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Science Quest 8 Chapter 4: Systems — living connectionsAnswersThink about the human bodyWhat is the function of blood?The function of blood is to transport oxygen around the body.Why do you need a skeleton?We need a skeleton to protect the organs and to keep the body erect and straight.What are bones made of?Bones consist of a special type of tissue called connective tissue, which is made up of proteins, minerals and vitamins.What makes your bones move?Bones move when muscles connected to them at a joint contract and pull on them.Which human blood type is the most common?Blood type O is the most common.How many chambers does a human heart contain?The human heart consists of four chambers: two atria and two ventricles.What causes the ‘lub dub’ sound that your heart makes?The ‘lub dub’ sound that your heart makes is caused by the opening and closing of the valves within the heart.What is special about cardiac muscle?Cardiac muscle is an involuntary muscle, which means it contracts by itself. It looks very similar to smooth muscle but is very different. The contractions it makes are very powerful.Why aren’t all of your teeth the same shape?Teeth are different shapes because they have different roles. Some teeth are for chewing, whereas others are for grinding. Therefore, they need to be different shapes and sizes.In which organ is urine produced?Urine is produced in the kidney.Your questGetting below the surface1. to 5. Answers will vary.Understanding and inquiring4.2Driven by curiosity?1. to 3. Answers will vary.4. The da Vinci? Mitral Valve Repair is the most effective and least invasive treatment for open-heart surgery using robotics. It involves small incisions to the chest instead of the usual open-heart procedure. It was named after Leonardo da Vinci because he created the first robot.5. The Treatise on painting is a collection of writings produced by Leonardo da Vinci that argued that painting was a science. 6.Answers will vary. The Codex on the flight of birds was a series of folios developed by Leonardo da Vinci that examined the flight behaviour of birds and formed the basis of his development of flight machines. 7. and 8. Answers will vary.9. Scientific understanding of human body systems can determine how we respond to public health issues as it helps us to develop cures and ways to fight the different pandemics that the world today can face. 10. to 14. Answers will vary.4.3 Working together?anisms, like all other matter in the universe, are made up of atoms.2.(a) Atoms are the basic units of matter. A molecule is a group of atoms. An organelle is made up of thousands of molecules. Cells contain a variety of organelles.(b) Cells are the basic units of living things and many cells of a similar type make up a tissue. Organs consist of one or more groups of different tissues, and several organs working together make up a system.3.Unicellular organisms are made up of only a single cell, while multicellular organisms are made up of more than one cell. Multicellular organisms are made up of a number of body systems working together while unicellular organisms are not.4. Mitochondria; these organelles convert glucose into energy that the cells can use.5.Cells may differ in their size, shape and the number and types of organelles that they contain depending on the main function of the cell within the organism; different functions require different cellular characteristics.6. Muscle tissue contains cells with many mitochondria so that the energy requirements of the tissue (which are larger than other forms of tissue) can be met.7.(a) nerve, epithelial, skeletal (bone), connective, muscle, blood(b) Examples may include: stomach, heart, lungs, brain, liver, skin, small intestine, large intestine, gall bladder, eyes, kidneys, testes, ovaries.(c) Examples may include: digestive, respiratory, circulatory, excretory, sensory, nervous, musculoskeletal and reproductive systems.8.(a) trachea, lungs(b) heart, blood vessels (arteries, veins, capillaries)(c) oesophagus, stomach, large intestine, small intestine, liver, pancreas, gall bladderNote: In some editions, the text of question 9 is incorrect. ‘(e) Skeletal tissue’ should be ‘(e) Epithelial tissue’.9. (a) E(b) C(c) B(d) A(e) DNote: In some editions, the text of question 10 is incorrect. ‘(d) Reproductive system’ should be ‘(d) Nervous system’.10. (a) B(b) C(c) A(d) D(e) E11.(a) The digestive system supplies your body with the nutrients it requires to function effectively from the food that you eat.(b) The respiratory system is responsible for getting oxygen into your body and carbon dioxide out.(c) The circulatory system is responsible for transporting oxygen and nutrients to your body’s cells, and taking wastes such as carbon dioxide away from them.12. (a) False; cellular respiration involves using glucose to produce energy.(b) True(c) False; the circulatory system transports oxygen and nutrients to your body cells, and transports wastes such as carbon dioxide away from them.(d) False; arteries transport blood away from your heart while veins transport blood to your heart.(e) True13. to 16. Answers will vary.4.4 Digestive system — Break it down1.(a) salivary glands; (b) epiglottis; (c) stomach; (d) pancreas; (e) small intestine; (f) large intestine; (g) rectum; (h) anus; (i) appendix; (j) gall bladder; (k) liver; (l) oesophagus; (m) mouth2.Molar: to grind food Premolar: to roll and crush foodIncisor: to cut and bite foodCanine: to shear and tear through tough food3. (a) Chemical digestion(b) Lipases(c) Proteases(d) Substrate4. Peristalsis is a series of involuntary muscular contractions that force partly digested food down the oesophagus. It pushes food into the stomach for further digestion.5. (a) Mechanical digestion is the physical breakdown of food into smaller pieces and takes place mainly in the mouth with your teeth cutting and grinding the food.(b) Enzymes made by the pancreas are secreted into the small intestine to chemically digest the components of food.(c) Bile is produced in the liver and then transported for storage in the gall bladder until needed. Then, bile is transported from the gall bladder to the small intestine where it helps break up fats and oils.(d) The small intestine is lined with finger-like villi that increase the internal surface area of the intestine. Nutrients are absorbed through the villi into underlying capillaries, which carry the nutrients through the body via the bloodstream.(e) Bile emulsifies fats and oils in the small intestine so that lipases can break them down.6. When enzymes get too hot, they become denatured so they can’t work anymore.7.Mouth, oesophagus, stomach, small intestine, large intestine, anus.8. (a) H(b) D(c) G(d) C(e) F(f) E(g) A(h) B9. If you swallow food in large pieces, it takes a long time to digest. Digestion is much faster if the food is in small pieces so that there is a greater surface area for chemicals to act on. The process of mechanical digestion breaks food down into even smaller pieces and chemical digestion breaks food down chemically into molecules that are small enough to pass across the small intestine membranes into the blood.10. (a) Incisors; (b) molars and premolars11. Answers will vary.12. When you have diarrhoea, undigested food moves through too rapidly for enough water to be absorbed into your body.13.(a) False; chemical digestion occurs when chemicals in your body react with food to break it down.(b) True(c) True(d) False; peristalsis is the term used to describe the muscular contractions that push food down your oesophagus to your stomach.(e) True(f) False; denaturing changes their chemical composition so that they can no longer function as enzymes. They are not ‘killed’.14. Peristalsis squeezes food down the oesophagus by repeated waves of muscle contractions, even if you stand on your head.15.Over time, the amylase in the saliva secreted in your mouth breaks down the starch in the bread into glucose, which has a sweet taste.16. to 20. Answers will vary.21.Part of systemStructural featuresFunctionOesophagusAbout 25 centimetres long; composed of two layers of musclesSqueezes food down from the mouth to the stomach by muscular contractions (called peristalsis)StomachDilatable; contains three sections; composed of muscles and mucusChurns and mixes food; releases enzymes that begin to break proteins down; releases hydrochloric acid, which activates enzymes and destroys unwanted bacteriaSmall intestineAbout 6 metres long; consists of the duodenum, jejunum and ileum; villi increase the surface area for absorptionReleases enzymes that, with pancreatic enzymes and bile, complete the digestion of food; food absorbed into the bloodstream from the small intestineVilliMinute finger-like projections found in the small intestineIncrease the surface area of the small intestine for more efficient absorptionLarge intestineConsists of the caecum, colon, rectum and anusBacteria in the large intestine make vitamins that are absorbed and used by the body; water and minerals are absorbed into the bloodstream here.22. to 29. Answers will vary. 4.5 Digestive endeavours1. Coeliac disease is a condition in which the person is intolerant to gluten (a substance found in wheat, oats, barley and rye), which damages the villi of the small intestine. These individuals should follow a gluten-free diet.2. 1 in 703. Answers will vary but should include:Both involve the use of an endoscope.Gastroscopy:involves passing the endoscope through your mouth, down the oesophagus and into your stomach and duodenumtakes 5 minutes.Colonoscopyinvolves inserting the endoscope through the rectum to observe the colontakes 30 minutes.4. Australian scientists Barry Marshall and Robin Warren received the 2005 Nobel Prize in Medicine for their discovery that linked Helicobacter pylori bacteria to gastroduodenal disease. Their discovery dramatically improved the treatment of peptic ulcer disease.5.Answers will vary. An example is given for the second hypothesis.A group of students use mouthwash regularly for a period of about two weeks. Before they begin to use the mouthwash, they test for the presence of bacteria in the mouth. After using the mouthwash for two weeks, they again test for the presence of bacteria in the mouth. If there are fewer bacteria after two weeks, this does not prove that tooth-decaying bacterial species are destroyed by mouthwash, but it does show that the use of mouthwash destroys some bacterial species in the mouth. Some of these bacteria may be responsible for tooth decay.Note: Students may compare no brushing (with mouthwash) with no brushing (no mouthwash), or brushing (with mouthwash) with brushing (no mouthwash). That is, brushing or no brushing is a controlled variable.6. to 12. Answers will vary.4.6Circulatory system — blood highways1. (a) E(b) F(c) H(d) G(e) B(f) C(g) A(h) D2.Blood in mammals consists of plasma (serum and fibrinogen), cells (red and white blood cells) and platelets. Blood transports nutrients, oxygen and wastes around our body and helps us fight disease.3.Blood vesselDescriptionArteriesThick elastic, muscular wallsCarry blood under high pressure away from your heartVeinsThinner walls with valves to prevent backflow of bloodCarry blood to the heartCapillariesMost numerous and smallest blood vesselsOnly one cell thickSite of exchange of materials to and from cells to vessels4. Red blood cells: 45 per cent of blood; no nucleus; cytoplasm with haemoglobin; carry oxygen White blood cells: less than 0.1 per cent of blood; have nucleus; colourless cytoplasm; help fight diseaseBlood platelets: less than 0.01 per cent of blood; aid in clotting the blood5. Arteries take blood away from your heart, and veins take blood towards your heart. Between arteries and veins are capillaries that deliver oxygen and nutrients to your cells and remove wastes such as carbon dioxide from your cells.6. (a) The left atrium and ventricle contain oxygenated blood, whereas the blood in the right atrium and ventricle is deoxygenated.(b) The walls on the left side are thicker and more muscular because they need to pump the blood from the heart to the rest of the body.(c) Systolic pressure is measured when the heart contracts and diastolic pressure is measured when the heart relaxes. Blood pressure is expressed as systolic pressure/diastolic pressure.7. Valves in the heart prevent the blood from flowing backwards and so keep it going in the correct direction.8. Blood pressure is caused by the building up of pressure in the arteries due to the pumping action of the heart and the narrow size of the blood vessels. Systolic blood pressure is the pressure when the heart contracts and diastolic pressure is the pressure when the heart relaxes.9. (a) 60–100 times/minute(b) Activities involving exercise and some moods, such as fear, anger and excitement, may cause the heartbeat to increase.(c) The rhythmic beating of the heart is maintained by the heart’s pacemaker.10. Cardiac muscle is unusual because it never tires.11.Part of the systemStructural featuresFunctionArteriesThick, elastic, muscular wallsCarry blood under high pressure away from your heartVeinsThinner wallsValves that prevent the backflow of bloodCarry blood to the heartCapillariesSmallest blood vesselsClose to cellsLink between arteries and veinsCarry oxygen and nutrients to the cells and remove carbon dioxideRed blood cells5–6 million per mm3No nucleusCytoplasm with haemoglobinCarry oxygen and carbon dioxide12. to 14. Answers will vary.15.Blood group O is the most common. Blood group AB is the least common.16.(a)Blood group O(b) All blood groups(c) Blood groups O and A17. Blood group AB can receive transfusions from all blood types.18. Answers will vary.19. (a) The white blood cells are stained purple and have a nucleus. The remaining cells stained red that do not have a nucleus are the red blood cells.(b) Red blood cells do not have a nucleus and are disc shaped.(c) Red blood cells are in greater abundance as they make up a greater proportion of the blood. They are required constantly to carry oxygen and nutrients to cells and remove carbon dioxide and waste from every cell of the body. White blood cells can come from anywhere in the body when required to fight an infection.20. A possible reason why people living at high altitudes usually have more red blood cells than people at low altitudes is that there is less oxygen in the air at higher altitudes. Having more red blood cells means that there is more haemoglobin, so more oxygen from the air can be carried in the blood.21. Insects and lobsters have an open circulatory system, which means their entire body cavity is filled with blood. The part near the head is the aorta and the part near the back contains sacs that make up the hearts. This vessel contracts and forces the blood through the body cavity.22. Graph should include: Plasma ~55%; Red blood cells ~45%; White blood cells ~0.1%; Platelets ~0.01%;23. to 27. Answers will vary.28.(a) Aorta (b) Capillaries in intestines(c) Pulmonary artery(d) pulmonary vein29.Aorta → intestine → liver → right atrium → right ventricle → pulmonary artery → lung → pulmonary vein → left atrium → left ventricle30. to 35. Answers will vary.4.7Transport technology 1. Varicose veins are swollen, twisted and painful veins and are caused by defective valves that allow the blood to drain backwards and pool in the veins closest to the skin surface.2. An electrocardiogram shows the electrical activity of a person’s heart. They are useful in diagnosing heart disease or abnormalities.3. Valves in the heart open and close to stop the blood flowing backwards as it moves to and from the different chambers of the heart.4. ECG patterns that differ from the normal pattern indicate various heart abnormalities.5. Heart valves and valves in veins are similar in that they both prevent the backflow of blood.6. Cell typeColourComposed ofRed blood cellRedHaemoglobinHBOCsVery dark redSterilised haemoglobin from a variety of sources that has been genetically engineeredPFCsWhiteSynthetic7. (a) Muscles are contracted until R and then relaxed.(b) Relaxed(c) There are not a lot of peaks in the abnormal ECG, which suggests that there are more contractions than relaxations.(d) The person may be having a heart attack.8. Artificial hearts are made of synthetic materials such as titanium and polyurethane plastic. Artificial hearts are powered by batteries to pump blood continuously around the body.9. Blood loss can cause death because it leads to a lack of oxygen being transported throughout the body.10. to 13. Answers will vary.14. (a) The organs most successfully transplanted into humans are the kidneys.(b) The most commonly transplanted organs are the heart, kidneys, liver, lungs, pancreas, intestine and thymus. Generally, the donor must be dead or brain dead, and such transplants may raise a number of ethical issues. If the donor is living and donates a kidney or part of the liver, then they may have health issues for the rest of their lives.(c) Donor and organ recipients are matched primarily by blood and tissue type but also by weight and age.(d) After an organ transplant, recipients need to take immunosuppressant drugs to protect the transplanted organ from being rejected by the immune system.15. to 33. Answers will vary.4.8Respiratory system — breathe in, breathe out1. (a) G(b) H(c) B(d) C(e) D(f) A(g) E(h) F2.(a) Mouth/nose trachea bronchi bronchioles alveoli(b) Alveoli capillaries pulmonary vein left atrium left ventricle aorta arterioles capillaries body cells(c) Body cells capillaries venules vena cava right atrium right ventricle pulmonary artery lungs(d) Capillaries alveoli bronchioles bronchi trachea mouth/nose3. (a) Oxygen breathed out ? of oxygen breathed in(b) Some of the oxygen breathed in is absorbed by the body cells, which use it in the process of cell respiration.(c) Carbon dioxide breathed out 100x carbon dioxide breathed in(d) The extra carbon dioxide is generated by the body cells as a waste product of cell respiration.(e) Answers will vary.4. The oxygen diffuses into red blood cells in capillaries that surround the alveoli. Once inside the red blood cells, oxygen binds to haemoglobin to form oxyhaemoglobin. The oxygenated blood travels from your lungs via the pulmonary vein to the left atrium of your heart. From here, it travels to the left ventricle where it is pumped under high pressure to your body through the aorta. The oxygenated blood is then transported to smaller vessels (arterioles) and finally to capillaries through which it diffuses into body cells.5. Breathing is the process by which air is taken into and expelled from the lungs.Cellular respiration is a chemical reaction performed in the cells by which glucose and oxygen are combined to produce water, carbon dioxide and energy for the cell.The respiratory system is the organ system made up of the trachea and lungs, which contain bronchi, bronchioles and alveoli. 6. Part of systemStructural featuresFunctionTracheaNarrow tube commonly called the windpipe that divides into the bronchiAir moves through it when it enters the body.AlveoliTiny air sacs found within the bronchiolesExchange of gasesLungsTwo large, cone-shaped organsSit on diaphragmHoneycomb appearanceOne on each side of the heartAllow you to breatheCapillariesThin-walled vessels that connect veins and arteriesDiffusion of wanted and unwanted gases and nutrients from the cell7.(a) Trachea(b) Bronchi(c) Bronchioles(d) Alveoli8.(a) Your nose filters out unwanted particles.(b) Blowing the nose removes microbes and toxins from the body.(c) You can choke as the food may pass down the trachea.9. A spirometer is an instrument for measuring the vital capacity of the lungs.10. to 14. Answers will vary.4.9Short of breath? 1.Air pipes to the lungs become narrower during an asthma attack.2. The airways are already inflamed because of the infection.3. An asthma trigger is something that causes an asthma attack.4. The two main types of asthma medication are preventers and relievers. Preventers make the lining of the airways less sensitive and therefore less likely to be triggered. Relievers open up the airways once an attack has started.5. to 9. Answers will vary.10.(a) Anaphylaxis Australia Inc. is a non-profit organisation that provides information, training and support to allergy sufferers, particularly food allergy sufferers.(b) Identifying the signs of anaphylaxis and how to administer an EpiPen?(c) An EpiPen? is a shot of adrenalin that is administered to the thigh of a person suffering from anaphylaxis.11. (a)(b) Answers will vary. An example is given. In the 1940s and 1950s, most men smoked. It was fashionable for men to smoke and many men first started smoking while serving in World War II. As the link between smoking and lung cancer was established, smoking became less fashionable, many men gave up smoking and fewer young men started smoking. Smoking was a lot less fashionable for women than for men in the 1940s and 1950s.(c) Answers will vary but the percentage for both genders may be about 20 per cent.12. (a) (i) People who smoke 10 cigarettes a day are about 20 times more likely to develop lung cancer than non-smokers. (ii) People who smoke 30 cigarettes a day are almost 3 times more likely to develop lung cancer than people who smoke 10 cigarettes a day. (55% risk versus 20% risk)(b) (i) $30 (ii) $210 (iii) $10 92013.(a)The incidence of lung cancer deaths increased gradually from about 1915 until 1940. Then it increased rapidly to about 1970. From 1970 to 1980 it decreased slightly. (Note: This question relates to lung cancer deaths and not the incidence of lung cancer.)(b) About 1940–1945(c) About 1970(d) Lung cancer takes a number of years to develop so the peak in smoking did not result in lung cancer being diagnosed and causing death for about 25 years.(e) About 2000–2010. Female smoking peaked around 1976–1980, so a peak in female lung cancer deaths should occur 20–25 years later.14. to 15. Answers will vary.16.(a) At the end of each duct in a bronchiole, there are a number of sac-like structures called alveoli, grouped together like interlinked caves. These structures produce a surfactant that reduces surface tension to allow gas exchange of carbon dioxide and oxygen.(b) The structure of the alveolus increases its surface area-to-volume ratio, which increases the rate of gas diffusion.(c) Smoking affects the ability of an alveolus to perform its function as it does not allow the alveolus to produce the surfactant for efficient gas exchange to take place.4.10 Excretory system — taking out the trash!1. (a) C(b) F(c) E(d) B(e) D(f) A2. Excretion refers to any process that gets rid of unwanted products or wastes from the body.3. 4. When you drink a lot of water, more is absorbed from your large intestine and your kidneys produce a greater volume of dilute urine.5. Excess salt may be removed from your body in your urine.6. In haemodialysis, a machine removes wastes such as urea from the blood.7. (a) The kidney contains millions of nephrons which filter waste from the blood.(b) Urine is produced in the kidneys.(c) Alcohol is converted to carbon dioxide and water in the liver. The CO2 is carried from the liver to the lungs, where it is exhaled. Alcohol may reduce the reabsorption of water by the kidneys, resulting in more urine.8.(a) Ureter: carries urine from the kidney to the bladderUrethra: carries urine from the bladder to outside the body(b) Bowman’s capsule: filters useful substances from the blood wastes passed on from the glomerusglomerus: filters wastes from blood(c) bladder: stores urinekidney: makes urine9. (a) To pump blood from the arm into the dialysis tubing(b) To remove bubbles so that they are not sent into the body(c) To ensure that blood is kept the same temperature as the body10. You would expect to find urea and wastes in used dialysing solution.11. Red blood cells are too large to pass through the dialysis tubing.12. Answers will vary but should include: Dialysis is similar to the kidneys in that it removes wastes from the body and is different because it is done externally to the body and involves machinery, apparatus and solutions.Dialysis solution contains glucose at the same concentration as the blood so that glucose is not lost from the blood in the dialysis machine. In the kidneys, some glucose is lost from the blood and must be recovered into the blood (reabsorbed). 13. (a)(b) Water is in the greatest quantity as most substances are dissolved in it and both liquids need to flow.(c) Proteins and glucose are found in the blood but not in the urine.(d) Chloride and urea are in a higher concentration in urine than in blood. This is because they are wastes and concentrated in the urine before excretion.(e) Chlorine and urea would be present at even higher concentrations in the urine when the body is dehydrated and at a lower concentration when fully hydrated. Proteins may be found in urine if kidneys are not functioning correctly.14. Answers will vary.15. (a) Men have a longer urethra than females, and it is also the part of the reproductive system in which sperm travel.(b) The amount of blood in the body increases dramatically when pregnant, which leads to a lot of extra fluid being processed through the kidneys and moving to the bladder. The uterus also applies pressure to the bladder as it grows.(c)In later life in males, the prostate gland may become enlarged and affect the urethra leading to urinary problems.(d) Some fruits and vegetables, large amounts of coffee and other fluids(e) Many diseases use urine tests for diagnosis. These include kidney disease, diabetes, Alzheimer’s disease, certain cancers and STIs.16. to 17. Answers will vary.4.11Musculoskeletal system — keeping in shape 1.(a) E(b) G(c) A(d) D(e) B(f) C(g) F2.(a)Ligaments are bundles of strong fibres that hold your bones together.(b) Cartilage stops your bones from scraping against one another.(c) Synovial fluid stops your bones from scraping against one another.3.Immovable joints such as the plates in your skull provide a thin layer of soft tissue between the bones that absorb enough energy to prevent the bone from breaking.4. Answers may vary. Examples are given.(a) Knee, elbow(b) Hip, shoulder (c) Between skull and spine(d) Plates of the skull5. A ligament holds your bones together whereas a tendon connects your muscles to bones.6. As you raise your forearm, the triceps relax and the biceps contract.7. Part of systemStructural featuresFunctionBonesMade of soft cartilage when born and is replaced over the first 20?years of your lifeNeeds calcium and phosphorusConsists of connective tissueProtects your organs and allows you to moveCartilageVery soft and rubberyCan change into boneThree types: hyaline, fibrocartilage, elasticProvides support and rigidity, and allows bones to pass over one anotherJointsFound where two bones meetMay be immovable, pivot, hinge or ball and socketAllows movement of bonesSkeletal musclesStriated muscleAttached to bonesMovement 8. Smooth muscle is a smooth involuntary muscle that forms the walls of hollow organs such as those found in the digestive system. It controls slow, involuntary movements.Skeletal muscle is striated and brings about voluntary movement of the various bones of the skeleton. Cardiac muscle is an involuntary, striated muscle found in the walls of the heart. It is responsible for the contractions of the heart.9. Dietary rickets is a bone disease caused by vitamin D deficiency; the body is unable to regulate levels of calcium and phosphorus in the bones. 10. Skeleton B is missing its mandible.Skeleton C is missing its right tibia. Skeleton E is missing its right patella.11. To reduce the likelihood of torn muscles and tendons, basketball and netball players stretch before and after a game.12. If the cartilage in your knee joint wore out, the bones would rub against one another causing a lot of pain.13. to 17. Answers will vary.4.12Same job, different path1. Cell, tissue, organ, system, multicellular organism2. Answers will vary.3. Glucose + oxygen → carbon dioxide + water + energy4. Gaseous exchange provides oxygen to the cells and removes carbon dioxide.5. Herbivores and carnivores eat different types of food so need different ways of breaking down the food.6. AnimalSimilaritiesDifferenceFishComposed of muscle and contains valvesTwo-chambered heart; blood pumped from heart to the gillsAmphibianComposed of muscle and contains valvesThree-chambered heartMammal Composed of muscle and contains valvesFour-chambered heart7. (a) Lungs, trachea, bronchi, diaphragm(b) Heart, blood, veins, arteries, capillaries(c) Kidneys, ureter, urethra, bladder8. Answers will vary.9. Canine teeth are used for gripping prey and tearing and ripping meat; herbivores are plant eaters and so don’t eat meat.10. Many dinosaur fossils contain teeth, which allow modern scientists to make educated guesses as to what they ate. This in turn gives clues as to metabolism and size.11. to 14. Answers will vary.15.(a) Cow: four-chambered stomach with large rumen; small and large intestines are longKoala: small stomach; large caecumTasmanian devil: intestine and colon both short; small caecumHoney possum: digestion of nectar generally not required; very short intestine for digestion of pollen(b) The differences in the digestive systems depend on their diets. The cow eats mainly grass and small herbs; the koala eats gum leaves; the Tasmanian devil is a carnivore; the honey possum eats nectar and pollen.16.FeatureMammalFishNumber of chambers in the heart42Times blood travels through heart in each circulatory tripOnceTwiceName of gaseous exchange respiratory organLungsGills17. to 22. Answers will vary.Looking back 1. to 5. Answers will vary.6.(a)A: left atrium; B: left ventricle; C: right ventricle; D: right atrium; E: pulmonary vein; F:?lungs; G:?vein; H: capillary; I: artery; J: intestines(b) Left side blue; right side red(c) (i) Oxygenated (ii) Deoxygenated(iii) Oxygenated(iv) Oxygenated (v) Oxygenated(d) Blood vesselStructureFunctionArteriesThick, muscular, elastic wallsCarry blood away from the heart (under high pressure), usually oxygenated blood (except pulmonary artery)VeinsThin elastic walls with valves insideCarry blood to the heart, usually deoxygenated blood (except pulmonary vein)CapillariesSingle cell thickProvide nutrients and oxygen to cells and remove wastes7. The purpose of digestion is to break food down into tiny particles that can pass across the membranes from the small intestine into the bloodstream so that nutrients in the food can be used by our cells.8. Mechanical digestion is the process of physically breaking food down into small pieces. Chemical digestion is the process where chemicals react with the food to break it down so that the digested food particles can be absorbed into the bloodstream and cells can use the nutrients.9. (a) Salivary glands: produce saliva, which lubricates the food and contains amylase that begins the digestion of complex carbohydrates, such as starch(b) Epiglottis: a flap of tissue that closes off your trachea (windpipe) so that food doesn’t go down to your lungs and cause you to choke(c) Stomach: churns food and begins the digestion of proteins; hydrochloric acid activates protease enzymes and helps to kill harmful bacteria(d) Pancreas: produces enzymes that digest food in the small intestine(e) Small intestine: site of most digestion of carbohydrates, proteins and lipids, and where nutrients pass into the bloodstream(f) Large intestine: reabsorbs water, salts, vitamins and remaining sugars so that they can be reused by the body(g) Rectum: final part of large intestine where faeces are stored(h) Anus: where faeces pass through to be excreted(i) Appendix: has no role in digestion but may help fight disease(j) Gall bladder: stores bile, which is made in the liver and breaks fat into droplets for transport to the body(k) Liver: redirects glucose and other nutrients around the body, stores glycogen (formed from glucose), makes bile, detoxifies some harmful substances and makes urea.(l) Oesophagus: muscular walls contract to move food from the mouth to the stomach(m) Mouth: where food and saliva are mixed to break down into smaller pieces10. to 16. Answers will vary.17. (a) (i)Heart, veins, arteries, capillaries (ii) Lungs, bronchi, trachea, diaphragm(iii) Kidneys, bladder, urethra, ureters(b) Answers will vary.18. to 19. Answers will vary20.(a) (i) Stage 2; (ii) Stage 1(b) Responses will vary.21. (a) The atria of the heart have contracted.(b) The heart ventricles have contracted.(c) The atria have relaxed(d) The ventricles have relaxed22. to 23. Answers will vary. ................
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