Biology Grade 9 Review 2023 PDF

BIOLOGY GRADE 9 Mauritius Institute of Education Ministry of Education, Tertiary Education, Science and Technology BIOLOGY GRADE 9 i  Professor Vassen Naëck - Head Curriculum Implementation,Textbook Development and Evaluation...

BIOLOGY GRADE 9 Mauritius Institute of Education Ministry of Education, Tertiary Education, Science and Technology BIOLOGY GRADE 9 i  Professor Vassen Naëck - Head Curriculum Implementation,Textbook Development and Evaluation BIOLOGY TEXTBOOK DEVELOPMENT PANEL MAURITIUS INSTITUTE OF EDUCATION Dr Sarojiny Saddul-Hauzaree - Coordinator, Associate Professor, MIE Dr Shakeel M C Atchia - Lecturer, MIE Karuna Baguant - Educator Maya Mohabeer - Educator Nandini Sukhoo-Busawon - Educator Design Kamla Ernest - Chief Technician, MIE Leveen Nowbotsing - Graphic Designer, MIE Rakesh Sookun - Graphic Designer, MIE Acknowledgements The Grade 9 biology textbook panel wishes to thank: - Dr Anwar Bhai Ramjaun (Associate Professor, MIE), Dr Ravhee Bholah (Associate Professor, MIE), Mohun Cyparsade (Associate Professor, MIE) and Dr Fawzia Narod (Associate Professor, MIE) for their contribution.  elina Hookoomsing (Senior Lecturer, MIE), Majhegy Murden-Louise (Lecturer, MIE), Suryakanti Anu Fulena -H (Lecturer, MIE) and Kamini Moteea (Lecturer, MIE) for proofreading. GRADE 9 BIOLOGY TEXTBOOK REVIEW PANEL Mr Mohun Cyparsade - Overall Coordinator, Associate Professor, MIE Dr Shakeel M C Atchia - Biology Coordinator, Lecturer, MIE Maya Mohabeer - Educator Oumée Salmaa Peerbaccus - Educator Design Sanjna Kathapermall - Graphic Designer, MIE Vedita Jokhun - Graphic Designer, MIE © Mauritius Institute of Education - 2023 ISBN: 978-99949-75-31-0 Consent from copyright owners has been sought. However, we extend our apologies to those we might have overlooked. All materials should be used strictly for educational purposes. ii FOREWORD The MIE produced a set of new textbooks for Grades 1-9 based on the National Curriculum Framework and Teaching and Learning Syllabus for the implementation of the Nine Year Continuous Basic Education (NYCBE) reform. These have been key to curriculum transaction in the classroom. However, curriculum development is a dynamic enterprise that constitutes constant review and readjustment in relation to the evolving contextual factors and needs of Educators and learners. As such the Grade 9 Science textbook was reviewed taking into consideration the insights and views of stakeholders as well the emerging trends in Science Education. Even though dedicated textbooks are now available for each of the Science subjects, namely Biology, Chemistry and Physics, for ease of use, the guiding philosophy has remained unchanged. The content is contextualized, incremental and founded on basic scientific skills developed in Grades 7 and 8. As in all curriculum endeavours, a number of contributors have been involved in the review of the Grade 9 textbook. I remain appreciative of the efforts of the panel who, at the inception, gave the textbook its orientation. I thank the review team for finetuning the resource in the light of feedback obtained to enhance teaching and learning experiences. The Educators who were part of the validation process have also played an important role in ensuring that the reviewed Science textbooks are sound. Last, but not the least, the Graphic Designers are to be thanked for their continuous collaboration in the development of apt educational resources. I wish all users of the Science textbooks an enriching and enjoyable experience. Dr Hemant Bessoondyal Director Mauritius Institute of Education iii  PREFACE The Grade 9 biology textbook is in compliance with the National Curriculum Framework (NCF, 2017) and the Teaching and Learning Syllabus (TLS, 2017) for science. The textbook ensures a smooth transition from the earlier grades by building upon content learnt up to Grade 8. The textbook is conceptualised in such a way that it includes a number of inquiry-based activities and accompanying tasks for learners. In line with the constructivist approach, the activities will enable learners to build and reinforce understanding of science concepts. As such, a conscious effort must be made to actively engage pupils in all activities and to allow them to manipulate specimens, materials, simple equipment and apparatus safely and under supervision. The use of everyday experiences and contexts that students can easily relate to is favoured. Care is taken to incorporate learner-centred strategies like project-based learning and concept mapping to actively engage the learners in the learning process and to provide for independent learning. Furthermore, whenever relevant, applications of the biological concepts learnt in real life situations are highlighted. Additionally, the activities seek to develop in students the necessary skills, attitudes and values for scientific inquiry. Students must be given ample time to actively engage in the activities, communicate their findings and observations in multiple ways, discuss with their friends and teachers and think before writing down their answers. Though many questions are incorporated within the activities, educators are encouraged to prompt learners with additional questions while implementing them in the classroom. The textbook includes important features that support effective assessment. “Test yourself” is for formative purposes and are meant to reinforce and consolidate understanding of the concepts learnt and the inquiry skills that students have developed. At the end of each unit, the questions are scaffolded so that students can apply their knowledge and understanding to solve simple as well as challenging questions. More importantly, for Grade 9, the textbook seeks to provide relevant and authentic assessment materials for the purpose of the National Certificate of Education (NCE) assessment at the end of the NYBCE cycle. The “End of Unit Exercises” provides educators with opportunities to assess learners’ understanding of concepts addressed in the units and to provide timely feedback and support. This section comprises a variety of exercises, such as fill-in-the-blanks, matching, multiple choice and structured questions, amongst others. It is recommended to encourage learners to develop higher order thinking skills and to justify their answers as and when appropriate as this promotes critical analysis and deeper conceptual understanding. Using a differentiated approach, educators are expected to develop more assessment exercises or to adapt those provided to assess learners of different abilities. iv The “What I have learnt” icon summarises the concepts learnt through the inquiry-based activities. The “Find out” icon aims at encouraging students to look for information beyond the scope of the textbook and to develop the habit and skills of looking for information from various sources. The “Did you know?” icon is included to trigger students’ interest and curiosity about science. This section not only provides them with interesting information related to the concepts being addressed but it also helps to stimulate their curiosity and stretch their imagination further. Suggestions are made for “Project work” to promote cooperative learning. A “Summary of unit” and “Concept map” are incorporated at the end of each unit to clearly summarise all the key and relevant concepts learnt. With the visual impact that graphic organisers afford, students can make connections among concepts in the hope that learning is aided, consolidated and eventually a high retention rate is ensured. It is sincerely hoped that the textbook helps motivate learners, stimulates their interest in science and develops the habits of mind and skills for scientific inquiry. Dr (Mrs) Sarojiny Saddul-Hauzaree Coordinator The Science Panel v  Table of Contents Biology: UNITS B1-B4 UNIT B1 Blood Circulatory System Pg 1 - 28 UNIT B2 Reproduction Pg 29 - 52 UNIT B3 Biodiversity Pg 53 - 66 UNIT B4 Nutrition in Plants Pg 67 - 93 vi  Blood Measurement Circulatory in Science Unit System Unit B1 1 Unit Blood Circulatory System B1 Learning Outcomes At the end of this unit, you should be able to: State that the human circulatory system consists of the blood, the heart and the blood vessels Show an awareness that the heart is a pumping organ distributing blood throughout the body List the four main components of blood as blood plasma, red blood cells, white blood cells and platelets Outline briefly the function(s) of red blood cells, white blood cells, platelets and blood plasma Calculate magnification of drawings of blood cells Compare the structure of the different blood vessels: arteries, veins and capillaries Relate the functions of different blood vessels to their structures Define a pulse and locate a pulse point List examples of cardiovascular diseases such as stroke and heart attack Show an awareness of the different factors that contribute to cardiovascular diseases and the preventive measures Interpret data from graphs related to cardiovascular diseases In Grade 7 and 8, you learnt about different organ systems in living organisms, such as the respiratory and digestive systems. In this unit, you will learn about the blood circulatory system, which is the main transport system in the human body. The main functions of the blood circulatory system are the transport of substances and protection of our body against diseases caused by germs. Blood Circulatory System The human blood circulatory system consists of three main components, as shown in Figure 1. Blood circulatory system Blood Blood vessels Heart Figure 1: Main components of human blood circulatory system 1  tinU Blood Circulatory System Unit B11 You will now learn about each component of the blood circulatory system. The Heart Figure 2: External structure of the human heart The human heart, as shown in Figure 2, is a muscular organ which is approximately the size of a clenched fist. It pumps blood into blood vessels to all parts of the body. Let’s start with this simple activity to locate the position of the heart in the human body. ACTIVITY 1.1 - Locating the position of the heart By following the instructions and answering the questions below, you will be able to locate the position of your heart. 1. Observe carefully your teacher who will show the chest region of the body. 2. Place one hand in the middle of your chest. 3. Then move slightly to the left until you feel a movement in your chest. This is the location of your heart. 1. Describe the type of movement you feel in your chest. _______________________________________________ ________________________________________________ 2. Draw the exact location of the heart in Figure 3. _______________________________________________ ________________________________________________ 3. Discuss and predict what are represented by the blue and red structures in Figure 3. Blue: ___________________________________________ Red: ___________________________________________ Figure 3: Blood circulatory system in human 2  Unit Blood Circulatory System Unit B1 1 WHAT I HAVE LEARNT The heart is located in the middle of the chest, slightly leaned to the left. The heart pumps blood into blood vessels to all parts of the body. The Blood You might have noticed a red fluid coming out of an open wound. This fluid is known as blood. When blood is observed under a microscope, many different types of cells are seen in a liquid medium, known as plasma. Figure 4 shows that blood consists of approximately 55% plasma, 41% red blood cells and 4% of white blood cells and platelets. Plasma (about 55%) Platelets White blood cells Red blood cells (about 41%) Figure 4: Composition of blood Blood Plasma Blood plasma is a pale yellowish liquid consisting mainly of water and dissolved substances such as glucose, salts, gases (e.g. oxygen), proteins and waste substances. These dissolved substances are transported in the body. Blood cells and platelets Blood cells and platelets make up about 45% of the blood. Red blood cells are the most abundant (41%). There are also white blood cells and fragments of cells known as platelets. 3  tinU Blood Circulatory System Unit B11 Red Blood Cells (RBCs) Activities 1.2 and 1.3 will allow you to learn about the structure and function of red blood cells. ACTIVITY 1.2 - Examining blood under a microscope You will now observe human blood under a light microscope with the help of your teacher. Describe your observation of the human blood smear, as seen under the microscope. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ Figure 5 shows how human blood appears under the light microscope and Figure 6 shows the enlarged image of a red blood cell. Red blood Red blood cells cell Figure 5 Figure 6 TEST YOURSELF Guidelines for drawing: 1. Referring to Figure 6, draw a red blood cell in the space below. 1. Use a sharp pencil. Make sure that your diagram is larger than the red blood cell 2. Draw clear labelled in Figure 6. continuous lines. 3. Do not shade your diagram. 4. Draw a diagram of appropriate size (usually two-third of given space). 5. Keep your diagram to the left of your page and use the right-hand side for labels. 6. Use a ruler for horizontal label lines (not arrows). 7. Draw proportional diagram. 4  Unit Blood Circulatory System Unit B1 1 2. Using a ruler, measure and record the diameter of your drawing across its widest part. Diameter of a red blood cell in your drawing = ___________________ mm 3. Measure and record the diameter of a red blood cell in Figure 6. Diameter of a red blood cell in Figure 6 = ___________________ mm 4. Given that magnification is defined as the number of times that an image appears bigger than the real object, calculate the magnification of your drawing using the following formula. Show your working. Diameter of your drawing Magnification of the drawing (RBC) = Diameter of red blood cell in Figure 6 Magnification of the drawing = ___________________ ACTIVITY 1.3 - E  xploring the structure and main function of red blood cells (RBCs) From the previous activity, you have been able to recognise and draw a simple diagram of a red blood cell. In Activity 1.3, you will learn about the structure and the main function of red blood cells. Figure 7 is a labelled diagram of a cross section of a RBC and Figure 8 is a labelled diagram of a typical animal cell. Cell membrane Cytoplasm containing the red pigment haemoglobin Flattened (concave) shape Figure 7: Cross section of a red blood cell Cell membrane Nucleus Cytoplasm Figure 8: Cross section of a typical animal cell 5  tinU Blood Circulatory System Unit B11 Observe the diagrams in Figures 7 and 8 to answer the following questions. (a) Compare a red blood cell and a typical animal cell based on the features given in Table 1. Then fill the table accordingly. Table 1: Comparison between a RBC and a typical animal cell Features Typical animal cell Red blood cell Shape of cell Nucleus Haemoglobin (b) By referring to Figures 7 and 8, state the features that are common to both cells. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ (c) The red pigment (haemoglobin), found in RBCs, binds and carries oxygen throughout the body. On the basis of what you learnt in activities 1.2 and 1.3, suggest how the structure of a red blood cell is adapted to its main function of carrying oxygen around the body. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ WHAT I HAVE LEARNT 1. Blood consists of plasma, red blood cells, white blood cells and platelets. 2. Red blood cells have red pigment haemoglobin, which carries oxygen around the body. 3. RBCs are adapted to carry oxygen as follows: The cytoplasm has haemoglobin. There is no nucleus in RBCs and thus can accomodate more haemoglobin. RBCs have a flattened shape with biconcave sides that gives a large surface area, allowing oxygen to diffuse rapidly in and out. 6  Unit Blood Circulatory System Unit B1 1 White Blood Cells (WBCs) There are fewer white blood cells in the blood compared to red blood cells. They are also larger than red blood cells and have a nucleus. Figures 9 and 10 show two different types of WBCs. Figure 9 Figure 10 White blood cells are the major components of the body’s immune system. WBCs protect the body against diseases by killing pathogenic germs (very small organisms which cause diseases). How white blood cells kill germs? White blood cells as shown in Figure 9 engulf and digest germs such as bacteria and viruses which enter the body. WBCs as shown in Figure 10 produce antibodies which destroy or help in the destruction of germs. DID YOU KNOW… Antibodies are proteins that can bind to foreign bodies (e.g bacteria and viruses) to destroy them. Platelets You have studied the different types of blood cells earlier in this unit. Platelets are small cell fragments found in blood. In Activity 1.4, you will learn about the importance of platelets in the body. 7  tinU Blood Circulatory System Unit B11 ACTIVITY 1.4 - Exploring the importance of platelets in the body Read the extract below and answer the questions which follow. Ronaldo falls while playing football and injures his knee. Blood oozes from his wound as shown in Figure 11. After some time, he notices that the bleeding has stopped, and a dark red clot has formed on the surface of the injury. Figure 11: Ronaldo What do you think will happen to Ronaldo if the bleeding is not stopped? _____________________________________________________________________ _____________________________________________________________________ What happened to Ronaldo can be explained as follows: 1. While playing, he fell on his knees and was injured. 2. The tiny blood vessels of the damaged skin broke open. 3. Blood started oozing from blood vessels causing bleeding. 4. Platelets gathered at the site of injury cause formation of blood clot. 5. The blood clot stopped the bleeding. Importance of blood clotting: It prevents excessive blood loss from the body when a blood vessel is damaged or breaks open. It also prevents entry of germs or microbes at the site of the wound. WHAT I HAVE LEARNT 1. White blood cells protect the body against foreign bodies such as germs by: (i) engulfing and digesting the germs. (ii) producing antibodies that destroy or help to destroy germs. 2. Platelets help in blood clotting that stops blood loss and prevents entry of germs in case of injury. 8  Unit Blood Circulatory System Unit B1 1 Table 2 summarises the blood components and their respective function(s). Table 2: Functions of blood components Blood components Function(s) Transports digested food (e.g. glucose), waste Plasma substances (e.g. urea) and gases (e.g. CO2) Have haemoglobin that transports oxygen Red blood cells in the body as oxy-haemoglobin Engulf and digest germs such as bacteria and viruses White blood cells Produce antibodies which destroy or help in destruction of germs Platelets Help in blood clotting Blood Vessels As we have seen earlier, blood is transported to all parts of our body through tube-like structures, known as blood vessels. There are three main types of blood vessels, namely (i) arteries, (ii) veins and (iii) capillaries. All blood vessels form a continuous tubular system that transports blood throughout the body. Figure 12 shows how arteries divide to form tiny vessels known as capillaries which eventually join to form veins. from heart to heart capillaries artery vein Figure 12: Blood Vessels 9  tinU Blood Circulatory System Unit B11 Structure of blood vessels Figures 13, 14 and 15 show sections through an artery, a vein and a capillary respectively. Outer wall Thin layer of muscle and elastic fibres Small lumen Large lumen Thick layer of muscle and Outer wall elastic fibres Single layer of cells Single layer of cells Figure 13: An artery Figure 14: A vein Very small lumen Wall made of a single layer of cell Figure 15: A capillary DICTIONARY CORNER Lumen: central hole in a blood vessel where blood flows. In Activity 1.5, you will differentiate between an artery, a vein and a capillary. ACTIVITY 1.5 - C  omparing the structure of the artery, vein and capillary By referring to Figures 13, 14 and 15, compare and contrast the structures of the different blood vessels, based on the features given in Table 3 below. Then, fill in the table with appropriate word(s) or phrase, as shown in the example. Table 3: Comparison of artery, vein and capillary Features Artery Vein Capillary Size of lumen small/narrow large/wide very small Thickness of wall Number of distinct layers of wall 10  Unit Blood Circulatory System Unit B1 1 (i) Write down one feature common to all the blood vessels. __________________________________________________________________________ (ii) Now complete the Venn diagram to show features that are: (1) common (2) different among the three types of blood vessels Artery Vein Capillary Functions of blood vessels Table 4 summarises the functions of the blood vessels. Table 4 Type of blood vessel Function Carries blood: away from the heart Artery rich in oxygen* under high pressure Carries blood: towards the heart Veins rich in carbon dioxide (less oxygen)* under low pressure Allows exchange of substances between blood and cells in adjacent tissues. Nutrients (e.g glucose) and Capillaries oxygen move out of capillaries. Carbon dioxide and other waste products (e.g. urea) move into capillaries from cells. DID YOU KNOW… *A  ll arteries carry oxygenated blood except the pulmonary artery and all veins carry deoxygenated blood except, the pulmonary vein. 11  tinU Blood Circulatory System Unit B11 Adaptations of the structure of blood vessels to their functions You have learnt about the different blood vessels, their structure and functions. Now, you will relate the structure of the blood vessels to their respective functions. Some features of artery related to its functions: - A small lumen maintains a high pressure of blood so that blood reaches all parts of the body. - A thick wall, consisting of muscle and elastic fibres, allows stretching and recoiling of arteries to maintain blood flow. - A thick wall accomodates blood with high pressure. Some features of vein related to its functions: - The wall is thinner and less muscular than arteries as veins carry blood at low pressure. - Valves, as shown in Figure 16, prevent backflow of blood in veins. - The large lumen allows blood to flow under low pressure. - The thin wall allows the vessel to squeeze under the action of adjacent skeletal muscles so that local pressure is set in veins. Valves open allowing blood Valves close to to move up prevent blood from flowing backward Figure 16: Role of valves in veins Features of capillary related to its function - The one-cell thick wall of a capillary allows exchange of substances between blood and surrounding cells - There are small gaps between cells lining the capillary wall. This allows white blood cells to squeeze through these gaps from blood into infected tissues. 12  Unit Blood Circulatory System Unit B1 1 Pulse At the beginning of this unit, the heart was introduced as the organ of the circulatory system which pumps blood around the body. When the muscles of the heart contract, blood is pumped out of the heart into arteries to all organs of the body. A heart beat occurs every time the muscles of the heart contract. When blood is pumped into an artery, its wall stretches and recoils to maintain the flow of blood under high pressure. The stretching and recoiling of the artery walls is known as a pulse. Each heart beat gives rise to a pulse. ACTIVITY 1.6 - L  ocating a pulse A pulse can be located at few specific sites in the body. One is on the wrist, as shown in Figure 17. The pulse may be located by placing two fingers (index and middle fingers) at the base of the Figure 17 thumb in the region of the wrist. Then, press the two fingers slightly until a pulse is felt. Another is at the side of the neck, just under the jaw as shown in Figure 18. The pulse is located by placing two fingers (index and middle fingers) under the angle of the jaw using very light pressure. Figure 18 WHAT I HAVE LEARNT 1. A pulse is the result of stretching and recoiling of an artery every time the heart pumps blood in an artery. 2. A pulse may be felt at the wrist region or the neck region. 13  tinU Blood Circulatory System Unit B11 Cardiovascular Diseases We have discussed earlier in this unit about the components of the blood circulatory system. Now you will explore some common diseases related to the blood circulatory system. A person’s lifestyle may affect the proper functioning of both blood vessels and the heart. This can lead to cardiovascular diseases, which are non-communicable diseases. Some common examples of cardiovascular diseases are: Heart attack If the artery which supplies blood to heart muscles is partially blocked as shown in Figure 20, it will decrease supply of oxygen and nutrients to heart muscles. This may lead to a heart attack. Stroke If an artery supplying nutrients and oxygen to the brain is blocked, it may lead to a stroke. This may cause paralysis of parts or whole body. Fatty deposit Figure 19: Healthy artery Figure 20: Blocked artery DID YOU KNOW… Hypertension This is a condition when blood pressure increases above the normal range. It can damage the lining of blood vessels. 14  Unit Blood Circulatory System Unit B1 1 Factors contributing to cardiovascular diseases In Grade 8, you learnt about some factors that contribute to cardiovascular diseases. The main causes of cardiovascular diseases and the preventive measures are summarised in Table 5. Table 5 Cause of Cardiovascular Explanation Preventive measures diseases S alts cause hypertension Reduce salt 1. High intake of salt in diet which damages the lining in the diet of blood vessels. Reduce saturated 2. Diet with excess F atty deposits block fats including saturated fats the arteries as shown cholesterol in the and cholesterol in Figure 20. diet Eat healthy diet 3. Obesity It puts strain on the heart. Exercise regularly T he heart muscles lose its tone and becomes 4. Lack of exercise Exercise regularly less efficient in pumping blood. N  icotine damages the Stop cigarette 5. Smoking cigarettes heart and the arteries. smoking I t tends to increase the blood pressure A  void the causes 6. Stress that may damage the of stress lining of blood vessels. DID YOU KNOW… Blood donation, which has become an important event in several educational institutions including MIE, can save lives of people as blood is essential to help patients survive surgeries, cancer treatment, chronic illnesses, and traumatic injuries. 15  tinU Blood Circulatory System Unit B11 ACTIVITY 1.7 Figure 21 shows the number of deaths caused by heart attack in men and women per 100,000 people in a given population. Number of deaths caused by heart attack per 100,000 people Figure 21: Variation in the number of deaths by heart attack over time Observe the graphs carefully and then answer the following questions. (a) (i) W  hat happened to the number of deaths between 1924 and 1936 in both men and women? Men: ________________________________________________________________ Women: _____________________________________________________________ (ii) S uggest two reasons to explain your observation in part (a)(i). _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ (b) (i) Which group (men or women) had the highest number of death due to heart attack? _____________________________________________________________________ _____________________________________________________________________ 16  Unit Blood Circulatory System Unit B1 1 (ii) S uggest two reasons to explain your answer in part (b)(i). _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ (c)(i) Referring to Figure 21, identify the number of deaths in men in the year: 1972: _________________________________________________________________ 1987: ________________________________________________________________ (ii) U  sing the answers of part (c)(i), calculate the percentage change in death from year 1972 to 1987. Show your working. (iii) Suggest two reasons for the decrease in death from 1972 to 1987. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ WHAT I HAVE LEARNT 1. Cardiovascular diseases are diseases that affect the proper functioning of the heart and the blood vessels (mainly arteries). 2. Two examples of cardiovascular diseases are heart attack and stroke. 3. The main factors that contribute to cardiovascular diseases are unhealthy diets, obesity, lack of exercise, smoking cigarettes and stress. 17  tinU Blood Circulatory System Unit B11 Summary of unit 1. The human blood circulatory system consists of the blood, the blood vessels and the heart, where the heart pumps blood into blood vessels to all parts of the body. 2. Blood is composed of liquid plasma, red blood cells, white blood cells and platelets. Plasma consisting of water and dissolved substances, is involved in the transport of substances in the body. Red blood cells carry oxygen throughout the body. White blood cells protect the body against diseases caused by germs. Platelets are small fragments of blood cells that help in blood clotting. 3. The 3 main types of blood vessels are the artery, capillary and vein. Arteries carry oxygenated blood away from the heart, under high pressure. V  eins carry deoxygenated blood away from tissues back to the heart, under low pressure. Capillaries allow exchange of materials between blood and adjacent tissues. 4. A pulse, caused by stretching and recoiling of the artery wall, may be felt at the wrist or neck region. 5. Cardiovascular diseases are the diseases of the heart and/ or blood vessels. Common examples of cardiovascular diseases are heart attack and stroke. 6. Cardiovascular diseases have been associated with various casual factors, such as: diet with high level of salts and saturated fats (including cholesterol), smoking cigarettes, lack of physical activity and stress. 7. Some preventive measures of cardiovascular diseases are: choosing a healthy lifestyle in order to reduce stress, avoid smoking cigarettes, reducing intake of fats/cholesterol and salt in diet and regular exercise. 18  Unit B1 Blood Circulatory System BLOOD CIRCULATORY SYSTEM Cardiovascular diseases (non-communicable diseases) H  igh intake of salts and saturated fats Consists of in diet Some causes Obesity Smoking cigarettes Lack of exercise Heart Reduce fats Blood Blood Vessels (muscular organ) (especially saturated) Prevention and salt in diet consists of such as function Regular exercise Pumps blood Common Stroke around the body examples Heart attack Blood cells Plasma Veins Capillaries Arteries produces types consists of Deoxygenated carry blood (except Platelets  ater and dissolved W Heart beat Pulse Red blood White pulmonary structure (fragments of cells) substances such as cells blood cells vein) function nutrients, oxygen etc Blood towards felt function heart one-cell With the following Blood at low thick wall adaptations pressure small At wrist functions blood lumen At neck regions clotting S  ite of exchange Disc-shape/ Ingest and Large lumen between blood Biconcave sides digest germs structure Thick wall and adjacent Small lumen Have valves tissues structure Thick wall Produce antibodies to kill or help Contain in destruction of germs oxygenated blood haemoglobin carry (except pulmonary artery) blood away from heart 1 To carry oxygen B1 Blood Circulatory System Unit function Unit around body blood at high pressure No nucleus 19 when mature  tinU Blood Circulatory System Unit B11 1. Match each term in Column A with its function in Column B. Column A Column B Blood carry blood away from the heart Heart pumps blood Arteries connect arteries and veins Veins transports materials around the body Capillaries carry blood back to the heart 2. Read carefully and state whether each statement is true or false. (a) Blood is a red liquid which flows in blood vessels. ___________________ (b) Blood is made of plasma and cells only. ___________________ (c) Blood plasma represents about 45 % of the blood. ___________________ (d) The solid components of blood comprise red blood cells and platelets only. ___________________ END OF UNIT EXERCISES (e) Red blood cells are more numerous than white blood cells in the human blood. __________________ (f) There is a large central nucleus in mature red blood cells. ___________________ (g) Haemoglobin carries oxygen in red blood cells. ___________________ (h) White blood cells recognise and kill germs. ___________________ (i) Antibodies are produced by red blood cells to kill germs. ___________________ (j) Platelets help in blood clotting. ___________________ 3. Fill each blank with the appropriate term given below. heart, arteries, veins, nutrients, carbon dioxide, capillaries, high, away, pumps (a) Veins carry blood ___________________ from other organs back to the heart. (b) Blood flows under ___________________ pressure in arteries. (c) ___________________ leaves blood in capillaries to enter cells of adjacent tissues. (d) The ___________________ , blood vessels and blood make up the blood circulatory system. (e) Blood vessels that carry blood away from the heart are called ___________________. (f) The blood flowing in veins is rich in ___________________. (g) Blood moves from arteries to veins through tiny blood vessels known as ___________________. (h) Heart ___________________ blood throughout the body. (i) Arteries branch off to form network of ___________________. (j) Blood flows away from the heart in ___________________. 20  Unit Blood Circulatory System Unit B1 1 4. Fill in the blanks by choosing the appropriate term from the list below. valves, wrist, glucose, cells, ingest, blood clotting, exchange (a) Food substances such as ___________________ and amino acids are carried in the blood. (b) White blood cells can ___________________ germs and digest them. (c) Platelets are important in ___________________. (d) Capillaries are tiny vessels consisting of a single layer of ___________________________ allowing ___________________ of substances between blood and adjacent tissues. (e) ___________________ in veins allow blood to flow in one direction only. (f) A pulse can be felt at the base of the ___________________. 5. Circle the correct answer. (a) Which of the following is a yellowish solution making about 55 % of blood? END OF UNIT EXERCISES A. Cytoplasm B. Water C. Plasma D. Glucose (b) Blood leaves the heart under ___________________ through the arteries. A. Very low pressure B. Low pressure C. High pressure D. No pressure (c) The red pigment found in red blood cells is known as ________________. A. Haemoglobin B. Chlorophyll C. Antibody D. Iron (d) Which of the following is involved in the destruction of germs? A. Red blood cells B. Plasma C. White blood cells D. Platelets (e) Which of the following statements is true about the type of blood carried in arteries? A. Blood rich in oxygen under high pressure B. Blood rich in carbon dioxide under high pressure C. Blood rich in oxygen under low pressure D. Blood rich in carbon dioxide under low pressure (f ) Which of the following statements is true about the heart? A. It is a muscular organ pumping blood. B. It is a hollow organ without any muscle tissue. C. It is an organ that does not have right and left sides. D. It is an organ that has no connections with any blood vessels. 21  tinU Blood Circulatory System Unit B11 (g) Which of the following statements is true about blood vessels? A. The diameter of the lumen of an artery is bigger than that of a vein. B. The diameter of the lumen of a vein is bigger than that of an artery. C. The diameter of capillaries is the largest compared to arteries. D. The diameter of a lumen of capillary is larger than that of a vein. (h) Cardiovascular diseases are the result of: A. Regular exercise B. Diet rich in salts and fats C. A healthy diet D. Stress-free lifestyle 6. Figure 1(a) is a section through an artery and Figure 1(b) through a vein. A D B END OF UNIT EXERCISES C E Figure 1(a) Figure 1(b) (a) Label the parts A- E. A _________________________________________________ B _________________________________________________ C _________________________________________________ D _________________________________________________ E _________________________________________________ (b) State two differences in structure between an artery and a vein. 1. _______________________________________________________________________ 2. _______________________________________________________________________ (c) State how arteries and veins differ in their functions. ________________________________________________________________________ ________________________________________________________________________ (d) Explain briefly how the structure of an artery helps in its function. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 22  Unit Blood Circulatory System Unit B1 1 (e) Name a structure present in veins but not visible in Figure 1(b). State one function of the structure. Structure: __________________________________________________________________ Function: __________________________________________________________________ 7. (a) What is the term used for non-communicable diseases related to the blood circulatory system. _______________________________________________________________________ (b) Give two examples of the disease you mentioned in part (a). 1. ______________________________________________________________________ 2. ______________________________________________________________________ (c) List two factors that contribute to the disease given in part (a). END OF UNIT EXERCISES 1. ______________________________________________________________________ 2. ______________________________________________________________________ (d) How can you prevent the disease stated in part (a)? _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ (e) If an artery supplying blood to the muscles of the heart is partially blocked, how can it affect the functioning of the heart? 1. ______________________________________________________________________ ______________________________________________________________________ 2. ______________________________________________________________________ ______________________________________________________________________ 8. (a) Define a pulse. _______________________________________________________________________ _______________________________________________________________________ (b) Name two areas where you can locate a pulse in your body. _______________________________________________________________________ _______________________________________________________________________ 23  tinU Blood Circulatory System Unit B11 (c) How is a pulse related to a heart beat? _______________________________________________________________________ _______________________________________________________________________ 9. Figure 2 shows a sample of blood as seen under the microscope. Observe carefully and answer the following questions. C A B END OF UNIT EXERCISES Figure 2: Blood Smear (a) Which of the cells A, B or C is the red blood cell? _______________________________________________________________________ (b) Give two reasons to support your answer in part (a). _______________________________________________________________________ _______________________________________________________________________ (c) State two functions of white blood cells in our body. 1. ______________________________________________________________________ 2. _____________________________________________________________________ (d) Suggest when the number of white blood cells may increase beyond normal amount in the blood. _______________________________________________________________________ _______________________________________________________________________ (e) When blood capillaries are damaged, platelets become active causing the formation of blood clot. Give two reasons why blood clotting is important. _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ (f ) On Figure 2, indicate the blood plasma using the letter D. 24  Unit Blood Circulatory System Unit B1 1 (g) Name three substances present in blood plasma. 1. ______________________________________________________________________ 2. _____________________________________________________________________ 3. ______________________________________________________________________ (h) Name another component of blood not shown in Figure 2 and state its function. Blood component: __________________________________________________________ Function: __________________________________________________________________ 10. Figure 3 shows part of the circulatory system. A ________________ END OF UNIT EXERCISES B ________________ ________________ C Blood coming from heart Blood going to Figure 3 the heart (a) Name the structures A, B and C on Figure 3. (b) How does blood circulation in structure A differ from C? _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ (c) (i) State the function of structure B. _____________________________________________________________________ _____________________________________________________________________ (ii) How is structure B adapted to its function? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ (d) How does structure A allow blood to flow in one direction only? _______________________________________________________________________ _______________________________________________________________________ 25  tinU Blood Circulatory System Unit B11 (e) Explain why the blood in structure C is under high pressure when it leaves the heart. _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ 11. Coronary heart disease develops when the coronary artery, shown in Figure 4, is blocked by fatty materials. The coronary artery supplies blood to the heart muscles. END OF UNIT EXERCISES coronary arteries Figure 4: External structure of the heart (a) Give two ways in which the heart is affected when fats are deposited on the inner wall of coronary artery. 1. ____________________________________________________________________________ 2. ____________________________________________________________________________ (b) Table 2 shows the percentage of people who died of coronary heart disease from 2012 to 2020 in Mauritius and Rodrigues. 26  Unit Blood Circulatory System Unit B1 1 Table 2 Year Percentage death caused by coronary heart disease in Mauritius Rodrigues 2012 19.1 12.7 2014 19.8 16.9 2016 11.5 15.4 2018 16.1 11.9 2020 11.5 12.1 Figure 5 shows a line graph of percentage death caused by coronary heart disease in Mauritius. 20 18 END OF UNIT EXERCISES 16 Mauritius 14 12 10 2012 2014 2016 2018 2020 Year Figure 5: Death rate related to coronary diseases in Mauritius and Rodrigues (i) Fill in the blank space to label the Y axis on Figure 5. (ii) Using the information given in Table 2, complete Figure 5 by drawing a line graph showing the changes in death rate in Rodrigues. (c) (i) Calculate the percentage increase in death from year 2012 to 2014 in: Mauritius. ____________________ Rodrigues ____________________ (ii) Suggest two reasons that could have caused the increase in death rate by coronary heart diseases in both islands. _______________________________________________________________________ _______________________________________________________________________ 27  tinU Blood Circulatory System Unit B11 (d) Explain the change in percentage death from 2018 to 2020 in Mauritius. _______________________________________________________________________ _______________________________________________________________________ END OF UNIT EXERCISES 28  Food Reproduction Unit and NutrientsUnit Unit B2 1 2 Unit Reproduction B2 Learning Outcomes At the end of this unit, you should be able to: Define reproduction as the process of producing new individuals of the same kind or species State the importance of reproduction in living things Distinguish between the two modes of reproduction: sexual and asexual Identify, label and give the main function of the different parts of the male and female reproductive systems in man Define sexually transmitted diseases (STDs) as diseases that are spread from an infected to uninfected individual, through sexual contact List examples of sexually transmitted diseases such as HIV/AIDS and syphilis Interpret data from graphs related to sexually transmitted diseases In Grade 7, you learnt about a few characteristics of living things. For example, living things grow, move, feed, respire and excrete. Another characteristic of all living things is the ability to reproduce. Each and every organism can live only for a certain period of time. It may ultimately die of old age, diseases, in accidents or killed for food by other organisms. To ensure the continuity of various organisms on earth, new organisms must be produced. This process is called reproduction. The pictures below show examples of the parents and their respective offspring(s) /young(s). Parent Parent Offspring Offspring Mauritian Kestrel Giant Panda 29  tinU Reproduction Unit B21 Reproduction is the production of new individuals of the same kind or of the same species. DICTIONARY CORNER 1. A species is a group of living organisms which can reproduce among themselves producing fertile offspring(s). 2. Offspring is the young born of living organisms. Now that you are aware that all organisms reproduce, suggest what may happen if organisms stop reproducing. _____________________________________________________________________________ _____________________________________________________________________________ ACTIVITY 2.1 - Identifying Ways of Reproducing Through Activity 2.1, you will learn that organisms reproduce in different ways. The pictures show different species. Observe and predict how these organisms reproduce. The first example is done for you. Dogs reproduce by giving birth. _______________________________________________ _______________________________________________ _______________________________________________ _ 30  Unit Reproduction Unit B2 1 Types of Reproduction The two main types of reproduction through which organisms produce new individuals are: (a) Asexual reproduction (b) Sexual reproduction Asexual reproduction Asexual reproduction takes place in organisms such as bacteria, fungi (e.g. yeast) and amoeba. Some plants can also carry out asexual reproduction. Activities 2.2 and 2.3 will help you explore the process of asexual reproduction. ACTIVITY 2.2 - Exploring Asexual Reproduction in Amoeba Figure 1 represents the process of asexual reproduction in amoeba. Amoeba is a unicellular organism usually found in water bodies such as ponds. Cytoplasm Nucleus Parent cell New organisms Figure 1: Asexual reproduction in amoeba Study Figure 1 carefully and answer the questions below. (a) State the number of parent cell(s) involved to produce new organisms. _______________________________________________________________________ (b) Are the new organisms identical to the parent? _______________________________________________________________________ (c) Are the new organisms identical to each other? _______________________________________________________________________ 31  tinU Reproduction Unit B21 ACTIVITY 2.3 - Observing Asexual Reproduction in Yeast Your teacher will show you a slide of living yeast cells under the microscope. Materials needed: Yeast, sugar, microscope, microscope slide, coverslip, dropper, thermometer. Procedure used in preparing the slide: 1. Pour 125 cm3 of warm water of approximately 30-35oC into a beaker. 2. Then add 5 g of sugar and 5 g of yeast into the beaker and mix the content. 3. Using a dropper, transfer a drop of the mixture on a clean microscope slide and place a coverslip over the drop. 4. Observe the mixture under the high power of a microscope. Figure 2 shows how the yeast cells appear under the high power of a microscope immediately after preparing the slide. Figure 3 shows the yeast cells one hour later. Immediately One hour later Yeast cell Figure 2 Figure 3 Refer to Figures 2 and 3 to answer the following questions. (a) Fill the table below with The total number of yeast cells, irrespective of difference in size. A description of how the yeast cells appear. Table 1 Figure 2 Figure 3 Number of yeast cells Description of yeast cells 32  Unit Reproduction Unit B2 1 (b) Based on the observations recorded in Table 1, describe briefly how yeasts carry out asexual reproduction. _______________________________________________________________________ _______________________________________________________________________ Watch the Video on asexual reproduction in yeast https://www.youtube.com/watch?v=GFEgB_ytDZY Asexual Reproduction in Plants Asexual reproduction in plants occurs when a part of the plant such as the root, stem or leaf (but not seed) grows into a new plant. One example is the strawberry plant as shown in Figure 4. The parent plant produces runners which extend out of the soil. In contact with soil, a new plant is formed at the end of each runner. The new plant is genetically identical to the parent plant. Figure 4: Strawberry plants reproducing asexually Another example of a plant that reproduces by asexual reproduction is the potato plant. In the following activity, we will investigate asexual reproduction in potato plant. 33  tinU Reproduction Unit B21 ACTIVITY 2.4 - Investigating Asexual Reproduction in Potato Plant You can work in groups for this experiment. Materials needed: Fresh and sprouted potatoes, magnifying lens, tile, scalpel, water and a pot with potting soil. Instructions: 1. Using a magnifying glass, observe the scars or ‘eyes’ found on the fresh potato. Describe your observation. ______________________________________________________________________________ 2. Observe the sprouted potato and record your observation. Figure 5 shows an example of a sprouted potato. DICTIONARY CORNER Tuber: a swollen underground stem Figure 5: Potato tuber with sprouts Observation: ______________________________________________________________________________ 3. Cut the sprouted potato into several portions. Make sure that each potato piece has at least one sprout. 4. Transfer the potato pieces in a pot of soil and water the pot regularly for few days. 5. Observe and record your findings on a daily basis. Describe your observations. ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 34  Unit Reproduction Unit B2 1 Give two reasons to justify that potato plants reproduce by asexual reproduction. 1. ____________________________________________________________________________ ______________________________________________________________________________ 2. ____________________________________________________________________________ ______________________________________________________________________________ WHAT I HAVE LEARNT 1. A single parent is involved in asexual reproduction. 2. There are different types of asexual reproduction. For example: An amoeba divides equally to form two new individuals. A parent yeast cell gives rise to small buds that eventually separate and mature into new yeast cells. Strawberry plants can reproduce asexually using runners. Potato plants reproduce asexually using tubers (stem swellings). A potato tuber has many ‘eyes’ which form sprouts. Each sprout may then develop into a new plant which is genetically identical to the parent plant. 3. Offsprings produced during asexual reproduction are genetically identical to each other and to the parent. DICTIONARY CORNER Genetically identical means having the same genes and hence the same features. 35  tinU Reproduction Unit B21 Sexual Reproduction Now that you understand the process of asexual reproduction, let us learn about sexual reproduction. Figure 6 shows a cat family. Figure 6: A cat family Study Figure 6 carefully and answer the following questions. (a) How many parents do you see in Figure 6? ____________________________ (b) Are the offsprings identical to each other? ____________________________ (c) Are the offsprings identical to their parents? ____________________________ (d) Suggest the type of reproduction involved in mammals such as cats. _______________________________________________________________________ Two parents are involved in sexual reproduction and offspring(s) produced are neither identical to the parents nor to each other. WHAT I HAVE LEARNT 1. Two parents are involved in sexual reproduction. 2. Offsprings produced during sexual reproduction are neither genetically identical to the parents nor to each other. 36  Unit Reproduction Unit B2 1 ACTIVITY 2.5 - Comparing Sexual and Asexual Reproduction Based on what you have learnt earlier in this chapter, complete Table 2 to compare and contrast between asexual and sexual reproduction. Table 2 Asexual Sexual Number of parent(s) involved Are new organisms formed identical to each other? Are new organisms formed identical to their parents? Sexual Reproduction in Humans The two main stages of sexual reproduction in humans are gamete formation and fertilisation. Gamete formation Gametes are specialised sex cells produced by the male and female reproductive systems. Testes are the male reproductive organs which produce the male sex cells. Ovaries are the female organs in which the female sex cells are produced. The male sex cells are called sperms and the female sex cells are called eggs or ova (singular: ovum). You will learn about the reproductive systems in Activities 2.6 and 2.7. Fertilisation During sexual intercourse, the male gametes are released into the female reproductive tract. A sperm cell then fuses with an egg/ovum by the process of fertilisation producing a fertilised egg called a zygote. The zygote then develops into an embryo which eventually develops into a foetus, as shown in Figure 7. Foetus Figure 7: Sexual reproduction in humans WHAT I HAVE LEARNT Sexual reproduction involves the production and fusion of sex cells called gametes. 37  tinU Reproduction Unit B21 The Human Reproductive Systems In the previous section, you have learnt that in sexual reproduction, gametes are required to form new individuals. Activities 2.6 and 2.7 will help you identify the organs that are responsible for the production of gametes and other related organs that form part of the reproductive systems. The Male Reproductive System ACTIVITY 2.6 - Identifying the parts of the male reproductive system Figure 8 shows the front view of the male reproductive system. The function of each part of the system is summarised in the same diagram. Urinary bladder Seminal vesicle It is a tube that Sperm duct carries sperms to the urethra. Prostrate gland It is a tube that carries urine Urethra or semen (contains sperms) to the outside of the body. Penis Testis It is the organ producing It is an organ that releases sperms. sperms in the vagina of the female reproductive system during sexual intercourse. It is a sac-like structure Scrotum that holds the testis outside the body. Figure 8: Front view of the male reproductive system Study Figure 8 carefully and answer the following questions. (a) Name the organ that produces the male gametes. ___________________________________________________________________________ (b) Name two other organs that form part of the male reproductive system. ___________________________________________________________________________ DID YOU KNOW… During sexual intercourse, an adult male releases about 250 million sperms. 38  Unit Reproduction Unit B2 1 (c) Figure 9 shows the side view of the male reproductive system. Refer to Figure 8 to label the structures by filling the blank boxes. Urinary bladder Figure 9: Side view of the male reproductive system The Female Reproductive System ACTIVITY 2.7 - Identifying the parts of the female reproductive system Figure 10 shows the front view of the female reproductive system with the functions of the different parts. It is the place where ferlilisation occurs. Oviduct Ovary It is the place where Uterus the foetus grows and It produces eggs. develops. Cervix It is the place where sperms It separates the uterus Vagina are released during sexual from the vagina. intercourse. It is also the birth canal.