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BIOLOGY NOTES CIE IGCSE All you need, nothing more, nothingless By: IBRAHIM HASHME Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The Main Characteristics of Living Organisms The seven characteristics of living organisms, which are defined as: • nutrition as taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them • excretion as removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements • respiration as the chemical reactions that break down nutrient molecules in living cells to release energy • sensitivity as the ability to detect or sense changes in the environment (stimuli) and to make responses • reproduction as the processes that make more of the same kind of organism • growth as a permanent increase in size and dry mass by an increase in cell number or cell size or both • movement as an action by an organism or part of an organism causing a change of position or place Classification and diversity of living organisms Concept and use of a classificatory system Define and describe the binomial system of naming species as a system in which the scientific name of an organism is made up of two parts showing the genus and species. The first part is the genus, and starts with a capital letter, while the second part is the species, and starts with a lower-case letter. The classification system which is normally used is this one, based on the five kingdoms which contain groups/phylums which contain classes which contain orders which contain families which contain genuses which contain species. There are other types of classification systems like one based on DNA/RNA sequences, called cladistics. Main features of: Bony fish: 1. Have a gill cover (operculum) 2. Breathe through gills 4. Streamlined bodyfront of the head 2 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) 5. Are colored differently for camouflage 6. Covered with moist scales for protection 7. Have a lateral line for sensation 8. Adapted for life in water 9. Have a mouth and nostrils 10. Both fertilization and development is external 11. Poikilothermic 12. No parental care Amphibians: 1. Have four limbs 2. Have moist skin with fine capillaries for gaseous exchange through skin (when submerged) 3. Have an external ear drum 4. Eyes stick out so it can be above water while the rest of the body is submerged 5. Nostrils are at the top of the head, for the same reason as the eyes sticking out 6. Lay soft eggs in a jelly-like coat to absorb shock 7. Poikilothermic 8. Their tadpoles are able to live under water because: a. They have external gills for breathing b. They have tails to swim in water c. They have a streamlined shape to decrease the resistance of water 9. No parental care 10. External fertilization and development Reptiles: 1. Have dry scaly skin to reduce water loss, enabling them to live in dry places 2. Some of them spend a lot of time in water (eg. Crocodiles) 3. Lay eggs with water-proof shells 4. Have ear drums deep inside their heads 5. Mostly have four short weak limbs (excluding snakes) 6. Body is divided into head, neck, trunk, and tail 7. Internal fertilization, external development 8. No parental care 9. Poikilothermic 3 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Birds: 1. Are covered in feathers which: a. Act as an insulating layer b. Decrease the bird’s density to help it fly c. Covered in water proof oil so as not to absorb water 2. Have beaks which are modified depending on the food they eat 3. Have fore limbs in the form of wings 4. Have tails to control their direction during flying 5. Have eardrums deep inside heads 6. Females lay eggs with hard shells 7. Internal fertilization, external development 8. Homiothermic 9. Some parental care 10.Hollow bones and streamlined body for flight Mammals: 1. Have hairy skin or fur 2. Have an external ear flap 3. Females have mammary glands which secrete milk 4. Have four limbs 5. Have teeth with different types 6. Internal fertilization and development 7. Homiothermic 8. Full parental care 4 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Adaptations of organisms to their environment The main features used in the classification of: Flowering Plants: 1. Contain chlorophyll, make food using photosynthesis 2. Produce flowers for reproduction 3. Produce fruits which enclose seeds 4. Seeds germinate in favorable conditions to produce new plants The main features used to classify them into further groups are: Monocotyledons Dicotyledons/Eudicotyledons Have narrow leaves with parallel veins Have broad leaves with branched veins Seeds contain one Cotyledon Seeds contain two Cotyledons Have fibrous roots Have one main tap root with lateral roots The number of stomata is equally distributed in the upper and lower Stomata are usually found in the lower surface of leaves surfaces of leaves Floral parts are 3, 5, or their multiples Floral parts are 2, 4, or their multiples Arthropods: 1. They are invertebrates with segmented bodies 2. Have an exoskeleton made of chitin for protection and support 3. Have pairs of jointed legs for movement Insects (eg. Ants) Arachnids (eg. Spiders) Crustaceans (eg. Crabs) Myriapods (eg. Centipedes) Body divided into three regions:Body divided into two regions: Body divided into two regions: Body divided into two regions: Head, Thorax, and Abdomen Cephalothorax and Abdomen Thorax and Abdomen Thorax and Abdomen One pair of antenna attached No antenna, but they have Two pairs of antenna sensitive One pair of antenna to the head chelicerae/padipalps to to touch and chemicals hold/paralyze prey Three pairs of jointed legs Four pairs of jointed legs Four or more pairs of jointed Many pairs of jointed legs, growing out of thorax growing out of cephalothorax legs, each pair grows out of a each pair grows out of a separate segment separate segment One pair of compound eyes Several pairs of simple eyes Stalked compound eyes One pair of simple eyes Have wings at at least some No wings No wings No wings 5 stage of their life Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Annelids: (worms) 1. Elongated cylindrical bodies 2. Segmented bodies 3. Each segment has chaetae (bristles) for movement Nematodes: (round worms) 1. Unsegmented round bodies 2. Pointed at both ends 3. Circular in cross section Molluscs: (eg snails, octopuses, squids) 1. External or internal shell (mostly) 2. Have a muscular foot for movement, also produces mucus 3. Eyes usually at the end of stalks Viruses Bacteria Smaller than bacteria Larger than virus Protein coat Cell wall Cell membrane absent Cell membrane present Cytoplasm absent Cytoplasm present No cell organelles Few cell organelles Only carries out reproduction Carries out all functions of living organisms Can only live as a parasite in other cellCan live free or as a parasite Exception is yeast, a single celled fungus Bacteria Fungi Unicellular Formed of thread like structures known individually as hypha Cell wall made of proteins lipids and sugars Cell wall made of chitin or chitin and cellulose No distinct nucleus Several nuclei in each hypha’s cytoplasm Some types carry out photosynthesis No photosynthesis Reproduce by binary fission Reproduce by spores 6 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Learn how to use simple dichotomous keys Example of a Dichotomous Key for Animals 1a. This organism has an exoskeleton (go to question 2) 1b. This organism has an endoskeleton or no skeleton (go to question 3) 2a. This organism has thin black body and a red stripe on it's abdomen (go to question 4a.) 2b. This organism has a thick black body and large grey/brown abdomen (go to question 4b). 3a. Organism dwells on land (go to question 5) 3b. Organism dwells in the ocean (go to question 6) 4a. Organism is Latrodectus hasselti (black widow spider) 4b. Organism is Atrax infensus (funnel-web spider) 5a. Organism is totally covered in smooth scale-like skin (go to question 7) 5b. Organism has a textured coat or covering (go to question 8) 6a. Organism has 8 thick legs or tentacles (go to question 9a.) 6b. Has many string-like legs or tentacles (go to question 9b.) 7a. Scale-like skin is patterned in horizontal stripes over the body (go to question 10a.) 7b. Scale-like skin has one block color over most of it's body (go to question 10b.) 8a. Has fine fur-like covering (go to question 11) 8b. Has feather-like covering over most of it's body (go to question 12) 9a. Organism is Hapalochlaena lunulata (blue-ringed octopus) 9b. Organism is Chironex flecken (sea wasp) 10a. Organism is Psuedonaja texilis (tiger snake) 10b. Organism is Pseudechis porphyricus (red-bellied black snake) 11a. Has two opposing thumbs on the front paws (go to question 13a.) 11b. Has no opposing thumb on the front paws (go to question 13b.) 12a. Has large bone-like structure on a bald, blue-skinned head (go to question 14a.) 12b. Has feather-like covering over head with no bone-like structure (go to question 14b.) 13a. Organism is Phascolatarctos cinerus (koala) 13b. Organism is Vombatus ursinus (wombat) 14a. Organism is Casuarius casuarius (cassowary) 14b. Organism is Dromaius novaebollandiae (emu) 7 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Example of Dichotomous Key for Plants 1. Needles in bundles/groups. ( go to #2) 1. Needles single or flattened & scaly. (go to #6) 2. Needles in clusters. Tamarack 2. Needles 2-5 per bundle. (go to #3) 3. Five needles per bundle. White Pine 3. Needles in pairs. (go to #4) 4. Needles 3-4 inches long. Red or Norway Pine 4. Needles under 2 inches. (go to #5) 5. Bark dark gray. Jack Pine 5. Bark orange-brown. Scots Pine 6. Needles square, round or scaly. (go to #7) 6. Needles flat. (go to #9) 7. Needles scaly, flattened. Northern White Cedar 7. Needles square or round. (go to #8) 8. Needles 1/3-3/4 inch long, twigs hairless. White Spruce 8. Needles 1/4-3/4, new twigs with hair. Black Spruce 9. Shrub. Canada Yew 9. Tree. (go to #10) 10. Needles 1/2 inch long with short stem. Eastern Hemlock 10. Needles 3/4 –1 1/4 inches long, no stem. Balsam Fir (no need to memorize anything, simply learn how to use them) 8 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Living organisms are made of cells. Animal Cell Plant Cell No cell wall Has a cell wall made of cellulose Has no or temporary small vacuoles Has a large, permanent vacuole No chloroplasts Has chloroplasts (usually) Usually contains stored glycogen Usually contains stored starch Structure Functions Cell wall Supports, protects, and gives cells shape. Allows free movement of molecules. Cell membrane Envelopes the cell’s contents. Controls molecule movement in and out of cells. Nucleus Controls cell activities. Carries inherited information. Cytoplasm Contains and supports cell organelles. May contain stored food. Chloroplasts Absorb light energy and convert it into chemical energy during photosynthesis. Mitochondria Release energy using aerobic respiration 9 Vacuole Helps supporting the cell, regulates the absorption of water by osmosis, and serves as a storage facility. Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Relate the structure of the following to their functions: • ciliated cells – in respiratory tract, help mucus move along the trachea • root hair cells – absorption of water and minerals from soil. Also helps root stick into soil. • xylem vessels – conduction of dissolved substances from roots to leaves and support to the plant’s structure. • muscle cells – contract and relax in pairs, allowing movement. • red blood cells – transport of oxygen to tissues. Define (using examples covered later in notes): • tissue as a group of cells with similar structures, working together to perform a shared function • organ as a structure made up of a group of tissues, working together to perform specific functions • organ system as a group of organs with related functions, working together to perform body functions You should be able to calculate magnification and size of biological specimens using millimeters as units Movement in and out of cells Define diffusion as the net movement of molecules 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. Animal (liver) cell The importance of diffusion in Gases Solutes (liquids) Water as a solvent Necessary for gaseous exchange in all Dissolved salts diffuse through root hair Dissolving oxygen in water is necessary living organisms cells for marine life Necessary for obtaining carbon dioxide Absorption of dissolved food materials in Excretory products cannot be excreted and release of oxygen during many organisms, like amoeba, bacteria except if they are dissolved in water photosynthesis and fungi, is done using diffusion --- Dissolved excretory materials diffuse from Enzymes and hormones cannot be regions of their production to transport secreted except if they are dissolved in systems to be carried to excretory organs water --- Some digested food materials in humans Digested food cannot be absorbed except is absorbed by diffusion if it is dissolved in water --- --- Plants cannot obtain minerals unless they are dissolved in water All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Define active transport as movement of ions in or out of a cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration against a concentration gradient, using energy released during respiration The importance of active transport as an energy-consuming process by which substances are transported against a concentration gradient: 1. Ion/mineral uptake by root hair cells. The concentration of the ion/mineral in the cell is higher than the surroundings, therefore diffusion won’t work, and active transport must be used. 2. Glucose uptake by epithelial cells of the villi. The concentration of glucose in the epithelial cell is higher than the food being digested, therefore diffusion won’t work, and active transport must be used. Define osmosis as the diffusion of water molecules from a region of higher water potential (dilute solution) to a region of their lower water potential (concentrated solution), through a partially permeable membrane The importance of osmosis Plants gain water through osmosis in their roots from the soil. Without a water potential gradient, roots will lose water, and the plant will be dehydrated. Plant cells contain vacuoles, which, if not full with water, will cause the cell to become flaccid. If all the cells in a leaf become flaccid, the whole leaf will become flaccid, and then wilt. Plant cells therefore need water to remain turgid and keep firm. In animal cells, if they are surrounded with a high water potential, osmosis will take place, and if the water is not expelled some way or the other, the cell will burst. If an animal cell is surrounded with low water potential, the water in the cytoplasm will diffuse outwards, causing the cell to shrink. 11 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Enzymes Define the term catalyst as a substance that speeds up a chemical reaction and is not changed by the reaction Define enzymes as proteins that function as biological catalysts Enzymes work best and fastest at their optimum pH. If the pH is too high or too low, the enzyme will stop working until appropriate conditions are restored. Some enzymes may actually get denatured if the pH is on an extreme. Temperature also changes the activity of enzymes. As the temperature increases, so does enzyme activity. The enzymes and substrates move faster, meaning more successful collisions. It approximately doubles every 10°C higher you go. However, after it reaches approximately 37°C (body temperature) the rate of reaction falls dramatically due to the denaturing of enzymes, and cannot be restored. Enzyme activity can be explained in terms of the lock and key model, as shown in the below diagram. This means only one type of enzyme works on each substrate, and that same enzyme will not be able speed up any other reaction. The area on the enzyme which the substrate fits into exactly is called the “active site”, and high temperatures change the shape of this active site, therefore the reaction cannot occur anymore. 12 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The role of enzymes in the germination of seeds Seeds contain stored foods, in an insoluble form. During germination, the seed’s embryo needs food to grow and carry out the different metabolic activities needed for germination, therefore there are enzymes in the seed, albeit in an inactive form as the seed is nearly free of water. When water enters the seed while it is under suitable conditions, these enzymes become active to catalyze the gradual breakdown of stored insoluble food in the seed to a soluble form that can be used by the embryo till it forms green leaves, which are then used to make food using photosynthesis. The use of enzymes in biological washing powders Some stains are insoluble in water, therefore it is difficult to be remove using only water. Eg blood and egg stains. Biological washing powders contain enzymes, which act as catalysts to remove the stains by breaking them down into smaller, soluble molecules, so they can be washed and removed by water. Examples include: Lipases, used to break down fat-based stains into fatty acids and glycerol. Proteases, used to break down protein based stains into soluble amino acids. The use of enzymes in the food industry Pectinase is an enzyme that breaks down pectin. Pectinase helps to break down the cell walls. This  increases the volume of juice obtained (increases the yield)  lowers the viscosity of the juice (makes it more runny)  reduces the cloudiness of the juice, cause by suspended pieces of cell wall All of these effects improve the commercial quality of the juice. 13 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The use of microorganisms and fermenters to manufacture the antibiotic penicillin and enzymes for use in biological washing powders Fermenters are used in mass producing enzymes, as shown in the below diagram. To increase production of an enzyme using a microorganism, this method is used. The method includes placing a microorganism that produces an enzyme into a medium that supports growth of the microorganism, and applying an electrical current to the medium to introduce electrons into the medium. The method produces a higher enzyme productivity rate. In other words, the amount of the enzyme produced b the microorganism in a time period using the method is greater than a second amount that would be produced by the microorganism in the same time period when no electrical current is applied to the medium. The role of the fungus penicillium in the production of the antibiotic penicillin Penicillin is released by Penicillium fungus when its growth is inhibited by stress. So Penicillium fungus is grown under strictly controlled conditions (of pH, oxygen nitrogen sources and lactose) to induce maximum stress, without killing the fungus, so that penicillin yields are maximized. 14 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) NUTRITION Define nutrition as taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them The synthesis of large molecules from smaller basic units • Simple sugars (glucose, Fructose) to starch and glycogen • Amino acids to proteins • Fatty acids and glycerol to fats and oils The chemical elements that make up: • Carbohydrates: Carbon, Hydrogen, and Oxygen • Fats: Carbon, Hydrogen, and Oxygen (less oxygen than in carbohydrates) • Proteins: Carbon, Hydrogen, Oxygen, Nitrogen, and sometimes Sulfur FOOD TESTS: Benedict's test - for simple (reducing) sugars: -Make a solution of the substance to be tested in a boiling tube, and add Benedict's solution (blue). - Alternatively, add Benedict's solution to a small chunk (of solid fruit, etc) in a tube. - Heat the tube gently for about 2 minutes in the waterbath. A colour change from blue, through murky green to yellow/orange/red shows the presence of a simple (reducing) sugar. Actually an orange precipitate is formed so the (hopefully) initially clear solution not only changes colour but also becomes opaque. Iodine test - for starch: - Solid foods: Add a couple of drops of iodine solution (brown) directly to the substance to be tested, in a plastic dish. - Liquids: - Add 1-5 drops to test substance in a boiling tube or welled tile. - THERE IS NO NEED TO HEAT. The result is almost instantaneous, but the liquid needs to soak in to dry solids. A colour change from orange to blue-black shows the presence of starch. 15 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Biuret test - for Proteins: - Add Biuret solution (sodium hydroxide + small amount of copper sulphate) - blue, like Benedict's - to the test substance. - THERE IS NO NEED TO HEAT, but the result is not quite instantaneous. A colour change from blue to mauve shows the presence of a protein. Emulsion test - for Fats and Oils: Add ethanol to a very small amount of the test substance. Shake or crush (and possibly heat gently using a water-bath - CAREFULLY - DO NOT USE A BURNER! - ethanol is flammable!) in order to dissolve. Filter or dilute if necessary to obtain fairly clear liquid (which is of course a solution of fat in ethanol). Take another tube containing (tap) water, and pour the ethanolic solution (prepared above) into top. A white (milk-like) emulsion indicates the presence of fats or oils. 16 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The principal sources and importance of: •Carbohydrates: Sources: liver, potatoes, vegetables, milk, sugar cane, barley, grapes, fruits. Importance: 1. The production of energy using respiration. 2. It is stored in cells as energy sources (in plants-starch, in animals-glycogen) 3. Cellulose (a carbohydrate) is needed to form cell walls in plants. • Fats: Sources: meat, milk, cheese, butter, eggs, maize, cotton seed oil, and palm oil. Importance: 1. The release of energy using respiration 2. They form a part of the cell membrane 3. Stored in the body to: a. Act as a food reserve b. Protect and support certain organs c. To act as an insulating layer, reducing the rate of heat loss 4. Forms a water-proof layer on skin, fur and feathers. • Proteins: Sources: meat, milk fish, eggs, legumes (beans/lentils) Importance: 1. Source of energy in case of starvation 2. Growth and tissue repair 3. Formation of enzymes and hormones 4. Protection against diseases, because white blood cells and antibodies are made of protein • Vitamins (C and D only): Sources: C; citrus fruits and fresh vegetables. D; Butter, eggs, cod liver oil, formed in the skin when exposed to the sun’s rays. Importance: C; Helps wounds heal, keeps blood vessels healthy, keeps teeth and gum healthy, helps body use iron, stimulates the immune system. D; Promotes the absorption of calcium and phosphorous, enables the body to use these enzymes in the formation of teeth and bones. • Mineral salts (calcium and iron only): Sources: IRON; liver, egg yolk, red meat, leafy vegetables. CALCIUM; Milk, dairy products, many fruits and vegetables 17 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Importance: IRON; Necessary for formation of haemoglobin CALCIUM; Necessary for formation of teeth and bones and blood clotting • Fibre (roughage): Sources: all plant foods, cereal grains, barley, whole meal bread, brown rice. Importance: Stimulates peristalsis, preventing constipation. Makes the stomach feel full, helping the diet. • Water: Importance: 1. It is the main component of cytoplasm 2. Main component of plasma in the blood 3. Metabolic reactions can only take place in the presence of water 4. Food cannot be transported without being dissolved in water 5. The gas exchange in lungs takes place more easily in the presence of water 6. To excrete, substances must be dissolved in water 7. Sweat is necessary for the regulation of body temperature 8. Enzymes and hormones are secreted after being dissolved in water The deficiency symptoms for: Vitamin C: Causes scurvy, whose symptoms are: pain in joints and muscles, bleeding gums, delayed healing of wounds Vitamin D: Causes rickets in children, which makes bones soft and deformed. Slow dentition (growth and formation of teeth). Osteomalicia in adults. Iron: Anaemia, a disease which causes breathlessness and tiredness from small exercises, due to the lack of haemoglobin. Calcium: brittle bones, brittle teeth, slow dentition in children. 18 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The use of microorganisms in the food industry YOGHURT Steps: 1. The milk is heated to about 87°C to kill off any microorganisms found in the milk 2. It is then left to cool to about 35-40°C 3. A small amount of pre-prepared yoghurt is added as source of the needed microorganism 4. The milk is then left in an incubator at a suitable temperature, and during this period the bacteria feeds on the milk sugar (lactose) producing lactic acid and energy 5. The lactic acid changes the pH of the milk, and it coagulates, forming curds 6. The yoghurt is then preserved in a refrigerator, so as to stop the action of the bacteria, otherwise the lactic acid content would be too high and this makes the yoghurt sour SINGLE CELL PROTIEN Since microorganisms reproduce rapidly, and their cells contain a high proportion of protein, they are sometimes used as food. Steps: 1. The fermenter is first sterilized to avoid any negative effects brought about by other microorganisms 2. Any non-harmful bacteria/fungi/algae/plankton is brought to the fermenter 3. Sterilized nutritive materials are added, like air for aerobic respiration 4. The products are then taken to be used Food additives: Additive Uses/Benefits Coloring They alter and improve food color, and can replace the foods natural color if it was lost while processing Preservatives It kills microorganisms which may rot food, allowing it to last longer Antioxidants They prevent changes in taste and color from oxidation Emulsifiers Help in the forming of an emulsion from fat and water Stabilizers Protects the food from its own enzymes Flavorings Provide the food with an artificial taste or smell Health Hazards: 1. May cause hyperactivity in children 19 2. May cause allergic reactions 3. May develop sleeplessness and behavioral problems Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Plant nutrition Define photosynthesis as the fundamental process by which plants manufacture carbohydrates from raw materials using energy from light Equations: Carbon Dioxide + water Light Glucose + Oxygen Chlorophyll Light 6CO +26H O 2 C6H 12+ 6O 2 Chlorophyll Plant must have chlorophyll in order to photosynthesise, as this is the substance which converts light energy into chemical energy. Chlorophyll traps light energy and converts it into chemical energy for the formation of carbohydrates and their subsequent storage. Therefore, it goes without saying, light is a necessity as well. Plants also need carbon dioxide and water, to convert into oxygen and glucose. All these should be plentiful, otherwise the plant’s photosynthesis will slow down. Plants take in carbon dioxide from air through their stomata (on the leaves) using diffusion and they absorb water through their root hair cells using osmosis. Define the term limiting factor as something present in the environment in such short supply that it restricts life processes The three possible limiting factors of photosynthesis are carbon dioxide, temperature, and light intensity. When the carbon dioxide concentration is too low, the rate of reaction is low. The same happens with temperature and light intensity. At point P, a factor other than If it gets too light/CO2 conc. is now limiting cold, the plant the rate of photosynthesis. stops performing photosynthesis, the same, however, happens if it gets too hot. In glasshouse systems, the air inside is enriched with carbon dioxide, and there is optimum light and temperature, so that the 20 photosynthesis of plants is at its maximum rate. Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Chloroplasts are distributed throughout the leaf to allow the absorption of sunlight and, in turn, the the process of photosynthesis to occur. They are concentrated the most at palisade cells, so that all the available sunlight is absorbed. Stomata are the “holes” through which the gas diffusion occurs, allowing CO2 to enter. The oxygen produced in the mesophyll cells from photosynthesis is easily diffused outwards and out because of the large surface area (due to air spaces), this large surface area also allows the mesophyll cells to easily absorb CO2. These air spaces allow the gases to circulate. This is called gas exchange. Vascular bundles (xylem and phloem): xylem supports the leaf and transports water and minerals, and phloem moves the produced foods to other parts of the plant. 21 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The importance of: • Nitrate ions: for protein synthesis (making proteins) • Magnesium ions: for chlorophyll synthesis (making chlorophyll) The effects of nitrate ion deficiency: The plant has poor growth and yellowed leaves The effects of magnesium ion deficiency: Plant leaves become yellow The uses of nitrogen fertilizers Since nitrogen fertilizers provide nitrogen ions, it allows plants to form more proteins, and therefore promotes the growth of plants and fruits. The dangers of overuse of nitrogen fertilizers Excess nitrogen can be dangerous to agriculture. Water may pass from the plants to the soil resulting in the wilting of the plant. In case of heavy rainfall, the fertilizer may be washed away in rivers and which may result in the rapid growth of water plants, thus decreasing the amount of oxygen in the water and causing an increase in the amount of bacteria as the plant and other creatures die. In short it also causes water pollution. Define the term balanced diet as the daily intake of food containing the right amount of each nutrient to meet the body’s requirements, which depends on age, sex, activity of an individual, and climate. Malnutrition is not eating too little; it is eating the wrong amounts of some nutrients, too much or too little. (an unbalanced diet) The effects of malnutrition in relation to: Starvation: a massive lack of nutrition in all forms/not enough nutrition to survive, leads to famine. Coronary heart disease: eating too many fats in the forms of fatty acids and cholesterol, may lead to heart attack. Constipation: if there is a lack of fibre in the diet, the speed of food along the intestines slows down, causing the over-absorption of water, making the food drier than usual, leading to an uncomfortable egestion. Obesity: too many fats and carbohydrates in the diet leads to their storage as fat, causing obesity. 22 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Modern technology has resulted in increased food production because of: 1. Modern agricultural machinery, like tractors instead of the old plows. This increases the production rate of a farm. 2. Chemical fertilizers, this makes fruits and plants grow larger faster. 3. Herbicides, this kills off weeds which may compete with crops, and decrease production 4. Pesticides, this keeps pests (bugs/bacteria/fungi) which may harm plants away, by killing them. 5. Artificial selection, this is when farmers only allow the best of cattle/crops to breed with each other, making crops/cattle better/bigger over time. The problems of world food supplies The supply of food is falling, while demand is rising. This causes a rise in prices and less affordability, causing famines. The problems which contribute to famine 1. Increasing population, less food to feed more people. 2. Unequal distribution of food, some areas get more food than others. 3. Drought, there is no water for cattle/crops. 4. Floods, this kills off many crops and destroys property, reducing affordability. Define ingestion as taking substances (e.g. food, drink) into the body through the mouth Define egestion as passing out of food that has not been digested, as faeces, through the anus The alimentary canal: Food goes through the organ(s) associated with part Mouth salivary glands Oesophagus Stomach Duodenum pancreas, liver, Small gall bladder Intestine Ileum Colon Large Intestine Rectum 23 Anus Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Roles of parts of alimentary canal: Mouth: the food is ingested through here, and starch is broken down because saliva contains the enzyme amylase (chemical digestion). It also increases food surface area through mechanical digestion so it is easier to absorb food later on. Oesophagus: transports food from the mouth to the stomach. Stomach: digests food chemically and mechanically. Small intestine: final chemical digestion takes place here, and nutrients from the food are absorbed here as well and transported throughout the body in the bloodstream. Large intestine: water and vitamins from food is absorbed in the large intestine, and then the remaining food is egested through the anus as faeces Define digestion as the break-down of large, insoluble food molecules into small, watersoluble molecules using mechanical and chemical processes. 24 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Molars: broader and larger than pre-molars, used for crushing and grinding Pre-molars: broad, for grinding and crushing Canines: pointed to pierce and hold food, also tears food Incisors: have sharp edges to bite and cut food Causes of dental decay: When certain bacteria feed on food left between/on teeth, they produce acids, which dissolve the enamel, and keep dissolving, as they get closer to the pulp, the tooth keeps getting more irritable. The bacteria feed mainly on sugars. Proper care of teeth: Brush teeth to remove any remaining food, with fluoride toothpaste. Also, drink fluoridated water and partake in less sugar. Food should contain enough calcium, phosphorous, and vitamin D which are necessary for the formation of enamel. Your food should also contain Vitamin C, as this keeps the cement of the tooth healthy. How fluoride helps prevent tooth decay: 1. By speeding up the “fixing” process. The presence of fluoride attracts other minerals to a cavity, and these minerals reform the tooth 2. By making the tooth more resistant to decay, this is because the reformed part of a tooth is composed of more resistant material 3. By disrupting a bacteria’s ability to digest sugar. The less sugar digested, the less acid produced, meaning less cavities. Arguments for and against the addition of fluoride to public water supplies FOR: 1. It helps teeth resist decay 2. It helps in healing by formation of new enamel 3. It is very cheap 4. It is an easy solution to helping people resist decay AGAINST: 1. It can mottle teeth in concentrations higher than 2ppm 2. People have no choice in the matter 3. There may be negative long term effects of fluoride 25 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) CHEWING: The chewing muscles contract and relax to move the lower jaw up and down, this makes the food between teeth to be cut and crushed. The tongue helps by moving food between teeth. Peristalsis: this is the toothpaste tube-like motion of the alimentary canal to move food along. the process is: above the food the circular muscles contract while the longitudinal ones relax, and the opposite takes place around the piece of food. This moves the food along. Bile emulsifies fats, meaning it make large fat droplets smaller, therefore increasing its surface area so enzymes can work faster. Chemical Digestion: is important because it breaks down insoluble molecules to produce smaller, soluble ones which can be absorbed. Enzyme Substrate End-products Where it is secreted Amylase Starch Maltose Salivary glands (in saliva) and Pancreas Lipase Fats Fatty Acids and Glycerol Pancreas and Intestine Protease Protein Amino Acids Stomach, Pancreas and Intestine Absorption: Define absorption as movement of digested food molecules through the wall of the intestine into the blood or lymph. The small intestine is the region for the absorption of digested food. The small intestine’s inside is covered in villi, which is extremely important, as it greatly increases the small intestine’s surface area, allowing for a much higher rate of absorption. The lacteal is a lymph vessel (part of the lymphatic system) and the epithelium is the villus’s epithelial tissue. The vein at D joins up with other veins at other villi and forms the hepatic portal vein, which transports absorbed food to the liver, which is dissolved in the blood it contains. The small intestine absorbs water from food along w3th the first section of the large intesti3e (the colon). The small intestine absorbs 5-10dm per day while the colon absorbs 0.3-0.5dm per day. 26 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Assimilation: Define assimilation as movement of digested food molecules into the cells of the body where they are used, becoming part of the cells After food is transported to the liver it stores any excess glucose in the form of glycogen. The liver also converts amino acids to proteins and breaks any excesses of them. The fats that where absorbed are used as an energy storing substance. Define deamination as removal of the nitrogen containing part of amino acids to form urea, followed by release of energy from the remainder of the amino acids The liver is the site of breakdown of alcohol and other toxins. Transportation The functions of: Xylem: carries water and minerals throughout the plant and provides mechanical support to the plant. Phloem: carries sugars and other nutrients from the leaves to cells for consumption or storage. POSITIONS: Root Leaf 27 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Stem Root hair cells: They are present in roots to absorb water and mineral ions, and, due to the “hair” they have a large surface area, allowing for faster absorption. Also, they help the roots to stick in the soil. Water is absorbed by a root hair, and then moves to the root cortex cells, then to the xylem, which then takes it to the mesophyll cells in the leaves. (The water is taken straight up the stem to the leaves, where it travels through the stalk, then the midrib, then the veins. It then diffuses towards the mesophyll cells.) Tanspiration: Define transpiration as evaporation of water at the surfaces of the mesophyll cells followed by loss of water vapour from plant leaves, through the stomata The water vapour, when lost, is lost through the surfaces of cells, and then it is present in the air between the leaf cells (the air spaces) and it then diffuses outwards through stomata. Therefore the water is lost. When the temperature is increased, the rate of transpiration also increases, because the water evaporates faster due to the increased kinetic energy it contains. The transpiration rate of a plant decreases if the air surrounding it is more humid, because diffusion is slower, there is a high water potential outside. An increase in light intensity would increase the transpiration rate because the stomata open more to obtain carbon dioxide from the air for photosynthesis. 28 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Wilting: wilting occurs when the cells in a plant lose water to the extent that the cells in its leaves become flaccid. The main cause of wilting is when a plant has a higher rate of transpiration than water uptake. Water uptake: is the process where transpiration produces a tension, or pull, from above, creating a water potential gradient in the xylem, and drawing water molecules up the plant. Adapted to: Desert Pond Garden Leaf Reduced to spines, less surface Little or no cuticle, there is no Usually broad, flat. area means less water lost. need to conserve water. Shaped like ribbons so as to not get pulled off by water currents. Contain air spaces to keep plant afloat and to allow for quicker gaseous exchange. Contain lots of chloroplasts because light intensity is usually low. No stomata. Stem Swollen, containing water-storage Little or no cuticle, there is no Normal tissue. Photosynthesis occurs need to conserve water. Elastic so here. Stomata present here. as not to get cut off by water Surface is shiny to reflect heat acurrents, contain air spaces to light. Thick waxy cuticle to reducfloat. water loss. Root Shallow, wide spread, to quickly Very weak, or absent, because Normal collect water from rainfall or there is no need to absorb overnight condensation. water/mineral ions. No root hairs present. Translocation: Define translocation in terms of the movement of sucrose and amino acids in phloem; • from regions of production • to regions of storage OR to regions of utilisation in respiration or growth Systematic pesticides are pesticides which the plants absorb, and then it gets transported throughout the plant in the phloem. 29 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Transport in humans Describe the circulatory system as a system of tubes with a pump and valves to ensure one-way flow of blood Describe the double circulation in terms of a low pressure circulation to the lungs and a high pressure circulation to the body tissues Blood flows to the lungs at a lower pressure because in the other circuit, the blood needs to be transported over longer distances, and through thinner vessels. Starting in the right atrium, the blood flows through the tricuspid valve to the right ventricle. Here, it is pumped out of the pulmonary semilunar valve and travels through the pulmonary artery to the lungs. From there, blood flows back through the pulmonary vein to the left atrium. It then travels through the mitral valve to the left ventricle, from where it is pumped through the aortic semilunar valve to the aorta and to the rest of the body. The (relatively) deoxygenated blood finally returns to the heart through the inferior vena cava and superior vena cava, and enters the right atrium where the process began. Valves ensure that the blood won’t flow backwards. Though not visible here, there are also coronary arteries that encircle the heart (branched off the aorta) and supply it with the required food and oxygen. Physical activity increases heart rate, because muscles need more energy to carry out respiration, and this means the blood has to supply them with more oxygen and food as well as take more waste products away. Coronary heart disease occurs when some of the heart muscle is starved and dies due to the blockage of the coronary artery supplying that part. Its causes include the eating of too many fats, as they precipitate on the inner walls of the arteries. This results in blockage. Smoking helps this precipitation, and stress speeds it up because of an increase in blood pressure. Alcohol also causes this disease. It can be prevented by eating a healthy diet, exercising, quitting smoking, maintaining a healthy body weight, and laughing every once in a while to reduce stress. 30 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Names of main blood vessels To the lungs from the heart - pulmonary artery from the lungs to the heart - pulmonary vein to the liver - hepatic artery, from the liver hepatic vein another blood vessel goes to the liver from the intestines - it is the hepatic portal vein to the kidney - renal artery, from the kidney - renal vein Two main veins go to the heart - the vena cava and the pulmonary vein Two main arteries come from the heart - aorta and pulmonary artery Arteries Blood in the arteries is under high pressure generated by the heart. The arteries have:  thick outer walls  thick layers of muscle and elastic fibres (because of high pressure)  narrow lumens They (normally) carry oxygen-rich blood to cells Veins The blood in veins is under lower pressure than the blood in arteries. The veins have:  thin walls  thin layers of muscle and elastic fibres  relatively wide lumens  valves to avoid backward flow They (normally) carry oxygen-poor blood to cells Capillaries Capillaries have:  very thin, one cell thick walls They supply the body’s cells with oxygen-rich blood  pores to allow white blood cells to squeeze through (reason for thin walls)  very narrow lumens, red blood cells travel single-file Capillaries release tissue fluid to bathe body cells; it contains food, hormones, minerals, antibodies, and water. It then takes the waste products. 31 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) White blood cell Red blood cells Components of blood: red blood cells, white blood cells, platelets and plasma The functions of blood: • Red blood cells – haemoglobin and oxygen transport • White blood cells – phagocytosis (process in which phagocytes engulf and digest microorganisms and cellular debris; an important defense against infection) and antibody formation • Platelets – causing clotting • Plasma – transport of blood cells, ions, soluble nutrients, hormones, carbon dioxide, urea and plasma proteins 32 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) The immune system is the system responsible for body protection. It causes: 1. Phagocytosis: vasodilation takes place in the infected area, meaning more blood passes out of the vessels, and the white blood cells in the blood engulf and digest microbes. 2. Antibody production: the white blood cells enlarge and, increasing in number, and then beginning to produce antibodies, which remain fixed on their surface. They then migrate to the site of infection and release these antibodies to attack germs. 3. Tissue rejection: when an organ or something similar is transplanted into the body, it may reject it because the antigens it produces are recognized as foreign chemicals to the white blood cells in the body. The lymphatic system is responsible for the circulation of body fluids, including tissue fluid and fatty acids + glycerol, throughout the body (it makes them enter the blood after collecting them). It is also responsible for developing lymphocytes, a type of white blood cell. The other type is phagocytes. Lymphocytes are responsible for antibody production and phagocytes for phagocytosis. Blood clotting: fibrinogen is plasma protein present in the blood (synthesized in liver). When a blood vessel is cut the prothrombin comes in contact with collagen (in wall of blood vessel). This causes the conversion of prothrombin to thrombin. Thrombin is then in turn responsible for conversion of fibrinogen to fibrin. The fibrin molecules can then attach to one another to form big long strands which form the clots - blocking holes etc. Respiration Define respiration as the chemical reactions that break down nutrient molecules in living cells to release energy The uses of energy in the body of humans: 1. muscle contraction 2. protein synthesis 3. cell division 4. active transport 5. growth 6. the passage of nerve impulses 7. the maintenance of a constant body temperature Define aerobic respiration as the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen Glucose + oxygen carbon dioxide + water C6H 12+66O 2 6CO 2 6H O 2 33 Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Define anaerobic respiration as the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen In muscles during hard exercise: glucose lactic acid C6H 12 6 2C 3 O6 3 in microorganism, yeast: Glucose alcohol + carbon dioxide C6H 12 6 2C 2 5H + 2CO 2 The anaerobic respiration of yeast is used to make carbon dioxide bubbles in dough, then, when baked, the carbon dioxide expands and the ethanol evaporates. Baking also kills the added yeast. The anaerobic respiration of yeast is also used in brewing, where the alcohol produced makes the drink alcoholic, and the carbon dioxide produced makes it fizzy. Aerobic respiration releases 36 ATP, which is much more than the 2 ATP released by anaerobic respiration. During exercise, a lot of food and oxygen is needed to respire and produce energy for the contraction of muscles. Therefore, the rate and depth of breathing increases to obtain the necessary oxygen and get rid of the produced carbon dioxide. The heart also beats faster to supply the muscles with enough food and oxygen, contained in the blood. Ata a certain limit, the heart and lungs cannot supply materials any faster but the muscles still need more energy. This is why anaerobic respiration is carried out, which produces lactic acid, which gets deposited in the muscles, causing fatigue. After the exercise is over, you continue breathing hard because extra oxygen is needed to oxidize the lactic acid (ie to recover the oxygen debt) The features of gas exchange surfaces in animals 1. large surface area 2. very thin 3. elastic 4. moist 5. supplied with a dense network of capillaries Inspired air: 20-21% oxygen, 0.03-0.04% carbon dioxide, less water vapour Expired air: 16% oxygen, 4% carbon dioxide, more water vapour Lime water can be used as a test for carbon dioxide, when atmospheric air is pumped into it, little or no white precipitate is formed, however, when 34 expired air is pumped into it, the limewater turns milky due to the white precipitate formed. Page All notes written and produced by Ibrahim Hashme, hell yeah, I’ll be cheap about it to make sure y’all don’t take credit ;) Breathing in: first, the external intercostal muscles contract, causing the internal ones to relax, which raises the rib cage upward and outward. The diaphragm also contracts and stretches tto a more flattened shape. The volume in the rib cage thus increases. This causes the pressure in the lungs to decrease, and therefore the air outside, which has a higher pressure, rushes into the lungs. Breathing out: first, the internal intercostal muscles contract, causing the external ones to relax, which moves the rib cage downward and inward. The diaphragm relaxes and changes to a more dome-like shape. The volume in the rib cage thus decreases. This causes the pressure in the lungs to increase, and therefore the air inside, which has a higher pressure, rushes out into the atmosphere. The trachea is lined with ciliated cells, whose cilia move mucus, which is secreted by goblet cells, along the windpipe. This mucus is sticky, and any pathogens and particles in inspired air should get trapped in it. The mucus is then moved to the stomach by the cilia’s motion and digested. Physical activity increases the rate and depth of breathing. This is because it increases the rate of respiration, and this means a higher carbon dioxide concentration in the circulating blood. This lowers the pH, and the brain ddetects this and orders the lungs to breath deeper and faster. EXCRETION Define excretion as the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements. Substances should include carbon dioxide, urea and salts. The kidney functions to: 1. remove urea and excess water 2. reabsorb glucose and some salts The liver changes excess amino acids into urea, which is then excreted as urine. Alcohol, drugs and hormones are also broken down in the liver. In nephrons, the renal capsule does “ultra filtration”, meaning it absorbs almost all the
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