G8 Integrated Science Book 2A Answers PDF

Hong Kong Baptist University Affiliated School Wong Kam Fai Secondary and Primary School Integrated Science 2024-2025 Grade 8 Book 2A Science Journal Name:_______________________ Cla...

Hong Kong Baptist University Affiliated School Wong Kam Fai Secondary and Primary School Integrated Science 2024-2025 Grade 8 Book 2A Science Journal Name:_______________________ Class:_________________ ( ) GA Group:____________________ p.1 Goal Setting SPECIFIC MEASURABLE ATTAINABLE RELEVANT TIMELY What is your goal? How will you keep track How will you achieve your How will this goal help When will you of your progress? goal? Make a plan! you? achieve this goal? Setting goals can be a great way to challenge yourself to make healthy lifestyle changes. Set yourself up for success in science by making your goals SMART! My goal is: ▢ to partially understand basic scientific knowledge and science process skills. ▢ to completely understand basic scientific knowledge and science process skills. ▢ to acquire advanced level of scientific knowledge and scientific thinking. ▢ to further explore scientific knowledge and issues which are out of textbook and note. ▢ to improve my test results by _________ % from last year. I will track my progress by ▢ revising what I have learnt right before term-end assessment. ▢ regularly revising what I have learnt once per month. ▢ regularly revising what I have learnt once per two to three weeks. ▢ regularly revising what I have learnt once per week. ▢ regularly revising what I have learnt nearly every day. I will achieve this goal by doing the following ▢ completing all graded assignments. ▢ completing all ungraded classwork in this booklet. ▢ completing most/all questions in the workbook. ▢ making concept map/summary table for chapters. ▢ reviewing mistakes in quiz and dictation. ▢ actively participating in experiments. ▢ seeking help from teachers’ questions when I need help in studying. ▢ participating in science programmes/activities/competitions/workshops outside school. ▢ others: ___________________________________________________________________ These methods help me because I hope they can improve my skills of ▢ comprehending questions ▢ explaining ideas effectively in English ▢ using science terminologies properly ▢ logical reasoning ▢ graph reading/data analysis ▢ calculations ▢ cautiousness I will complete this goal by the end of Term 1. p.2 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 101 – Unit 1.3 Laboratory Safety (Advanced Level) Date: ________________ Marks: ___________ /________ Hazard warning labels Hazard warning labels are used for labelling dangerous chemicals. Name the following labels. (8 marks) Explosive Oxidizing Flammable Toxic Corrosive Irritant Harmful Carcinogenic Multiple-choice questions 1. At the end of the laboratory period, which of the following is the correct method for disposal of chemical waste? A. Pouring liquids in the sink and putting solids in the rubbish bin. B. Leaving them in beakers in the fume cupboard. C. Putting extra solutions and solids and reaction mixtures into labelled waste container. D. Putting extra solutions and solids down the sink. 2. Which of the following experiments should be carried out in a fume cupboard? (1) Experiment produces toxic vapour. (2) Experiment produces flammable vapour. (3) Experiment produces corrosive vapour. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 3. Which of the following actions is INCORRECT when working in the laboratory? A. Wear safety glasses when using a Bunsen burner. B. Return excess materials to the reagent bottle containing it. C. Report all accidents to the teacher. D. Turn off the Bunsen burner when not using it. p.3 4. Which of the following hazard warning labels should be displayed on a bottle of alcohol? A. B. C. D. 5. During cooking, some oil in a cooking pan catches fire. Which of the following methods can be used to put out the fire? (1) Use water to put out fire. (2) Cover the pan with a lid. (3) Use a carbon dioxide extinguisher to put out the fire. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 6. Which of the following activities is NOT included as an observation in laboratory? A. Smelling with nose B. Hearing with ears C. Feeling with hands D. Tasting with tongue Long question 7. Study the following diagram. Write down THREE aspects that are considered as UNSAFE in laboratory. 1. The test tube rack is too close to the edge of the bench. 2. The opening of the test tube is pointing to the girl. 3. The student’s long hair is not tied up. 4. She is not standing up. / The stool is too high for her. p.4  Unit 7 – Living Things and Air Unit 7.1 Air Summary of Tests of Gases Gases Test Observation for positive result 1. glowing splint The splint relights. Oxygen 2. burning splint The splint burns more brightly. 1. Pass carbon dioxide to limewater The solution changes from colourless to milky. Carbon dioxide 2. Pass carbon dioxide to The solution changes from red to yellow. hydrogencarbonate indicator 1. Dry cobalt chloride paper The paper turns from blue to pink. / Anhydrous cobalt(II) chloride paper Water (vapour) 2. Anhydrous copper(II) sulphate It turns from white to blue. (powder) (Refer to p.17-18 in Science Journal) Nitrogen, No simple tests N/A noble gases p.5 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 701 – Unit 7.1 Test of Gases Date: ________________ Marks: ___________ /________ 1. The table below shows the test results of an unknown gas sample. Test Result dry cobalt chloride paper pink hydrogencarbonate indicator yellow glowing splint goes out Which of the following gases is/are present in the gas sample? (1) oxygen (2) water vapour (3) carbon dioxide A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 2. A burning splint kept burning when it was put into a gas jar. What conclusion(s) can you draw from it ? (1) The gas jar contained nitrogen. (2) The gas jar contained oxygen. (3) The gas jar did not contain carbon dioxide. A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only 3. Ezra performed an experiment and a gas product was collected. He conducted the following tests to identify the gas product. The following table shows the results: Test Observation hydrogencarbonate indicator remains unchanged limewater no observable changes burning splint The burning splint goes out He then concluded that the gas is nitrogen. Explain, with reasons, whether you agree with Ezra. If not, draw another conclusion. (3) The results of hydrogencarbonate indicator and limewater tests show that the gas is not carbon dioxide The result of burning splint shows that the gas is not oxygen. Ezra’s conclusion cannot be sure/certain/guaranteed / It is possible to be other kinds of gases. p.6  7.2+ & 7.3+ Photosynthesis & Respiration Learning Objectives: Outline the subsequent use and storage of the carbohydrates made in photosynthesis, limited to: (a) starch as an energy store (b) glucose used in respiration to provide energy State the uses of energy in living organisms, including muscle contraction, cell division, growth, and the maintenance of a constant body temperature. Complete the following diagram and table about the relationship between photosynthesis and respiration. solar chemical carbon water glucose oxygen dioxide chemical Photosynthesis Respiration Where it takes Takes place only in plants Takes place in both plants and animals place When it takes place Takes place under the presence of light Takes place all the time Energy conversion Light energy is absorbed Chemical energy is released What does the process aim to Produces food for plants themselves Releases energy produce/release? starch as an energy store maintenance of a constant body glucose used in respiration to temperature provide energy growth muscle contraction Subsequent use of Extension cell division the product / cellulose to build cell walls energy sucrose for transport in the Extension phloem protein synthesis nectar to attract insects for the passage of nerve impulses pollination active transport p.7 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 702 – Unit 7.2 Photosynthesis Date: ________________ Marks: ___________ /________ 1. The diagrams below show the steps involved in a test for starch in green leaves. (The steps are not in the correct order) W X Y Z alcohol (soak the leaf in (boil the leaf) (wash the leaf) hot alcohol) (a) Arrange the above diagrams in the correct order. (1) X→W→Y→Z (b) (i) State the purpose of step W. (2) To remove chlorophyll from the leaf (1m) so that the colour change of the iodine solution can be shown clearly. (1m) (ii) Explain why Bunsen burner is not used to heat the test tube in this step. (1) Alcohol is flammable and may catch fire easily. (1m) (c) What kind of indicator should be used in step Z? State the colour change of the solution in step Z if starch is present in the leaf. (2) Iodine solution. The solution changes from brown to blue black. p.8 2. An experiment was carried out to find out if carbon dioxide is needed for photosynthesis. Stage 1 Two plants, A and B, of the same size and species were kept in a dark place for 48 hours. Stage 2 A leaf from each plant was then tested for the presence of starch using iodine solution. Both plants were placed in sealed glass containers, for 24 hours, as shown in the figures below. Stage 3 Plant A was in the presence of potassium hydroxide beads (which absorb carbon dioxide). Plant B was in the presence of glass beads. All other conditions needed for photosynthesis were provided for both plants. Stage 4 After 24 hours a leaf from each plant was tested for the presence of starch. (a) What is the purpose of stage 1? (2) To destarch / to remove all starch present in the plants before carrying out the investigation. (1) To make sure all the detected starch at the end is produced during the investigation. (1) (b) Explain the importance of stage 2. (1) To make sure all the starch has been removed. (c) What is the independent variable in this investigation? (1) Presence of carbon dioxide. (d) What is the dependent variable in this investigation? (1) Presence of starch. (e) State three variables that were controlled in this investigation. (3) Size of the plant / species of the plant / size of the glass cover / size of the pot / amount of soil in the pot / amount of water added into soil / temperature / light intensity / any reasonable answer p.9 (f) The stages involved in testing a leaf for starch are shown below. Use straight lines to match the stages with the correct reasons. One has been done for you. (g) Explain why chlorophyll is removed from the leaf before testing it for starch. (1) To observe the color change more easily. (h) Plant B was used as a control in the experiment. Explain the importance of this control. (1) To show that carbon dioxide is the factor responsible the difference observed between the two plants. (i) Complete the table below to show the results of the starch test for plants A and B at stages 2 and 4. Explain your answers. (6) Both plants have been destarched. Photosynthesis could not take place due to the absence of carbon dioxide Photosynthesis took place as carbon dioxide was available. p.10 3. The figure below shows a leaf, with white and green regions, that is attached to a plant. The plant had been kept in the dark for 48 hours and then a lightproof, black paper cover was placed over part of the leaf. The plant is left under the sun for 24 hours. After this time the leaf is removed from the plant and is tested for the presence of starch. (a) Record the colour you would see, if you had carried out this test, in each of the areas A, B, C and D. (4) area Colour A brown B brown C blue-black D brown (b) Explain the results for areas B and D respectively. (2) Chlorophyll is absent in area B thus no light can be absorbed, and no photosynthesis takes place. The paper cover blocks the light thus no photosynthesis takes place in area D. p.11 HKBUAS Wong Kam Fai Secondary and Primary School Practical Worksheet 703 – Unit 7.3 Respiration (Food as a source of energy) Date: ________________ Marks: ___________ /________ Topic Fair Comparisons Refer to textbook p.36-p.37 Energy conversion in burning food Aim To compare the amount of energy stored in different foods by burning them. The energy released by the burning food heats the water in the boiling tube. The greater the temperature of the water, the more energy the food released when it was burnt. Materials and apparatuses For each group: Boiling tube x 1 Stand and clamp x 1 lighter x 1 Burning spoon x 1 Bunsen burner x 1 foods Thermometer x 1 heatproof mat x 1 Photo B shows the kind of apparatus you need. Safety Precautions 1. Wear safety goggles. 2. Do not let the thermometer touch the boiling tube. Otherwise, the reading taken will not be accurate. 3. Do not clamp the thermometer and the boiling tube too tightly. Otherwise, you will break them. 4. Do not eat any of the foods. Plan your experiment List out the independent variable, dependent variable and any 3 controlled variables in the table below. Independent variable Dependent variable Controlled variables 1. same volume of water in the boiling tube The type of food The amount of energy stored in food 2. same mass of foods being burnt 3. size of boiling tube / distance between the burning food and the boiling tube / etc. 4. (NOT accept ‘time for boiling’, ‘size of food’) p.12 Procedure 1. Find the mass of a piece of food. Record its mass in Table C. 2. Carefully put the food on a burning spoon and heat it in a Bunsen flame. 3. Put 10 cm3 of water into a boiling tube. Record its temperature. 4. Light the food using a Bunsen burner and hold the burning food under the boiling tube. Make sure the flame is touching the boiling tube. 5. When the food has finished burning, record the temperature of the water again. Write down the temperature rise of water in Table C. 6. Let the food cool down, then carefully push what is left off the burning spoon and record its mass in Table C. If there is no food left on the burning spoon, write down 0 g for its mass in Table C. 7. Repeat steps A to F for other foods. Table C (data from experiment) Mass of food burnt Food used Initial Mass (g) Final Mass (g) Temperature rise (°C) (g) Table D Mass of food burnt Food used Temperature rise (°C) (g) Bread 2.0 4.0 Cheese 4.0 16.0 Cornflakes 4.0 14.0 Table D shows that burning the cheese produced the greatest change in water temperature. However, it is not a fair test because different masses of each food were burnt. We can make a fair comparison of the results by working out the temperature rise for each gram (g) of food burnt. We do this by dividing the temperature difference by the mass of food. Complete Table E so that we can compare the energy stored in bread, cheese and cornflakes fairly. Table E Food used Temperature rise per gram of food (°C/g) Bread 4.0 / 2.0 = 2 Cheese 16.0 / 4.0 = 4 Cornflakes 14.0 / 4.0 = 3.5 p.13 8. Calculate the temperature rise per gram of each kind of food (°C/g) in Table F. Table F (data from experiment) Food used Temperature rise per gram of food (°C/g) Discussion 1. According to your result, write down the foods in ascending order of its storage of energy amount per unit gram. 2. The result of order may not be accurate because of some practically unpredictable changes (ie. random errors). Give one possible error for this comparison. Not all of the heat energy is transferred to the water in boiling tube. Heat loss to the surrounding during burning. 3. Complete the following concluding sentence. The temperature of water ____increases____ after heating. The water gains _____heat / thermal____ energy from burning peanut. In burning the peanut, the ____chemical___ energy in peanut is converted into _____heat / thermal___ energy and ____light____ energy. 4. In food burning experiment, we observed how different foods release energy. This helps us understand the energy content of our food choices. Describe 3 similarities between the process of burning food and respiration. Both processes release energy. / Both processes require oxygen. / Both processes form carbon dioxide and water as the products. / Both processes convert chemical energy to other forms of energy. p.14  7.1+ & 7.3+ Physical Changes and Chemical Changes Learning Objectives: Identify physical and chemical changes and describe the differences between them. Describe chemical tests for the presence of water using anhydrous copper(II) sulfate. Changes to a substance can be categorized into two types: chemical and physical changes. Consider the following two changes to a piece of paper: The paper is cut into halves The paper is burnt in the air The piece of paper reacts with oxygen in the air. After the piece of paper was cut into several small Two new substances, carbon dioxide and water, pieces, there is no new substance formed. are formed. This is referred to as a physical change. This is referred to as a chemical change. Change of physical state of matter is an example of physical change. Iodine is a black solid. When heated, it turns into purple vapour (gas) directly without going through the liquid state. The process is called sublimation (verb: sublime). Another substance which can sublime at room condition is dry ice (solid carbon dioxide). Examples of Chemical and Physical Changes Chemical Changes Physical Changes Burning of fuels Changes in physical states Reactions between metals and acids Dissolving of solutes in solvents Reactions between acids and alkalis Thermal expansion / contraction Rusting of iron Sedimentation Electrolysis of water p.15 Exam question type: Explain whether a change is a physical change or chemical change Follow the method below: Example Answers: 1. Boiling is a physical change because there is no new substance formed. 2. Photosynthesis is a chemical change because new substances (glucose and oxygen) are formed. Checkpoint Classify each of the following processes as either a physical change or a chemical change. (a) Dissolving salt in tea (physical change / chemical change) (b) Filtration of muddy water (physical change / chemical change) (c) Distillation of sea water (physical change / chemical change) (d) Respiration in body cells (physical change / chemical change) (e) Photosynthesis (physical change / chemical change) (f) Water freeze into ice (physical change / chemical change) (g) Using limewater to test the presence of carbon dioxide (physical change / chemical change) (h) Evaporation of salt solution (physical change / chemical change) (i) Water droplets form on a cold can of soft drink (physical change / chemical change) (j) Perfume diffuses out of a balloon (physical change / chemical change) (k) Melting a wax candle (physical change / chemical change) *(l) Burning a wax candle (physical change / chemical change) *(m) Noodle is chewed into smaller pieces (physical change / chemical change) *(n) Noodle is digested by saliva (physical change / chemical change) *(o) Rainbow is formed after raining (physical change / chemical change) p.16 HKBUAS Wong Kam Fai Secondary and Primary School Practical Worksheet 704 – Physical Change and Chemical Change Date: ________________ Marks: ___________ /________ Topic Distinguishing Physical Changes and Chemical Changes Aim In this practical, you are going to observe three changes 1. Separating a mixture of iron and sulphur 2. Testing the presence of water using anhydrous copper(II) sulfate powder 3. Burning of a magnesium ribbon in air You are going to summarize the physical change(s) or chemical change(s) by describing and explaining observations. Materials and apparatuses For each group: For each group: For each group: anhydrous cobalt(II) chloride paper x 1 Boiling tube x 1 Magnesium ribbon (5 cm) anhydrous copper(II) sulfate powder x 1 Stopper x 1 Tongs test tubes Magnet x 1 Bunsen burner glass rod Iron filling Heatproof mat droppers Sulphur powder Lighter Safety Precautions 1. Put up a pair of safety goggles when using the Bunsen burner. 2. When burnt in air, magnesium ribbon gives a dazzling white flame. Do NOT stare at the flame directly for too long or it will damage your vision. Procedure and Questions 1. Separating a mixture of iron and sulphur 1. Describe how the mixture of iron filings and sulphur powder looks like. The mixture is a grey powder. 2. Put a magnet on the surface of the tube and move the magnet up and down. Record and explain your observation. Observation Explanation iron and sulphur are only physically mixed (/not The iron filings are attracted to and separated by the chemically joined together.) magnet while the sulphur powder is not. / Iron and sulphur keep their own properties. The mixture becomes more yellow in colour when Iron filings can be separated by the magnet because the iron filings are separated. it is magnetic, while sulphur powder is not and stays on the bottom. 3. Explain whether the above change is a chemical change or a physical change. It is a physical change because no new substances are formed. p.17  2. Testing the presence of water using anhydrous copper(II) sulfate powder 1. You are provided with some anhydrous copper(II) sulfate powder. Describe how it looks like. White solid / powder 2. Transfer a small amount of the powder into two test tubes respectively. Then, add a few drops of water and alcohol to each of the test tubes respectively. Record the colour change. Colour change water alcohol From white to blue No observable change 3. Add more water to half-fill the test tube with water. Stir the mixture until an observable change occurs. Name this process. Think whether this process forms new substance(s). Dissolving. (No new substances formed.) 4. Explain whether the above water test is a chemical change or a physical change. It is a physical change because no new substances are formed. 3. Burning a magnesium ribbon 1. Cut 5 cm magnesium ribbon. Describe how the magnesium ribbon looks like. It is a silvery solid. 2. Start the Bunsen burner. Hold the magnesium ribbon over the Bunsen flame (do NOT look at the flame directly!). 3. Describe your observations about the flame during burning and the appearance of the product. Observation The magnesium ribbon burns with dazzling white flame. Flame Appearance of A white solid is formed. the product 4. Explain whether the above change is a chemical change or a physical change. It is a chemical change because new substances (magnesium oxide) are formed. p.18 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 705 – Physical Change and Chemical Change Date: ________________ Marks: ___________ /________ 1. All of the following are chemical changes EXCEPT A. Dissolving sugar in water. B. Burning a piece of paper. C. Rusting of iron. D. Photosynthesis. 2. Which of the following is NOT a physical property of carbon? A. It can burn in the air. B. It is a solid at room temperature. C. It is denser than water. D. It is black in colour. 3. Which of the following processes involves a chemical change? A. Distilling sea water to obtain pure water B. Melting butter C. Testing carbon dioxide with water D. Magnetizing a compass needle 4. For each of the following changes, state and explain whether it is a physical or chemical change. Name the substance(s) formed if there is any. (a) A glowing splint relights in oxygen gas. Chemical change There are new substances formed. Carbon dioxide and water. (b) Boiling water Physical change There are no new substances formed. (c) Photosynthesis Chemical change There are new substances formed. Glucose and oxygen. (d) Respiration Chemical change There are new substances formed. Carbon dioxide and water. p.19 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 706 – Unit 7.4 & 7.5 Gas Exchange in Plants and Animals Date: ________________ Marks: ___________ /________ 1. The figure below shows the apparatus used in an investigation. (a) Complete the table below to show whether photosynthesis and respiration are happening in each tube. (4) photosynthesis respiration tube contents and conditions happening? happening? A pond weed in dark No Yes B pond weed in bright light Yes Yes C fresh water shrimp in dark No Yes D fresh water shrimp in bright light No Yes (b) The apparatus was left for several hours. Complete the table below by predicting the colour of hydrogencarbonate indicator in each of the four tubes. (4) colour of hydrogencarbonate indicator tube contents and conditions after several hours A pond weed in dark Yellow B pond weed in bright light Purple C fresh water shrimp in dark Yellow D fresh water shrimp in bright light Yellow p.20  2. Peter designs the following experiment to find out what kind of gaseous exchange occurs under light and dark environments. Experiment set-up is placed under strong sunlight for several hours. (a) After the experiment, what are the colours of hydrogencarbonate indicators respectively? Write the predicted results in the table below. Test tube A B C Colour of hydrogencarbonate indicator Yellow Purple Red (b) What gas does hydrogencarbonate indicator test for? How does the amount of that gas change in test tube B ? (2) ( Oxygen / Carbon dioxide ). The amount of that gas ( increases / decreases ). (c) Explain the change in the amount of the gas in test tube B. (2) The rate of photosynthesis done by the leaf is ( slower / faster ) than the rate of respiration There is ____net____ ( uptake / release ) of the gas, carbon dioxide, in the tube. (d) How does the amount of the gas change in test tube A ? (1) The amount of that gas (carbon dioxide) increases. (e) Explain the change in the amount of the gas in test tube A. (2) In the dark, the leaf only does ( respiration / photosynthesis ) There is only ( uptake / release ) of the gas, carbon dioxide, in the tube. (f) What is the use of test tube C ? (1) Act as control experiment / set-up (g) State TWO controlled variables of this experiment. (2) The amount of hydrogencarbonate indicator The size of tube (or other reasonable answers) p.21 3. Study the following experimental set-up. This experiment aims to investigate the rate of photosynthesis and the rate of respiration. light black box stopper snail water water plant P Q R S After six hours, a few drops of hydrogencarbonate indicator are added to each test tube. Some of the results are as follows: Test tube P Q R S Colour of red ? red ? hydrogencarbonate indicator (a) What is the use of adding hydrogencarbonate indicator to the test tubes? (1) It is used to indicate the carbon dioxide content in the water. (b) (i) Suggest the colour of hydrogencarbonate indicator in test tube Q. (1) Purple (ii) Explain your answer in (b)(i). (2) The rate of photosynthesis done by the plant is faster than the rate of respiration. There is a net uptake of carbon dioxide by the water plant by photosynthesis. (c) Comment on the rate of photosynthesis and rate of respiration of the organisms in test tube R with reasons. (2) The colours of hydrogencarbonate indicator in test tubes P and R are both red. This shows that there is no net change in the carbon dioxide content in R. It can be deduced that the rate of photosynthesis (consumption of carbon dioxide) and rate of respiration (production of carbon dioxide) are the same. p.22 4. A student measured the uptake and release of carbon dioxide from a plant during 24 hours. It was a bright, sunny day between sunrise and sunset. The graph below shows the student’s result. (a) State the time that sunrise occurred. (1) 0600 (b) State the times when there is no uptake or release of carbon dioxide. Explain why there is no uptake of release of carbon dioxide. (2) 0800 and 1900 The rate of photosynthesis is the same as the rate of respiration. (c) Why do plants release carbon dioxide at night? (2) Plants cannot perform photosynthesis at night due to the lack of light. However, plants continue to do respiration at night which releases carbon dioxide. Not acceptable: Plants do not do respiration during the day. (d) Why is it important for plants that carbon dioxide uptake during the day is greater than carbon dioxide released at night? (3) If carbon dioxide uptake is more during the day, more sugar/starch can be produced by photosynthesis. (1) Sugar/starch will then be readily available for respiration during the night which releases energy for the plants to use and carbon dioxide as a waste product. (1) The rate of carbon dioxide uptake during the day must be greater than carbon dioxide released at night or the plant will not have enough energy to survive. (1) p.23  7.5+ The Breathing System Learning Objectives: Identify in diagrams and images the following parts of the breathing system: lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries State the function of cartilage in the trachea Explain the role of goblet cells, mucus and ciliated cells in protecting the breathing system from pathogens and particles Identify in diagrams and images the internal and external intercostal muscles and diaphragm Structure Description a passageway for air from the nasal cavity to the larynx Pharynx a passageway for food and liquid to enter the esophagus a passageway for air from the pharynx to the trachea Larynx contains vocal cords which vibrate and produce sound when air passes over them. a flap of cartilage that covers the trachea during swallowing to Epiglottis prevent food from entering the airway windpipe that allows air to move from the larynx to the lungs Trachea surrounded by rings of cartilage which support the airways and keep them open during breathing a tube that transports food to the stomach Esophagus belongs to the digestive system, not the breathing system p.24  Cilia Ciliated epithelial cells Goblet cells Along the airway to the bronchioles, it is lined with goblet cells o They secret mucus which traps dust particles and pathogens like bacteria or viruses, preventing them from getting into the lungs and damaging the cells there. ciliated epithelial cells o They have tiny hairs called cilia (singular: cilium) which sweep out mucus where the dust particles and pathogens are trapped. Structure Description Ribs Bone structure that protects internal organs such as the lungs Control the movement of ribs causing inhalation and exhalation Muscles are only able to pull on bones, not to push on them Intercostal muscles This means there must be two sets of intercostal muscles: o external intercostal muscles to pull the rib cage upwards and outwards o internal intercostal muscles to pull it downwards and inwards Diaphragm A thin sheet of muscle that changes the volume of the chest cavity (thorax) p.25  7.5+ Inhalation and Exhalation Learning Objectives: Identify in diagrams and images the internal and external intercostal muscles Explain the role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes in the thorax leading to the ventilation of the lungs During inhalation 1. External intercostal muscles ( contracts / relaxes ) → pull the ribs ( upwards / downwards ) and ( inwards / outwards ) 2. Diaphragm ( contracts / relaxes ) and ( flattens / becomes dome-shaped ) 3. Volume of chest cavity (i.e. thorax) ( increases / decreases ) 4. Air pressure in the lungs ( increases / decreases ) 5. Air is drawn ( into / out of ) the lungs During exhalation 1. Internal intercostal muscles ___contracts___ → pull the rib ___outwards___ and ___upwards___ 2. Diaphragm ____relaxes__and __becomes dome-shaped___ 3. Volume of chest cavity (i.e. thorax) __decreases__ 4. Air pressure in the lungs __increases__ 5. Air is forced __out of__ the lungs p.26  7.5+ Gas Exchange at Air Sacs Learning Objectives: Describe the features of gas exchange surfaces in humans, limited to: large surface area, thin surface, good blood supply and good ventilation with air The air sacs are adapted with the following features for rapid diffusion of gases, resulting in efficient gas exchange. Large __surface area ___ - large number of air sacs - allows faster diffusion of gases across the surface ___Thin wall_____ - one-cell thick - provides a short distance for diffusion of gases Good ___blood supply____ - surrounded by blood capillaries - maintain a large difference in concentrations between the blood and the air sacs Good ___ventilation with air ____ (i.e. allows constant breathing) - maintain a large difference in concentrations between the blood and air sacs __Moist inner wall___ - allow gases to dissolve in the fluid for more efficient diffusion p.27 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 707 – Unit 7.5+ Gas Exchange in Animals Date: ________________ Marks: ___________ /________ 1. The figure shows the human gas exchange system. The functions of the parts of the gas exchange system are given in the table below. (a) Complete the table below. One row has been done for you. (6) function letter name structure that makes sounds A larynx bone that provides protection for the lungs E Rib airway that allows passage of air only into the right lung J Bronchus airway that allows passage of air into both lungs B trachea F: diaphragm contracts to increase volume of thorax F/G G: external intercostal muscle Internal intercostal muscle that contracts to lower the ribcage K muscle site of gas exchange M Alveoli/ air sacs (b) The gas exchange system contains cartilage. Describe the function of cartilage in the gas exchange system. (1) To keep the airways / trachea / bronchi / windpipe open p.28  2. The figure below shows part of the human gas exchange system. (a) (i) Name structure K. (2) bronchiole(s) (ii) Ciliated cells and goblet cells line structure L. Explain the function of these cells in structure L. (3) goblet cells release/produce mucus mucus traps dirt/ particles / pathogens cilia sweep / move the mucus out (of airway) (b) Gas exchange occurs at the alveoli (i.e. air sacs). (i) Describe how oxygen molecules move from the alveoli into the blood. (3) Moist lining allows oxygen to dissolve (1) and then diffuse (across the membrane) into the blood/capillaries (1) from high concentration to low concentration (of O2) / down the concentration gradient (1) p.29  (ii) During inhalation, air moves from the atmosphere into the lungs. Describe the mechanism of inhalation. (4) external intercostal muscles contract and cause the ribs to move upwards and outwards (1) diaphragm contracts and flattens to increase the volume of the thorax / lungs / chest (1) pressure in, thorax / lungs / chest, decreases (1) air moves into the lungs down a pressure gradient / from high pressure to low pressure (1) (iii) Name one gas that is found in a higher concentration in exhaled air than in inhaled air. Carbon dioxide / water vapour (c) Tobacco smoke affects the gas exchange system. Name two components of tobacco smoke and describe their effect on the gas exchange system. Component 1: tar (1) Effect: sticks to alveoli hence decrease the surface area for gas exchange / sticks and paralyzes the cilia hence mucus cannot be swept out (1) Component 2: carbon monoxide (1) Effect: (combines with haemoglobin in red blood cells permanently which) reduce oxygen transport in bloodstream (1) p.30 My Science Journal Unit 7: Living Things and Air I would give this unit a star rating of I would like to learn more about … because … because … The most interesting thing(s) that I have learned in this unit is(are) … because … The most challenging thing(s) that I have encountered in this unit is(are) … because … p.31  Unit 8 – Making Use of Electricity Unit 8.2 & 8.3 Usage of Ammeter and Voltmeter The ammeter shown has two ranges: 0-5 A (larger range) and 0-1 A (smaller range). (4 marks) (a) Leo wants to use the above ammeter to measure a current. However, he does not know the approximate value of this current. How should he do? First, he should use the positive terminal with a (i)_________________ (larger/smaller) range of measurement. If the reading is below 1 A, he should use the terminal with a (ii)_________________ (larger/smaller) range of measurement 5A 1A so as to get a more accurate reading. (b) Write the reading of each of the following ammeters. (i) _________2.5__________ A (ii) __________1.3__________ V p.32 HKBUAS Wong Kam Fai Secondary and Primary School PhET Simulation Worksheet 802 –- Unit 8.5 Series and Parallel Circuits Date: ________________ Marks: ___________ /________ Enter PhET simulation Circuit Construction Kit: DC. https://digital.oupchina.com.hk/junsci/video/jsci_phet_u8dccircuit_e.html Simulation by PhET Interactive Simulations, University of Colorado Boulder, licensed under CC-BY-4.0 (https://phet.colorado.edu). 1. Mandy connects a circuit according to the circuit diagram below. The voltage of each cell is 13 V. Bulb X has a resistance of 10 Ω. (a) Use the simulation to find out the ammeter reading when the switch is closed. (1) 2.60 A (b) Use the simulation to find out the voltmeter reading across bulb X. (1) 26 V p.33 3. Mandy wonders how the brightness of bulb X will be affected if one more identical bulb (Y) is connected in series. Construct circuit 2 using the simulation below. Then, close the switch. (a) Note the ammeter reading in circuit 2. (1) 1.30 A (b) Compare the brightness of bulb X in circuits 1 and 2. (1) Dimmer (c) Complete the paragraph below to explain the observation in (b). (4) One more bulb is connected in (i) ___series___ ( series / parallel ) to bulb X. The resistance of the path that current flows through (ii) ____increases_____ (increases / decreases). The current flowing through bulb X (iii) ____ decreases _____ (increases / decreases). Therefore, the brightness of bulb X (iv) ____ decreases _____ (increases / decreases). (d) Place the voltmeter across bulb X. Note the voltmeter reading across bulb X. (1) 13V (e) By comparing the voltmeter readings in circuits 1 and 2, we can also explain the change in brightness of bulb X in circuits 1 and 2 in terms of voltage. Complete the paragraph below to explain the observation in (b). (4) One more bulb is connected in (i) ___series___ (series / parallel) to bulb X. The resistance of the path that current flows through (ii) ____increases_____ (increases / decreases). The voltage across bulb X (iii) ____ decreases _____ (increases / decreases). Therefore, the brightness of bulb X (iv) ____ decreases _____ (increases / decreases). p.34 4. Mandy wonders how the brightness of bulb X will be affected if one more identical bulb (Y) is connected in parallel. Construct circuit 3 using the simulation. Then, close the switch. (a) Note the ammeter reading in circuit 3. (1) 2.60 A (b) Place the voltmeter across bulb X. Note the voltmeter reading across bulb X. (1) 26 V (c) Compare the brightness of bulb X in circuits 1 and 3. (1) Remains the same (d) Complete the paragraph below to explain the observation in (b) in terms of current and voltage respectively. (5) One more bulb is connected in (i) __parallel___ (series / parallel) to bulb X. The resistance in the branch where bulb X is located (ii) ___remains the same___ (increases / decreases / remains the same). The current flowing through bulb X also (iii) ___ remains the same ___ (increases / decreases / remains the same). OR The voltage across bulb X (iii) ___ remains the same ____ (increases / decreases / remains the same). Therefore, the brightness of bulb X (iv) ___ remains the same ___ (increases / decreases / remains the same). p.35 5. Mandy wonders what will happen if more identical bulbs are connected in parallel with bulb X. Construct circuit 4 using the simulation. Keep all the switches open. Circuit 4Note the ammeter readings in the main loop. (1) (a) (i) Close the switch(es) for the following branches. Ammeter reading Close the switch(es) in… Trend in the main loop branch 2 only 5.2 A Current in the main loop branch 2 and 3 only 7.8 A ( increases / decreases ) branch 2, 3 and 4 only 10.4 A when more bulbs are connected in parallel. branch 2, 3, 4 and 5 only 13 A (ii) What are the ammeter readings in each branch? How do they relate to the ammeter reading in the main loop? (2) 2.6 A in each branch. The sum of the current in all branches equals the current in the main loop. (b) (i) Close the switches in all branches. What happens? Name this potential hazard. (1) (Catch fire.) Overloading. (ii) Explain briefly why the incident in (b)(i) would happen. (1) Too many light bulbs connected in parallel to draw too much current from the electric cells. (iii) Suggest a safety device that should be added to the circuit to prevent such an incident. (1) Fuse (/circuit breaker) p.36 HKBUAS Wong Kam Fai Secondary and Primary School Worksheet 803 – Unit 8.5 Series Circuit and Parallel Circuit Date: ________________ Marks: ___________ /________ Series and Parallel Circuit P 1. Which of the following statements about the circuit below is correct? A. Light bulbs P and Q are connected in series. Q B. Light bulbs P and Q are connected in parallel. power supply C. Light bulbs P, Q and R are connected in series. D. Light bulbs P, Q and R are connected in parallel. R 2. Refer to the circuit below. Resistor P: 1  Resistor Q: 2  Resistor R: 1  (a) A student would like to measure the energy supplied by the battery to the mobile electrons. Describe how the measuring device should be connected in the circuit. A voltmeter should be connected across the electric cells in parallel. (b) A student would like to measure the number of electrons passing through resistor Q per second. Describe how the measuring device should be connected in the circuit. An ammeter should be connected in series / on the same single path with resistor Q. (c) If the current flowing through resistor P is 2 A, what is the current flowing through resistor R ? 2A (d) If the current flowing through resistor P is 1 A, what is the current flowing through resistor Q ? 2A p.37 3. In the circuit below, the three light bulbs are identical. The reading of ammeter A1 is 6A. A1 P Q A2 R A3 (a) What are the readings of ammeters A1, A2 and A3? Ammeter Reading Ammeter A1 6A Ammeter A2 2A Ammeter A3 4A (b) Arrange the brightness of light bulb P, Q and R. R>P=Q (1 mark for R > others; 1 mark for P=Q) (c) If light bulb R is broken, what are the readings of ammeters A1, A2 and A3? Ammeter Reading Ammeter A1 2A Ammeter A2 2A Ammeter A3 0A (d) If light bulb P is broken, what are the readings of ammeters A1, A2 and A3? Ammeter Reading Ammeter A1 4A Ammeter A2 0A Ammeter A3 4A p.38 4. Six identical light bulbs are connected in a circuit as shown below. P Q R X Y Z (a) Which light bulb(s) is/are the brightest? Light bulb Z (b) Which light bulb(s) has/have the same brightness as R? Light bulbs P and Q (c) If the voltage of the electric cell is 9 V, what is the voltage across the following light bulbs? Voltage Light bulb Z 9V Light bulb X 4.5 V Light bulb Q 3V (d) If light bulb Q is broken, what will happen to light bulbs P and X ? Light bulb P goes off. Light bulb X remains the same brightness. p.39 My Science Journal Unit 8: Making Use of Electricity I would give this unit a star rating of I would like to learn more because … about … because … The most interesting thing(s) that I have learned in this unit is(are) … because … The most challenging thing(s) that I have encountered in this unit is(are) … because … p.40