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An introduction to HKDSE Biology •Syllabus Basics and Important Notes HKDSE Biology curriculum framework: About SBA School-Based Assessment (SBA) is a component of the HKDSE examination, for both the Biology and Combined Science (Biology). It refers to assessments administered in schools and marked by the students’ own teachers. 1 How much does SBA account for? (a) Biology The SBA mark accounts for 20% of the final subject mark. The SBA comprises the assessment of: (1) practical related tasks which refer to students’ laboratory work and field work, and (2) non-practical related tasks (assignments). The examination and weightings Component of HKDSE Outline Paper 1 Compulsory Part Weighting Duration 60% 2.5 hours 20% 1 hour 20% S5–S6 Public examination Paper 2 Elective Part School-based (SBA) assessment Practical related tasks and non-practical related tasks (assignments) Starting from the 2014 HKDSE, students will be assessed on both the practical and non-practical related tasks in the SBA. The marks for practical related tasks will constitute 14% and those for non-practical related tasks will constitute 6% of the final subject mark. Practical related tasks Ability area A B Weighting 8% 12% S5 1 1 S6 1 1 Minimum number of assessments Moderation Assignments_non-practical related tasks u information searching u report writing u survey studies u field-studies u site-visit reports u pages designing posters/pamphlets/web u writing articles u building models u developing multimedia artefacts Curriculum emphasis and Generic skills to be demonstrated and assessed in assignment : Chapter 1 Biology: Exploring Life • Biology • Is the scientific study of life • Biology’s Most Exciting Era • The phenomenon we call life • Defies a simple, one-sentence definition Figure 1.1 • We recognize life • By what living things do…..??? • Some properties of life (a) Order (b) Evolutionary adaptation (c) Response to the environment (d) Regulation (e) Energy processing (f) Growth and development Figure 1.2 (g) Reproduction • Concept 1.1: Biologists explore life from the microscopic to the global scale • The study of life • Extends from the microscope scale of molecules and cells to the global scale of the entire living planet A Hierarchy of Biological Organization • The hierarchy of life • Extends through many levels of biological organization • From the biosphere to organisms 1 The biosphere Figure 1.3 • From cells to molecules 9 Organelles 1 µm Cell 8 Cells Atoms 10 µm 7 Tissues 50 µm 6 Organs and organ systems Figure 1.3 10 Molecules • An ecosystem consists of all the organisms living in a particular area – As well as the nonliving environmental components • All the living organisms in an ecosystem – Make up a community 2017/5/24 18 • A population – Consists of a localized group of individuals of a species • An individual living entity – Is an organism 2017/5/24 19 • The hierarchy continues downward with Organ systems Organs Tissues Cells Organelles Molecules 2017/5/24 20 1.2 Living organisms and their environments form interconnecting webs • Ecosystems are characterized by the cycling of chemical nutrients from the atmosphere and soil – To producers to consumers to decomposers and back to the environment which contains both living and nonliving components 2017/5/24 21 ENVIRONMENT natural world: • the natural world affects an organism survival • An organism have an impact environment – especially human 2017/5/24 22 on the 1.2 Living organisms and their environments form interconnecting webs • Two major processes are at work in an ecosystem: 1. The recycling of chemical nutrients 2. The flow of energy 2017/5/24 23 Energy Conversion • Activities of life require organisms to perform work, which depends on an energy source • The exchange of energy between an organism and its surroundings • Often involves the transformation of one form of energy to another Question • Explain how the photosynthesis of plants functions in both 1. the cycling of chemical nutrients 2. the flow of energy in an ecosystem. 2017/5/24 26 • Photosynthesis use light energy to convert carbon dioxide and water to make energy rich compounds/food, • making it the pathway for nutrients and energy for most organisms. It is the basis of the entire food chain for all living organisms. • Energy flows one-way through an ecosystem – From the sun to producers to consumers and exits as heat Sun Air Inflow of light energy O2 CO2 CO2 Chemical energy Producers Cycling of Chemical nutrients Decomposers H2O Soil Figure 1.2 Ecosystem 2017/5/24 Consumers 28 Loss of heat energy Question • Explain why cells are considered the basic unit of life They are the lowest level in hierarchy of biological organization at which properties of life actually appear. 2017/5/24 29 A Closer Look at Cells • The cell – Is the lowest level of organization that can perform all activities required for life Figure 1.5 25 µm The Cell’s Heritable Information • Cells contain chromosomes made partly of DNA, the substance of genes • Which program the cells’ production of proteins and transmit information from parents to offspring Sperm cell Nuclei containing DNA Egg cell Figure 1.6 Fertilized egg with DNA from both parents Embyro’s cells with copies of inherited DNA Offspring with traits inherited from both parents 1.3 Cells are the structural and functional units of life • A cell Is the basic unit of life that can perform all functions necessary for life including: 1. Regulate its internal environment 2. Take in and use energy 3. Respond to its local environment 4. Develop and maintain its complex organization 5. Divide to form new cells 2017/5/24 32 Two types of cells • Eukaryotic cells Contain membrane-enclosed organelles, including a DNA-containing nucleus • Prokaryotic cells Nucleus (contains DNA) Prokaryotic cell Eukaryotic cell Lack such organelles DNA (no nucleus) 25,000 Organelles Figure 1.3 2017/5/24 33 Question • What is the chemical basis of all life’s kinship / family relationship ? DNA / RNA is the genetic material for all living things 2017/5/24 34 UNITY AND DIVERSITY in Biological world 1.4 The unity of life: All forms of life have common features • DNA is the genetic information – For constructing the molecules that make up cells and organisms 2017/5/24 35 • Each species’ genetic instructions – Are coded in the sequences of the four building blocks making up DNA’s two helically coiled chains A C T A T A C C G T A G T Figure 1.4A 2017/5/24 A 36 DNA /RNA is the genetic code for ALL living things Genetic instructions are coded in the sequences of the four building blocks making up DNA. 2017/5/24 37 All organisms share a common set of features 1. Ordered structures 2. Regulation of internal conditions Figure 1.4B 2017/5/24 Figure 1.4C 38 3. Growth and development 4. Energy use –nutrition and respiration 5. Response to environmental stimuli 6. The ability to reproduce and evolve Figure 1.4D 2017/5/24 Figure 1.4E 39 1.5 The diversity of life can be arranged into three domains / superkingdom • Organisms are grouped (classified) into: – the prokaryotic 2 domains: • Bacteria and Archaea – the eukaryotic domain • 2017/5/24 Eukarya 40 SEM 3,250 • Domains Bacteria and Archaea SEM 25,000 Figure 1.5A Figure 1.5B 2017/5/24 41 • Domain Eukarya includes – Protists (protozoans and algae, falling into multiple kingdoms) – The kingdoms Fungi, Plantae, and Animalia 275 Kingdom Fungi Kingdom Animalia Protists (multiple kingdoms) Kingdom Plantae Figure 1.5C 2017/5/24 42 The three Domains of living things on Earth 1.6 Evolution explains the unity and diversity of life • Charles Darwin – Synthesized the theory of evolution by natural selection Figure 1.6A 2017/5/24 44 Fossils and Comparative Anatomy 45 unity and diversity in biological structures Concept Check Darwin proposed the theory of natural selection. 2017/5/24 47 Natural selection is an editing mechanism: That occurs when populations or organisms, having inherited variations, are exposed to environmental factors that favor the reproductive success of some individuals over others 1 Populations with varied inherited traits 2 Elimination of individuals with certain traits Figure 1.6B 3 Reproduction of survivors 2017/5/24 48 • All organisms have adaptations – That have evolved by means of natural selection Killer whale Pangolin Figure 1.6C 2017/5/24 49 Post-Darwin Evolution Evidence Molecular Evidence - Our increased understanding of DNA and protein structures has led to the development of more accurate evolutionary trees. 50 Did human descend from apes? Did human descend from apes? NO! according to to evolutionary theory, we are closed related and have a distant common ancestor Did human descend from apes? NO! according to to evolutionary theory, we are closed related and have a distant common ancestor The evolutionary tree of life The concept of evolution unites all living things and suggest that all living things might have a common ancestor Question • How does natural selection allow a population to adapt to its environment? On average, those organisms with heritable traits best suited for their local environment produce the largest number of offspring that survive and reproduce. This increases the frequency of these traits in the population. 2017/5/24 56 THE PROCESS OF SCIENCE 1.7 Scientists use two main approaches to learn about nature • Science – Is a way of knowing – Seeks natural causes for natural phenomena 2017/5/24 57 1. Discovery Science • In discovery science Scientists describe some aspect of the world and use inductive reasoning to draw general conclusions Inductive: LOGIC reaching a conclusion based on observation: generalizing to produce a universal claim or principle from observed instances 2017/5/24 58 2. Hypothesis-Based Science • In hypothesis-based science Scientists attempt to explain observations by testing hypotheses 2017/5/24 59 1.8 With hypothesis-based science, we pose and test hypotheses • Hypothesis-based science involves: Observations, questions, hypotheses as tentative answers to questions and Deductions leading to predictions, and then tests of predictions to see if a hypothesis is falsifiable 2017/5/24 60 Question • What is the difference between discovery science and hypothesis-based science? In the first, scientists make observations and describe objects and phenomena (inductive reasoning); in the second, they propose hypotheses, make deductions, and test predictions. 2017/5/24 61 Hypothesis Theory needing investigation: a tentative explanation for a phenomenon, used as a basis for further investigation The hypothesis of the big bang is one way to explain the beginning of the universe. 2017/5/24 62 Deduction •Drawing a conclusion: the process of drawing a conclusion from available information. •LOGIC reasoning: the forming of conclusions by applying the rules of logic to a premise 2017/5/24 63 A Case Study from Everyday Life • Deductive reasoning is used in testing hypotheses as follows – 2017/5/24 If a hypothesis is correct, and we test it, then we can expect a particular outcome 64 Figure 1.8A The hypothesis-driven scientific method (layer 1) Observations Question 2017/5/24 Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis 65 Figure 1.8A The hypothesis-driven scientific method (layer 2) Observations Question 2017/5/24 Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis 66 Figure 1.8A The hypothesis-driven scientific method (layer 3) Observations Question 2017/5/24 Hypothesis # 1: Dead batteries Hypothesis # 2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis 67 Five Steps of the scientific method 1. Observation come from others or results of earlier tests 2. Questions are asked about unclear aspects of the observations: How? Why? When? 3. Hypotheses are tentative explanation of a phenomenon phrased in such a way as to be testable. 4. Predictions are logical, testable outcomes of the hypotheses developed by the use of deductive reasoning. Predictions take the form of if (statement of hypotheses) is true, then (predictions). 5. Tests of prediction are performed to determine if the predictions are supported (fail to falsify) or falsified. 2017/5/24 69 On important quality of the hypotheses-based science A hypothesis must be testable. A hypothesis becomes credible when repeated attempts to disprove it fail. Hypothesis 2017/5/24 ---- theory ----- law 70 Controlled experiment -- one that is designed to compare an experimental group with a control group. • Ideally, the experimental and control groups differ only in the one factor the experiment is designed to test. • Without the control group, one could not rule out certain test areas as the cause of the difference. • This experimental design should leave only one factor to account for the difference in the two groups. 2017/5/24 71 Question • What are the required features of an hypothesis? It must be testable •It must be falsifiable 2017/5/24 72 Question • Why is it difficult to draw a conclusion from an experiment that is not controlled? Without a control you don’t know if the experimental outcome is due to the variable you are trying to test or due to some other variables. 2017/5/24 73 BIOLOGY AND EVERYDAY LIFE CONNECTION 1.8 Biology is connected to our lives in many ways: Biology in the news has an enormous impact on our every day lives. Some examples of biology in the news are endangered species, genetically modified crops, global warming, pollution, cloning, nutrition, emerging diseases, and medical advances. Technology is the practical application of scientific knowledge and discovery. Scientists speak of discovery while engineers speak of inventions. Scientists and engineers benefit from the work and success of each other. 2017/5/24 74 • Biology is connected to many important issues in our lives 1. Environmental problems and solutions 2. Genetic engineering 3. Medicine Figure 1.9 2017/5/24 75 Biology is Beautiful, Wonderful and Fun! 2017/5/24 76