3. Water moves up the stem in the xylem as a column of water due to the tension caused by water loss from the leaves and cohesion between the water molecules. 4. Water uptake occurs by osmosis from the soil solution (high water potential) into the root cells (lower water potential) transpiration Water is transported from the roots to leaves through the xylem vessels The loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata Factor affecting rate of transpiration 1) Temperature: at higher temperatures, evaporation rates increase. Desert plants have adaptations to minimise higher evaporation rates, eg. spines instead of leaves, fewer stomata and thick waterproof cuticles. 2) Humidity: at higher humidity, lower transpiration rates. 3) Other factors include wind speed and light intensity. Factor Effect on Description transpiration rate Temperature Increased Diffusion of water molecules is faster at higher temperatures.  How to test factors effecting transpiration? Water vapour loss Occurs through the surface of leaves. The larger the surface area of the leaf, the larger the evaporation (water loss). Occurs due to the large surface area of cells in the spongy mesophyll. Water vapour travels through interconnecting air spaces in the leaf mesophyll towards the stomata where it exits the leaf. Transpiration pull Water moves upwards in the xylem due to transpiration pull from the leaves. Water column in the xylem is kept due to adhesion and cohesion forces between water molecules and inside tube surface. Adhesion (when water molecules stick to the walls of the vessel or the force that is required to detach a liquid droplet from a surface that it contacts) Cohesion (the water molecules stick together- the attraction of molecules adhering to one another due to mutual attraction) Wilting Herbaceous plant stems and leaves rely on their cells being turgid to keep them rigid. (turgid means full of water) Wilting occurs when the rate of transpiration is faster than the rate of water absorption. In wilting, the water content of the plant cells decrease → become flaccid (soft) and no longer press against each other. Stems and leaves lose their rigidity and wilt. If this happens for a prolonged period, the plant eventually dies. Transloction Translocation: the transport of the products of photosynthesis (glucose and sucrose) from where they are produced ( the source) to the other parts of the plant where they are used (the sink). Translocation happens in the phloem only. Products can move in any direction. Through diffusion and active transport Amino acids and some minerals are also carried in the phloem. Source and Sinks Some parts of a plant may act as a source and a sink at different times during the life of a plant. A source is a location in a plant where a resource is taken up (ex. water and nutrients) or synthesized (glucose). A sink is a location where a resource is used. Example: potato plants – in winter, leaves and plants die. Glucose is stored as starch in the tuber under ground (a modified stem). In spring, the tuber acts as the source and the sink is the the new shoot and new leaves growing.  Other examples: tulips, sweet potato, jam, taro Topic 9 :Transport in Animals Class Slides Topic 9 Topic 9 - Outcomes The circulatory The circulatory system is a system of blood vessels with a pump and system valves to ensure one-way flow of blood It is made up of: 1) A medium - the fluid that carries materials around the body (e.g blood) 2) System of tubes - blood vessels 3) A pump that applies pressure to keep the fluid moving through the tubes (the heart) 4) Valves – to ensure one-way flow of blood Single circulation Fish have a two-chambered heart and a single-circulation This means that for every one circuit of the body, the blood passes through the heart once. Double circulation Mammals have a four-chambered heart and a double circulation. This means that for every circuit of the body, the blood passes through the heart twice. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs (the pulmonary circulation). The left side of the heart receives oxygenated blood from the lungs and pumps it to the body (the systemic circulation) Advantages of double circulation Blood travelling through the small capillaries in the lungs loses a lot of pressure that was given to it by the pumping of the heart, meaning it cannot travel as fast By returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body, meaning  cells can be supplied with the oxygen and glucose they need for respiration faster and more frequently The heart The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs The left side of the heart receives oxygenated blood from the lungs and pumps it to the body Blood is pumped towards the heart in veins and away from the heart in arteries The two sides of the heart are separated by a muscle wall called the septum. The septum separates the two sides of the heart, preventing the mixing of oxygenated and deoxygenated blood The ventricles have thicker muscle walls than the atria as they pump blood out of the heart and so need to generate a higher pressure The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle pumps blood at lower pressure to the lungs. The heart is made of muscle tissue which is supplied with blood by the coronary arteries The heart also needs its own blood supply so it has its own oxygen supply so it undergoes aerobic respiration (it comes through its coronary artery ) How does the heart pump blood? 1. Blood enters the heart from the lungs via the pulmonary vein and into the left atrium. 2. When the atria contracts, blood enters into the left ventricle through the atrioventricular valve. 3. When the left ventricle contracts, blood is then pumped out of the heart to the rest of the body through the aorta. 4. The blood from the body then returns to the heart through the vena cava and into the right atrium. 5. From the right atrium, blood gets pumped into the right ventricle through the atrioventricular valve. 6. The right ventricle then contracts and pumps the blood out to the lungs via the pulmonary artery. How to monitor heart activity? The heart can be checked through: 1) Making an ECG (electrocardiogram) that shows the regular pattern of the flow of electrical current through the heart muscle. 2) Measuring the pulse rate 3) Heart sounds: lub-dub caused by heart valves closing in sequence Heart rate (and pulse rate) is measured in beats per minute (bpm) Physical activity vs the heart Why does heart rate increase after exercise? So that sufficient blood is taken to muscles providing them with enough nutrients and oxygen So waste products are removed at a faster rate, and all excess waste products are removed from muscle cells This needs to be ‘repaid’ following exercise so the heart continues to beat faster to ensure that extra oxygen is still being delivered to muscle cells The extra oxygen is used to break down the lactic acid that has been built up in cells as a result of anaerobic respiration Coronary heart disease The heart is made up of muscle cells which need their own supply of oxygen and glucose for cellular respiration and need to be able to remove wastes like carbon dioxide. (like any cell they need to respire to create energy) This is supplied by the blood carried in the coronary arteries. If a coronary artery becomes blocked by fatty deposits called ‘plaques’ ( formed from cholesterol). If this occurs the arteries are not as elastic as they should be and cannot stretch to accommodate the blood which is being forced through them - leading to coronary heart disease. Risk Factors of coronary heart disease Poor diet (high in saturated fats) Stress (hormones produced increase blood pressure) Smoking (nicotine narrows blood vessels) Genetic predisposition Age (older more susceptible) Gender (males more likely) Prevention tips for heart diseases Quit smoking  Reduce animal fats inyour diet and eat more fruits and vegetables - reducing cholesterol levels in the blood Exercise regularly Treatment for heart diseases Pharmaceutical treatment: aspirin can be taken daily to reduce the risk of blood clots forming in arteries. CHD: Angioplasty treatment - A narrow catheter/tube is threaded through the groin up to the blocked vessel - A tiny balloon inserted into the catheter is pushed up to the blocked vessel and then inflated - This flattens the plaque against the wall of the artery, clearing the blockage - To keep the artery clear, a stent (piece of metal / plastic mesh) is also inserted which pushes against the wall of the artery - Sometimes the stent is coated with a drug that slowly releases medication to prevent further build-up of plaque CHD: Coronary bypass - A piece of blood vessel is taken from another part of the body (ie. the patient’s leg, arm, or chest) and used to create a new passage for the flow of blood to the cardiac muscle, bypassing the blocked area - The number of bypass grafts gives rise to the name of the surgery, so a ‘triple heart bypass’ would mean three new bypass grafts being attached Blood vessels There are three types of blood vessels in the body: Arteries - carry high-pressure blood away from the heart. Veins - carry low-pressure blood toward the heart. Capillaries - carry blood at low pressure within tissues. Arteries Having thick muscular walls with elastic fibres  - helps the arteries to expand and relax as blood is pumped out of the heart. Blood found in arteries is under high pressure. - The thick walls of the arteries withstand the high pressure. Narrow lumen (central tube) with a smooth lining - that blood flow is un-obstructed. Veins Carries blood from tissues back to the heart. Blood carried by veins is at low pressure. Valves are present to prevent backflow - ensuring flow is one way. Large walls and thin diameter - ensure that there is little resistance to the flow of blood Note: Arteries carry oxygenated blood, and veins carry deoxygenated blood. However, the pulmonary artery and pulmonary vein differ, as they pass through the lungs: The pulmonary artery carries deoxygenated blood. The pulmonary vein carries oxygenated blood Function of valves in veins Prevent blood from moving in the wrong direction Capillaries Capillaries carry low-pressure blood through tissues. Capillary walls are considered “leaky” and are only one cell thick. Fluid leaks out of the capillary into tissue, forming tissue fluid. - allows for the diffusion of compounds into and out of the capillaries. Thin walls mean that diffusion - More efficient, as substances don’t have to travel far Capillary transfer of materials Tissue fluid is formed when substances leak out of capillaries. It aids in transferring materials from blood to tissues. Oxygen and nutrients move DOWN the concentration gradient and into tissue fluid (low concentration) CO2 and waste products move DOWN the conc. gradient, from tissue fluid, into capillaries (low conc.) How they all link Arteries divide more as they get further away from the heart. These narrow vessels connecting with capillaries are called arterioles. Likewise, veins divide into venules as they get further away from the heart Shunt vessels Shunt vessels can redirect blood flow to specific areas of the body where it’s needed, like to muscles when we exercise, or even to regulate body temperature (to skin when hot, or to internal organs when cold) → Major blood vessels in your body Mesenteric - referring to the intestines Hepatic - referring to the liver Renal - referring to the kidneys Lymphatic The lymphatic system runs in coordination with the circulatory system. Because capillaries have “leaky” walls (they are only one cell thick so they need to be able to easily diffuse in and out of the cell), this means that excess fluid will seep into tissue. If too much fluid is lost, this could have many negative consequences. Lymphatic vessels collect this excess fluid and put it back into the bloodstream. Structure of the system Lymph vessels carry lymphatic fluid. Before this passes back into the bloodstream, this gets filtered out by lymph nodes. Lymph nodes contain lymphocytes (white blood cells) which fight infection. Bone marrow, which is associated with the lymph system, produces these lymphocytes. Blood Composition of blood Blood is made up of: Plasma, which transports CO2, dissolved nutrients, ions, minerals and hormones Red Blood Cells (RBC), which transport oxygen White blood cells, which fight infection Platelets, which are responsible for blood clotting Red blood cells RBCs are rich in haemoglobin, which is a spherical shaped protein that contains iron, which binds oxygen. Haemoglobin allows RBCs to transport oxygen throughout the body. A single RBC contains about 300 million haemoglobin molecules, so a RBC can transport 1.2 billion molecules of oxygen! RBCs main function is to carry oxygen, and they have the following adaptations to do so: Biconcave shape: increases the surface area they have to absorb oxygen. No nucleus or mitchondira: more room for haemoglobin. Small size and flexible: allows them to move through thin capillaries. White blood cells WBCs are part of the immune system. There are many types of WBCs; some include: Phagocytes - which perform phagocytosis. This is where pathogens are engulfed and digested (think about it as an eating cell) Lymphocytes - which can produce antibodies which destroy pathogens and neutralise toxins Platelets and clotting Platelets help form clots, which limit blood loss and prevent the entry of pathogens. Wounds release clotting factors that attract platelets to sites of injury. Platelets convert fibrinogen (which is present in the blood) to fibrin at these sites. Fibrin acts as a mesh to trap platelets and RBCs to form a scab Topic 10:Disease and Immunity Class Slides: Disease and immunity Outcomes Topic 10 - Diseases and Immunity Pathogens Pathogens are disease causing bacteria Some are made of cells others don’t contain cells How do pathogens cuase disease By distributing toxins e.g. a bacteria releases toxins which irritate the lining of the gut (why you throw up body trying to get rid of bacteria; bacteria trying to find a new host) Once this happens the bacteria multiplies resulting in the organism quickly producing a large colony of damage cells (bionary division; very quickly a large colony of bacteria is produced) Immune response- once the cells have been notified of the disease the body begins to swell and soreness occurs due to the body directing blood to the area for healing Infectious disease Infectious diseases are caused by pathogens. Examples of infectious diseases: E. coli (bacteria) causes food poisoning. HIV virus causes AIDS. Various fungi cause athlete’s foot. Head lice.  Transmssile diseases Transmissible diseases are diseases in which the pathogen can be passed from one host to another. (COVID, Chickenpox) Having an Infectious disease doesn’t mean that the disease is neccicerially transmissible. How do diseases spread Transmissible diseases can spread through: Direct contact. This is contact with blood or other body fluids. Contact with open wounds Kissing or sexual contact Breast feeding Sneasing Indirect contact. Contaminated surfaces Contaminated food Animals The air Mechanical barriers Mechanical barriers physically prevent the entry of pathogens into the body. Examples include The skin: covers almost all parts of your body preventing infection from pathogens. If it is cut or grazed, it immediately begins to heal itself (a scab is formed) Some features the skin has to protect our body is - Dryness: which prevents the growth of pathogens - Glands: secrete antibacterial and antifungal chemicals - Keratin: which provides resistance, which protects pathogens from entering The hairs in the nose: make it difficult for pathogens to get past and upfurther into the nose so they are not inhaled into the lungs. Chemical barriers Substances produced by the body cells that trap / kill pathogens before they can get further into the body and cause disease. Examples include Mucus: made in various places in the body, pathogens get trapped in the mucus and can then be removed from the body (by coughing, blowing the nose, swallowing etc) the cilliated cells transport mucus (from goblet cells) containing pathogens into the stomach where they are killed Stomach acid: contains hydrochloric acid which is strong enough to kill any pathogens that have been caught in mucus in the airways and then swallowed or have been consumed in food or water Immune cells Phagocytes Different types of white blood cell work to prevent pathogens reaching areas of the body they can replicate in Phagocyosis Phagocytosis is the process of engulfing and digesting pathogenic cells. Phagocytes are mobile white blood cells, they engulf the bacteria and take it to a vaculoe, another vacule containing enzymes combines with the bacteria vacuole and digests the bacteria then ‘spit’ out the dead remains of the bacteria. Lymphocytes (b cells - made in your bone marror) making antibodies B cells produce antibodies - which clump pathogenic cells together so they can’t move as easily (agglutination). They make antibodies specific for killing a particlular pathogen. These antibodies work like enzymes and they lock onto a particular pathogen. The lymphocytes create antibodies which latch onto the antigen if bacteria cells grouping them together (this process is called agglutination) Antibyotics All cells have a cell membrane. On the outside of the cell membrane there are things such as receptors, and molecules (they can be called antigens) These are known as antigens and are specific to that type of cell. Each pathogen has its own antigens, which have specific shapes. How antibodies work Lymphocytes have the ability to ‘read’ the antigens on the surfaces of cells and recognise any that are foreign They then make antibodies which are a complementary shape to the antigens on the surface of the pathogenic cell. This leads to the direct destruction of pathogens (meaning the virus disappears) The antibodies are like glue clumping the pathogen by the antibodies on their cell membrane and then phagocytes are  called to destory masses of the virus/bacterua (the antigen on the outside of the membrane ) The antibodies are then engested by the phagocytes and broken down into amino acids and reabsorbed back into the body for other uses Immune response 1.The initial response of a lymphocyte encountering a pathogen for the first time and making specific antibodies for its antigens can take a few days, during which time an individual may get sick. Your body has every antibody and antigen it will ever have this means when you get a new virus your body needs to find the antibody, This happens by your virus get trapped in a lymphnode and each antibody checks if they have the right one this can take a while 2. Lymphocytes that have made antibodies for a specific pathogen for the first time will then make ‘memory cells’ that retain the instructions for making those specific antibodies for that type of pathogen. 3. In the case of reinfection by the same type of pathogen, antibodies can very quickly be made in greater quantities and the pathogens destroyed before they are able to multiply and cause illness. For example the initial exposure is COVID, you feel sick as you develop enough antibodies. After you have enough they will get rid of the virus, some of the b cells (which contain the specific antibody called memory cells) will contain the antibody till the second time your exposed to the virus. This means the second time you get the virus your immune response is faster and you wont get as sick. Because virus change over time with new strains your body is constantly storing and creating new antibodies. How your body develops immunity It does not work with all disease-causing microorganisms as some of them mutate fairly quickly and change the antigens on their cell surfaces Therefore, if they invade the body for a second time, the memory cells made in the first infection will not recall them as they now have slightly different antigens on their surfaces (e.g. the cold virus) Active immunity Is the defence against a pathogen by antibody formation in the body. Active immunity is gained after an infection by a pathogen or by vaccination. Active immunity is slow acting and provides long-lasting immunity Passive immunity Passive is the transport without the use of evergy This is when ready-made antibodies, from another source, are introduced to the body Passive immunity is a fast-acting, short-term defence against a pathogen by antibodies acquired from another individual The body does not make its own antibodies or memory cells in passive immunity, hence the name Examples of passive immunity From mother to infant via breast milk - this is important as it helps the very young to fight off infections until they are older and stronger and their immune system is more responsive Injected antibodies for certain diseases where the individual is already infected and a fast response is required, like rabies or tetanus Vaccination Vaccinations give protection against specific diseases, and boost the body’s defence against infection from pathogens without having to be exposed to a dangerous death leading disease. The level of protection in a population depends on the proportion of people vaccinated How does vaccination work ? 1. Vaccines allow a dead or altered form of the disease-causing pathogen, which contains specific antigens, to be introduced into the body in small amounts. In this weakened state, the pathogen cannot cause illness but can provoke an immune response- causing immunity to a disease. Ie. after you get a vaccine you feel a bit sick 2. Antigens trigger an immune response by lymphocytes which produce complementary antibodies.your b cells 3. Memory cells are produced that give long term immunity. These cells are able to react more quickly and strongly on subsequent infections. What do vaccinations do? If a large enough percentage of the population is vaccinated, it provides protection for the entire population because there are very few places for the pathogen to reproduce - it can only do so if it enters the body of an unvaccinated person. There is always a change that not all the people can be vaccinated (herd immunity is when over 90% of the population is vaccinated) If the number of people vaccinated against a specific disease drops in a population (less that 90%) it leaves the rest of the population at risk of mass infectio. This is because there is a more likely chance to come across people who are infected and contagious. This increases the number of infections, as well as the number of people who could die from a specific infectious disease How to prevent disease The simplest way to prevent disease is to stop pathogens from spreading This means keeping up good hygienez, effective sanitation and waste disposal to contain and dispose of pathogens safely. Hygienic food preparation Human foods need to be protected from microorganisms as they can spoil the food (decomposers) or be pathogenic and cause disease. Most people with Salmonella infection have diarrhea, fever, and stomach cramps. Avoid contamination of food by bacteria- wash hands, cooking utensils and surfaces carefully during preparation and pack, transport and store with care.  Prevent bacteria from multiplying in food by keeping it at a safe temperature. (between 5-60oC don’t keep food in that temperature for too long or changing between temperatures too many times) Destroy any remaining bacteria- cook the food thoroughly. Good personal hygiene Washing hands with water and soap removes pathogens from the skin. Use tissues to catch sneezes and coughs and dispose of them quickly Wash hands after using the bathroom. Waste disposal Waste food is a food source for flies and other insects which can act as vectors so it should be disposed of in sealed containers. Rubbish bins should be c