Bio Chapter 2 PDF

5 Chapter 2 microscope light microscope : image coloured image only nucleus, chloroplast(chlorophyll), vacuole, cell wall can be seen 1600x Q) discuss briefly the impact of the advance in microscopy of the study of cells Ele...

5 Chapter 2 microscope light microscope : image coloured image only nucleus, chloroplast(chlorophyll), vacuole, cell wall can be seen 1600x Q) discuss briefly the impact of the advance in microscopy of the study of cells Electron microscope produces image with higher magnification and resolutions. This enable scientist to discover the structure of cell organelles. Scanning electron microscope: 3D external structure 200000x  1 Transmission electron microscope : 2D internal structure 1500000x 1  2 operating add iodine solution to stain the specimen the light → to make the cell structure more distinct/ visible microscope Inve To observe more cells within the field of view rted → reduce the distance between the slide and the objective ima Raise the stage/lower the body tube by turning the course ge adjustment knobuntil the object is at the position position to the slide Step for focusing from low power to high power : 1.Focus with a lower power objective 2. Search the field with the low power objective by turning the course adjustment knob/fine adjustment knob 3. Adjust the position of the slide until it is located in the centre of the field 4. Focus with a high-power objective by turning the nosepiece 6. Turn the fine adjustment to get a sharp focus 5.Adjust the light source to brighten the view if necessary ( diaphragm/ condenser) (6-7) keep watching the stage from the side. raise the stage by turning the course adjustment up until the object nearly touches the slide look through the focused image by turning the fine adjustment knob. Adjust the source to brighten the view if necessary 2  3 Blurred to sharp →rotate the fine adjustment knob to get a sharper focus cell label questions : structure small particles → ribosome Endoplasmic reticulum (x rought / smooth) Finding out the organelles by the type of cell: 1.X is organelle name (1) 2.What is the cell responsible for/the function of the cell.(1) 3.abundant of organelles was found for function of the organelles (1) 4.function of other type of cells, so the don’t have much organelle X (1) ＊＊show comparison Finding out the type of cell by number of organelles 1.Z is most likely to be a xxxx cell (1) 2.It has large amount of organelle to function (1) Similarities and differences Both of them xxxxxx Z cell has vvvvv but S cell does not 3  4 abundance of organelles in different type of cells 4 5 5  6 eukaryotic and prokaryotic Chapter 3 membrane whole cell membrane : structure and Q1) state the components: the Phospholipid can move laterally permeability Q2) to describe the cell membrane Phospholipid → arrange into a bilayer structure in a tail to tail format.The hydrophobic tails point inwards. The hydrophilic head points outwards to the bathroom solution and point inward to the cytoplasm Protein → intersperse among the phospholipid bilayer Q3) explain the arrangement of phospholipid The hydrophilic tails point inwards as they are repelled by the aqueous solution The hydrophilic head point outwards towards bathing solution as it dissolves with the aqueous solution inside and outside of the cell. They arrange in a bilayer and tail-to-tail format. Q4) explain how protein and phospholipid affect the permeability of the cell membrane to different substances Phospholipid bilayer allows fat soluble molecules/hydrophobic/nonpolar molecules to diffuse more readily across membranes(1) Samall charged molecules can dissolve in the hydrophobic zone and diffuse freely through the phospholipid layer.(1) The hydrophobic in the stone forms a barrier to those molecules which 6  7 are polar/hydrophilic/ions(1) Channel protein acts as open pores for diffusion of ions and polar substances(1) Carrier proteins find with specific molecules and bring them to the opposite side of the membrane(1) Carrier protein can facilitate diffusion of some molecules e.g. glucose (1) Carrier protein allows active transport of molecules(1) ATPase catalyses the hydrolysis of ATP to liberate energy for active transport (1) Phospholipid structure and the permeability of the membrane : Q)The phospholipid arranges tail to tail to form a bilayer (1) It allows lipid soluble/ non-polar substances to go through as they dissolve in the hydrophobic zone of the bilayer. (1) The hydrophobic tails of the phospholipid molecules point inwards (1) Forming a inner hydrophobic zone (1) Which acts as a barrier, and the membrane and permeable to charge molecules (1) Protein : 7  8 **transport by carrier/channel protein is undirectional permeability property: and property 1. Flexible of the cell → the phospholipid and protein molecules can move about slightly membrane → the cell membrane can break and fuse to change shape during cell division and growth 8  9 2. The cell membrane is differentially permeable →the core the of the membrane is water+hating Describe and explain how oxygen and sodium ions are transported through the artificial or cell membrane Q1) Oxygen molecules are nonpolar and small. They dissolve in hydrophobic zone in the phospholipid the bilayer. Passing through both membranes at the same rate. Sodium irons are charged and they are repelled by the bilayer and cell membrane. They can be transported by channel or carrier proteins. As these proteins are absent and artificial membrane, it cannot move across the membrane Movement of substances across the membrane: Factors that affect the permeability of the cell membrane 1. Temperature Experiment 1) Aim : to investigate facts of temperature on the prmeability of the cell membrane IV : temperature DV : permeability of cell membrane Q)Explain why it is important to rinse the beetroot cubes thoroughly before immersing into water ? Run the root cubes in the water to wash away the pigment left on the beetroot. This can show that any change in the colour intensity of solution is due to permeability of cell membrane at diff. Tep. 9  10 Q) what is the general tendency of colour intensity of distal water at different temperature? What can this trend indicate? The high temperature, the high intensity of red colour in the solution. This indicates that the higher the temperature the higher the permeability of the beatroot cell membrane. Q) explain the effect of temperature on the membrane permeability? 嘔晒嗰大段嘢出嚟 2. Organic solvents e.g. ethanol and alcohol →phospholipid of the membrane dissolve in organic solvents. The cell membrane and vacuole would be damage →（release pigmanet and colour intensity ) Fluid mosaic Q1)draw the fluid mosaic model : model Q2)Justify/ explain the model Fluid → the phospholipid can move laterally Mosaic → protein interpose on the surface of the membrane in a mosaic pattern in an asymmetrical manner diffusion definition:net movement of particles down the concentration gradient Evenly distributed/reached equilibrium →no net movement but still move randomly Exchange of materials →obtain useful and remove waste (gas exchange ) Absorption of nutrition 10  11 osmosis water potential= solute concentration+ hydrostatic pressure →it is the tendancy for water molecules to move from one place to another →more solute, stronger attraction between solute and water molecules, What large decreases water potential wut small Molecules are too large to pass through It requires a differentially permeable membrane Dialysis tubing is made from cellulose. It is differentially permeable and has small pores which allows small molecules such as H2O molecules to diffuse through but not large molecules such as sucrose molecules Q1)State the change in water level in the dialysis tubing and explain Water level of dialysis tubing rises. The water potential of the distilled water is higher than that of 20% sucrose solution. There is a net movement of water molecules from water to sucrose solution a differentially permeable membrane by osmosis. 11  12 Aim: to show osmosis across a dialysis tubing Q1) why should we rinse the outside of the tubing with water before setting up the apparation ? To remove the sucrose molecules on the outside of the tubing which may affect the results Q2) setting up a control and state its significant The control set up should have the same apparatus with the experimental set up except the sucrose solution inside the dialysis tubing should be replaced by same volume of water, the control set up is used to show that the change in the liquid level and the experimental set up is due to the sucrose solution inside the dialysis tubing Q3) referring to the experimental set up explain the change in liquid level. Potential of the distilled water is higher than that of the sucrose solution. There is a net movement of water molecules from the water to sucrose solution by osmosis. So, there is a rise in the liquid level. Conclusion ; osmosis can only take place when there is a water potential gradient between a differentially permeable membrane 12  13 Q2)Why did the water level stop moving As water enters the dialysis tubing, this increases the water level and it creates hydrostatic pressure which stops the movement of water molecules from further entering the tube. the water potential of warer inside and outside tube are the same/They have reached equilibrium There will not be any more net movement of water molecules. So the water stops moving. Ways the increase the rate of rise of water level in the capillary tube 1. Raise the water level to 30 C 2. Use a capillary tube with a smaller internal diameter 3. Use a longer piece of dialysis tubing →increase surface area 4. What can be deduced from the result 1. the water potential outside the dialysis tuning is higher than that of inside the tube 2. Solute if the solution in the dialysis tubing cannot pass through the diaysis tuning Conclusions that we can draw from the result 1. There is a net movement of water into the dialysis tubing Q3)describe and explain 1. It starts rising at ＿ 2. The slope is getting less steep 3. It stops rising in point ＿ （describe) As small water molecules enter 20% sucrose solution 13  14 →the water potential gradient between sucrose solution and distilled water decreases →the slope decreases over time →rate of osmosis decreases (Explain ) Q4) to deduce the value of water potential of (b) with reasons As the water level stops increasing → water potential gradient doesn’t exist between the bathing solution and the 10% sucrose solution → as the water potential of distilled water is zero, the water potential in the dialysis to tubing is 0 as well Q5) explain why water level stops further moving after it reached equilibrium state To increase water level in the capillary tubes create a hydrostatic pressure which prevents further net movement of water molecules into the dialysis tubing Q6)state the difference of the two curves 30% has a steeper slope and its curve is higher 14  15 Q7)state the difference between two slopes and explain The slope is steeper for 40° C When temperature increases, it increases the kinetic energy of water molecules. Water molecules will move faster. This will increase the rate of osmosis. It takes less time to reach equilibrium potato 15  16 reason :The skin of the potato acts asa barrier to water/the skin after potato is in permeable to water. Therefore, no water movement will occur. 16  17 State the difference and explain : The slope is steeper in (3) than (2) The rate of osmosis is faster because there is a larger surface area for osmosis to take place 17  18 Q8)Explain the change in (a) As the potato is boiled, the cell membrame becomes fully permeable. There is a net movement of water molecules diffuse into 10% sucrose solution down the water potential gradient. While the net movement of sucrose diffuse out to distilled water However sucrose has a larger size so the rate of sucrose diffusing into the 10% is slower than the rate of water diffusing into the sucrose solution So in (a) the water level rises Q9)Explain the change in (b) After some time, the sucrose molecules have diffused out of the 10% sucrose solution and the concentration of sucrose in the potato cavity and outside Q10) how can the student be sure that tge RBC in the tube has reached 18  19 equilibrium with the surrounding solution at the time when he made the observations ? Oberve the __ again some time The __should remain the same of it has reached equilibrium the the previous observation Explain : 19  20 **flaccid →failed to press against each other →soft 1. Which one has a higher water potential 2. Hypo/iso/hyper 3. There is a net movement of water molecules from ＿＿to ＿＿ through a differentially permeable membrane by osmosis 4. Change/ state of the cells **bursting of RBC leading to the leak of hemoglobin (haemolysis) a read solution ,at be resulted Absorption of water in human intestines and plant roots from soil Preservation of food →concentrated salt/ sugar →water is drawn out from microorganisms which growth may cause food decay →they will die or stop growing due to lack water 20  21 active transport Requires energy from respiration of cells →high rate of at =high rate of respiration =a lot of mitochondria Decrease the rate = crease the rate of respiration →low tem. low oxygen concentration, cyanide Function Obtain additional useful materials which are already inn high concentration in cells Absorption in nutrition (glu+amino) Absorption of minerals from soil into plant roots 21  22 phagocytosis →It is the uptake of large particles into cells by packaging the particles into vacuoles form from the cell membrane **energy is needs to change the shape of the cell membrane Important of unicellular organisms’ nutrition (Amoeba) WBC engulf harmful substances → important for body defence against disease Chapter4 anabolic and catabolic graph 22  23 experiment volume of gas collected with time graphs ** Total amount of product form depends on concentration and volume of substrate/enzy me. As these are the controlled variables Q1a)Describe 1.from time 0-Xs, the volume is increasing 2.the slope becomes less steep 3.from the time X onward, the volume stops increasing Q1b)explanation As the (enzyme) breaks down the (substrate), forming (product). So the volume of (product) increases. Rate of (product) released decreases as the amount of product formed per second is decreasing. So the collision between enzyme and substrate is decreasing.The formation of enzyme substrate complex 23  24 decreases. All substrate are used up so no more formation of products. Q2a) describe 40 C It has a steeper slope Q2b)explain 40 C As the temperature increases, the kinetic energy of substrate and enzyme increases. Collision between them increases. Therefore there is the increased formation of enzyme substrate complex. The rate of product formed increases. it reaches.(amount of product) at a shorter time. Factors that affect the enzyme activity : 1. Temperature 24  25 2. pH 3. Cyanide (inhibitors ) 4. Heavy metals e.g. mercuric ion, lead(ll) ions, copper(ll)ions experiment Method : 1. Production of product , disappearance of substrate → perform the test (after incubating the mixture at a given tem,pH for a IV be as fixed period of time ) specific as possible Setting up controls DV= enzyme the action of enzyme/show that it is an enzyme/ ivolves an activity enzyme : Set up a identical test tube +Boil the enzyme instead of fresh xxx How are you confirmed that the results obtain is action of an enzyme in solution A? Prepare and another two witches identical to tube xx, except the solution/enzyme has been boiled the reaction is due to the presence of enzyme: Set up a identical test tube +Enzyme →water Show that the reaction is due to the presence of substrate/enzyme doesn’t react with water to produce product Set up a identical test tube except that distilled water is used instead of substrate solution Structured questions What is the action of enzyme ion substrate The enzyme converts sustrate into xxxxx Aim and respective tem. : to investigate the action of the enzyme →comparing boiled/fresh (A) Enzyme is a heat sensitive substance which cannot speed up the breakdown of substrate into product when it is boiled © To study the effect of temperature on enzyme activity →water bath Why do we need to leave the tubes in the beaker for 10 minutes before starting the reaction? So that we can ensure the content of the test tubes have reached their respective temperatures When temperature increases from 0-xx, enzyme activity increases (Rate of xxx increases with increasing tem.) When temperature increases from xx-yy, the enzyme activity decreases (The rate of xxx decreases as temperature increases ) The optimum temperature for the enzyme activity is xxx (C+(Rate) To study how to high and low temperature affect the enzyme activity Based on your results, did use the action of low and high temperatures on enzyme activity. At low temperature, enzyme is inactive. But it can become active again and higher temperature. And high temperature, enzyme is denatured. It cannot function again in low temperature. 25  26 Enzyme is inactive at low temperature while it is denatured at high temperature(C) Study the effects of PH on enzyme activity How to vary the independent variable pH? I am making enzyme with solution of different pH How to measure the dependent variable enzyme activity ? To measure the amount of disappearance of starch, the larger they clear sound the higher the enzyme activity What are the purpose of setting (**no enzyme) 1. Distilled water → to check whether the results observed are due to enzyme alone and not water 2. acid+water → to check whether an asset can breakdown substrate 3. alkaline +water → to check whether an alkaline can break down substrate Why is this necessary to incubate the substrate at a certain temperature? To provide a constant temperature for fair comparison and temperature at which enzyme can work well What do the diameter of the clear zone show? They showed the amounts of substrate broken down, which intern indicate the enzyme activity. The larger is the clear song, the larger is the enzyme activity. Conclusion : enzyme is most active in xxx medium properties 1. they are specific in action →active site with specific shape for certain substrate to fit in →lock-and-key hypothesis 2. Reusable 3. →needed in relatively small amount 4. Protein in nature →easily affected by pH and tem. 5. They are biological catalysts daily Food making applications Cheese making (not important ) Proteases(cows' stomachs)coagulate milk to produce cheese Fruit juice extraction Pectinase can help break down pectin in plant cell walls and in the juice →increase the yield of juice extracted+break make the juice looks clear. Liquid-centred chocolate production Invertase added into solid sugar fillings →helps break down the sugars into more soluble forms → solid sugar fillings to gradually turn into liquid upon storage. Cooking papain(a protease extracted from papayas ) → helps break down the proteins in meat so that the meat becomes softer. Environmental protection Detergent 26  27 ✅ Biological washing powders ( proteases* and lipases) →help break down the insoluble proteins and lipids in stains into soluble products then it can be removed by water easily Cosmetic cleansers ( papain ) →help break down dead cells in the skin. →make skin softer and smoother. Textiles Stonewashed jeans production →cellulase helps break down the cellulose fibres in the jeans Medicine Lysozyme( drug ) to treat some bacterial infections. → help break down the cell wall of certain bacteria and kill them Chapter 5 food formation and fumction food test Extended/ substances source Aim: to test for questions the presence of food substances in food using xxx carbohydrat carbohydrates glucose 1. Glucose excessive es →fruits and →glucose carbohydrat honey test paper es are galactose → stored as milk dairy glycogen in products liver and Frustose muscles, or →fruits and 2. Reducing as fat in honey sugar → skin Moltose → Benedict’s germinating test Note:monosaccharides/simp barley le sugar are small molecules Lactose and are soluble in water →found in Glucose : main energy sugar cane source Sucrose →directly broken down to →found in release energy during milk , diary 3. Starch → respiration products iodine test →an immediate energy source for body activities Polysaccharides: Not sweet and soluble 27  28 Glycogen (form from Experimnet glucose ) Diastic paper is →energy reserve in animal commonly →broken down into glucose used for to release energy when testing the needed presence of →abundant in liver and glucose in muscles urine. It turns **since they are not soluble from blue they are good for being the green to food reserve in cells as they brown (pos.r) are not transported away by water easily. Eq)What is the purpose of testing Starch (form from glucose ) glucose with →energy reserve in plants / Benedict’s solution? main energy source for body To show that the car activities change of Benedict →abundant in test if reducing rice,wheat,potatoes,taros sugar is present. Cellulose (form from Eq) what is the glucose ) purpose of Titan → form cell wall and a glucose solution with source of dietary fibre diastic paper ? To show the colour Sports drink (有glucose ) change of diastic directly absorbed so can paper if glucose is provide immediate energy present Eq) what is the purpose of testing distilled water with diastic paper/ Benedict’s solution ? To show that water alone can’t give positive result in xxxxx /to show that the colour change of xxxx due to the presence of (thing being tested) but not water 28  29 Lipid fat : grease spot test Extended Meat,lard, (positive result ) Saturated fats and Butter,cheese Put a drop of the unsaturated fats food sample onto a The fatty acids in Oil: piece of filter paper lipids can be Peanut and let it dry saturated or oil,corn oil , → A translucent* unsaturated Canola oil spot will remain on Lipids that are rich the filter paper in saturated fatty →immerse the filter acids are called paper into an saturated fats*. 1. Phospholipid to form organic solvent and They are often solid cell membrane take it out. at room 2. Lipid stored in →The translucent temperature. adipose tissue can spot will disappear if Taking in too much act as energy it is formed by lipids. saturated fats may reserve lead to 3. Subcutaneous fat Eq) how is a cardiovascular can act as shock translucent spot diseases* like heart absorber to protect caused by lipids disease and internal organs ans different from the stroke*. heat insulator one caused by Trans fats 4. Each gram of lipid distilled water after Trans fats* are provide twice drying ? produced when amount if energy The translucent spot plant oils are tyam carbohydrates caused by lipids is solidified in an 5. Produce lipid permanent, but the industrial process, hormones translucent spot or when they are 6. Involved in the caused by water exposed to very absorption, transport disappears as water high temperatures and storage of evaporates during cooking (e.g. lipid-soluble vitamins deep-frying). Trans 7. In soluble in what Eq) what is the of fats are found in type of soluble and ethane on the oil cakes, bread and organic solvents spot? deep-fried foods. It can dissolve and They are also wash away oil linked to cardiovascular diseases. Why do people suffer from deficiency diseases if they adopted fat-free diet ? Without fat in the diet, they cannot obtain sufficient fat soluble vitamins(A,D) Leading to deficiency disease like night blindness(A) or 29  30 rickets (D) Importance of fat to the growth of adolescents ? Lipids as a raw material for producing sex hormones(1) which are important for sex sexual development of adolescent. As the material for producing a phospholipids for cell membrane(1) for the rapid cell division(1) to support the growth of adolescence Protein foods like Albustic paper meat, fish, amino acids +dipeptide eggs, beans, → polypeptide milk and dairy products Proteins in our body ( 20 amino acid) polypeptide coils and Twelve amino folds in a specific acids way (non-essential →form 3-dimensional ) structure →produced in →the H-bond holds the our body amino acids together The remaining in a specific way amino acids ✅N(S,P) (essential) →obtained from our diet Deficiency ： Kwashiorkor → children suffering from this disease grow poorly and have weak muscles. They have 30  31 a swollen abdomen because of the accumulation of tissue fluid Vitamin Vitamin A Fish liver oils, Functions liver, eggs, It is needed for the milk and dairy formation of a pigment in the products are retina* of our eyes. The rich in vitamin pigment is necessary for carrots, vision in dim light. pumpkin, It is important for keeping sweet the cornea", skin, lining of potatoes ano the alimentary canal" and mangoes) breathing system* healthy contain carotene Deficiency (orange poor vision in dim pigment) light/night blindness* →converted drying up of the cornea to vitamin A in and skin our liver. easy infection of the lining of the lungs and trachea Vitamin D Function promotes the absorption of Sunlight calcium and phosphate Fatty fish →essential for keeping (such smalon bones and teeth strong and tuna),fish →very important ot children liver osli, liver for hardening of bones and eggyolk development of teeth Deficiency Rickets in children Vitamin C Function Fresh DCPIP solution growth and repair of vegetables decolourize connective tissues which and fruit :bell help keep body structures in peppers, When we compare place. broccoli, the vitamin content healing wounds. guavas and in different food, we It promotes the absorption kiwi fruits assume that vitamin of iron from plant foods. C is the only helps the immune system substance that can work properly to protect the decolourize DCPIP body from diseases. solution water-soluble and heat-sensitive will be How to compare the destroyed by heat amount of vitamin C 31  32 in the food samples? Deficiency(scurvy): The more Symptoms number/volume of weak and bleeding gums extract to poor healing of wounds decolorized the small red spots on the skin DCPIP the least joint pain amount of vitamin C Minerals Calcium Canned involved in blood clotting, sardines, sending messages im the milk,dairy nervous system, muscle products, tofu contraction and component of bonds and some green teeth vegetables Deficiency Rickets in children → Osteoporosis for elderly → Iron a component of Beef, liver, haemoglobin beans,cabbag e, spinach Deficiency and Anaemia raisins →faint easily →not enough o2 to support the brain Dietary fibre function : Vegetables, and water 1. Add bulk to food to fruits and stimulate peristalsis wholemeal and facilitate products digestion 2. Hold water to soften faces Deficiency: Constipation Balanced Age : why should we eat nitrates is not an diet Children require the more/less ()? essential greatest amount of Grain → they component of energy per unit body provide us with human diet, but mass energy readily calcium → high metabolic rate(to Veg/fruits → they salts(minerals ) generate more key to keep are rich in minerals, care their bodies warm) → high vitamins and dietary growth rate and high rate of fibre they are Vegearians heat lost (highest surface needed for Advantage: area to volume ratio) maintaining health low fat contends (1) 32  33 Large amount of Meat/fish/milk → Reduce risk for protein calcium and they are rich in heart iron → they are protein they are diseases/obesity growing actively, needed for the (1) these nutritions are growth and repair of needed to build up body tissues High contents of body tissues Fat,oil → eating too dietary fibre (1) much of these can This helps Sex : lead to various stimulate peristalsis Men : need more health problems and prevent energy than women constipation/reduce ○ → a larger d his risk of colon body size cancer/avoid over and are more eating muscular → higher metabolic rate ○ Less subcutaneou s fat → higher rate of heat loss Women：need more iron → replace the loss of iron during menstruation periodically Body status Pregnant women :more energy,more protein, iron ○ Energy and protein are needed for the growth of foetus ○ Iron is needed for the formation of foetal red blood cells Breast-feeding mothers → they need an extra supply of various types of nutrition → need it for milk production A woman dietary requirements of calcium increase during the breastfeeding period 33  34 Mother contains right amount of protein and fat/enzymes to help digesting the food/antibodies that provide immunity to the baby Eating too little Starvation = 1. break down glycogen and fat to release energy 2. Muscle protein → break down of stored fat and muscle protein results and weight loss →thin and weak → deficiency desease Eating too much Excess lipid and diet are stored as fat in the body Excess sugar, starch and protein may also be comforted into fat and stored in the body →overweight (serious =obesity ) Chapter 6 Organs Function Questions Mouth teeth →chewing food (Phy ) what will happen if no (Ingestion) →increase SAT for enzyme to act on xxxx teeth ? (Digestion) (Mastication) Food cannot to (verb) to Saliva (neutral ) →amylase,mucus, small particles, less water mechanical digestion ○ Salivary amylase(works best less surface area for in a slightly alkaline medium) enzyme to act on,takes starch → maltose (di) longer digestion time to (disaccharide) break food down into ○ Water → dissolve food small soluble particles. substance → we can taste the food also soften food ○ Mucus =sticky materials →helps binding food together 34  35 Moistens and lubricates the food during swallowing → easier to be swallowed After chewing the food is called a bolus(soft mass) Esophagus Swallowing The tongue rises to push the bolus towards the pharynx →The soft palate moves up to prevent the bolus from entering the nasal cavity →larynx rises so that epiglottis moves downwards and covers the opening of the trachea which prevents the bolus from entering the trachea → enters the espophagus peristalsis Longitudinal and circular muscle( smooth muscle ) work in pair (i.e one contract then one relax) →contract alternatively →wave-like movement → smaller pieces of food, increase surface area, increase the place for an act on, increase digestion rate When circular muscle contracts →lumen size decreases also the longitudinal muscle will relax to squeeze the food forward When circle muscle relaxes and longitudinal muscle contract →Lumen size increases →Food can slide through the lumen **its speed is affected by the bulk of food taken in Stomach (Digestion) churning → breakdown foot into smaller pieces,increase surface area for enzyme to tube A ✅ solution A →no food substance is act on , also helps to mix the food with digestive and inside Pepsin →kind of proteases →breaks down present tube B ❌ solution A →food substance is still protein into peptides present HCL → provide an acidic medium for the →conclusion : solution action of pepsin is responsible for the Also, most bacteria/microorganisms in food breakdown of food are killed substance Mucus → protect stomach wall from being 35  36 detested by pepsin/damaged by HCL In the stomach coagulation, being in After a few hours in the stomach, the food semi-solid form can we becomes a creamy liquid — chyme retained in the stomach for a longer period of Absorb a small amount of water time for protease to digest it Gastric reflux : Most likely to occur if a person has a meal just before sleeping → after the release of gastric juice increases, which increases the pressure inside the stomach. Also, the stomach and oesophagus are at the same level while sleeping Putting a Waterfield balloon in the stomach → as a space inside the stomach is reduced. It is easier for the woman to have a sense of fullness less food would be eaten. If the energy input is that than the energy used, Fat reserve will be mobilised to produce energy. Liver 1. produce bile and regulate blood glucose level 2. Produce bile a. bile salt to emulsify lipid into small droplets ↑SAT for enzyme to act on b. Bile pigment =break down of heamoglobin c. NaHCO3 →neutralizes the acidic chyme to protect the small intestine from being damaged+ an alkaline medium for the action of the enzymes in the small intestine d. Deamination →excess aa are broken and the liver by deamination → the amino groups of the acids are removed and converted to 36  37 urea which is released into the bloodstream and most of it is excreted in urine, the remaining parts of aa are converted into carbohydrates or lipids(Deliver non-essential aa and convert some aa into other aa ) e. Regulating the blood glucose level which may affect the functioning of cells → excess glucose are stored in liver as glycogen , as some glucose in blood are used by cellular respiration , the glucose level falls between meals, the liver converts the stored glycogen back into glucose and release it into the blood f. Convert excess carbohydrates into a minute acid into lipid g. Breakdown old RBC install iron which is used for making new RBC →many Fe so the liver is very red h. Storage (lipid-soluble A,D)and production of vitamins →carotene is changes into Vit A i. Detoxification → it contains enzymes which help break down certain mouth toxic substances e.g. alcohol,drugs) in the blood into harmless substances which are then pass out of the body Pancreas produce pancreatic juice blocked pancreatic duct Lipase (major organ ) 1. Pancreas is a Pancreatic amylase **catalyse major organ that remaining starch produces lipase, Proteases if it is blocked protein →peptides then pancreatic peptides →amino acids lipase cannot Sodium hydogencarbonate reach the duodenum, fat If the pancreas is blocked food cannot be →faeces would contain a lot of fat digested and is egested in the faeces 2. Digestive 37  38 enzymes accumulate in the pancreas it will digest the tissue of the pancreas/digest the cell membrane of pancreatic tissue cells Gall bladder stored bile and secret it to the small Dietary restriction of a intestine by bile duct patient whose gallbladder has been removed: Should take less fat, Gallbladder style to which is released into the duodenum when fatty food is present in small intestine Effect of removal of gallbladder : Bile produce in the liver cannot be stored in the gallbladder, when bile enters the duodenum, insufficient amount of file is released for emulsifying fat in the food to small oil droplets, the surface area for the action of lipase decreases, fat digestion slows down Small Intestinal juice is produced by some glands main food substance intestine in the wall of the small intestine absorbed = (Digestion Slightly alkaline Carbo,lipid(fat,oil) and Contains water, mucus and sodium Protein,vit,min… absorption) hydrogen carbonate Removing the small Peristalsis in the small intestine intestine can reduce 1. Moves and pushes the food along body weight? the intestine Digestion and 2. Mix the food with digestive juices absorption of food is 3. Increase the context between Fila reduced energy ,intake and digestive food to facilitate becomes less than absorption energy furniture in the body. This may lead too ✅epithelium of small intestine specialised cells → have carbohydratrase (di to mono) and proteases (pep to aa )etc mobilisation of fat. Medicine that stimulates 38  39 embedded in their membrane the peristalsis can cause diarrhoea → Insufficient Feature and explanation minerals and vitamins very long → allows sufficient time for will be absorbed as the complete digestion and absorption digestive food is moved Inner wall of the small intestine is too fast in the intestine. highly folded with finger light There may also be projections villi →increase surface excessive loss of water. area for absorption of digested food particals Microvilli → further increase surface area for absorption of digested food **villi doesn’t secret enzymes one-cell thick(幅圖講冇講唔可以寫) epithelium is very thin → it is only , providing a short distance for diffusion of food market into the blood, so that absorption can take place rapidly Lacteal and the capillaries in the villi (reduces blood from aorta )→ allows to absorb the food molecules to be carried away rapidly ( rapid transportation ) , so that a steep concentration gradient of molecules is maintained across the wall of small intestine. Which can increase the rate of diffusion of food molecules/ network of capillary provides a larger surfacs area as a result the rate of diffusion of substances increases Peristalsis of longitudinal and circular muscle → bring the digestive molecules into close contact with the villi for absorption, Keeping a steep concentration gradient of molecules across the wall of small intestine to increase the rate of diffusion of food molecules (There are also large amounts of MT in the cells → increase respiration rate to release more energy ATP for active transport of digested food e.g. aa,glucose ) Baby →shorter intestine → shorter time for the food to stay in small intestine shorter →time for digestive enzyme to act on the food → food is not fully digested so less time for the food to be absorbed (poor absorption ) Absorption of lipid and lipid soluble vit 39  40 into the lacteal ： Fatty acids and glycerol enter the epithelium of lacteal by diffusion → into epithelial(表皮 細胞) cells they combine into find lipid droplets → lymph vessels →vena cava →heart →pulmonary archery →lung →pulmonary vein →heart →aorta (hepatic vein →liver) Vit A,D absorbed into the lymph in the lacteals by diffusion Absorption of water and multicellular molecules into the capillary： mono/simple sugar ,aa,minerals, vitC → absorb into the blood capillary by diffusion and active transport Absorption of most digested food into the blood increases the water potential of the contents in the small intestine/ gut content→ water is drawn into the blood by osmosis ** absorption of digestive food in the small intestine is accompanied by the absorption of water (ilieum) at the same time Why does the fluid inside the lacteal of the intestine villi becomes milky after a meal? It is because of the presence of fat in (food) the digested products are absorbed into the lacteal in the form of oil droplets/fat as a result there will be numerous oil droplets/far in the lymph Large absorption of remaining food Medicine that intestine particles(minerals, vit), water stimulates the (Absorption) →form feaces contraction of (egestion) 太快→ larger portion of water will be muscles in the Colon absorbed faeces will become hard intestinal wall will →constipation stimulate 太慢→ larger portion of water will persistalsis remain in the faeces → diarrhoea →rapid removal of faeces Removal Whether this small intestine or the large → Pieces more because intestine in the major sites of water less water can be absorption absorbed Small intestine 1. this is major site of food absorption the absorbed food helps absorption of water. 2. does Martin test is longer than the large intestine so the time for water absorption is longer/ larger SAT fur 40  41 H2O absorption 3. The war of the smallest is highly folded with the large number of villi so the SAT for water absorption is larger Egestion/defaecation and faeces undigested and absorbed materials Semi+solid waste containing dietary fibre,bacteria, secretions from alimentary canal Dead cells from intestinal war and a small amount of water Brown → bike pigment Temporarily stored in rectum At the anus there is a ring of muscles called anal sphincter, when the sphincter relaxes and the muscle of the rectum contract, faeces are push out if the anus Asssimilatio Water soluble (aa,glucose ) n → they are directly absorbed into the blood capillary, this will lower the water potential of blood inside the capillary, so it will also draw water inside the capillary by osmosis Water-soluble food molecules → some are stored and some are processed and carried away from the lever to the heart Glucose ○ Broken down by cellular respiration for releasing energy ○ excess glucose is converted into glycogen the liver and 41  42 muscles and stored there. It may also converted into lipid Lipid ○ Used by cells to make cell membrane and some lipid hormones ○ Energy reserve →broken down to release energy for cellular activities when body is short of glycogen ○ Excess → stored in adipose tissue Amino ○ Used by cells to make different types of protein for growth and repair ○ Raw materials for making enzymes, antibodies and protein hormones ○ Broken down to release energy when carbohydrates and lipids stored in our body are used up/starvation ○ Excess → cannot be stored in the body and a broken down and are broken down in the liver through deamination 42  43 Chapter 7 why do we need to remove waste CO2 produced from a breathing cellular respiration and obtain useful system materials O2 for cellular respiration Unicellular organisms are relatively small and have a larger surface areas to volume ratio →Gas exchange takes place effectively by diffusion across the cell surfaces Multicellular organisms such as humans have a small surface areas volume ratio →diffusion over body surface is in adequate for gas exchange. →so human have involved a breathing system to move air into an out of the body for effective gas exchange. Why surface area cannot be compared between multicellular and unicellular organisms As a size of them are not the same, so we cannot take the volume of size into account Surface area violent racial will be a fair way to compare them when we swallow, the larynx rises and the epiglottis,pharyn oesophagus covers the epiglottis. x, larynx trachea →Prevent food and drink from enetring the oesophagus trachea thus prevent choking When you are eating, the floor is going down to the oesophagus If you talk when eating, has to pass through the focal cord in the trachea. to epiglottis is no longer covering the trachea so the food will enter the trachea causing choking 43  44 Structure nasal cavity →pharynx(common passage for air and food )→larynx →trachea →bronchi (overview ) →bronchioles (L,S) → structure cartilage cilia mucus-secre smooth elastic blood (on ciliated ting cells muscles fibre vessels/ epithelial Capillaries cells) function prevent the sweep the secrete contraction to warm and respiratory mucus mucus to and relaxation the describtion track from towards trap the dust of smooth inhaled air collapsing xxxxx particles and muscles helps →avoid due to microorganis regulate the irritation of pressure ms diameter of the lungs changes the airway during It is a protein enhance breathing substance airflow /when air So there are passes many RER Involuntary through it to produce control= we mucus cannot control it Much MT presents for higher respiration to release more energy for producing more mucus 44  45 + (F) nasal cavity ✅ Many MT is ✅ ✅ ✅ capillaries needed for higher respiration to release more energy(ATP ) for the briefing action of Celia which speaks mucus to pharynx trachea ✅ C ✅ ✅ ✅ ✅ ✅ blood vess → allows the oesophagus to expand when food is swallowed bronachos ✅R ✅ ✅ ✅ ✅ bronchioles ✅ ✅ ✅ ✅ ✅ (L) (S) 冇講大細=L ❌ ❌ ❌ ❌ air sac why dose do not ✅inhale contain →stretch mucus? to allow Because if it the lung to contains inflate mucus, it will accurate in exhale the air sac →recoiling Making the of the water stretch thicker, so elastic the diffusion fibre help distance will force air increase, so out of the the rate of lung 45  46 gas exchange will decrease ❌bacteria nor virus ) ** nostrils in the nasal cavity filters larger dust particles ( Lung Air Sac /alveoli Right :3 lobes →made of epithelium Left : 2 leave space for the heart →pulmonary archery (low O2 contend) heart → pass through air sac→diffusion of O2 and CO2 →pulmonary vein (high O2 contend )→heart →cells for respiration CO2 level decreases O2 level increases Blood pressure decreases Glucose level decreases Uptake of O2 air is inhaled → accident in the air dissolved in water film → oxygen diffuses into RBC Removal of CO2 CO2 diffuses out of the blood → CO2 diffuses into the air in the air sac - →air is exhaled Q1)Why is having a smaller air sac more efficient than bigger air sacs for gas exchange For the same volume, (no) small spheres have a larger service irritative volume ratio than the largest sphere(1) Therefore the diffusion rate for gas exchange will be higher. Diffusion of gas will be faster Adaptive features of air sac +explanation 1. Large number of as → increase service area for diffusion of gases 2. Very thin walls of air sac → the epithelia making up the walls are only one-cell thick, reducing the diffusion distance of gases 3. Moist inner surface → epithelium secrets of watery fluid to keep the inner surface of the air sack moist, so that O2 in inhaled air dissolves in the water film lining in the inner surface of the air sacs before diffusion takes place 4. Rich supply of capillary → allows rapid transport of gases to and away from the air sacs, maintaining a steep concentration gradient of gases between the 46  47 air and blood for efficient diffusion of gases/net worth of capillary provides a larger surface area so the rates of diffusion of substances increases 5. Walls of the air sex are in close contact with capillaries → reduces the diffusion distance of gases Q2) explain why oxygen dissolves in the water film first Pleural membrane and pleural fluid Pleural membrane secrete pleural fluid , the fluid holds two layer of membrane together and also act as a lubricant to reduce fructiob between the membranes during breathing movements inhalation and Inhalation exhalation Rib-cage model Bell-jar model Exhalation Diseases smoking Covid Cancer Pneumonthorax → Chapter 8 47 48 48