Guided teaching hours: 9 hours

Transcription

1 Organising animals and plants Chapter overview Guided teaching hours: 9 hours In this chapter, students will learn about the organisation of animals and plants. They should be able to recognise the components of blood, describe their functions, and summarise the process of blood clotting. They should recognise the three main types of blood vessel, link their structures with their functions, and understand the importance of a double circulatory system. In studying the heart, students should be able to describe the main structures of the human heart and their functions. They should be aware of problems that can develop in the blood vessels and their treatments. They should know how the heartbeat is maintained by the pacemaker, and why some people may have problems with their heart and may need an artificial pacemaker or artificial heart. Students should be able to compare different treatments of heart problems. Students will study breathing and gas exchange, and should recognise the main structures of the gas exchange system along with their functions. They should know that gas exchange happens in the alveoli and describe adaptations of alveoli. They should be able to describe the processes of ventilation and gas exchange and the differences in composition of inhaled and exhaled air. In studying plant tissues and organs, students should be familiar with the different plant tissues and their functions. They should recognise plant organs such as a leaf. They should understand that the roots, stem, and leaves form a plant organ system for transport of substances around the plant. They should be able to state the functions of xylem and phloem tissue. In studying transpiration, they should understand the function of stomata and recognise factors that affect transpiration rate. This resource sheet may have been changed from the original. 1

2 Lesson.1 The blood WS: 1.4, 1.5 MS: 1c Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells, and platelets are suspended. Students should know the functions of each of these blood components. Students should be able to recognise different types of blood cells in a photograph or diagram, and explain how they are adapted to their functions. State the main components in blood. Recognise the components of blood from photomicrographs. Describe the function of each component in blood. Summarise the process of blood clotting. View blood under a light microscope and recognise components. Explain how red blood cells are adapted to their function. Why do we have blood? (10 min) Ask students why we have blood. Students discuss the answer with a partner. Ask for feedback from the class and use it to create a list of ideas on the board. Blood cells (5 min) Show students a photomicrograph of a sample of blood. Ask them if they can name any of the structures. Main Blood components (4 min) Allow students to work in pairs to study prepared microscope slides of blood smears under a light microscope. Students should be able to use Figure 4 in the student book to identify and name red blood cells, white blood cells, and platelets. Students then use the student book to complete a table showing the components of blood, their functions, adaptations, and percentage compositions. Practical: Blood components Interactive: Blood and blood cells Suggest how white blood cells are adapted to their function. Estimate the diameter of a red blood cell and comment on its uncertainty. Evaluate in detail a model of the blood. Blood model (10 min) Build a model of blood by adding sunflower oil (plasma), small red counters (red blood cells), white marshmallows (white blood cells), and lentils (platelets) to a large beaker. Ask the students what each part represents, what its function is, and how much of each you should put in to make an accurate representation of the composition of blood. Blood and blood cells (5 min) Interactive where students summarise how different components of the blood are adapted for their function. They then decide whether statements are true or false. This resource sheet may have been changed from the original. 2

3 Lesson.2 The blood vessels WS: 1.5 MS: 1a, 1c, 1d The heart is an organ that pumps blood around the body in a double circulatory system. The body contains three different types of blood vessel: arteries veins capillaries. Students should be able to explain how the structure of these vessels relates to their functions. Students should be able to use simple compound measures such as rate and carry out rate calculations for blood flow. State the three main types of blood vessel and recognise them from diagrams. Estimate heart rate. Explain how the structure of blood vessels relates to their function. Comment on how accurate estimations are. Explain in detail the importance of a double circulatory system. Explain how to make estimates more accurate in terms of precision of data. Heartbeat estimation (5 min) Ask students to estimate how many times they think their heart beats in a minute and write this value down. Ask a few students for their estimates. The circulatory system (10 min) Show students a diagram of the circulatory system. Point out the main structures (heart and blood vessels). Ask them to trace the path of blood through the system and discuss with a partner what happens at each capillary bed. Main Blood flow (40 min) Using a diagram of the circulatory system, discuss with students the path the blood takes through the body. Explain that humans have a dual circulatory system and explain what this means and why it is important. Point out the locations of arteries, veins, and capillaries on the diagram. Ask students to use information from the student book to draw sketches and make notes on their structure and function. Students then work in pairs to measure each other s pulse. First counting how many beats they can feel in 5 seconds, then 10 seconds, 30 seconds, and finally 60 seconds. Students then use their measurements for each timeframe to estimate beats per minute. Compare their results with their estimates from the starter Heartbeat estimation, if used. Discuss why estimating is useful, but not as accurate as measuring. Activity: Blood flow Interactive: Which vessel? Which vessel? (10 min) Interactive where students match the blood vessel to the correct diagram. They then match the descriptions to the correct blood vessel. Fish circulation (5 min) Show the class an image showing a fish s single circulatory system. Ask them to say how it is different from This resource sheet may have been changed from the original. 3

4 human circulation. Lesson.3 The heart WS: 1.3, Students should know the structure and functioning of the human heart. The heart is an organ that pumps blood around the body in a double circulatory system. The right ventricle pumps blood to the lungs where gas exchange takes place. The left ventricle pumps blood around the rest of the body. Knowledge of the blood vessels associated with the heart is limited to the aorta, vena cava, pulmonary artery, pulmonary vein, and coronary arteries. Knowledge of the names of the heart valves is not required In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack Describe the function of the heart. State the main structures of the human heart. List examples of problems that can develop in blood vessels in the human heart. Describe the function of the main structures of the human heart. Describe the problems that can develop in blood vessels in the human heart, and their treatments. Suggest advantages and disadvantages of using stents and statins. The structure of the heart (10 min) Introduce the structure of the human heart using a diagram. Ask students to suggest some ways in which the function of the heart could be disrupted. Circulation review (5 min) Starting with a unit of blood in the right side of the heart, pick students to state where the blood will go next until it has done a complete circuit. Main Sheep heart dissection (40 min) This can be done as a demonstration or grouped practical. Students should draw a simplified and labelled diagram of the heart based on the dissection. Students who do not wish to be involved with the practical due to religious or moral objections can complete the questions in the student book, then complete the Bump up your grade worksheet to understand the role of valves in controlling direction of blood flow Practical: Sheep heart dissection Bump up your grades: Valves and blood flow Interactive: Describing the heart This resource sheet may have been changed from the original. 4

5 of oxygen for the heart muscle. Stents are used to keep the coronary arteries open. Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit. Explain in detail how the structure of the different parts of the human heart is related to their function. Recognise the main structures of the heart when carrying out a heart dissection. Evaluate the use of stents and statins in treating problems with blood vessels. in the heart. Ask students to predict what the effect of a blockage in one of the coronary arteries would be. After initial discussion in pairs, allow them to use information from the student book to write a short answer. Discuss the effects of fatty build-ups as a class. Ask students to write advice to an imaginary patient who has been told they need to have a stent fitted and then take statins for the rest of their life. Students should explain the function of the stent and statins, and also what the operation will involve. Heart misconceptions (5 min) Present the class with a series of incorrect statements about the heart based on common misconceptions and ask students to correct them, for example, the blood goes into one side of the heart and then the other (in fact both sides are full of blood at the same time). Describing the heart (10 min) Interactive where students label a diagram of the heart to show the different structures. They then summarise the flow of blood through the heart. Lesson.4 Helping the heart WS: 1.3, 1.4 MS: 1b The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker. Artificial pacemakers are electrical devices used to correct irregularities in the heart rate Students should be able to evaluate the advantages and disadvantages of treating cardiovascular diseases by drugs, mechanical State that the heartbeat is maintained by a group of cells that acts as a pacemaker. Give some ways in which the heart can stop functioning efficiently. Describe why a person may need an artificial pacemaker or an artificial heart. Heart problems (10 min) Show the students a diagram of the outside of the heart. Ask them to discuss in small groups what can go wrong with the heart. Listen to their ideas as a class. Heartbeat (10 min) Tell the class that the heart rate of the average person is 70 beats per minute. Ask them to calculate how many times the average human heart beats in a year. Working scientifically: Which one should I have? Interactive: How does it work? WebQuest: Heart This resource sheet may have been changed from the original. 5

6 devices, or transplant. Mains transplants In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. Students should understand the consequences of faulty valves. Faulty heart valves can be replaced using biological or mechanical valves. In the case of heart failure a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery. Explain why an irregular heartbeat is detrimental to health. Describe why people may have objections to heart transplants. Summarise the advantages and disadvantages of different treatments for heart problems. Explain how a natural pacemaker maintains the heartbeat. Suggest how an artificial pacemaker regulates an irregular heartbeat. Evaluate in detail the different methods used in the treatment of heart problems. Controlling the heartbeat (15 min) Ask students to consider what causes the heart to pump. Reveal that it works from an electric current that your body produces. Fill a water balloon with water. Use a pen to draw the four heart chambers. Explain that an electrical current produced by a group of cells called the pacemaker in the right atrium causes the top of the heart to contract. Squeeze the balloon at the top so all the water goes to the bottom. Explain that the electrical current then moves down the heart. Squeeze the balloon at the bottom, so all the water goes back up to the top. Link this movement to the cardiac cycle studied in Topic.3. Then use this model to show an irregular heartbeat where the top and bottom do not pump in a coordinated manner. Which one should I have? (25 min) Students look at the advantages and disadvantages of artificial pacemakers, biological valves, artificial valves, artificial hearts, and heart transplants, including ethical issues. They help patients to come to a decision about which they should choose. Benefits and drawbacks of treatments (10 min) Play the role of a person who needs a heart transplant. Ask the students questions about why you may need an artificial heart, how it works, and any concerns you have about a heart transplant, including ethical issues. How does it work? (5 min) Use the interactive, which lists many different treatments for cardiovascular disease. Students link each treatment to the explanation of how it works. Lesson.5 Breathing and gas exchange MS: 1c This resource sheet may have been changed from the original. 6

7 2.2.2 Students should know the structure and functioning of the human lungs, including how lungs are adapted for gaseous exchange. List the main structures of the gas exchange system. State that gas exchange happens in the alveoli. Use data in the form of percentages to describe the differences between the composition of inhaled and exhaled air. Describe the function of the main structures of the gas exchange system. Describe how alveoli are adapted for gas exchange. Describe the processes of ventilation and gas exchange. Evaluate in detail a model of the lungs. Explain in detail how the adaptations of alveoli result in efficient gas exchange. Inhaled and exhaled air (10 min) Use the interactive to assess students understanding of how the composition of different gases differs between inhaled and exhaled air. Students sort percentages of gases to describe inhaled and exhaled air. Discuss why the composition changes and introduce the concept of gas exchange in the lungs. How do you breathe? (5 min) Ask students to write down a short paragraph that explains how you breathe in and out. Ask them to exchange ideas with a partner and choose some pairs to present their explanation to the rest of the class. Mains Lung model (15 min) Present to the class the bell jar model of the lungs. You may have a large model or can make one easily using a plastic bottle and balloons. Ask the students how they would use this to show inhalation and exhalation. Many will think that you blow air into the neck of the bottle. Demonstrate how it is in fact the contraction and relaxation of the diaphragm that changes the volume and hence pressure of the inside of the chest cavity and this results in inflation and deflation of the lungs. Use this to address any misconceptions. Interactive: Inhaled and exhaled air Activity: Ventilation Bump up your grade: How we breathe in and out Explain the differences between the composition of inhaled and exhaled air. Ventilation (25 min) Explain to students the mechanisms of ventilation and the exchange of gases in the alveoli. Then, ask students to label a diagram of parts of the gas exchange system, describe their function, any adaptations of each structure, and explain what happens during gaseous exchange. How we breathe in and out (10 min) Bump up your grade worksheet where students use a model of the lungs to understand how volume changes result in pressure changes and cause inhalation and exhalation. This resource sheet may have been changed from the original. 7

8 Labelling the system (5 min) Display a diagram of the gas exchange system and invite students to name the parts. Lesson.6 Tissues and organs in plants Students should be able to explain how the structures of plant tissues are related to their functions. Plant tissues include: epidermal tissues, which cover the plant palisade mesophyll spongy mesophyll xylem and phloem meristem tissue found at the growing tips of shoots and roots. The leaf is a plant organ. Knowledge limited to epidermis, palisade and spongy mesophyll, xylem and phloem, and guard cells surrounding stomata The roots, stem, and leaves form a plant Recognise examples of plant organs and state their functions. Use a light microscope to view a crosssection of a leaf. State the functions of different plant tissues. Describe how plant organs are involved in the transport system. Use a microscope to identify the different tissues in a cross-section of a leaf. Explain how the structures of tissues in the leaf are related to their functions. Plant organs (10 min) Interactive where students match plant organs with their functions and then label a diagram to show the main structures of a plant stem and root cross-section. A sense of scale (5 min) Tell the class that the giant redwood tree can have a trunk that is 40 metres tall. Ask them to calculate how many plant cells of length 100 μm can fit end-to-end up the trunk. Mains Looking at leaves (40 min) Supply groups of students with named diagrams of the plant tissues xylem, phloem, meristem, and epidermal. Ask them to discuss the organs where each tissue is found, their functions, and how each is adapted for its function. Students then use light microscopes to study prepared slides of leaf cross-sections. They use a labelled diagram to identify the cells Interactive: Plant organs Practical: Looking at leaves Go further: Plant defences This resource sheet may have been changed from the original. 8

9 organ system for transport of substances around the plant. Suggest what type of plant organs unfamiliar structures are. Use a light microscope to draw a crosssection of a leaf and calculate scale. Suggest functions for unknown plant tissues. and tissues they can see and describe their functions. Ask students to explain how their functions are related to their structure. Name the organ (5 min) Display a range of plant organs from different plants (roots, stems, leaves, and flowers) and ask students to name what type of organ it is. Discuss similarities between organs from different plants and recap their functions. Tissue adaptations (10 min) List the different tissues in the leaf and Ask students to state one adaptation of each. This could be done using mini-whiteboards. Lesson.7 Transport systems in plants MS: 2a, 2d, 5c Students should be able to explain how the structure of xylem and phloem are adapted to their function. Xylem tissue transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream. Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. The movement of food through phloem is called translocation. Describe the function of xylem and phloem tissue. Describe evidence for movement of water through xylem. Describe why transport in plants is important. Explain how the structure of xylem and phloem is adapted to their functions. Substance journeys (10 min) State the names of some substances that are transported in plants (water, mineral ions, sugars) and ask students to describe their journey where did they start, where are they going, and how will they get there? Aphid attack (5 min) Show the class images of aphids attacking a plant and a magnified image of an aphid feeding on a plant that shows its sharp mouthparts. Question students about what the aphid is feeding on and why this damages the plant. Main Xylem and phloem (20 min) Supply students with celery sticks that Practical: Xylem and phloem Interactive: Xylem and phloem This resource sheet may have been changed from the original. 9

10 Phloem is composed of tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls. Detailed structure of phloem tissue or the mechanism of transport is not required. Explain in detail how the rate of transport through a plant can be measured. have been left overnight in ink. They cut the sticks to see how the dye has stained the xylem walls. Students then look back at Topic B1.5 in the student book and explain how the structure and function of xylem cells are adapted for their function. Then introduce how sap is tapped from trees in order to make maple syrup. If possible, show photos of a video from the Internet. Discuss with the class where the sugars in the tree trunk (stem) come from and how they are transported, or translocated, in the phloem. Ask students to look back at Topic B1.5 in the student book and explain how phloem cells are adapted for their function. Label the diagram (5 min) Provide groups of students with two sticky notes that say xylem and phloem. Display a series of images showing transverse and cross-sections of roots, stems, and leaves to show the vascular systems. Ask them to stick their labels on the diagrams to explain how their structures are linked to their functions. Xylem and phloem (10 min) Interactive where students complete sentences about xylem and phloem. They then choose whether statements describe xylem or phloem. Lesson.8 Evaporation and transpiration MS: 2b, 2d Xylem tissue transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream. The role of stomata and guard cells is to control State that transpiration is the evaporation of water vapour from the leaves. State the function of stomata. Calculate the mean number of stomata on a given area of leaf. Stomata (5 min) Show the class a magnified image of a stoma and ask them to discuss what it could be and its function. In and out (10 min) Draw or project an image of a leaf on the board. Ask students to copy this and add arrows to show the movement of gases into and out of the leaf. Review their ideas and explain that gas Practical: Investigating stomata Maths skills: Calculating the mean This resource sheet may have been changed from the original. 10

11 gas exchange and water loss. Describe how transpiration maintains the movement of water from roots to leaves. Describe how the opening and closing of stomata is controlled by guard cells. Use sampling to estimate the number of stomata on a leaf. Evaluate drinking from a straw as a model for transpiration. Explain in detail how stomata control transpiration. Suggest reasons for differences in the number and distribution of stomata, as well as their adaptations. exchange happens in the leaf carbon dioxide enters and oxygen leaves. This happens through tiny holes on the leaf called stomata. Main Investigating stomata (10 min) Explain that water vapour can also move out of the leaf through the stomata. Introduce this as transpiration. Ask students to define the words transpiration, transpiration stream, stomata, and guard cells. Demonstrate how you can carry out a epidermal peel to view stomata under the microscope. Ask students to discuss in small groups what you could investigate about the stomata using this method and how you would go about doing so. Examples include comparing the number of stomata on different types of plant, on different leaves on one plant, and in different areas of a leaf. Discuss the use of sampling to study different leaves and different areas on a leaf. Students then carry out the practical in small groups. They count the number of stomata in several fields of view before calculating a mean and writing a conclusion. Calculation sheet: Mean Interactive: Transpiration terms Transpiration terms (10 min) Interactive where students match up key words with their definitions then explain how water moves through a plant. Plant adaptations (10 min) Show students images of the leaves of marram grass and cacti. Ask them to suggest how their stomata may be specially adapted, and why. Lesson.9 Factors affecting transpiration MS: 1a, 1c, 2a, 2d, 4a, 4c, 5c This resource sheet may have been changed from the original. 11

12 2.3.2 Students should be able to explain the effect of changing temperature, humidity, air movement, and light intensity on the rate of transpiration. Students should be able to understand and use simple compound measures such as the rate of transpiration. Students should be able to: translate information between graphical and numerical form plot and draw appropriate graphs, selecting appropriate scales for axes extract and interpret information from graphs, charts and tables. Recognise the factors that affect transpiration. Describe how a potometer can be used to estimate the volume of water lost by a plant. Identify control variables when investigating rate of transpiration. Explain why temperature, humidity, light intensity, and amount of air flow affect the rate of transpiration. Describe the differences between a moving bubble potometer and a mass potometer. Make a prediction using scientific knowledge when investigating rate of transpiration. Apply particle model to explain in detail why temperature, humidity, light intensity, and amount of air flow affect the rate of transpiration. Summarise plant adaptations to control water loss, and explain how they work. Evaluate in detail the use of a potometer to measure the rate of transpiration. Drying clothes (10 min) Display an image of clothes drying outside on a washing line. Use the interactive, where students select what factors would affect how quickly washing dries and then sort whether descriptions would increase or decrease the rate of drying. Then discuss the fact that clothes dry because of evaporation, the rate of which is increased by high temperature, low humidity, and degree of air flow (wind). Observing water loss (5 min) The day before the lesson, set up a potted plant so its aerial parts are enclosed in a plastic bag. Show the class the plant and ask them to explain why there is condensation inside the bag. Main Factors affecting transpiration (40 min) Explain to students that the rate of evaporation increases as temperature increases, humidity decreases, and air flow increases. Demonstrate how a mass potometer and a moving bubble potometer can be used to measure the uptake of water by a plant. Discuss how leaving the equipment in different conditions would affect the rate of water uptake, and why. Mention why light intensity increases rate of transpiration (it does not affect evaporation). Ask students to draw diagrams of the equipment and describe briefly how it works. Students then make a prediction and plan a fair test to investigate one of the factors that affect the movement of water through a plant by transpiration. Factors that affect transpiration (5 min) Read out a series of conditions and for each one ask students to stand up if they think it will increase the rate of transpiration or sit down if they think it will decrease the rate of transpiration. Interactive: Drying clothes Activity: Factors affecting transpiration Wilting (10 min) Show an image of a plant that has wilted. Ask students to explain why this has happened, and how it helps prevent This resource sheet may have been changed from the original. 12

13 further water loss. This resource sheet may have been changed from the original. 13