Introducing Biology PDF

1 Introducing biology Sophia, the human-like robot Sophia the robot Think about…...

1 Introducing biology Sophia, the human-like robot Sophia the robot Think about… 1 Which characteristics of Sophia is a robot equipped with artificial intelligence*. ‘She’ can organisms does Sophia have? recognize faces, understand what people say and give a reply, and 2 Why do biologists not consider walk. Although Sophia looks much like a human, biologists do not Sophia an organism? consider her a human or an organism. (Answers on p. 17) Watch more artificial intelligence 人工智能 Acknowledgements and Important Notice: All questions from the HKDSE, HKCEE and HKALE are reproduced by permission of the HKEAA. Unauthorized use of the aforementioned questions in this electronic version is prohibited. I Cells and Molecules of Life 1.1 What is biology? Welcome to the world of biology*! Do you know what biology is? biology Biology is the scientific study of organisms*. Their structures, In Greek, ‘bio’ means ‘life’ life cycles, classification and interactions with other organisms and and ‘logy’ means ‘study’. their environment are some areas of study in biology. Fig 1.1 A biologist studying the growth of plants A Characteristics of organisms Organisms carry out vital functions* necessary for maintaining life. These vital functions are the characteristics of organisms. Based on these characteristics, biologists distinguish organisms from non-living things. 1 Organisms reproduce and grow Organisms produce new individuals of their kinds (offspring*) through reproduction* (Fig 1.2 and 1.3). The offspring grow* in size and often in complexity* too. After reaching maturity, the offspring reproduce like their parents do. Fig 1.2 Rice plants produce seeds that Fig 1.3 A hen and its chicks grow into new plants biology 生物學 complexity 複雜性 grow 生長 offspring 後代 organism 生物 reproduction 生殖 vital function 重要功能 1– 2  1 Introducing biology 2 Organisms obtain food and respire Organisms obtain food in the process of nutrition*. Plants make their own food by photosynthesis* (Fig 1.4), whereas animals obtain their food by feeding. Some of the materials from food are used for growth and repair. Some are broken down to release energy through respiration*. Organisms use energy for carrying out vital functions such Fig 1.4 A potato plant makes its own as reproduction. food by photosynthesis 3 Organisms detect and respond to stimuli, and move Organisms can detect and respond to stimuli* in their environment. This ability is called irritability*. It enables organisms to find food, find mates and escape from danger. A response may involve movement* (Fig 1.5). Fig 1.5 A lion sees its prey and runs after it 4 Organisms excrete to maintain a relatively constant internal environment The maintenance of a relatively constant internal environment in an organism is called homeostasis*. This provides a stable environment for the functioning of the cells making up Cross-link the organism. Excretion* contributes Reproduction, growth, to homeostasis by removing metabolic nutrition, respiration, irritability, movement, wastes (e.g. carbon dioxide and urea*) homeostasis and excretion from the body (Fig 1.6). will be discussed in detail in later chapters. Fig 1.6 An elephant removes its metabolic wastes in urine excretion 排泄 homeostasis 體內平衡 irritability 感應性 movement 運動 nutrition 營養 photosynthesis 光合作用 respiration 呼吸作用 stimulus 刺激 urea 尿素 1– 3 I Cells and Molecules of Life B Importance of studying biology Why do we study biology? Studying biology not only increases our knowledge about the living world, it also brings the following benefits to us. 1 Studying biology helps us develop appreciation of and respect for all organisms and the environment. Cross-link 2 Learning how biologists develop their ideas and designing our own We will look at how scientific investigations help develop our ability to think and solve biologists solve problems scientifically on p. 6. problems scientifically. Special lights in our refrigerator Is it true? Has any fair can help increase the vitamin C test been done? content in vegetables. 3 Studying biology helps us better understand health issues, environmental issues and many social issues. It also helps us make lifestyle choices and informed decisions. Are electronic cigarettes less harmful than regular Should our country parks be developed for residential cigarettes? purposes to ease our housing problem? 1– 4  1 Introducing biology Are viruses organisms? Distinguishing between organisms and non-living things is not as simple as you might think. For example, viruses* can reproduce after entering living cells. But without living cells, viruses do not show any characteristics of organisms. Thus viruses are considered as being on the borderline between living and non-living. Fig 1.7 Influenza viruses (×130 000) 1 What is biology? Biology is the scientific study of organisms. 2 What are the characteristics of organisms? a Organisms reproduce and grow. b Organisms obtain food and respire. c Organisms detect and respond to stimuli, and move. d Organisms excrete to maintain a relatively constant internal environment. Level 1 Questions 1 and 2: Complete the sentences with suitable words. 1 The ability of an organism to detect and respond to stimuli in its environment is called. p. 3 2 The maintenance of a relatively constant internal environment in an organism is called. p. 3 Level 2 3 When we breathe out, carbon dioxide is removed from our lungs. This is an example of A irritability. B respiration. C growth. D excretion. p. 3 virus 病毒 1– 5 I Cells and Molecules of Life 1.2 How can we study biology? A Scientific method Scientists study the natural world using the scientific method*. There is no single scientific method, but it usually involves a few basic steps. Hypothesis is supported 1 Making 2 Asking 3 Proposing 4 Making 5 Testing the 6 Drawing observations a question a hypothesis* a prediction hypothesis a conclusion Proposing a revised or Hypothesis new hypothesis is falsified* Fig 1.8 Basic steps of the scientific method These steps are explained below using an investigation of bats carried Watch this to prepare for out by Lazzaro Spallanzani in the 1790s. your class and answer the questions. 1 Making observations Video & questions Scientists are curious about things in nature. They make observations of these things by using one or more of their five senses (e.g. sight, smell or touch). 1 Making observations 2 Asking a question How can bats avoid hitting any objects in the dark? Bats can fly and avoid hitting any objects in the dark. Bats have small eyes and big ears. falsify 證偽 hypothesis 假說 scientific method 科學方法 1– 6  1 Introducing biology 2 Asking a question Scientists ask questions about the observations they make. The questions determine what will be investigated. 3 Proposing a hypothesis Using their background knowledge, logical reasoning and creative imagination, scientists suggest a reasonable answer to the question. This answer which tries to explain what is observed is called a hypothesis. The hypothesis must be testable, e.g. by doing experiments or making further observations. But in investigations which do not require explanations of observations, hypotheses are not needed. For example, scientists need not propose a hypothesis if they investigate the change in the population of Chinese white dolphins in the past 10 years. ? Can you give another example of investigations which do not require a hypothesis? 4 Making a prediction The prediction can be stated Before testing the hypothesis, scientists predict what the expected results in an if-then format: will be if the hypothesis is correct. If … (what happens in an experiment), then … (expected results). 3 Proposing a hypothesis 4 Making a prediction Bats rely on their sense of hearing If bats lose the sense of to avoid hitting objects in the dark. hearing when their ears are blocked with wax, then the bats will hit objects when they fly. wax 1– 7 I Cells and Molecules of Life 5 Testing the hypothesis One way of testing hypotheses is doing experiments in laboratories or in nature. Many factors, called variables*, might affect the result of an experiment. Below are three important kinds of them. Independent variable* is the factor under investigation. It is purposely changed to study its effect on another variable. Dependent variable* is the factor that is measured. Its change depends upon the independent variable. Controlled variable* is the factor that is kept the same. In a well-designed experiment, only one independent variable is to be changed, while all other variables are kept the same. To ensure a fair test, there are often an experimental group and a control* group. The control group is identical to the experimental group, except that the factor under investigation is absent. It aims to ensure the result of the experiment is due only to that factor. 6 Drawing a conclusion After doing an experiment, scientists analyse the results and conclude whether the hypothesis is supported or falsified. A hypothesis may become If the results match the prediction, the hypothesis is supported. a theory* with increased evidence and acceptance in If the results do not match the prediction, the hypothesis is falsified the scientific community. (or rejected). Scientists may need to propose a revised or new hypothesis for testing again. 5 Testing the hypothesis 6 Drawing a conclusion The results support my hypothesis! I conclude that bats rely on their sense of hearing to avoid hitting objects in the dark. The bats with the The bats without sense of hearing do the sense of hearing not hit the wires. hit the wires. Experimental group Control group Independent variable Presence of the sense of hearing Dependent variable Whether the bats hit the wires and ring the bells Controlled variables Size of the bats, darkness of the room, number of wires, etc. control 對照 controlled variable 控制變量 dependent variable 因變量 independent variable 自變量 theory 理論 variable 變量 1– 8  1 Introducing biology B Performing a scientific investigation Let us use the scientific method to solve problems in daily life. The following example and guidelines will help us learn the skills. Scenario Kelly’s mother bought a papaya, but it was unripe and not good to eat. She put it into a container that stored rice. She explained to Kelly that this could speed up the ripening of the papaya. Kelly wondered if the presence of rice speeds up the ripening. Does the presence of rice speed up the ripening of papayas? Task Design and carry out an investigation to find out the answer to Kelly’s question. 1– 9 I Cells and Molecules of Life 1 Designing a scientific investigation Aim What is the aim of this investigation? To study the importance of rice in speeding up the ripening of papayas. Problem to investigate What is the problem to be investigated? Does the presence of rice speed up the ripening of papayas? Hypothesis Propose a hypothesis to the problem. The presence of rice speeds up the ripening of papayas. Principle behind the design of this investigation a How can the hypothesis be tested? Compare the rates of ripening of two papayas, one of which is kept in a container with rice, and the other in a container without rice. b Predict the results based on the design of the investigation. If a papaya is kept in a container with rice, then the papaya will ripen more quickly. c Identify the variables. i What is the independent variable? How will it be manipulated? Presence of rice. Put rice into one of the containers. Do not mix ‘dependent ii What is the dependent variable? How will it be measured? variable’ up with Rate of ripening of each papaya. It is measured by observing the ‘measurement’. A dependent variable can often be degree of yellowing of each papaya every day. measured in more than iii What are the controlled variables? one way. Initial degree of yellowing and size of the papayas, size of the containers, etc. d Is it necessary to set up a control? Why? Yes. To ensure that the presence of rice is the only variable that affects the rates of ripening of papayas. Making valid assumptions e An assumption* is something that is accepted as true without any relies on our prior proof. What assumptions are made in this investigation? observations or work done by other people. The two papayas are identical. The difference in the volume of air in the containers is insignificant to the ripening of papayas. assumption 假設 1– 10  1 Introducing biology Procedure What is the procedure of this investigation? Is there any precaution* to be taken? 1 Prepare two identical transparent containers. Fill one of the containers with rice until it is half-full. 2 Put an unripe papaya into each container. Then cover the two containers. 3 Leave the two containers at room temperature for a week. Observe and record the degree of yellowing of the papayas every day without taking them out of the containers. transparent containers papayas rice Experimental set-up Control set-up 2 Carrying out a scientific investigation Data is the observations Carry out this investigation. Record the data as the results. and/or measurements. Results How should the data be presented? Degree of yellowing (arbitrary unit)# Container Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 With rice 0 1 2 2 3 4 4 Without rice 0 1 2 2 3 5 5 # The greater the number, the higher the degree of yellowing Conclusion A large sample size, random What conclusion can be drawn from this investigation? sampling and repeated The presence of rice does not speed up the ripening of papayas. measurements help reduce the chances of drawing incorrect conclusions. 3 Writing a report of a scientific investigation Once the investigation is completed, we write a report. That report allows other people to understand what we have found out, and to repeat our investigation. Skill builder on p. 12 and 13 shows how to write a report. precaution 預防措施 1– 11 I Cells and Molecules of Life Skill builder Writing a report of a scientific investigation Below is a sample report of Kelly’s investigation of the ripening of papayas. Aim To study the importance of rice in speeding up the ripening of papayas. Introduction 1 Problem Does the presence of rice speed up the ripening of papayas? 2 Hypothesis and prediction The hypothesis explains the problem. The prediction is based The presence of rice speeds up the ripening of papayas. If a on the design of the experiment. papaya is kept in a container with rice, then the papaya will Remember a hypothesis is not ripen more quickly. needed in certain scientific investigations. 3 Principle In this investigation, the rates of ripening of two papayas Principle includes the following: are compared. Two identical containers are prepared. One a The rationale of the design container is half-filled with rice. One papaya is kept in the b The independent variable and the container with rice, and the other is kept in the container way of manipulating it without rice. c The dependent variable and the way of measuring it The independent variable is the presence of rice. It is d The controlled variable(s) manipulated by putting rice into one of the containers. e The critical assumptions made The dependent variable is the rate of ripening of each papaya. It is measured by observing the degree of yellowing of each papaya every day. The controlled variables are the initial degree of yellowing and size of the papayas, size of the containers, etc. It is assumed that the two papayas are identical. The difference in the volume of air in the containers is also assumed to be insignificant to the ripening of papayas. Materials and apparatus transparent container 2 unripe papaya 2 List all the materials and apparatus, rice and state the quantity needed. 1– 12  1 Introducing biology Procedure 1 Two identical transparent containers were prepared. One of Write each step in the correct order the containers was half-filled with rice. in past passive voice. Also explain all precautions taken. 2 An unripe papaya was put into each container. Then the two containers were covered. 3 The two containers were left at room temperature for a week. The degree of yellowing of the papayas was observed and recorded every day. Observations were made without taking the papayas out of the containers to minimize disturbance to the papayas. Results Degree of yellowing (arbitrary unit)# Results should be presented in Container appropriate form(s), e.g. tables, Day Day Day Day Day Day Day graphs, labelled diagrams, 1 2 3 4 5 6 7 photographs. With rice 0 1 2 2 3 4 4 Without rice 0 1 2 2 3 5 5 # The greater the number, the higher the degree of yellowing Discussion 1 The papaya in the container without rice (control) ripened Discussion includes the following slightly faster. This showed that the presence of rice did not (if applicable): speed up the ripening of the papaya. a Interpretation of the results (e.g. trend or pattern in data, 2 The degree of yellowing was not consistent in different parts relationship between the of the two papayas. The judgment of the degree of yellowing independent and dependent variables) was also subjective. These lowered the accuracy of the b Possible sources of error and results. how they affect the accuracy of the results 3 The container in the experimental set-up was half-filled with c Any anomalous* data and its rice. The difference in the volume of air in the containers significance might have a significant effect on the ripening of papayas. d Validity of assumptions based on the results 4 To increase the reliability of the results, more papayas should e Limitations of the design of the be used. Averaged data should also be used for analysis. investigation 5 The degree of yellowing of papayas should be observed by f Suggestions for improvement and further investigations more than one person to minimize subjectivity. Cards showing different degree of yellow should also be used as a reference. 6 An equal volume of plastic beads should be put in the container in the control. This ensures that the volume of air in the two containers is the same. Relate the conclusion to the hypothesis. Do not introduce Conclusion new information nor make generalizations. The presence of rice does not speed up the ripening of papayas. anomalous 異常的 1– 13 I Cells and Molecules of Life Design an investigation of the effect of fresh pineapple 1.1 on the setting of jelly Scenario Peter and Mary were preparing jelly for a party. Why did the I think fresh pineapple contains They put some fresh pineapple into a jelly jelly not set? something that prevents the solution and put the solution in the refrigerator jelly from setting. to set. The next day, they found that the jelly had not set. Mary suggested that the fresh pineapple contained something that had prevented the jelly from setting. Task Design and carry out an investigation to test Mary’s hypothesis. Write a full report of your investigation. Simulation 1.1 Level 1 Level 2 1 Amy is making observations of a bird called 2 John investigated whether acids could Common Magpie*. prevent apples from turning brown. He sprayed a piece of cut apple with vinegar and left it in the air for 30 minutes. He found that the apple did not turn brown. Which of the following set-ups is the appropriate control for this investigation? A leaving the apple in the air for 60 minutes instead of 30 minutes B using pear instead of apple Which of the following is not an C spraying the apple with distilled water observation of the bird? instead of vinegar A The bird is 45 cm long. D using a whole apple instead of a piece B The bird makes a chak-chak-chak of cut apple p. 8 sound. C The bird feeds on both insects and fruits. D The bird is considered a symbol of luck in Chinese culture. p. 6 Common Magpie 喜鵲 1– 14  1 Introducing biology 1.3 Nature of science Learning biology is not just learning biological concepts. Understanding the nature of science* (what science is and how science works) is just as important. Various aspects of it can be illustrated in the history of the development of biological knowledge. Let us look at the following example. There will be more examples in other chapters to help you better understand the nature of science. Do organisms arise from non-living things? For thousands of years, people believed that organisms could arise from non-living things by spontaneous generation*. This was because they saw maggots* on rotting meat and they thought that maggots arose from rotting meat spontaneously. In 1668, Francesco Redi observed that maggots appeared a few days after Science advances through reasonable flies moved around a piece of meat. He hypothesized that maggots were skepticism* produced by flies. Redi questioned whether spontaneous generation really happened although it was a long-held belief. This attitude drove him to investigate and later spontaneous generation was disproved. Doing science requires creativity Based on his hypothesis, Redi predicted that if flies were kept away from and imagination meat, maggots would not appear. He then designed and carried out an Redi kept flies away from the meat using a experiment as follows to test his hypothesis. piece of gauze. A good scientific Redi’s experiment experiment must include carefully designed controls gauze Redi did a controlled experiment. jars What are the meat ? independent, dependent and Experimental set-up Control set-up controlled variables in (jar not covered) (jar covered) Redi’s experiment? maggot 蛆 nature of science 科學本質 skepticism 懷疑態度 spontaneous generation 自然發生 1– 15 I Cells and Molecules of Life After a few days, Redi observed that maggots appeared only in the experimental set-up but not the control set-up. These results supported his hypothesis. However, the belief about spontaneous generation continued. At that time, the discovery of microorganisms* which seemed to come from nowhere also strengthened the belief. In 1745, John Needham did an experiment. He boiled a flask of broth to Science is a process of ongoing inquiries kill the microorganisms in it and stoppered the flask. A few days later, After the work of Redi, the broth turned into a cloudy solution containing microorganisms. biologists continued Needham concluded that the microorganisms did arise spontaneously. to investigate whether spontaneous generation happened. Needham’s experiment after a few days stopper microorganisms boiling the flask appeared Lazzaro Spallanzani did not agree with Needham. He suspected that Needham did not boil the broth long enough to kill all the microorganisms. In 1775, he carried out a similar experiment and obtained different results. Spallanzani’s experiment after a few days Experimental set-up Scientists have to explore using different boiling for a no sealing microorganisms techniques and longer time of flask appeared methods to find out a good solution to a after problem a few days Spallanzani modified Control set-up Needham’s experiment. He boiled the broth for a longer time and sealed the flask by melting the boiling for a seal the flask no microorganisms longer time appeared glass at its mouth. microorganism 微生物 1– 16  1 Introducing biology These results showed that microorganisms did not appear in boiled broth when the flask was sealed. However, many people were not convinced. They argued that air was required for spontaneous generation to happen. See how Pasteur falsified This idea was not falsified until almost a century later by Louis Pasteur. the idea of spontaneous generation in Reading to learn on p. 20. What is the nature of science? Give some examples of its aspects. The nature of science is about what science is and how science works. Below are some aspects of the nature of science: a Science advances through reasonable skepticism. b Doing science requires creativity and imagination. c A good scientific experiment must include carefully designed controls. d Science is a process of ongoing inquiries. e Scientists have to explore using different techniques and methods to find out a good solution to a problem. f Scientists build on the work of other scientists. Recall Think about... (p. 1) 1 Sophia can detect and respond to stimuli, and move. 2 Sophia does not reproduce and grow, obtain food and respire, etc. Suggested answers to ? p. 7 An investigation of the life cycle of an unknown insect (or other reasonable answers) p. 15 Independent variable: Whether flies are allowed to reach the meat Dependent variable: Whether maggots appear on the meat Controlled variables: Size of the meat, size of the jars, temperature, etc. 1– 17 I Cells and Molecules of Life Key terms 1 assumption 假設 11 irritability 感應性 2 biology 生物學 12 movement 運動 3 control 對照 13 nature of science 科學本質 4 controlled variable 控制變量 14 nutrition 營養 5 dependent variable 因變量 15 organism 生物 6 excretion 排泄 16 photosynthesis 光合作用 7 grow 生長 17 precaution 預防措施 8 homeostasis 體內平衡 18 reproduction 生殖 9 hypothesis 假說 19 respiration 呼吸作用 10 independent variable 自變量 20 scientific method 科學方法 Concept map Biology the scientific study of studied by organisms scientific method part of characteristics nature of science detect and respond excrete to maintain reproduce obtain food to stimuli, a relatively constant and grow and respire and move internal environment 1– 18  1 Introducing biology fever from dead bodies to women. To Exercise test his hypothesis, he requested doctors in Clinic I to wash their hands before Section 1.1 handling deliveries. i Suggest a suitable group for Level 1 comparison of the results. (1 mark) MC ii State the expected result if his 1 Which of the following life processes is carried hypothesis is correct. (1 mark) out by plants but not animals? p. 6–8 A respiration B excretion C photosynthesis D reproduction p. 1, 2 Section 1.3 Level 2 Section 1.2 4 It was once believed that plants grew by absorbing materials from the soil. In the 17th Level 1 century, Jan Baptist van Helmont designed an MC 2 A student carried out an investigation of the experiment to test the idea. He planted a young cleaning effect of different brands of washing tree in a pot of dry soil, covered the pot and powder. He soaked clothes with an oily stain watered it regularly for five years. in washing powder solutions. Which of the young tree following is/are the controlled variable(s)? (1) brand of washing powder cover (2) duration of soaking (3) volume of washing powder solution pot A (1) only B (1) and (2) only The table below shows the initial and final C (2) and (3) only D (1), (2) and (3) masses of the tree and dry soil. p. 8 Initial mass (kg) Final mass (kg) Level 2 Tree 2.27 76.74 3 In the 19th century, childbed fever* was Dry soil 90.72 90.66 common among women giving birth a What is the purpose of covering the pot? in hospital. It was believed that fear of (1 mark) hospitalization caused the fatal disease. b i State the hypothesis tested. (1 mark) In 1864, Dr Ignaz Semmelweiss found that the ii What is the expected result if the death rates of childbed fever in Clinic I and hypothesis mentioned in your answer Clinic II were 10% and 4% respectively. to b i is correct? (1 mark) a Is the hypothesis ‘fear of hospitalization iii Is the hypothesis supported or falsified caused childbed fever’ supported by the by the result? Explain your answer. death rates? Explain your answer. (2 marks) (2 marks) b Semmelweiss observed that doctors in c Give one aspect about the nature of science Clinic I handled deliveries straight after that can be demonstrated in the above dissecting dead bodies. Midwives in historical event. Give a reason to support Clinic II did not dissect dead bodies. He your answer. (2 marks) hypothesized that doctors spread childbed p. 7, 15, 16 childbed fever 產褥熱 1– 19 I Cells and Molecules of Life Reading to learn Read the article below and answer the questions. Falsifying the idea of spontaneous generation In 1775, Lazzaro Spallanzani showed that microorganisms did not arise spontaneously in boiled broth when the flask was sealed. However, many people were not convinced. They argued that air was required for spontaneous generation to happen. Louis Pasteur hypothesized that microorganisms found in broth came from microorganisms in the air. In 1859, Pasteur used two flasks with an S-shaped neck to do an experiment (Fig 1.9). The neck of each flask allowed air, but not microorganisms on dust particles, to reach the broth. The results matched his prediction and falsified the idea of spontaneous generation. Experimental set-up cool down break the neck microorganisms boil the broth appeared after a few days Control set-up cool down no microorganisms boil the broth appeared after a few days Fig 1.9 Pasteur’s experiment Questions 1 What was Pasteur’s prediction of the results? (1 mark) 2 What was the purpose of setting up the control in Pasteur’s experiment? (1 mark) 3 Elaborate on how Pasteur’s investigation can be used to demonstrate the following aspects of the nature of science listed in the table. (3 marks) Nature of science Elaboration Science is affected by the technology and the types of equipment available at the time. Scientists have to explore using different techniques and methods to find out a good solution to a problem. Scientific knowledge is tentative and subject to change. 1– 20