Brain Teaser Tease Can the mother’s eating habits during pregnancy cause mutation? Science Science Gallery The birth rate of Down syndrome babies is 1 to 800. The risk is higher if the mother’s age is more than 35. 5.3.1 5.3 Mutation Types of Mutations Look at Photograph 5.5 below. Can you see the differences in each individuals in the photographs compared to a normal individual? What causes the differences? Photograph 5.5 Differences in individuals Have you heard of mutation? What is mutation? Mutation is a spontaneous and random change that takes place in the genes and chromosomes that can cause changes of characteristics to the offspring who inherits the modified genes. There are two types of mutations, chromosome mutation and gene mutation. Figure 5.15 shows the types of mutations and their examples. Types of mutations Chromosome mutation Gene mutation Down syndrome Colour blindness Turner syndrome Sickle cell anaemia Klinefelter syndrome Thalassemia Albinism Haemophilia Figure 5.15 Types of mutations and examples 90
Figure 5.18 Karyotype of a male with Klinefelter syndrome (a) Down syndrome (Extra chromosome number 21) Down syndrome occurs because there is an extra chromosome in chromosome number 21. A person with Down syndrome has 47 chromosomes compared to a normal person who has 46 chromosomes. A person with Down syndrome has characteristics such as physical and mental retardation, short neck, slanted eyes and short stocky body. (b) Turner syndrome (XO) A person with Turner syndrome has less number of sex chromosomes compared to a normal person. The total number of chromosomes is 45 chromosomes (44 + XO) only. A person with Turner syndrome is a female who has a missing X chromosome. A person with Turner syndrome will not undergo the development of secondary sexual characteristics of a female. (c) Klinefelter syndrome (XXY) A person with Klinefelter syndrome has more number of sex chromosomes compared to a normal individual. The total number of chromosomes is 47 chromosomes (44 + XXY). A person with Klinefelter syndrome is a male with an extra chromosome X. A person with Klinefelter syndrome has female characteristics such as breasts and small testis as well as sterile. Figure 5.16 Karyotype of a male with Down syndrome Figure 5.17 Karyotype of a female with Turner syndrome 1 2 3 4 5 6 13 14 15 16 19 20 21 22 17 18 7 8 9 10 11 12 XY 1 2 3 4 5 6 13 14 15 16 19 20 21 22 17 18 7 8 9 10 11 12 X 1 2 3 4 5 6 13 14 15 16 19 20 21 22 17 18 7 8 9 10 11 12 X X Y 5.3.1 Chromosome Mutation Chromosome mutation occurs when there are changes in the number or structure of the chromosome. These changes occur as a result of a defect during the cell division process. Genetics Chapter 5 91
Science Science Gallery In November 2016, the Ministry of Health Malaysia launched a thalassemia check initiative that targeted the whole country involving Form 4 students. This step was taken to reduce the percentage of babies born with thalassemia. Counselling and appropriate guidelines will be given to individuals who are confirmed as carriers so that they do not choose a partner who has thalassemia. (a) Colour blindness A person who is colour blind has mutant recessive genes on chromosome X. These persons are unable to differentiate between red and green. This disease is controlled by a recessive gene on the X chromosome. This genetic disease usually occurs in males. (b) Sickle cell anaemia This disease is caused by the spontaneous change that occur at the gene responsible for production of haemoglobin. The person with sickle cell anaemia has an abnormal red blood cell shape that is sickle-shaped, affecting the transport of oxygen. This disease is caused by a recessive gene on the autosome. Photograph 5.6 Sickle-shaped red blood cell and normal red blood cell (c) Thalassemia Thalassemia is a type of genetic disease that is caused by the mutation of the gene that controls the production of haemoglobin. A person with thalassemia has small red blood cells and the lifespan of the cells is shorter. This condition can cause severe blood deficiency. (d) Haemophilia A person with haemophilia has difficulty in the clotting of his blood. This is because mutation has occurred at the gene producing the blood clotting factor. This person will lose blood continuously if wounded or injured. Gene Mutation Gene mutation is caused by chemical changes that occur to a gene. Gene mutation causes changes in characteristics that are controlled by the gene. 5.3.1 92
Factors that Cause Gene Mutation and Chromosome Mutation Mutation may occur spontaneously (naturally) during cell division process. Mutation can also occur due to external factors known as mutagens. What are the mutagens that you know? Aim: To gather information and prepare a presentation about the factors that cause gene mutation and chromosome mutation. Instructions: 1. Carry out this activity in groups. 2. Gather separate information about the factors that cause gene mutation and chromosome mutation. 3. Gather the information related to the examples of gene mutation such as colour blindness, sickle cell anaemia, thalassemia and haemophilia. 4. Record the information on a flip chart paper. 5. Pin up your group’s work product in the class so that it can be seen by other groups. 6. Write comments about the work product of other groups on the flip chart papers. ... ... Activity 5.3 Gallery Walk 5.3.2 Figure 5.19 Factors that cause mutation Pregnancy at a late age Radioactive rays Carcinogens Ultraviolet rays X-rays Natural Factors that cause mutation Book Magazine Website 21st Century Skills Genetics Chapter 5 93
Gene Disorder Disease Alleles also carry the disease trait that can be inherited in a family. Figure 5.20 shows the inheritance of a type of gene disorder disease when a man who suffers from the gene disorder disease marries a woman who is a gene disorder disease carrier. Figure 5.20 Inheritance of a type of gene disorder disease Most of the genes that control a trait are located on autosomes. However, there are also traits that are located on sex chromosomes. This trait is known as the sex-linked trait and the genes that are located on the sex chromosomes are called sex-linked genes. For example, the blood clotting failure traits that cause haemophilia. Haemophilia is a genetic disease that is experienced by a person when the blood at his wound takes a longer time to clot. Haemophilia is only inherited when there is a recessive allele that causes the diseases on the X chromosome. If there are no recessive alleles at X chromosomes, there is no haemophilia disease. Study the schematic diagram for haemophilia inheritance on the following Figure 5.21 and Figure 5.22. 5.3.3 3 Gene disorder disease sufferer Parent : Gene disorder disease carrier Mother (Carrier) XB Xb Meiosis Xb XB Father (Colour blind) Xb Y Phenotypes : Genotypes : XB Xb Offspring genotypes : Xb Xb XB Y Xb Y Daughter (Carrier) Offspring phenotypes : Daughter (Colour blind) Son (Normal) Son (Colour blind) Meiosis Fertilisation X Y b Gametes : 94
Figure 5.21 Schematic diagram for inheritance of haemophilia if the father is normal and the mother is a carrier Figure 5.22 Schematic diagram for inheritance of haemophilia if the father is normal and the mother is a haemophiliac XH is the dominant allele (normal) and Xh is the recessive allele (haemophilia). 5.3.3 Father (Normal) 3 Mother (Carrier) XH Xh Meiosis Xh XH XH Y Offspring genotypes : Daughter (Normal) Offspring phenotypes : Daughter (Carrier) Son (Normal) Son (Haemophilia) Meiosis Fertilisation X Y H Gametes : XH Xh XH XH XH Y Xh Y Parental phenotypes : Parental genotypes : Father (Normal) 3 Mother (Haemophilia) Xh Xh Meiosis Xh Xh XH Y XH Xh XH Xh Xh Y Xh Y Meiosis X Y H Daughter (Carrier) Daughter (Carrier) Son (Haemophilia) Son (Haemophilia) Offspring genotypes : Offspring phenotypes : Fertilisation Gametes : Parental phenotypes : Parental genotypes : Genetics Chapter 5 95
Gene disorder disease can be identified through amniocentesis and karyotyping. How do we identify a gene disorder disease, teacher? EN. HARIZ EN. HARIZ HARIS There are two methods that can be used to identify gene disorder diseases: • amniocentesis • karyotyping Karyotype produced from these methods will be used to identify any abnormalities in the chromosomes. This is to detect any gene disorder disease at an early stage. 5.3.3 Figure 5.23 Steps in amniocentesis Amniocentesis Amniocentesis is used to identify foetal cell abnormalities from the 15th to the 20th week of pregnancy. At the beginning, the position of the foetus in the uterus is detected using the ultrasound technique to ensure safe foetal position. This amniotic fluid is then centrifuged to separate the amniotic fluid and foetal cells. A needle will be inserted carefully through the mother’s abdomen penetrating the wall of the uterus. 1 Amniotic fluid that contains floating foetal cells is extracted. 2 The separated foetal cells will be used to obtain the karyotype. 4 Foetal cells 3 Karyotyping http://bukutekskssm.my/ Science/F4/Pg96_1.mp4 VIDEO Amniocentesis http://bukutekskssm. my/Science/F4/Pg96_2. mp4 VIDEO 96
5.3.3 5.3.4 Application of Genetic Research to Improve Quality of Life Genetic research has been carried out in various fields for the benefit of humans. Among the genetic researches that can increase the quality of human life are forensic science, gene therapy and genetic genealogy. Forensic Science Forensic science is one of the science and technological fields that carries out the study on crime investigation by identifying and confirming the chronology of an incident based on scientific evidence obtained. Forensic science plays an important role in the legal system in terms of preparing scientific based information through physical evidence analysis. During an investigation, the evidence is gathered at the place of the incident or from the person involved, analysed in the laboratory and then, the analytical result is presented in the court. Photograph 5.7 A forensic scientist examining fingerprints in the lab Figure 5.24 Steps in karyotyping The cells are transferred into a tube and centrifuged to concentrate the cell. The cells are transferred into a new tube containing fixative. The solution from the tube is taken and put onto a microscope slide where a dye is added so that the chromosome is clearer. The slide is observed under the microscope and a photograph is taken. The photograph of the chromosomes is cut and arranged to form a karyotype. This karyotype is used to detect any gene disorder disease. Another chemical is added to stop mitosis at the metaphase stage. Incubated for 2 or 3 days. Karyotyping A chemical is added to stimulate mitosis Foetal cell/ body tissue sample Genetics Chapter 5 97
Gene Therapy Gene therapy is a technique that is still at an experimental stage. It is aimed at repairing the mutated genes (abnormal/defective) that cause diseases such as cystic fibrosis, haemophilia and sickle cell anaemia. This technique is carried out by introducing a normal gene into the cell or tissue of the patient to replace the defective genes. Figure 5.25 The process of gene therapy 5.3.4 DNA and Forensic Science http://bukutekskssm.my/ Science/F4/Pg98_1 INFORMATION Gene Therapy http://bukutekskssm.my/ Science/F4/Pg98_2 Genetic Genealogy http://bukutekskssm.my/ Science/F4/Pg98_3 The patient’s stem cells are genetically modified. The normal genes are inserted into the virus. The modified virus is added to the patient’s stem cells. These cells are injected into the patient. The genetically modified cells produce desired protein or hormone. 6 2 3 4 5 The stem cells are extracted from the patient. 1 INFORMATION INFORMATION 98
Genetic Genealogy Genetic genealogy is a genetic accumulation study to determine the family pedigree or hierarchy, ancestry and its history. DNA tests are used in the study. Aim: To gather information and prepare a presentation about genetic research. Instructions: 1. Carry out this activity in groups. 2. Gather information about the application in genetic research such as the following: (a) forensic science (b) gene therapy (c) genetic genealogy 3. Gather the information above from various sources and present the outcome of your group discussion in class. ... ... Activity 5.4 The Effect of Genetic Research on Human Lives Genetic research is a very useful field in biology. The genetic research is a technique that is widely used to change the genes in medical and agricultural fields. There are a few advantages and disadvantages of genetic research that have emerged due to human behaviour. Let us carry out an activity to widen our knowledge and take into account the opinions of other friends about the advantages and disadvantages of genetic research in terms of economic, welfare, ethics, psychological and social. Aim: To debate on the effects of genetic research. Instructions: 1. Form two debate teams and invite a few teachers as adjudicators. 2. Debate the topic “Genetic research brings about more advantages than disadvantages” in terms of genetic screening based on the following aspects: (a) economy (insurance, job opportunities) (b) welfare (family institution) (c) ethics (d) psychology (e) social ... ... Activity 5.5 Debate Result Showcase 5.3.4 5.3.5 21st Century Skills 21st Century Skills Genetics Chapter 5 99
Formative Practice Formative Practice 5.3 1. What is mutation? 2. List three factors that cause mutation. 3. List the advantages and disadvantages of genetic research. 4. What problems will arise if ethics and values are not practised in genetic research? 5.4 Genetic Engineering Technology What is genetic engineering? Genetic engineering is the term used for genetic modification of an organism. Genetic engineering was first introduced around 1971-1973 and is known as genetic engineering science. Genetic engineering, is usually related to recombinant DNA, genetically modified organisms (GMO) and gene therapy. Recombinant DNA Technology Recombinant DNA technology is a technology that combines two different species to produce a new genetic characteristic. For example, DNA from a plant can be combined with a bacterial DNA, or a human DNA is combined with DNA from fungi, to create a hybrid DNA. A more detailed example is, the production of human insulin using bacteria. The production of this insulin can help people who suffer from diabetes mellitus. 1. DNA is cut with restriction enzyme 2. Plasmid DNA is cut with restriction enzyme 3. Recombinant DNA is introduced into a bacterial cell 4. Recombinant bacteria multiplying in fermentation tank and producing human insulin 5. Extraction and purification of human insulin Figure 5.26 The making of insulin through recombinant DNA technology 5.4.1 1. Human insulin gene 3. 4. 2. Human pancreatic cell Bacterial cell Plasmid DNA Recombinant bacteria DNA DNA Restriction enzyme Fermentation tank 5. Recombinant DNA Human insulin Human insulin Recombinant DNA Technology http://bukutekskssm.my/ Science/F4/Pg100.mp4 VIDEO 100
Genetically Modified Organism (GMO) Have you ever heard of the term GMO? GMO is the abbreviation for Genetically Modified Organism, that is an organism (plant, animal, bacteria or virus) which has been genetically modified for a particular purpose. This technology combines genes from two different species. This can be done by combining an animal gene with a plant gene or a bacterial gene. This will produce a genetically modified organism (GMO) with new characteristics that might not be possible to be produced through the traditional crossover process. The new organism has a few specific changes that are needed to increase commercial quality. A few plants that have been produced are plants that can resist pests or diseases. This application can be seen in paddy, maize and palm oil cultivation. Bigger fruits, higher nutritional value and resistance to pests and diseases are the characteristics of the product desired in the agricultural field. One of the benefits of crops produced through genetic modification is a reduction in the use of pesticides. Therefore, it can reduce environmental pollution. Photograph 5.8 Example of genetically modified food Brain Teaser Tease Is this a product of genetic engineering? Activity 5.6 Aim: To search for information about genetic engineering such as recombinant DNA, gene therapy and genetically modified organism. Instructions: 1. Carry out this activity in groups. 2. Gather information about recombinant DNA, gene therapy and genetically modified organism (GMO). 3. Do a multimedia presentation about the topics that were discussed. Multimedia Presentation 5.4.1 21st Century Skills Creation of an Insect Resistant Tomato Plant http://bukutekskssm.my/ Science/F4/Pg101.jpg INFORMATION Genetics Chapter 5 101
The Effects of Genetic Engineering Technology in Life Genetic engineering technology Aim: To debate on the effects of genetic engineering technology in life. Instructions: 1. Prepare the debate topic for your class. For example, the debate topic that can be considered is as follows: “Genetic engineering has more advantages than disadvantages” 2. Divide the class into two groups. One group is the proponent and the other is the opponent. 3. The debate can be carried out in the class or school hall. ... ... Activity 5.7 Debate 5.4.2 Disadvantages 1. The product of genetic changes causes allergy and side effects to the consumers that suffer from allergy. 2. Genetic research produces new species that can cause the original species to become extinct. 3. Can cause side effects such as mutation to the consumers. 4. Genetic modification may be used unethically to produce biological weapons that can harm humans. 5. Produce organisms that have high resistance to pesticides. Advantages 1. Identifies and determines hereditary diseases and consequently treat the disease. 2. Produces quality plants and livestock. 3. Produces plants and livestock that has high resistance towards diseases compared to the earlier generation. 4. Produces more plants that require shorter time to harvest. 5. Produces insulin and enzymes from bacteria that can improve human health. Figure 5.27 Advantages and disadvantages of genetic engineering technology 21st Century Skills 102
Ethics in Genetic Engineering Technology 1. Genetic research needs to be carried out with high integrity so that it is not morally and religiously wrong. 2. Genetic engineering technology can help humans in terms of health such as insulin synthesis to help humans who suffer from diabetes mellitus. 3. Genetic engineering technology can help humans in solving the problems of food shortage and crop damage. 4. Ethics and values must be practised when carrying out genetic engineering experiments so that it does not touch on religious and moral sensitivities. 5. To prevent the misuse of genetic engineering technology, laws and regulations should be enforced to educate the researchers on the development of genetic engineering. Formative Practice Formative Practice 5.4 1. What is meant by genetic engineering? 2. Explain the meaning and give one example of recombinant DNA, gene therapy and GMO. 3. State three advantages and disadvantages of genetic engineering technology. 5.5 Variation Look at your friends and teachers around you. Do they look the same or different? Why? The difference that exists among us is caused by variation. Variation is the differences in characteristics among individuals from the same species. Look at the example of variation in Photograph 5.9. Can you state the examples of variation that can be seen in this picture? Photograph 5.9 Variation among students 5.4.3 5.5.1 Genetics Chapter 5 103
5.5.1 Continuous Variation and Discontinuous Variation Continuous variation is the variation that shows differences that are not distinct or not clear between individuals in the same population. Examples of continuous variation in humans are height and body weight. Can you think of other examples of continuous variation that you can see among your friends and family members? Continuous variation is quantitative. These characteristics can be measured and are represented by a normal distribution curve. Look at the normal distribution graph in Figure 5.28 below. Continuous variation is determined by genes but can also be influenced by environmental factors. As an example, the skin colour of an individual is determined by genes that are inherited from his mother and father. However, the individual can have different skin colour when he stays at two different locations. 1 0 145-149 150-154 155-159 160-164 165-169 170-174 175-179 180-184 2 Number of students 3 4 5 6 7 8 9 Height (cm) Figure 5.28 Continuous variation Discontinuous variation is the variation that shows differences that are distinct or very clear between individuals of the same population. Examples of discontinuous variation in humans are the ability to roll the tongue, types of fingerprints, earlobes and blood groups. Can you think of other examples of discontinuous variation that you can see among your friends and family members? 104
The graph for discontinuous variation is in discrete shape. The bar chart is used to represent discontinuous variation. Discontinuous variation is qualitative. Discontinuous variation is determined by genetic factor only. Hence, the traits for discontinuous variation can be inherited from one generation to the next generation, and they are not influenced by environmental factors. Photograph 5.10 An example Figure 5.29 Discontinuous variation of discontinuous variation (Source: National Blood Centre) Aim: To investigate the type of variation for height and body mass among the students. Material: Graph paper Apparatus: Measuring tape, weighing machine Instructions: 1. Measure the height of every student in the class. 2. Record the height data in the table below according to the height range of the students. 3. Plot a histogram of the number of students against the height range. 4. Repeat steps 1 to 3 for body mass. Result: Height (cm) 130 – 134 135 – 139 140 – 144 145 – 149 150 – 154 155 – 159 160 – 164 165 – 169 170 – 174 Number of students Activity 5.8 5.5.1 Blood group A B AB O Number of individuals (a) Unable to roll the tongue (b) Able to roll the tongue Genetics Chapter 5 105
Body mass (kg) 35 – 39 40 – 44 45 – 49 50 – 54 55 – 59 60 – 64 65 – 69 70 – 74 75 – 79 Number of students Questions: 1. What is the frequent height and body mass range? 2. What is the shape of the height and body mass histograms that you have plotted? 3. Is there any difference that is distinct between the height and body mass of students in the class? Activity 5.9 Aim: To investigate the type of variation for the ability to roll the tongue among students. Material: Graph paper Instructions: 1. Gather information of those who are able and not able to roll their tongue in the class. 2. Record the data in the table below. 3. Plot a bar chart of number of students against their ability to roll their tongue. Result: Characteristic Ability to roll the tongue Trait Able Unable Number of students Questions: 1. What is the shape of the bar chart that you have plotted? 2. Is there any distinct difference between the ability to roll the tongue among the students in the class? 5.5.1 106
Aim: To gather information about variation. Instructions: 1. Carry out this activity in groups. 2. Gather information about: (a) factors that cause variation (b) the importance of variation 3. Record the information on a flip chart paper. 4. Put up your group’s work on the classroom wall. 5. A member from each group will present to other groups. ... ... Activity 5.10 Gallery Walk Figure 5.30 Factors that cause variation Factors that cause variation Factors that Cause Variation Can you state the factors that cause variation? Let us do the following Activity 5.10 to gather the information. 5.5.1 Genetic factor Environmental factor Crossing over between homologous chromosomes during meiosis enables the exchange of genetic materials and produces a new genetic combination. Independent assortment of chromosomes produces gametes that have different genetic information. Random fertilisation between male and female gametes produces zygotes with different genotype combination. Chromosome and gene mutations produce new phenotypes due to changes in genetic information. Environmental factors such as pH, sunlight, temperature, water, climate and nutrition can cause changes in the characteristics of organisms. For example, – a person will have dark skin colour if he is often exposed to sunlight. – eating excessively will make a person fat. – the Hydrangea sp. flower is blue if planted in acidic soil and pink in alkaline or neutral soil. 21st Century Skills Genetics Chapter 5 107
Importance of Variation Formative Practice Formative Practice 5.5 1. What is meant by variation? 2. (a) Name two types of variations. (b) Compare and contrast both types of variations that you stated in question 2(a). 3. State two genetic factors that cause variation. 4. How does environmental factor causes variation? Explain it by providing suitable examples. 5. State three importance of variation. 5.5.1 Variation in organisms enables the organisms to adapt themselves to their environment. Individuals with different characteristics from the majority group are able to withstand, adapt and survive with the changes in the environment. If all individuals are the same, they will become extinct when a drastic change happens in the environment. Variation enables us to easily differentiate and recognise each individual in the same species. Variation allows natural selection, that is, an organism with suitable characteristics will continue to live, whereas an organism with less suitable characteristics will become extinct. The evolution of organism occurs through natural selection. Variation helps organisms to camouflage in order to protect themselves from predators. Variations in animals and plants can increase their value. For example, as a result of genetic engineering and selective breeding, animals and plants with new genetic characteristics can be produced according to the characteristics desired. This can increase the quality and quantity of the product. 108
GENETICS Inheritance Variation Mutation Cell Division Mitosis Importance DNA Meiosis Importance Continuous Discontinuous Mechanism of inheritance Genetic Engineering Technology Type of technology Ethics Effects Chromosome mutation Gene mutation Gene disorder diseases Genetics Chapter 5 109
After studying this chapter, you are able to: 5.1 Cell Division Explain gene, deoxyribonucleic acid (DNA) and chromosomes in the nucleus. Compare and contrast mitosis and meiosis. Justify the importance of mitosis and meiosis. 5.2 Inheritance Explain inheritance in humans. Communicate the inheritance mechanisms. 5.3 Mutation Describe the definition of mutation and types of mutations. Explain with examples the factors that cause gene mutation and chromosome mutation. Explain with examples gene disorder diseases with their characteristics and their screening method. Discuss genetic research application to increase living quality. Debate the effects of genetics research on human life. 5.4 Genetic Engineering Technology Justify genetic engineering technology. Debate the effects of genetic engineering technology in life. Justify ethics in genetic engineering technology. 5.5 Variation Communicate continuous variation and discontinuous variation. Self-reflection Self-reflection Summative Practice Summative Practice 5 1. (a) Figure 1 shows the structure of a chromosome. P Figure 1 (i) Name the structure marked P. Objective Questions http://bukutekskssm. my/Science/F4/Q5 QUIZ 110
(ii) State three basic components that form the structures that you named in question 1(a)(i). (b) How many chromosomes can be found in the human body cell? (c) Explain the difference between autosome and sex chromosome. 2. Figure 2 shows a phase in the cell division process. Figure 2 (a) State the phase shown in Figure 2. (b) At this phase, explain the behaviour of chromosomes. (c) Name the process that occurs at this phase. Explain its impact on organisms if this process does not occur. (d) State the animal cell that carries out the process of cell division as in Figure 2 above. 3. Figure 3 shows two stages in a cell that undergoes mitosis. P Q Figure 3 (a) Name stage P. (b) State the behaviour of chromosomes during stage Q. (c) Name an organ in humans and an organ in plants that undergo mitosis. Mind Challenge Challenge 4. Figure 4 shows the karyotype that is analysed after Mrs K undergoes amniocentesis. (a) What is the probability that causes Mrs K to undergo this procedure? (b) (i) What is the name of the disease that will be suffered by the foetus in Mrs K’s womb? (ii) What is the sex of the foetus? 1 2 3 4 5 6 13 14 15 16 19 20 21 22 17 18 7 8 9 10 11 12 XY Figure 4 Genetics Chapter 5 111
Support, Movement and Growth Endoskeleton Exoskeleton Hydrostatic skeleton Support Ecdysis Skeletal system Axial skeleton Appendicular skeleton Cartilage Tendon Muscle Centre of gravity Keywords 6 Chapter 112
Animal and Human Movement Cheetah is the fastest terrestrial animal on Earth. Cheetah can move from 0 to 96 km per hour in just three seconds. Do you know who is the fastest man on Earth? The title for 'The Fastest Man on Earth' is held by Usain Bolt from Jamaica who broke the world record for the 100-metre sprint in 9.58 seconds. How do animals and humans move? Let us learn more about this. Anda akan belajar tentang: support, movement and growth in animals human movement and growth support, growth and stability in plants Digest Science What is the advantage of an endoskeleton compared to an exoskeleton? Why is an exoskeleton not found in insects such as cockroaches? What is the type of skeleton found in the earthworm that provides support to its body? What are the factors that affect the stability of animals? What kind of support system can be found in humans and plants? You will learn about: 113 Support, Movement and Growth Chapter 6
6.1 Support, Movement and Growth in Animals Type of Support in Animals What is the support system for animals? Skeleton is the support system for all types of animals. There are three types of support for animals, that are, endoskeleton, exoskeleton and hydrostatic skeleton. Endoskeleton Endoskeleton is the type of support for all vertebrates including humans. Endoskeleton is made up of internal bones and cartilage. Endoskeleton plays a role in supporting the body weight, protecting the internal organs and maintaining the body shape. Besides that, endoskeleton also becomes the basic attachment for muscles to move body parts. backack Vertebrates consist of fish, amphibians, reptiles, birds and mammals. Photograph 6.1 Examples of animals that have endoskeleton Photograph 6.2 Examples of animals that have exoskeleton Brain Teaser Tease What is the type of skeleton in a snake? Endoskeleton or hydrostatic skeleton? Exoskeleton Exoskeleton is the type of support for most invertebrates. Exoskeleton consists of an outer layer of waxy chitin or shell. Exoskeleton functions to support the body weight, maintain body shape and support internal organs of animals. Besides that, exoskeleton is also the base for muscle attachment. Crocodile Fish Frog Cat Crab Scorpion Spider Prawn 6.1.1 Eagle 114
Photograph 6.3 Examples of animals that have a hydrostatic skeleton Hydrostatic skeleton Some invertebrates with soft bodies such as worms do not have any bones in their bodies. These animals are supported by a hydrostatic skeleton. The hydrostatic skeleton consists of a muscular wall that encloses the body cavity that is filled with fluid. The fluid exerts pressure on the muscular wall of the body in all directions causing the animal's body to be firm. This hydrostatic skeleton maintains and controls the animal's body shape. Hydrostatic skeleton also plays a role in the movement of the animal. Activity 6.1 Aim: To prepare a multimedia presentation on the types of supports in animals, that are, exoskeleton, endoskeleton and hydrostatic skeleton. Instructions: 1. Carry out this activity in groups. 2. Gather information from various sources such as books, video and the Internet about support and movement of animals. 3. Create a multimedia presentation on: (a) types of skeleton (b) the function of types of skeleton mentioned in (a) (c) examples of animals with each type of skeleton 4. Present the multimedia presentation to your friends and teacher. Multimedia Presentation Exoskeleton Size with Growth Growth can be measured and observed by plotting a graph of growth unit against time. This graph is called the growth curve. Growth unit can be used to measure height (cm), volume (cm3 ), wet mass (g) and dry mass (g). The growth curve that is formed shows growth phases and growth rate undergone by the organism. Leech Star fish Jelly fish Earthworm 6.1.1 6.1.2 21st Century Skills 115 Support, Movement and Growth Chapter 6
The growth curve of all organisms basically is sigmoid in shape. It is different according to the type of organism. However, the growth curve of animals with exoskeleton is different and unique. The growth curve of the animals with exoskeleton such as the cockroach and grasshopper can be seen in stages. This is because the exoskeleton of these types of organisms is made up of hard chitin and it is unable to expand. These characteristics will prevent the growth of the animals that have exoskeleton such as the prawn, beetle, crab and grasshopper. To overcome this problem, the animals will shed the exoskeleton repeatedly until they reach adulthood. The process of shedding the skin is called ecdysis. During the ecdysis process, a new and soft exoskeleton is formed under the old exoskeleton. Figure 6.2 shows the growth curve of animals that have an exoskeleton. Figure 6.2 Growth curve of animals with exoskeleton Figure 6.1 Sigmoid-shaped growth curve Photograph 6.4 The insect sheds the hard exoskeleton During ecdysis, the animals with exoskeleton will suck in air to expand their bodies. The action of sucking air will break the previous exoskeleton that is hard. A rapid growth will occur to increase the size of the organism before the new exoskeleton hardens. 6.1.2 Old exoskeleton Time Growth Time (days) Body length (cm) I II III IV Egg Insect moults its skin (ecdysis) I – V are the nymph stages Adult V The vertical part shows growth that occurs dramatically. The horizontal part (I, II, III, IV, V) shows the zero growth stage (no growth occurs) and it is called the instar. A new skeleton that is soft is formed below the old skeleton. 116
Animals with exoskeleton will always undergo a few stages of ecdysis before reaching adulthood. This ecdysis stage causes the animals growth curve graph to be step-shaped. At the nymph stages, the animals will eat a lot to build new tissues and increase their weight. A hormone will control every stage of the ecdysis. Aim: To study the growth curve of animals with exoskeleton. Apparatus: Ruler Procedure: 1. Observe the five grasshopper nymphs and an adult grasshopper in the table below. Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Grasshopper A B C D E Adult 2. Measure the length of grasshopper nymph A (from the head to the end of the abdomen) using a ruler. 3. Record the length of nymph A in the table below. 4. Repeat steps 2 and 3 using the pictures of the grasshopper nymphs B, C, D, E and the adult grasshopper. Observation: Day Length of the grasshopper (cm) 1 2 3 . . . . . 30 Questions: 1. Plot the growth curve of the grasshopper. 2. Why does the grasshopper growth curve have such pattern? 3. Explain the metamorphosis process of the grasshopper based on the growth curve. Activity 6.2 The growth curve graph of animals with an exoskeleton is step-shaped. If you remember a ladder, you will remember the graph for insect growth. 6.1.2 Inquiry 21st Century Skills 117 Support, Movement and Growth Chapter 6
Relating the Hydrostatic Skeleton with Movement How does an earthworm move? Let us see how the hydrostatic skeleton helps an earthworm with its movement. Movement of Jellyfish http://bukutekskssm.my/Science/ F4/JellyfishMovement.mp4 6.1.3 The antagonistic (opposing) action of the circular muscles and longitudinal muscles exerts a hydrostatic pressure on the fluid in the earthworm body. When the earthworm body becomes thinner and longer, the hydrostatic pressure transfers the fluid in its body to the rear end of the body. What would happen to the fluid when the earthworm body thickens and shortens? The body fluid will be transferred to the part shortened by the hydrostatic pressure causing the rear of the earthworm to be stretched to the front as shown in Figure 6.5. The earthworm has a hydrostatic skeleton, which means its body cavity is filled with fluid. The earthworm moves on land with the aid of chaetae, that is, the bristles found at the side of its body. There are two types of muscles on the walls of the earthworm’s body, known as the circular muscles and longitudinal muscles as shown in Figure 6.3. The muscles in the earthworm also act antagonistically (opposing). When the circular muscles contract, the longitudinal muscles relax causing the earthworm body to become thin and long. When the longitudinal muscles contract and circular muscles relax, the earthworm body will become thicker and shorter. VIDEO 118
Figure 6.3 Hydrostatic skeleton in the earthworm Figure 6.4 The arrangement of the circular muscles and longitudinal muscles in the earthworm 6.1.3 Longitudinal muscles contract Posterior Anterior Rear end Front end Chaetae Circular muscles relax Circular muscles contract Longitudinal muscles relax fi Otot lingkar pada hujung anterior mengecut fi Otot membujur mengendur fi Segmen badan memanjang fi Otot membujur mengecut manakala otot lingkar mengendur fi Badan cacing tanah memendek fi Keta mencengkam tanah fi Hujung posterior ditarik ke hadapan fi Pengecutan dan pengenduran otot dari anterior ke posterior secara berselang seli membolehkan cacing tanah bergerak ke hadapan Fluid-filled body cavity Chaetae Longitudinal muscle Circular muscle Figure 6.5 The way the earthworm moves Chaetae Anterior Key: Direction of movement Wave of contraction Front end Posterior Rear end • The earthworm moves with the aid of the contraction and relaxation of the circular and longitudinal muscles that take place antagonistically from the anterior part to the posterior part. • When the longitudinal muscles contract and the circular muscles relax, the segments on the body of the earthworm will shorten and thicken. The chaetae at this segment of the body will grip the ground. • At the same time, the other segments will become longer and thinner. This occurs because the circular muscles at these segments contract and the longitudinal muscles relax. The chaetae at these segments will release the grip to allow the body of the earthworm to lengthen and move forward. 119 Support, Movement and Growth Chapter 6
Activity 6.3 Aim : To prepare a multimedia presentation to explain the hydrostatic skeleton. Instructions: 1. Carry out this activity in groups. 2. Gather information from various resources such as books, videos and Internet related to hydrostatic skeleton and movement. 3. Prepare a multimedia presentation on hydrostatic skeleton. 4. Find and share information on the role of fluid pressure in the body cavity in the movement of animals such as the worm and the jellyfish. 5. Present the multimedia presentation to your friends and teacher. Science Science Gallery The backbone of four-legged terrestrial animals such as the camel and the horse curves up or down. This condition gives stronger support to the muscles attached to the backbone. The curvature enables the backbone to withstand the gravitational force that acts on the animals. The Functions of the Endoskeleton in Animals Vertebrates that have endoskeleton are divided into terrestrial vertebrates, aquatic vertebrates and birds. In this subtopic, we will learn the functions of the endoskeleton in all three types of vertebrates. The skeletons of these animals are different according to the habitat of the vertebrates. Terrestrial Vertebrates Terrestrial vertebrates need a strong and firm skeleton to support the body. These animals have a big skeletal frame that is compatible to their body size. The body weight of the terrestrial vertebrates is supported especially by the pectoral girdle and pelvic girdle. An elephant needs a strong pectoral girdle and pelvic girdle to support its body weight. Both these girdles are joined with the legs as shown in Figure 6.6 below. Figure 6.6 Endoskeleton of an elephant Multimedia Presentation 6.1.4 Pectoral girdle Pelvic girdle 21st Century Skills 120
Figure 6.8 Endoskeleton of a bird Activiy 6.4 Aim: To gather information on differences in the functions of the endoskeleton of terrestrial vertebrates, aquatic vertebrates and birds. Instructions: 1. Carry out this activity in groups. 2. Gather information from various resources such as books, videos and the Internet. 3. Prepare a multimedia presentation on: (a) the differences in each skeleton in terrestrial vertebrates, aquatic vertebrates and birds (b) the examples of animals for each type of skeleton 4. Present the multimedia presentation to your friends and teacher. Multimedia Presentation 6.1.4 Aquatic Vertebrates Aquatic vertebrates have a smaller endoskeleton compared to their body. The pectoral girdle and the pelvic girdle of the aquatic animals are small and weak. Aquatic vertebrates such as the whale can grow larger than the size of their skeleton. This is because the weight of the aquatic animals is supported by the buoyancy force. Birds A bird has the bone structure that is adapted for flying. The flat and wide sternum bone (breast bone) of the bird functions as a place for the attachment of muscles for flight. The bones of the bird are also hollow and light. Besides, the size of a bird’s skull is small compared to other animals' skull and this makes it easy for birds to fly. 21st Century Skills Pectoral girdle Pelvic girdle Figure 6.7 Endoskeleton of a whale Sternum 121 Support, Movement and Growth Chapter 6
Brain Teaser Tease A baby has 275 bones at birth, whereas an adult has 206 bones. Why does this difference occur? The Human Skeletal System The human skeleton is made up of 206 bones of various sizes and shapes. The human skeleton can be divided into two parts, that are the axial skeleton and the appendicular skeleton. The axial skeleton consists of the skull, the vertebral column, the sternum and the ribs. The appendicular skeleton consists of the pectoral girdle, the upper limbs, the pelvic girdle and the lower limbs. Figure 6.9 The human skeleton Axial skeleton Cranium Vertebral column The vertebral column consists of 33 small bones or vertebrae. These bones that are connected form a strong and flexible column. This vertebral column has a very important function, that is to protect the spinal cord. Front view Side view Skull 6.1.5 3D Model The human skull consists of two parts, that are the cranial bones and the facial bones. The function of the cranial bones is to protect the brain. Facial bones serve to provide the basic shape or the framework for the face and also to support the teeth. Ribs and sternum The human ribs consist of 12 pairs of ribs that are joined to the thoracic vertebra at the back. Seven pairs of ribs are attached to the sternum directly and three more ribs are indirectly connected by cartilage. Two more pairs (the last two) hang free. The sternum and the ribs function to protect the main organs, that are the heart and the lungs. Sternum Thoracic vertebrae 1 2 3 4 5 6 7 8 9 10 11 12 122
The pelvic girdle is connected to the axial skeleton. The pelvic girdle is formed from a pair of hip bones. The pelvic girdle supports weight, protects the bladder and the reproductive organs. Pectoral girdle There is a pair of pectoral girdles in the human body. The pectoral girdle connects the upper limbs to the axial skeleton. The pectoral girdle consists of the clavicle and the scapula. The upper limb consists of the humerus, radius, ulna, carpus, metacarpus and phalanx. The end of the humerus, that is ball-shaped, is attached to the pectoral girdle. The lower end of the humerus is attached to the radius and ulna. The radius and ulna are attached to the carpus bones to form the wrist. The metacarpus bones form the palm and are attached to the carpus bones. The phalanx bones that form the fingers are attached to the metacarpus bones. Appendicular Skeleton Clavicle Scapula Humerus Carpus Metacarpus Phalanx Radius Ulna Femur Tibia Phalanx Metatarsus Patella Fibula Tarsus Upper limb Pelvic girdle Lower limb The lower limb consists of the femur, tibia, fibula, tarsus, metatarsus and phalanx. The upper end of the femur that is ball-shaped is attached to the pelvic girdle. The lower end of the femur is attached to the tibia and fibula. The tibia and fibula are the bones of the calf. The lower ends of the tibia and fibula are attached to the tarsus, that is, the ankle. The tarsus is attached to the metatarsus bones to form the foot. The metatarsus is attached to the phalanx or the bone of the toe. 6.1.5 123 Support, Movement and Growth Chapter 6
HAIKAL Aim: To identify and name the bones in the human skeleton. Instructions: 1. Carry out this activity in groups. 2. Take the diagram of the human skeleton from your teacher. 3. Take turns to label the human skeletal system. 4. Put up the diagram on the notice board in your classroom. ... ... Activity 6.5 Round Table Comparing the Strength of the Compact Bone with the Hollow Bone Terrestrial vertebrates such as elephants have big, compact and strong bones. This is because the whole of its body weight is supported by the endoskeleton. Birds have hollow bones to enable them to fly. Hollow bones have several advantages: (a) light and strong (b) allow the vertebrates to move more quickly (c) need less calcium and phosphorus Which bone is stronger? The compact bone or the hollow bone? I am not sure. Let us do the experiment below. Aim: To compare the strength of the compact bone with the hollow bone. Problem statement: Is the hollow bone stronger than the compact bone? Hypothesis: The hollow bone is stronger than the compact bone. Variables: (a) manipulated: Type of cylinders (hollow or compact) (b) responding: Number of textbooks that can be supported by the cylinders (c) constant: Length and diameter of the cylinder Materials: A4 paper, cellophane tape, box covers Apparatus: Textbooks, scissors Procedure: 1. Make a hollow cylinder with a diameter measuring 2.5 cm. Stick the upper and lower ends of the paper roll with cellophane tape. Make three more similar rolls. 2. Stick each cylinder at the corners of the box cover and name the structure as table model A as in Figure 6.10(a). 3. Make a compact cylinder with a diameter measuring 2.5 cm. Stick the upper and lower ends of the paper roll with cellophane tape. Make three more similar rolls. Experiment 6.1 6.1.6 21st Century Skills 124
4. Stick each cylinder at the corners of the box cover and name the structure as table model B as in Figure 6.10(b). Hollow cylinders Box cover Compact cylinders Model A Model B Figure 6.10(a) Figure 6.10(b) 5. Place the textbooks one by one on top of each table model A and B until the paper rolls bend. Result: Cylinder Number of textbooks that can be supported Hollow Compact Conclusion: Is the hypothesis of this experiment accepted? What is the conclusion of this experiment? Questions: 1. What is represented by: (a) the paper rolls of table model A? (b) the paper rolls of table model B? 2. Suggest two advantages of the support system that is represented by the paper rolls of table model A. Support Systems and the Factors of Stability in Animals A good support system enables an animal to move more smoothly and efficiently. The stability of an animal is different according to the point of equilibrium of the animal's support system. Between these animals, which is more stable? Can you explain? NADIA Photograph 6.5 Two animals with different points of equilibrium 6.1.6 6.1.7 125 Support, Movement and Growth Chapter 6
The centre of gravity refers to the point of equilibrium of a support system or an object. It is the point where the weight of the support system or the object acts to balance the position of the support system or the object. The position of the centre of gravity plays an important role in animals. Generally, animals that have a lower centre of gravity are more stable than animals that have a higher centre of gravity. For example, the giraffe is less stable when standing because of the higher centre of gravity compared to the tortoise and the crocodile that are stable naturally as they have a lower centre of gravity. Figure 6.11 Factors that affect the stability of an object Brain Teaser Tease Can you explain why Formula 1 cars are designed lower in height than ordinary cars? Stability is the ability of an object to maintain its original position. There are two factors that affect the stability of an object or a support system that is: 1. Centre of gravity – An object that has a higher centre of gravity is less stable compared to an object that has a lower centre of gravity. 2. Base area – An object with a big base area is more stable compared to an object with a small base area. 6.1.7 Photograph 6.6 Animals with different positions of centre of gravity Centre of gravity P is more stable than Q Base area R is more stable than S R S Base area Base area Factors that affect the stability of an object Q P Centre of gravity Centre of Gravity Factors that Affect Stability Giraffe Tortoise Crocodile 126
Among the challenges faced by tall animals is to maintain the stability in their daily lives. As an example, the tall giraffe faces difficulty in drinking water compared to other animals. To overcome this problem, the giraffe has to increase the base area of the support system by spreading its legs as shown in Photograph 6.7 below. This action will lower the centre of gravity of the giraffe so that it does not fall easily. Photograph 6.7 The way the giraffe maintains the stability of its body Photograph 6.8 The way the kangaroo maintains the stability of its body (Source: Biology, a functional approach, 4th edition) The same condition is also faced by the kangaroos. This is because kangaroos jump and stand using two hind legs. The front feet or forelegs of the kangaroo are not used for standing. This condition causes the kangaroo to become unstable and to fall easily when not moving. To overcome the problem, the kangaroo uses its tail as the support system to prevent itself from falling. The tail is used as a strut to increase the base area of the kangaroo when not moving. 6.1.7 Tail as a strut Foreleg Hind leg Solutions for Animals with Stability Problem 127 Support, Movement and Growth Chapter 6
Formative Practice Formative Practice 6.1 1. State the importance of a support system. 2. Explain the meaning of exoskeleton, endoskeleton and hydrostatic skeleton. 3. Explain the growth curve of an animal with exoskeleton. 4. What is the meaning of ecdysis? 5. State the two factors that affect the stability of an animal. 6. (a) What is centre of gravity? (b) What is the relationship between the height of an object and its stability? The skeletal system and muscles enable humans to move. The contraction and relaxation of the skeletal muscles produce movement. The skeletal muscles act in pairs and in opposite direction to one another. Each muscle pair that acts in opposite direction is known as antagonistic muscles. The movement of these muscles enables humans to walk, jump, run, swim, crawl and carry things. Figure 6.12 shows the antagonistic movement of muscles. Figure 6.12 Antagonistic movement of muscles to bend and straighten the arm Functions of Joints and Muscles in Movement The joint is the meeting place between two or more bones. The joint that allows the limbs to move is called the movable joint (for example, the hinge joint at the elbow) whereas the joint that does not allow the limbs to move is called the immovable joint (for example, the joint at the skull). Figure 6.13 shows the example of hinge joint at the arm. The muscles that are involved in the hinge joint movement are the biceps and triceps. 6.2 Human Movement and Growth 6.2.1 Biceps contract Triceps relax Arm bends 3D Model Biceps relax Triceps contract Arm straightens 128
Science Science Gallery The ligament is an elastic, flexible and strong connective tissue that joins two bones. This characteristic of being strong and elastic enables the ligament to hold and connect the bones and allow movement. Muscles are tissues that are formed by aligned fibres. The muscle cell contains mitochondria that generates energy for contraction and relaxation of the muscles. Figure 6.13 Example of the movable joint (hinge joint) Figure 6.14 Functions of the synovial fluid, cartilage and tendon at the joint The synovial fluid functions to lubricate and provide nutrients to the cartilage. The synovial fluid also acts as a lubricant in the joint. The cartilage or cartilaginous bone acts as a cushion and protects the joint. The cartilage functions to reduce friction. The tendon is a connective tissue that connects muscles to the bone. The tendon consists of a combination of fibres that are strong and inelastic. The muscle contraction force will be transferred to the bone through the tendon. Triceps Ligament Tendon Hinge joint Radius Ulna Biceps Bone Muscle 6.2.1 129 Support, Movement and Growth Chapter 6
Science Career Orthopaedist Orthopaedist is a specialist doctor who treats injuries such as bone fractures, backbone defects or bone deterioration such as osteoporosis. The orthopaedist helps patients to undergo the skeletal muscle recovery process. Chiropractor Chiropractor is a practitioner of complementary medicine that is related to diagnosis and treatment of mechanical muscle system, skeleton and backbone disruptions. Physiotherapist Physiotherapist is known as the medical limb rehabilitator or medical rehabilitation officer. Physiotherapist helps patients recover and ensures each patient’s physical function is at a high level. The Problems Related to Joints and Muscles in Daily Life Title: Problems related to joints and muscles in daily life. Related topic: Functions of joints and muscles in movement Suggested time period: 1 week Problem: Among the problems related to joints and muscles that occur frequently are the injuries to the joints and muscles caused by physical activities, and knee pain among the elderly. Based on this, discuss how these problems can be prevented. Resources: • Websites • Other related references such as journals related to medicine and balanced diet. Explain suitable ways or methods to prevent injuries to joints and muscles. The result can be presented in the form of PowerPoint. ... ... Activity 6.6 Problem-based Learning Human Growth Pattern Human growth is a process where changes occur in terms of size, total number of cells, weight, shape size, and body function. It is a permanent and irreversible process. This growth occurs due to the increase in number of cells in the body. Human growth occurs to the whole body and is different according to the sex and age. Figure 6.15 Human growth stages Infant Child Adolescent Adult Aged 6.2.2 6.2.3 21st Century Skills 130
Infancy The rate of growth is not as high as the rate of growth at the infancy stage. At this stage, the rate of growth of a male child is higher compared to that of a female child. Balanced diet is crucial at this stage for a balanced growth. Childhood At the early stage of teenage (13-15 years old), both genders undergo rapid growth. The male teenager will undergo slower growth compared to the female teenager. At this stage, the female teenager is usually taller and bigger compared to the male teenager. At the same time, secondary sexual characteristics for teenagers begin to develop. At the age of 16-18 years, the rate of growth will begin to decrease for the female teenager and will stop eventually. This is different with the male teenager where his growth will continue until the age of 18-20 years. Due to this, the male teenager usually looks bigger compared to the female teenager. Adolescence Old age At this stage, the human growth will come closer to a complete stop. Human body begins to shrink and muscle parts become smaller as well as the skin begins to dry. This stage is from 0-3 years. Male and female infants undergo the same growth. Their rate of growth is very high. At this stage, balanced diet is important for the infant's balanced growth. Human Growth Stage Adulthood At this stage, the adult male is taller and bigger than the adult female. This condition occurs because male growth has a longer duration compared to female growth. At this stage, human growth will become constant and nearly zero. This means that human growth stops except for certain parts such as the nails, skin and hair. 6.2.3 131 Support, Movement and Growth Chapter 6
CHEONG Let us look at the human growth curve. What is the shape of the curve? Science Science Gallery Premature aging or the “Progeria” disease is a type of disease that seldom occurs. This disease occurs at the child stage and causes a child to look like an adult. Science Science Gallery Puberty is a stage that occurs at the early adolescent stage. Secondary sexual characteristics begin to develop and become distinct, and sexual organs mature. Figure 6.16 Human growth curve (Source: Junior Biology, Learning Space Australia) 6.2.3 6.2.4 Age (year) Height (cm) Childhood Adolescence Adulthood Old age 0 3 13 20 65 Infancy Rapid growth Slow growth Rapid growth Minimal growth Negative growth (size of body reduces) Growth Pattern Between Males and Females The growth rate of males is different from the growth rate of females. From the infancy stage until early childhood stage, males and females grow at the same rate. Then, males grow a little more rapidly than females beginning at the age of 4. In females, puberty begins earlier, between the ages of 12 to 14. At this stage, females grow more rapidly than males; they are taller and heavier than males of the same age. Nevertheless, after the age of 14, males undergo rapid growth compared to females. The rate of human growth is rapid at the infancy stage. After that, the rate becomes slower at the childhood stage. The rate of growth becomes rapid again at the adolescence stage, and becomes slower once again when it reaches adulthood. This growth pattern forms an "S-shape" (sigmoid curve) as in Figure 6.16. The growth curve enables us to determine the rate of human growth at different stages throughout the growth of life. For humans, the growth will stop when it reaches maturity. 132
Figure 6.17 Growth curve for males and females Formative Practice Formative Practice 6.2 1. State two parameters that can be used to measure the human growth rate. 2. Explain the shape of the growth curve for males and females. 3. Describe briefly the effect of diet on growth rate. 4. How can the growth rate be measured? Support, Growth and Stability in Plants 6.3 Why you think plants require support? A support system will help plants to stand vertically to obtain sunlight. The support system ensures the leaves are exposed to sunlight to carry out photosynthesis. Support is also needed to accommodate the plant weight and provide strength to withstand wind. The main support for plants is the stem and root. The plant stem supports its own stem weight and also the weight of leaves, flowers and fruits. The root provides support to the plant by gripping the soil. There are also some plants that have roots on the soil to provide support. Science Science Gallery During the examination of babies and children at the health clinics or hospitals, characteristics such as the body mass, height and the diameter of the head are the normal measurements taken by the nurse or doctor to monitor their growth development. 6.2.4 6.3.1 Age (year) Height (cm) Males 0 2 50 70 90 110 130 150 170 190 4 6 8 10 12 14 16 18 Females Stem Root Photograph 6.9 The main support system in plants 133 Support, Movement and Growth Chapter 6
Support System of Terrestrial and Aquatic Plants Terrestrial Plants Terrestrial plants can be divided into: (a) woody plants (b) herbaceous plants (non-woody) Woody plants are usually big and tall such as the rambutan tree and angsana tree. The support system for woody plants is the hard, strong and tough woody tissue. This tissue is built from lignin, a tough and hard complex substance. Non-woody plants depend on stored water in the cells of the stem for support. These plants obtain their support from the turgidity of the cells. Non-woody plants are soft and they will wilt when they lack water. Some plants form a special structure to provide additional support, and some climb onto other supports to obtain sunlight. Additional supports in woody plants are the buttress roots, prop roots and stilt roots. For the non-woody plants, the additional supports are tendrils, clasping roots and hollow stems. Photograph 6.10 Characteristics that provide support to plants Buttress roots are found in big and tall trees such as the durian tree and angsana tree. Prop roots are roots that grow from stems or branches into the soil to support the plant. This type of roots is present in the banyan tree, pandan tree and fig tree. Stilt roots support mangrove plants living in swamps. Clasping roots hold onto another plant or structure for support. Clasping roots are found in orchid plants and money plants. Tendrils is a fine and coiled structure that wraps around other plants or objects for support. Tendrils are present in cucumber, bitter gourd and pumpkin plants. 6.3.1 134
Determining the Age of Woody Plants There are a few methods to determine the age of the woody plants. The most common method is to determine the growth rings that are present in the plant stem. Photograph 6.12 and Figure 6.18 show the methods to count the growth rings that are found in the trunk of woody plants. Aquatic Plants Aquatic plants do not have woody tissue for support, unlike the land plants. Aquatic plants obtain their main support from the water buoyancy force. Besides that, the aquatic plants also have stems and leaves that have aerenchyma tissue. The aerenchyma tissue which consists of thin-walled cells, form air spaces in the aquatic plants. The buoyancy of these plants is aided by the air spaces. For some aquatic plants, the plants swell and have hollow and big stems to increase the buoyancy force such as the water hyacinth and lotus. Photograph 6.12 A method to count the growth rings seen in the cut of a woody plant trunk 6.3.1 6.3.2 Photograph 6.11 Examples of aquatic plants (a) Water hyacinth (b) Lotus 1 2 3 4 5 6 7 Aerenchyma Tissue http://bukutekskssm. my/Science/F4/ Pg135.jpg INFORMATION First method 1. The selected tree is cut down. 2. The tree trunk is cut across as in Photograph 6.12. 3. The growth rings seen in the trunk are counted. 4. One ring represents one year of the tree's age. 135 Support, Movement and Growth Chapter 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 Figure 6.18 A method to count the growth rings found in the woody plant trunk that has been bored Science Science Gallery Tall woody trees such as timber trees (chengal tree) have buttress roots that grow extensively on the surface of the ground and the tap root that penetrates deep into the earth. The diameter of the trunk is usually big to ensure it is stable and strong. Relating the Support System and Stability in Plants A plant is said to be stable in its position if it does not fall easily. The plant stability is influenced by the centre of gravity and the base area. The lower the centre of gravity, the more stable the plant. Can you predict which is more stable in terms of the position of the centre of gravity, the bougainvillea or the durian tree? Second method 1. The tree is not cut but is bored using a special drill. 2. The tree is drilled to 75% of the drill depth or half the diameter of the tree. 3. The drill bit is removed and the growth rings are counted. 4. This method will save the tree from being cut. Aim: To study the relationship between the support system and the stability of plants. Materials: Balsam plant (herbaceous plant), lotus plant (aquatic plant), hibiscus plant (woody plant), A4 paper, pencil Instructions: 1. Carry out this activity in groups. 2. Study and gather information about the support system of the plants provided. 3. Relate how the support system of the plants help in their stability. 4. Create a portfolio based on the information gathered. 5. Present your findings in front of your friends. ... ... Activity 6.7 Result Showcase 6.3.2 6.3.3 21st Century Skills Determining the Age of a Tree http://bukutekskssm. my/Science/F4/ Pg136.mp4 VIDEO 136
Plant Growth Pattern Formative Practice Formative Practice 6.3 1. Why do plants require support? 2. What is the difference between the support of the terrestrial and the aquatic plants? Explain. 3. How does the herbaceous plant obtain its support? Aim: To study the growth pattern of a green bean plant. Problem statement: What is the growth pattern of a green bean plant? Hypothesis: The growth pattern of a green bean plant is sigmoid-shaped. Variables: (a) manipulated: Time (b) responding: Height of sprout (c) constant: Type of seed Materials: Green bean seeds, cotton wool, water Apparatus: Petri dish, pincers, ruler Procedure: 1. Immerse three green bean seeds in a Petri dish filled with water until they swell. 2. Keep the apparatus in a dark place for a night. 3. Transfer the green bean seeds into another Petri dish filled with wet cotton wool. 4. Measure the length of each green bean seed using a ruler. 5. Repeat step 4 every day for seven days and record the height of the green bean sprouts in the table. 6. Calculate the average height of the green bean sprouts and record in the table. 7. Plot a graph of height of the green bean sprouts (mm) against time (day). Result: Time (day) Height (mm) Sprout 1 Sprout 2 Sprout 3 Average 0 1 2 3 4 5 6 7 Conclusion: Is the hypothesis of this experiment accepted? What is the conclusion of this experiment? Questions: 1. Give a review about the shape of the graph that has been plotted. 2. Relate the growth of the sprout with the shape of the graph. Experiment 6.2 6.3.4 137 Support, Movement and Growth Chapter 6
Plant SUPPORT, MOVEMENT AND GROWTH Human Growth Movement Joint Muscle Injury Knee pain Exoskeleton Support system in terrestrial plants Support system in aquatic plants Relationship between support system and stability Growth pattern Terrestrial vertebrate Bird Animal Hydrostatic skeleton Aquatic vertebrate Function Problem Male Female Human growth pattern Endoskeleton 138
Summative Practice Summative Practice 6 1. Figure 1 shows the human skeletal system. R Figure 1 (a) (i) Name the structure labelled R. After studying this chapter, you are able to: 6.1 Support, Movement and Growth in Animals Explain with examples the types of support in animals. Relate the size of exoskeleton with growth. Relate hydrostatic skeleton with movement. Elaborate the function of endoskeleton in animals. Dissect the human skeletal system. Carry out an experiment to differentiate the strength of compact bones with hollow bones. Relate support system with animal’s stability. 6.2 Human Movement and Growth Explain the functions of joints and muscles in movement. Generate ideas regarding problems with joints and muscles in daily life. Explain the pattern of human growth. Compare and contrast the growth pattern between males and females. 6.3 Support, Growth and Stability in Plants Explain the support systems of terrestrial and aquatic plants. Determine the age of woody plants. Relate the support system with stability in plants. Carry out the experiment to determine a plant’s growth pattern. Self-reflection Self-reflection Objective Questions http://bukutekskssm. QUIZ my/Science/F4/Q6 139 Support, Movement and Growth Chapter 6