Science Notes Form 1-3 PDF

SCIENCE NOTES THREE- YEAR JUNIOUR SECONDARY SCHOOL SYLLABUS FORM ONE NOTES 1 THE INTERACTION OF SCIENCE, TECHNOLOGY AND SOCIETY Science is a way of finding out how things happen so that we can understand the world around us. It is made up of 3 basic scien...

SCIENCE NOTES THREE- YEAR JUNIOUR SECONDARY SCHOOL SYLLABUS FORM ONE NOTES 1 THE INTERACTION OF SCIENCE, TECHNOLOGY AND SOCIETY Science is a way of finding out how things happen so that we can understand the world around us. It is made up of 3 basic sciences;4 BIOLOGY;is the study of living thing [plants and animals. CHEMISTRY;the study of changes that happen to matter. PHYSICS;deals with the study of matter and energy. TECHNOLOGY;can be described as making machines ,objects and systems to meet people’s needs. CHARACTERISTICS OF TECHNOLOGY *Involves design. *Involves making /producing. *It is concerned with values. THE DIFFERENCE BETWEEN SCIENCE AND TECHNOLOGY SCIENCE TECHNOLOGY Pursues knowledge and understanding for Make objects and devices to meet its own sake. people needs. Involves discovery through careful Involves design, invention and production experimentation Tries to be as value free as possible. It is driven by society and its needs IMPACT OF TECHNOLOGY ON SOCIETY Below are some examples of changes brought about by technology:  Communication – technologies such televisions, radios, cell phones, internet, have made it easier, cheaper and faster to communicate all over the world. Most people are informed because information is accessible (easy to get).  Transport – cars, trains, air crafts e.t.c have made it easier for people to travel around the world quicker.  Medical – medical practitioners are now able to diagnose and treat diseases e.g. the use of scanners, x-rays, respiratory machines e.t.c  Jobs - have been created to manufacture the different technologies for examples people are employed to make cars computers, tractors pens and pencils. Although technology has a lot of benefits for our society , it has also brought things that are not desirable.Some of these include the following Jobs are lost as new technology means that some jobs that people did by hands are done by a machine example farmers are able to plough large fields in a short time using tractors.. Some technologies create waste such as used oil , plastic bags ,empty cans ,bottles and board boxes. People do not always dispose of the waste properly and a result, the environment becomes polluted. Technology is used to design new weapons such as guns, land mines and bombs that people use to fight and kill each others. When technology fails it may cause serious accident leading to death of many people. Continued use and reliance an technology can make us dependent on it and thus be THE INFLUENCE OF SOCIETY ON TECHNOLOGY Although society is changed or influenced by technology ,it also influence the development of new technology.The need ,interest, preference , cultural and environment of society have a big influence in the development of technology. Below are examples of how society influence technology *The need for people to communicate with the others any where and at any time led to the development of mobile phones, internet and technology. 2 *New situation such as discovery of HIV/AIDS has result in the development of new technology used to test a persons HIV status. *The need by society for quicker, smaller and more powerful technology has led to the use of memory sticks and card, powerful laptop computers, very small cell phones and small digital cameras. Countries often compete against each other to be best in a particular field. Often they can gain an advantage over their opponents by developing new technology. For example, the crimes of some countries compete to develop the best and most powerful weapons so that they conquer their enemies when there is war. When now technology is very expensive or of poor quality, people will not buy it. This force producer to come up with cheaper and better quality technology that people can afford ENVIROMENTAL ISSUES RELATED TO TECHNOLOGY There are some environmental issues related to the manufacture and we of technology such as; POLLUTION Pollution is when waste products, chemical and material are found in our environment when it should not be there. Technology creates waste such as used plastics, oil and metal. If the waste is not disposed of properly, it can pollute the air, land and water. Cars produce smoke though their exhaust system which pollute the air and can be dangerous to our health Technology such as fertilizers can damage the environment if they are not used properly.The run off of some fertilizers results in excessive nutrients in lakes, rivers and dams. This promotes the growth of algae and creates conditions that kill under water vegetation and fish. Pesticides do not only kill unwanted pest but also kill other animals that are useful to us such as bees , Runoff of pesticides into water source can also kill fish and animals that live in the water. Some technologies pollute the atmosphere. This contributes to changes to our climates for example smoke released from various industries as well as gives released cars leading to global warming. Deforestation Manufacturing materials such as chairs tables and toilet paper need us to cut down trees to obtain the wood that is needed. The cutting down of trees to provide the materials to make the technologies leave the soil bare promoting soil erosion HEALTH ISSUES RELATED TO TECHNOLOGY Technology important positive influence on our healthy.Many of us would be crippled, very ill or even dead if it were not for improvement in our health include: *X-ray technology allows us to see inside the human body so that we can identify broken bones. *the development of vaccine technology has meant that diseases that used to cause death and illness no longer affect us. *The development of drugs such as antibiotics and painkillers has meant that many diseases can be cured or made more bearable. Technology that puts people to sleep during surgical operations (anesthetics) has meant that operations can now be carried out safely and painlessly. 3  DOING SCIENCE The process scientific investigation The first step in nearly all scientific investigations is to ask a question. The question is usually about something that the scientist has observed and wants to know more about, eg What is happening? Why has it happened? How does it happen? A scientific question is one that is measurable or very clear and specific. A non- scientific question is general, not measurable, and can mean many different things, eg How big is the pond? Questions form a hypothesis. Hypothesis is the possible/explanation to a scientific question, intelligent guess. eg why did some things float in water and others sinks? Try the simple investigation # Fairs test / experiment Fair test is an experiment in which only one factor is changed. This means that the results of the experiment are unquestionable / valid. # controlling variables are things that can be changed and may affect the final result. Independent variable is the variable that you are interested in that will be changed in an investigation. All the other possible variables must stay the same. If more than one variable changes, then you do not know which variable has caused the effect. Dependent variable is the variable that you think will be affected by the change in the independent variable. Control group is something that is used to compare your experimental group to. Without a control, you cannot tell whether or not a change has happened in your experimental group. Experimental group is the group in which you made a change to the independent variable that you are interested in. Refer to Tebogo’s experiment in Diamond science ‘A FRESH START ’BOOK1PAGE 16 TO 17 SCIENCE PROCESS SKILLS Observing experimenting Inferring Communicating Predicting Comparing Interpreting Predicting Classifying Analyzing Controlling variables Solving problems making hypotheses 4 Unit 2: PROCESS OF SCIENTIFIC INVESTIGATION Question Hypothesis Experimentatio n Conclusion Communication 1. QUESTIONING  Scientific investigation starts with scientific questions from the identified problem.  The scientific questions must be clear, specific and measurable.  In the diagram below a scientist realized that plants in Plot B are growing better than those in Plot A.  He asked the scientific question: ’’Why plants in Plot B grow taller than those in Plot A?’’ 2. HYPOTHESISING  Hypothesis is a possible answer or explanation to a scientific question.  For the above plots he hypothesized that ‘’Plants in Plot B grow taller than those in Plot A because the owner added compost manure to their soil’’ 5  3. EXPERIMENTING  After hypothesis, an experiment or investigation is planned and carried to prove the hypothesis correct or incorrect.  From the above hypothesis it is predicted that: ’’ if compost manure is added to the soil it will make bean plants grow taller than those on the soil without manure’’  Possible VARIABLES( factors that may be changed and may affect end results of the experiment) for the investigation are listed eg 1. Amount of water to be used when watering 2. Amount of light to the plants 3. Type of seeds used 4. Time frame allowed for growth 5. Whether the soil has compost or not  The INDEPENDENT VARIABLE (factor we are interested in and will be changed) is identified ie ‘’ whether compost will be added to the soil or not’’  Other variables remain constant or unchanged.  The DEPENDENT VARIABLE (factor affected by change on the independent variable is also stated ie ‘’height of the bean plants’’  Seeds planted in the soil with compost will be the EXPERIMENTAL GROUP (where a change in the independent variable has been done)  Seeds planted in the soil without the compost will be the CONTROL GROUP(one that will be compared to the experimental group)  After planning an investigation is conducted CONDUCTING A SCIENTIFIC INVESTIGATION/EXPERIMENT  State the AIM eg ‘’The aim of the experiment is to find out whether bean plants grow taller in soil with compost or soil without compost’’  List APPAPARATUS (equipment to be used during the experiment) eg  compost  plant pots  sandy soil  ruler bean seeds  water  measuring cylinder  Outline the METHODOLOGY (step by step activities to be carried). Read page 19-20 on the text book)  During the experiments observations are made and recorded. 6  After stated time frame, the bean plants will be measured and their results recorded on a table eg Time( in weeks) 1 2 3 4 5 Bean A height (without compost) 6 9 12 18 20 Bean B height( with compost) 10 15 20 25 35  From a table , the results can be converted to graphs or charts eg (a) Bar chart on weekly Heights of Bean A and Bean B (b) Pie chart on heights of bean A and Bean B 7  ( c) Line graph on heights of bean A and Bean B. Weeks 4. CONCLUSION  Records from observations, tables, graphs or charts will be analysed and a decision/ conclusion will be made.  For an example; from the above graphs, Bean B grew taller than Bean A, so the conclusion will be ‘’Compost helps plants grow taller’’  This means our hypothesis was correct. In some situations the hypothesis can be incorrect. 5. COMMUNICATION  Lastly, the findings are reported to other interested people in details.  Report is important because other people may repeat the experiment or ask questions in relation to the findings. WORKING SAFELY IN THE LABORATORY Working in the laboratory can be dangerous if the right steps are not, taken to avoid accidents and injuries. Safety means being protected against harm which could be caused by hazards around us. Hazards are things around us that could cause damage to us if they are not used safely, eg sharp tools. Common hazards in the laboratory  Open flames from burners which can cause burns if people are not aware of them  Poisonous and corrosive chemicals that can, cause burns or even death if, not used appropriately.  Electricity and appliances, which can cause electric shocks if, not set-up or used properly. 8   Glass equipments and apparatus if not handled or used properly the glass breaks(broken glasses)  Wet/slippery/polished fool.  Flammable gases used in the laboratory (gas leakage or gases not tightly closed after use they could cause fire when lighting the matchstick) Classification common laboratory hazards  Biological hazards – are dangers to health that may be caused by contact with animals / Plants can cause allergies. Bad reaction of the body to substances that may be in the plant / on the animal’s skin. Some animals can carry diseases / even plants are poisonous.  Chemical hazards – Chemical that may be poisonous / may burn / damage your skin / Clothing eg dangerous chemicals include common acids such as sulphuric acid, hydrochloric acid etc.  Physical hazards – This type of hazard may be encountered when you are working with high voltage (very powerful) electricity sources and with high energy radiation sources as X – rays. SAFETY SYMBOLS Safety symbols Hazardous substances in the laboratory normally carry safety symbols are shown below. SAFATY GUIDELINES 1. You mast not ran in the lab but move carefully If, you run, you can trip and fall and spill chemicals that may harm people, you can also knock into others who are doing experiments and this can cause harm to them. 2. You must not eat , taste or drink anything in the lab unless your teacher instructs you to do so. The lab how many chemicals that may be poisonous and dangerous which could contaminate your food or drink. 3. Listen to all instructions the teacher gives you and carry them out correctly. This will ensure that you perform the action correctly. 4. Do not enter the lab until your teacher tells you to do so. 5. Always wear protective plastic goggles to protect you eyes against dangerous chemical, fumes or explosions busy with an experiment. 6.Don’t inhale directly to smell any gas or other chemicals.You must waft the smell to your nose with your hand. 7. Don’t point the open end of a test tube you are heating to anyone.So that if the liquid does shoot out of the tube, it does not heart you or those around you. 8. Don’t pour unused chemicals back into stock bottle. 9. Don’t ouch any apparatus or chemicals unless your teacher told you to do so. 9 SAFE LABORATORY TECHNIQUES Although it is very important to follow the safety guidelines in the lab to reduce the risk of accident and injuries ,it is important for you to know the correct safety techniques to use when working in the lab. Some of the safety methods or techniques are:.Always wear good protective’s gloves when you have to handle hot things such as burners, tripod, gauze a hot container. If you are heating a liquid in a test tube, then you should always use tongs 0r a damp. You should also point the mouth of the test tube away from yourself and others so that if the liquid does shoot out of the tube, it does not hit you or those around you If you are instructed to smell something in a tube or a container, then waft the fume coming from the container towards your nose using your hand. Never place your nose. in or near the end of a container to see how things smell because the fumes may be toxic or very unpleasant, if taken in large quantities. If you heat a flammable liquid such as methylated splits, alcohol, never heat the container over a flame or burner because liquid will evaporate and the flames will flow on to the flame and catch fire. The container with a flammable liquid must be placed inside a beaker with water. Liquid must be placed inside a beaker of water which can be heated slowly. If you are asked to heat something in a beaker over a burner ,then a tripod and gauze should always be used.This makes a stable plat form for the beaker to rest on. Always add a concentrated acid e.g concentrated sulphuric acid to water, never add water to a concentrated acid. This is because small amount of water added to a concentrated acid in a tube may cause a large amount of heat to be produced and this can cause the content of the tube to shoot out of the test tube. 10 Scalars and vector Scalar -A physical quantity which has no direction.eg time, temperature, volume density e.t.c Vector- A physical quantity with has size [magnitude] and direction.eg acceleration, velocity, force e.t.c Resultant vector This is the overall results of the vectors acting on an object. Vectors can be added to a subtracted from each other.The overall effect on an object such as the speed that an object moves in, depends on the magnitude and direction affecting it, so in order to calculate resultant vector you can; Add the magnitude of vectors together if both vectors are acting in both exactly the same direction e.g. 32 32m 12m +12 44 SUBTRACT the magnitude of the vector from each other.If the vectors are acting in the opposite direction e.g 10km/h 10 km/h – 5km/h = 5km/h 5km/h CLASSIFYING QUANTITIES INTO SCALAR AND VECTOR QUALITY Scalar Vector quantity Temperature Acceleration [the rate at which speed of something is Length increasing and in what direction] Volume Velocity [the speed at which something is moving and Area the direction its moving Density Time Force Speed Wind speed/velocity Width MEASURING LENGTH Length is the distance between two points. The standard units of length is known as meter and its symbol is the letter (m) Other units are used depending on how big or small something is. Below are some of the units of length which are used to describe large or small distance between two points. The symbol used for these units are shown in the brackets. 1metre = 1000 millimeters [mm] 1 meter= 100 centimeters [cm] 1 kilometer =1000 meters[m] CONVERTING NON STANDARD UNITS INTO MEASUREMENTS INTO METRES IMPERIAL SYSTEM UNIT LENGTH USING THE METRIC SYSTEM 1 inch…………………….. 2.54 cm 1 foot ……………………. 30.48 [cm] 1yard …………………… 0.9144 m 1mile ……………………. 1.6 km 11 SOURCES OF ERROR WHEN MEASURING LENGTH  If the zero point of scale is not lined properly with one end of the object that is being measured then the length measurement could be shorter or longer than it should be  Always zero the instrument  If the ruler is not placed straight and lined up along the object that is being measured , then the measurement will be longer than it should be  Ensure that the measuring instrument is placed on a flat surface  If the ruler you are using is thick, then you may not get a different measurement depending on what you are looking for from when reading the scale on a ruler. This is known as parallax error and it could make the measurement too long or short. AREA DETERMINING THE AREA OF A REGULAR SHAPE Area is a measure of the size of the surface of something. The units of area are always in a squared unit. The standard unit for area is square metre ( m2). How to find area: length x width e.g. 5m x 3m = 15m2 Area of: a circle π × r2 Triangle 1 MEASURING VOLUME *The amount of space occupied by an object. *for regular figures like cubes,cuboids volume is dertermine by MEASURING VOLUME LENGTH=6M WIDTH=2M HEIGHT=4M The SI unit for volume is cubic is cubic metre [m3] and other units commonly used in cubic centimeter. For a liquid, a measuring cylinder is used.when using a measuring cylinder you must pay attention to the following; *You must know the volume shown by the smaller divisions.Different sizes of measuring cylinders use different divisions. 12 The water that has been displaced will be the volume of the object. MASS Mass is the amount of matter contained in an object. The standard unit of mass is kilograms (Kg). Because this fairly large amount, we also use the gram (g). 1000g = 1Kg ISTRUMENTS USED TO MEASURE BALANCE - Bathroom scale - Spring balance - Top pan balance - Lever arm balance - Triple beam balance Sources of error in the measurement of mass - Identify sources of error in the measurement of mass such as: - the instrument must be calibrated - It must be zeroed - Items must be put in the center of the instrument. DENSITY Density is the mass per cubic meter of the material. The density of the material always stays the same. Different materials have different densities. DENSITY = MASS / VOLUME VOLUME = MASS / DENSITY MASS = DENSITY X VOLUME UNITS - Kilogram per cubic meter - Gram per cubic centimeter N.B. the density of water is 1g/cmThe density of liquids can be measured using an instrument called the hydrometer. It consists of a glass tube with a scale on the side and weighed at the bottom with lead shot. The hydrometer floats in the liquid. If the liquid is more the hydrometer does not sink very deep. If the liquid is less dense it sinks much deeper. 13 BUOYANCE AND DENSITY It is the density of a material which controls whether it will float or sink. An object will float in a liquid if its density is less than that of the liquid in which it is placed. Buoyance is the upward force acting on an object & that it is the density of a material which controls the floating. TEMPERATURE Temperature is the degree of how hot or cold an object is. The instrument used to measure temperature is called a thermometer. A thermometer is a narrow tube inside a glass wall. At one end of the tube is a thin – walled bulb which contains a liquid. This liquid is usually mercury or coloured alcohol. The space above the liquid is filled with a gas, normally nitrogen. UNIT The standard unit of temperature is Degree Celsius. There are other scales such as Fahrenheit (oF) and the kelvin (K). To change Celsius scale to kelvin you add 273to the celsious scale. e.g. 30 oc to kelvin is (30 +273 = 303K) Kelvin to Celsious we subtract 273K from kelvin temperature. To convert celsious to Fahrenheit, multiply temperature by 1.8 and add 32. That is oF= (1.8 × oC) +32 Fahrenheit to celsious we subtract 32 from temperature and multiply by 0.56; oC= (oF -32)×0.56 DIFFERENCE BETWEEN CLINICAL AND LAB THERMOMETER CLINICAL LABORATORY Has a constriction (bend) it does not have a constriction It takes body temperature It takes temperature of the liquids PLACES a. Between buttocks b. Under armpits c. Under the tongue The narrow bend near the bulb stops the mercury from falling back into the bulb before you have had time to read the temperature. After reading the temperature you shake the thermometer so that mercury goes back into the bulb. The normal body temperature of a healthy person is about 37 degree Celsius. For a sick person, the temperature may be much higher or lower than 37 degree Celsius.. TIME There are many ways of measuring time. The standard unit of time is seconds (sec). 14  PENDULUM Pendulum is a mass on the end of a string. The number of times the pendulum swings can be used to measure time. One swing is the movement of the pendulum from one place out to one side, then the other, and back to the same place again. UNITS - Seconds - Minutes - Hours - Days - Weeks - Months - Years - Decade - Century INSTUMENTS USED - Clocks - Watches - Cell phones - Computers - Sirens EARLY (OLD) INSTRUMENTS - Shadows - Moon - Sundial - Hour glass CONVERSION OF UNITS 1minute = 60 seconds 1 hour = 60 minutes 1 year = 365 or 366 days 1 day = 24 hours 1 week = 7 days 1 month = 30 or 31 days 1 year = 12 months 1 decade = 10 years 1 century = 100 years LIVING MATTER CHARACTERISTICS OF LIVING THINGS We call living things ORGANIMS. Plants and animals are all living organisms. If something is alive it will carry out all seven life processes and these are: 1. Feeding Plants make their own food through the process of photosynthesis while animals eat plants and other animals. 2. Respiration Getting energy out of the food you eat is called respiration. All living organisms respire because they need energy. 3. Movement Plants move slowly when they grow. Roots move down into the soil & stems move towards light. Animals move their whole body from place to place. 4. Growth Plants carry on growing all their lives while animals grow until they reach a certain stage. 5. Excretion 15 Plants excrete through their leaves e.g. transpiring or removing oxygen as a waste gas. Animals breathe out waste carbon dioxide. Other waste substances leave the body in urine and in sweat. 6. Sensitivity Living things react to their environment. Plants move their leaves to face light, their flowers open in the morning and close at night. Animals have different sense organs. 7. Reproduction Plants make seeds that grow into new plants. Animals lay eggs and some give birth to live babies. CLASSIFYING ANIMALS One very clear feature that is used to classify animals is whether the animal has a backbone. An animal either has a backbone or it does not. Most animals have a structure supporting or protecting the whole body, or may be just parts of it. This structure is called a SKELETON. There are two types of skeleton. - An endoskeleton is found inside the body. It is made up of bones. An animal that has an endoskeleton has a backbone or vertebral column. Animals with a backbone are called VERTEBRATES. - An exoskeleton is found outside the body. Insects have an exoskeleton. It is hard and is called the CUTICLE. VERTEBRATES The vertebrates are classified into five main groups. MAMMALS - have young ones that are born alive - have milk – producing mammary glands (called breasts in humans) and suckle their young - have bodies covered with hair or fur - Are warm blooded – their body temperature stays almost the same even though the temperature of the environment changes. BIRDS - reproduce by laying eggs that are fertilized inside the female - have bodies covered with feathers and wings - are warm blooded - can usually fly REPTILES - reproduce by laying eggs, on land, that are fertilized inside the female - have bodies that are rough and covered with scales - breathe air through lungs - are cold blooded – their body temperature changes with the temperature of the environment, so when it gets hot their body temperature also rises, and when it gets cold their body temperature falls. AMPHIBIANS - reproduce by the female laying eggs, in water, which are immediately fertilized by the male - have bodies with smooth, moist skin - are cold blooded - live on land and in water FISH - reproduce by the female laying eggs, in water, which are immediately fertilized by the male - have bodies covered with scales - are cold blooded - live only in water INVERTERBRATES Animals without a backbone are called INVERTEBRATES. Two examples of invertebrates are: 16 ARTHROPODS MOLLUSCS Have hard exoskeletons and jointed legs. This main group is The bodies of molluscs have clear regions, though they are split into smaller groups such as insects, arachnids and quite different from the insects. myriapods. The head, the foot and the shell. When they are threatened, a) Insects – have bodies divided into three segments – the molluscs move into their shell for protection. Some molluscs head, the thorax and the abdomen. They have six legs and, have an internal shell, which we cannot see. E.g. snails, slugs often, two pairs of wings. E.g. flies and locusts. and octopuses. Other main groups of invertebrates include – b) Arachnids – have bodies that are usually divided into two roundworms, flatworms, starfish and jellyfish. parts – the head and the abdomen. They have eight legs. E.g. spiders, scorpions and ticks. c) Myriapods – have many legs and bodies made up of lots of segments (parts). E.g. centipedes and millipedes. CLASSIFYING PLANTS Plants are classified as seed - bearing plants (produce seeds) and non – seed bearing plants (do not produce seeds. SEED – BEARING PLANTS NON – SEED BEARING PLANTS These can be further divided into two broad groups. These plants do not produce seeds, but they reproduce by making structures a bit like seeds called SPORES. The different - FLOWERING PLANTS – which produce seeds in types of non – seed bearing plants include algae, mosses and flowers ferns. Inside seeds there are cotyledons which store food. Plants with seeds that have two cotyledons are called - ALGAE – are very simple plants which have no DICOTYLEDONOUS PLANTS OR DICOTS. Plants proper roots, stems or leaves. Examples of algae can with seeds that have one cotyledon are called often be seen in stagnant or slow – moving water in MONOCOTYLEDONOUS PLANTS OR MONOCOTS. ponds, ditches or rivers. Examples of monocots are: grass and wheat. Examples of - FERNS – have roots, underground stems and large dicots are: hibiscus and most of the other brightly coloured well developed leaves. They have veins which flowering plants. transport materials around the plant. Examples of ferns include stag’s horn fern. - CONIFERS – these are plants which produce seeds in cones. E.g. Christmas trees that people plant in their compounds. SUMMARY OF LIVING THINGS CLASSIFICATION ORGANISM PLANTS ANIMALS FLOWERING NON FLOWERING VERTEBRATES INVETEBRATES MONOCOTS DICOTS ALGAE MAMMALS BIRDS FISH REPTILES AMPHIBIANS ANTHROPOD SMOLLUCS CELLS All living things are made up of building blocks called cells. The CELL is the basic unit of life. Animals and plants made up of only one cell are called UNICELLULAR or SINGLE – CELLED ORGANISMS, and those made up of many cells are called MULTICELLULAR ORGANISMS. All cells have basic structure. 17 ANIMAL CELLS There are many different types of animal cell, but they all share the same basic structure. Microscopes are special instruments that can be used to observe very small objects which cannot be seen with the naked eye. Microscopes are used to make things look bigger. Animal cells have: SPECIALISED ANIMAL CELLS PLANT CELLS - no definite shape Plant cells share the same basic structure cytoplasm which may be different from the cell to - membrane cell depending on the job of the cell in the - nucleus plant. - vacuole Plant cells have: - a definite shape - cytoplasm inside the membrane - membrane - vacuole - nucleus - chloroplast - cell wall FUNCTIONS OF THE PARTS OF A CELL - NUCLEUS – controls the reactions or activities taking place in the cell - CYTOPLASM – substances can dissolve in the cytoplasm. The cytoplasm also gives the cell its shape by pushing out against the cell membrane. - CELL MEMBRANE – is selectively permeable. This means it allows some things to pass through it, but not others. It controls the movement of substances into and out of the cell. It also encloses the cell’s contents. - CELL WALL – it gives plant cells a rigid structure (shape) and is freely permeable to most substances – it allows them all to pass through it. - CHLOROPLASTS – contain a green pigment called chlorophyll. This enables plants to make their food by process of photosynthesis. - VACUOLE – It contains food such as starch, which has been produced by photosynthesis. SPECIALISED PLANT CELLS Plant cells may be specialized to do particular jobs within the plant. - Conducting cells – transport food and water, together with dissolved salts, throughout the plant. These include xylem cells and phloem cells. - Palisade cells – are found in the leaves. They have a very large number of chloroplasts because most of the plant’s photosynthesis takes place in these cells. 18  - Guard cells – are found in leaves. They have some chloroplasts. Their job is to open and close the stomata, the tiny pores that allow gases to pass in and out of the leaf. The inside walls of the guard cells are thicker and tougher than the outside walls. When water passes into the guard cell from the surrounding plant leaf cells, the outer wall of the guard cell stretches more than its inner wall and this makes the stoma open. PLANT AND ANIMAL SYSTEMS UNCELLULAR & MULTT-CELLULAR ORGANISMS A. Unicellular or single celled organisms If an organism is made up of just one cell, then it is called a unicellular or a single celled organism. They cannot be seen but they are everywhere around us, on our bodies, furniture, and gardens. Unicellular cause many diseases that affect plants & animals. Examples of unicellular organisms are bacteria, amoeba, yeast, paramecium, etc. B. Multi-cellular organisms Multi-cellular organisms are living things that are made up of more than one cell. They are also made up of more than one type of cell. Examples are trees, baboons, people, etc. The table below summaries the differences Uni-cellular organisms Multi -cellular organisms They are made up of one cell They are made up of more than one cell The cells may be grouped together but the group contains The groups of cells made up of more than one cell type one cell type The cells do not co-operate with each other The cells co-operate with each other They are microscopic Some are microscopic although most can be seen with the naked eye TISSUES, ORGANS AND SYSTEMS TISSUES ORGANS A tissue is a group of similar cells working together to carry Organs are structures in the body which are made up of out a certain function. several sorts of tissues grouped together to carry out a Examples of tissues in animals include: special function. - muscle tissue Examples of animal organs include: - the outer layer of skin (epidermis) - heart - bone - lungs - the lining of the alimentary canals - stomach - intestines Examples of tissues in plants include: - eyes - leaf epidermis - ears - xylem tissue - phloem tissue Examples of plant organs include: - roots - flowers - leaves - stem SYSTEMS A system is a group of organs working together for a common goal. Examples of systems include: SYSTEMS FUNCTION ORGANS INVOLVED SKELETAL The skeletal system provides support for the body. It Bones, cartilage, protects internal organs and provides attachment sites for tendons and ligaments. the organs and muscles. MUSCULAR Provides movement. Muscles work in pairs to move limbs, Skeletal, muscles it also controls movement of materials through some 19  organs such as intestines, and the heart, and the circulatory system. CIRCULATORY It transports nutrients, gases (such as oxygen), waste and Heart, blood vessels hormones around the body. NERVOUS Carries electrical impulses around the body. Brain, spinal cord, nerves RESPIRATORY Is to carry out gaseous exchange between the body and the Lung, nose environment DIGESTIVE Is responsible for breaking down the food and absorption Mouth, esophagus, of nutrients in the body stomach, intestines EXCRETORY Filters out waste material, poisons and excess water in the Kidneys, bladder body ENDOCRINE Sends hormones around the body Glands REPRODUCTIVE Produces cells which allows organisms to reproduce Animals: ovaries, penis, vagina, testes, etc Plants: pollen anthers, stamens, etc TRANSPORT Move nutrients and water around the plant Roots, xylem, phloem, stem GAS EXCHANGE Allows gaseous exchange between the leaves and the Leaves environment PHOTOSYNTHESIS Photo means light and synthesis means together Photosynthesis is a process whereby plants, some bacteria, and some protistans make their own food in the presence of sunlight and chlorophyll to produce oxygen and sugar. The photosynthetic process uses water and releases the oxygen that we absolutely must have to stay alive. Oh yes, we need the food as well! We can write the overall reaction of this process as: Sunlight Water + carbon dioxide carbohydrates + oxygen Chlorophyll And can be symbolized as: 6H2O + 6CO2 ----------> C6H12O6+ 6O2 Most of us don't speak chemicalese, so the above chemical equation translates as:Six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen Leaves and Leaf Structure 20 Plants are the only photosynthetic organisms to have leaves (and not all plants have leaves). A leaf may be viewed as a solar collector crammed full of photosynthetic cells. The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf. Cross section of a leaf, showing the anatomical features important to the study of photosynthesis: stoma, guard cell, mesophyll cells, and vein. Water enters the root and is transported up to the leaves through specialized plant cells known as xylem. Land plants must guard against drying out (desiccation) and so have evolved specialized structures known as stomata to allow gas to enter and leave the leaf. Carbon dioxide cannot pass through the protective waxy layer covering the leaf (cuticle), but it can enter the leaf through an opening (the stoma; plural = stomata; Greek for hole) flanked by two guard cells. Likewise, oxygen produced during photosynthesis can only pass out of the leaf through the opened stomata. Unfortunately for the plant, while these gases are moving between the inside and outside of the leaf, a great deal water is also lost. IMPORTANCE OF PHOTOSYNTHESIS - Produces oxygen needed by living organisms to survive - Produces food eaten by living things - Controls the level of carbon dioxide in the atmosphere RESPIRATION:Respiration is the process whereby oxygen and glucose are used to produce energy, water and carbon dioxide. WORD EQUATION FOR RESPIRATION Oxygen + glucose carbon dioxide + water + energy REPIRATION AND BREATHING Often people confuse breathing and respiration. Respiration refers to how the cells of the body use oxygen and + Respiration and photosynthesis are the opposite of each other. During the day when there is light, both photosynthesis and respiration take place but during the night plants respire more. So, during the day plants produce oxygen and during the night plants produce carbon dioxide. The relationship between the two is that photosynthesis uses the products of respiration, and respiration also uses the products of photosynthesis. Differences between respiration and photosynthesis Photosynthesis Respiration It only occurs in plants It happens in all cells types It takes place in chloroplasts and chlorophyll It takes place in the mitochondria It traps and store light energy It releases energy It produces oxygen and glucose It uses oxygen and glucose It uses water and carbon Produces water, carbon dioxide and energy 21 Effects of deforestation Scientists have shown that deforestation has a number of other effects on the environment such as: Deforestation Loss of shade loss of habitat burning less water released Soils dry out animals have nowhere to live less rain Increased soil animals become extinct carbon dioxide drought and desert erosion Is released into the formation happens atmosphere TRANSPORT IN PLANTS Together, the xylem and phloem are known as the vascular system of the plant. The differences between the xylem and the phloem are shown below: PHLOEM XYLEM It transports glucose Ti transports water and minerals Fluid can flow in either direction although flow is Fluids flow in one direction only, from the roots to the usually from leaves to the roots leaves The cells are living Its cells are dead TRANSPIRATION This is the loss of water from the leaf through stomata. SIGNIFICANCE OF TRANSPIRATION - It helps in the absorption and upward movement of water and minerals from roots to the leaves - It also helps in the temperature regulation - It protects the plant from heat injury 22 CONDITIONS THAT AFFECT THE RATE OF TRANSPIRATION 1. LIGHT – plants transpire more rapidly in the light than in the dark. This is mainly because light stimulates the opening of the stomata which means more water is going to be lost. Light also speeds up the rate of transpiration by warming the leaf. 2. TEMPERATURE – plants transpire faster at high temperatures 3. HUMIDITY – When the air surrounding a leaf is dry is said to have a low humidity. If the humidity is low, then diffusion of water out of the leaf through the stomata happens more easily and the rate of transpiration increases. If the humidity is high, then water cannot leave the leaf so easily. 4. WIND – when there is no wind, the air surrounding a leaf becomes more humid because the water vapour released by the leaf is not blown away and the rate of transpiration will be decreased. When a breeze is present, the humid air is carried away and replaced by a drier air, and the rate of loss of water increases. NUTRIENT CYCLES The carbon cycle Animals take in carbon compounds by eating plant material or other animals. Plants take in carbon in the form of carbon dioxide during photosynthesis to form carbohydrates. Therefore photosynthesis removes carbon dioxide from the atmosphere. Other processes such as combustion and respiration produce carbon dioxide and release it to the atmosphere. All animals and plants on the earth die and decay. During decomposition, carbon dioxide is produced and released into the atmosphere. The cycle continues as shown below. NITROGENCYCLE This is another very important element. Plants absorb it in the form of nitrates and use it in the form of proteins. When animals eat plants they take in this protein and change into animal protein. Below is a summary of ways in which nitrogen is absorbed from the atmosphere and released back into the atmosphere. 23 NATURAL RESOURCES Natural resources - These are things which were not made by human beings and they can be put to good use. Examples of important natural resources - people - water - minerals (e.g. diamond, copper, nickel, soda-ash etc) - wildlife - soil - energy (e.g. wood, coal, sun) Importance of Conserving Natural Resources to Local and National Economy Natural Resource Minerals - provide jobs, source of income, source of foreign exchange Wildlife Source of income since tourists pay for viewing them, source of employment, source of food Water Used in construction, watering plants and animals, transport, dissolving substances Soil Used in buildings, used to support plants growth, habitat for some animals Energy Source of heat, source of electricity which is used for different purposes like moving cars, trains, tractors ideal for life People Source of labour, manpower skills, produce what the country need for food, produce different commodities to have enough money to import and export certain necessities. Ways of Conserving Natural Resources Natural Ways of conserving the natural resource Resource Water Repair water pipes, fixing leakages, use right amount of water for any purpose, have storage tanks and rain gutters to store rain water, construction of dams. Recycling water Minerals People ploughing enough food to avoid hand outs from government in drought times, breeding and selling cattle to BMC as an alternative source of renewable sources since minerals are not renewable, recycling cans N.B reliance on agriculture and self-sufficiency avoid over dependence on mineral resources. Wildlife Having wildlife reserve or parks, having anti-poaching units, hunting licenses, setting hunting periods, recycling paper. Soil Avoid deforestation, avoid over stocking and over grazing, ploughing furrows across the slopes of hills, recycling glass Energy Servicing machines regularly to avoid energy waste, using alternative sources of energy, not wasting electricity e.g. keeping light off in rooms which are not used and using electricity saving bulbs, not leaving heaters on for prolonged times People Practice high standards of proper health care, personal hygiene, providing basic needs (food, clothing and housing) General ways of conserving resources - effective implementation of legislative (laws) - having national parks and game reserves - recycling of materials - use of alternative energy sources ( e.g. wind and solar energy) - improved education and training e.g. awareness on effects of water shortage will lead to sensible use of water - proper health care - proper disposal of sewage and refuse - family planning - practicing afforestration Recycling This is re-using materials which were used before. 24 Benefits of re-cycling - Saves use of natural resources, therefore it is a way of conserving natural resources - It avoids environmental pollution damage - It save money spent on refuse disposal by authorities Some materials that can be re-cycled - Plastic - Metals - Glass N.B plants and animals are decomposed to re-cycle nutrients in them. MATTER Matter is anything that has mass and takes up space. PROPERTIES OF MATTER - Matter has mass - Matter occupies space - Matter is made up of tiny particles - Matter exists in three states - One state of matter can be converted to another state depending on its temperature WHAT MAKES UP MATTER? 1) Atom- this is the smallest particle of matter that can take part in a chemical reaction or the smallest particle of matter that can exist on its own. - It can not be seen with a naked eye. Its diameter is about ten-millionth of a centimeter (1/10 000 000 cm). This means that ten million atoms can be fitted together on a line of 1cm long. - It is made up of three particles called protons, neutrons and electrons. General structure of an atom Shell Electron Neutrons Protons Nucleus Particle Position Charge Protons Nucleus Positive ( + ) charge Electrons Shells Negative ( - ) charge Neutrons Nucleus Neutral charge ( 0 ) N.B- electrons are found in shells, which orbit around the nucleus of an atom. The number of protons is equal to the number electrons, which is called the atomic number. Number Protons = Number of Electrons (e-) = Atomic Number (Z) Since protons and electron are equal in number and oppositely charged, their charges cancel each other and the atom is left neutral. So, an atom is a neutrally charged particle, that is, it does not have a charge. 25  STATES OF MATTER There are three states of matter - Solids - Liquids - Gases SOLIDS – In solids, the particles are LIQUIDS - In liquids, the particles GASES - In gases, the particles are very far apart and closely and neatly packed. The are still close together. However are free to move about. This is why gases expand to particles are so closely packed together liquid particles are free to move fill their containers. It is because gas particles move that they cannot move freely. They can about within the liquid. This is why freely that we can smell gases, such as a gas leak. only vibrate at fixed positions. This is liquids have a fixed volume but not a why solids have fixed volume and a fixed shape. fixed shape. - have no fixed shapes – they flow to take up -have fixed shapes -have no fixed shapes – they take the the whole container -are generally hard shape of their containers - cannot be detected by touching them -have high densities -are generally wet to the touch - have low densities -cannot easily be -have high densities - are easily compressed compressed(squeezed) -cannot easily be compressed - expand a lot when you heat them -do not expand much when you heat -expand a bit when you heat them -diffuse(mix and spread) quickly them -diffuse(mix and spread) slowly MATTER CHANGING STATE SUBLIMATION MELTING EVAPORATION FREEZING CONDESATION SUBLIMATION DIFFUSION Diffusion is the movement of particles from an area where they are in high concentration to an area where they are in low concentration until evenly distributed. This happens when two substances which are in contact mix together because of the movement of their particles. Gases diffuse faster than liquids because there are greater spaces between the particles in a gas, and the particles are moving faster. Solids only diffuse very slowly. Gases (fastest) – Liquid – solid (slowest). DIFFUSION IN EVERYDAY LIFE - Oxygen dissolved in our blood moves into our cells by diffusion - Micro – organisms take up food from their environment by diffusion - Carbon dioxide diffuse into the stomata of leaf during photosynthesis THE SCIENCE OF WATER  It is colourless  It is odourless (it has no smell)  It is tasteless  The boiling point of water is 1000C at sea level. (Water boils at about 980C in Botswana because of the higher altitude.)  Water freezes at 00C.  Many substances can be dissolved in water. This means water is solvent.  Water is a good evaporative coolant- as sweat evaporates from the body the water in it leaves s cooling effect. That is why sweating cools the body down. 26   Water has good heat conductivity- heat applied to water spreads quickly to other areas of the water. This is why our bodies do not get hot in some areas but stay cold in others.  Water gains heat slowly and lose it slowly. CHEMICAL TEST FOR WATER The standard test for water is to use cobalt chloride paper. TEST: Insert cobalt chloride paper in to the liquid that you want to test for water. POSITIVE TEST: Cobalt chloride paper turns from blue to pink if there is water present. NOTE: The test paper that has turned pink can be heated to evaporate the water molecules. This will turn the paper back to blue. CHEMICAL CONSTITUENTS OF A WATER MOLECULE A water molecule is made up of one atom oxygen and two hydrogen atoms. The two atoms of hydrogen are bonded by strong forces to the oxygen atom. Groups of these molecules form liquid called water. Water symbol: H2O ANOMALOUS EXPANSION OF WATER Liquids expand when they are heated and contract when they are cooled. However, there’s one liquid which behaves differently from others. This liquid is water. When water is cooled, it will contract, but only until it reaches a temperature of 4 0C. As it cools further and the temperature continues to drop, the water begins to expand. This is why bottles filled with water, sealed and then frozen often break. And also ice trays filled with water and put in to freezer, the level of ice is always higher than the level of water. This means that water in a solid state has its particles far apart from each other. As a result, solid water (ice) has a lower density than liquid water. This not a common feature of matter. It is always expected that solids should have a higher density than liquids. This unique behaviour of water is known as anomalous expansion of water. EFFECTS OF THE ANOMALOUS EXPANSION OF WATER Water expands when it freezes and as a result becomes less dense than water. This explains why ice floats on the surface of water.  Water that freezes in household pipes can expand and split the pipes. When the weather becomes warmer the ice in the pipe melts and pipe leaks water. These water leaks can flood a house.  Water that freezes in small cracks in rocks can expand and crack the rock. This is an important natural mechanism of erosion because it gradually breaks down the rock into smaller and smaller pieces. THE IMPORTANCE OF ANOMALOUS EXPANSION OF WATER TO THE LIVES OF MARINE ANIMALS 27 Ice floats on water because it is less dense than water. The ice acts as an insulator (something that prevents changes in temperature from happening) and stops sea water underneath from freezing. This leaves water available for animals to swim in. If ice was denser, this would mean that as the seas froze in the Arctic and Antarctic, the ice would sink to the bottom of the ocean, if there are any animals caught between the bottom of the ocean and the sinking ice, and then they would become trapped and be killed. Acids and bases PH- this is the degree of alkalinity or acidity PH scale- this is a scale of numbers used to measure the acidity or alkalinity. It ranges from 1(very acidic) to 14(very basic). A substance that has a pH value of 7 is neutral, that it is neither basic nor acidic. Different colours accompany the pH values. Acid- this is a substance that dissolves in water to give a pH of less than 7. -this is a proton donor Examples of acids - hydrochloric acid - sulphiric acid - nitric acid - citric acid - acetic acid - tartaric acid Properties of acids - have pH less than 7 - they dissolve in water - they have a sour taste - they turn blue litmus paper red - they neutralize a base to produce salt and water only - they react with carbonates to produce carbon dioxide gas, a salt and water - they react with reactive metals to produce salt and water only. Base- this is a substance that has a pH of more than 7. They neutralize acids to form salt and water only. Some bases are soluble in water while others are not. Those that dissolve in water are called alkalis. All alkalis are bases but not all bases are alkalis. Example of bases -Sodium hydroxide (caustic soda) -Potassium hydroxide (caustic potash) -Ammonia 28 -Ammonium hydroxide -Calcium hydroxide (lime) -Calcium oxide -Magnesium hydroxide -Magnesium oxide -Copper oxide -Zinc oxide -Iron oxide Examples of alkalis - Calcium hydroxide - Sodium hydroxide - Potassium hydroxide - Calcium hydroxide - Magnesium hydroxide - Ammonium hydroxide General properties of bases  Bases react with acids to neutralize them. PROPERTIES SHOWN BY ALKALIS ONLY  Alkalis are soluble in water  They have a greater pH than 7  They have bitter test  They feel slippery when they are between fingers  Alkalis turn red litmus blue ACID ALKALI INDICATOR An acid alkali indicator changes colour according to whether a substance is an acid or an alkali. Indicators are made from naturally occurring substance, especially plant material such as flowers, coloured leaves (not green) beetroots & carrots. The commonly used indicators are the: - LITMUS PAPER Litmus paper is produced from lichen (a simple plant). It exists in colour blue & red. Acidic Alkaline Neutral Red litmus paper Remains red Turns Remains red Blue litmus paper Turns red Remains blue Remains blue Phenolphthalein Colourless Pink Colourless UNIVERSAL INDICATOR Is a mixture of several substances and turns a range of colours depending on the pH of a substance pH value Colour of the indicator Strength 1 2 Red Strong acid 3 4 Pink 5 Orange Weak acid 6 Yellow 7 Green Neutral 8 Turquoise 9 Blue Weak alkali 10 Dark blue 11 12 Violet Strong alkali 13 14 How to prepare an indicator You will need two beakers, a funnel, some filter paper, heating apparatus and a beetroot cut into cubes. 29   Put the beetroot into a beaker. Add enough water to cover the beetroot.  Boil the mixture until the water has absorbed the colour of the beetroot.  Filter the mixture and allow it to cool  Keep the liquid to use as an indicator STORAGE OF CHEMIICALS Chemical can be dangerous. It is therefore very important that all chemicals are stored properly. Many casualties caused by chemical poisoning can easily avoided if chemicals are stored properly. Here are some important things to remember about storing chemicals, especially in the home.  Chemicals must be stored in their original containers to avoid confusion.  Chemicals should be stored on high shelves out of the reach of children  Chemicals should be locked in cupboards, and their use supervised by a responsible adult. WHAT TO DO IF AN ACCIDENT HAPPENS WITH CHEMICALS Accidents sometimes happen with dangerous chemicals both in the laboratory and at home no matter how carefully you read the instructions or follow the safety procedures. 1. Treating poisoning- poisoning happens when a chemical is accidentally swallowed, absorbed through the skin or breathed in. Follow the steps below to deal with the poisoning:  Poisoning on the skin: remove all contaminated clothing and flood the skin with water for 10 minutes. Then wash affected area gently with soap and water then rinse thoroughly.  Poison by inhalation: immediately get the person to fresh air. Avoid breathing fumes. Open all doors and windows wide. If the victim is not breathing, then apply artificial respiration.  Poison by swallowing: unless the victim is unconscious , having a fit or cannot swallow, give him or her milk or water immediately. Then call professional help about whether to make the victim vomit or not. N.B : YOU SHOULD TAKE INFORMATION ON THE KIND OF POISON THAT CAUSED THE ACCIDENT. 2. Treating chemical burns – chemical burns are also the result of accidents with chemicals in the laboratory. You should deal with accidents that cause chemical burns in the following ways:  Make sure the cause of the burn has been removed. Try not to come into contact with it yourself. If the chemical is dry, brush it off. Avoid brushing it into your eyes. Remove any contaminated clothing or jewellery.  Wash the chemical off the skin surface with running water for 15 minutes or more.  Wrap the burnt area with a dry sterile dressing or clean cloth. Minor chemical burns will generally heal without further treatment. However, if there is an overall body reaction, get medical help immediately. In severe cases, do no leave the victim alone. Watch for other reaction while calling for professional help. REPRODUCTION Reproduction is process whereby organisms produce new or younger versions of themselves. This happens when the male and female sex cell fuse to produce a zygote. THE MALE AND FEMALE SEX CELLS The sex cells produced by the male reproductive system are known as the spermatozoa cells. The sperm cells are very small, about 0.04mm in length and about 0.002mm wide. They look like small tadpoles. The female sex cell is known as the ovum (plural is ova). The ovum is 50 times larger than a sperm cell. 30 Male sex cells Female sex cells -the male sex cell is the sperm -The female sex cell is the ovum -millions of sex cells are produced in and released at a -only one ovum is produced and released at a time time -they are large, round cells -they are small cells that look like tadpoles -they cannot move by themselves -they can move on their own PARTS OF MALE REPRODUCTIVE SYSTEM AND THEIR FUNCTION The male sexual organs are outside. The system is made up of the testes, penis, scrotum, epididymis, sperm ducts, urethra and gland ( prostate glands, seminal vesicles and Cowper’s glands). Together these glands are called accessory glands. ORGAN FUNCTION Testes They produce sperm and male sex hormone called testosterone. Epididymis Stores sperms once they have been made in the testes. Scrotum It acts as a sack to hold the testes and to protect them. It also helps to keep the testes at the right temperature because its cooler than the body temperature. Penis This is an organ used to transfer sperm from male and it into the female’s vagina. It is also used for urinating. Urethra This is a which carries urine and the sperms through the penis Sperm duct Carries sperms from the testes to the urethra Accessory glands Makes the seminal fluids which enables the sperms to swim. THE FEMALE REPRODUCTIVE SYSTEM AND THEIR FUNCTIONS ORGAN FUNCTION Ovaries They produce the ovum and two of the female sex hormones, oestrogen and progesterone. Uterus This is a place where the fertilized ovum develops into a foetus. Oviducts (fallopian tubes) Tubes that transports ovum from the ovaries to the uterus, fertlisation also takes place here. Cervix Closes off the uterus during pregnancy Vagina This is where semen is deposited during sexual intercourse. Also acts as a birth canal. Vulva This is the outer part of the vagina that is on the outside of the body. 31 CHANGES THAT OCCUR AT PUBERTY When babies are born, they weigh between 3 – 4 Kg and they are about 50 cm tall. Over the course of the next few years they grow and develop rapidly until about 11 years. About 10 – 14 years on average, puberty begins. During puberty the body develops to adulthood. Puberty is controlled by hormones. CHANGES THAT OCCUR IN GIRLS AT PUBERTY On average, girls enter between the ages of 11 and 12. Once a girl enters, her ovaries begin to produce ova which can be fertilized by the sperm. The characteristics or changes occurring in girls at puberty -They grow taller and their hands & feet become longer. This is known as a growth spout. -the face changes with the jaw and nose becoming more prominent. -hair grows under the armpits and around genital parts. -hips become wider -breasts grow bigger -pimples may develop -menstruation begins -they become interested in boys CHANGES IN BOYS Boys enter puberty at the ages 12 to 14 years on average. Boys also start to produce sperm, and they can impregnant a girl. -there is rapid increase in height and bulk -the boy become muscular -hair grow around genital parts and they also grow beard -the genitals grow bigger -there may be mood swings and aggression -boys become interested in girls -pimples may develop The menstrual cycle Puberty in females is associated with the maturation of the females reproductive system and the girl begins to produce eggs (ova). Usually the ovum is produced at a time and this happens approximately 28 days although this time may vary slightly from one person to another- this period is as the menstrual cycle. MENOPAUSE Women are fertile from puberty until about the ages of 45 to 55 when the menstrual cycle become irregular and eventually stops permanently. When this happens it is known as menopause. 32 HORMONES THAT BRING ABOUT CHANGES AT PUBERTY These hormones are oestrogen, progesterone (found in females) and testosterone (found in males). These hormones have different functions and these are: OESTROGEN – produced in ovaries PROGESTERONE – produced in TESTOSTERONE - produced by testis ovaries -stimulates development of secondary -stimulates the thickening of the uterus -stimulates the development of secondary characteristics in girls wall so that it it is ready to receive the sexual characteristics in boys -stimulates the maturation of the ovum zygote if fertilization occurs. -stimulates sperm formation and development during the menstrual cycle -maintains the uterus in pregnancy -responsible for changes in aggression, mood -brings about mood and behavioural and behavior that happens to boys during changes that happen at puberty. puberty METHODS OF BIRTH CONTROL/CONTRACEPTIVES Contraceptives: An agent or device intended to prevent conception. Contraception is the birth control by the use of devices (diaphragm or intrauterine device or condom) or drugs or surgery. Contraceptives are used for family planning as they prevent pregnancy. They help couples decide whether or not to have children and some of them are used to prevent STDs even though their main job is to prevent conception. Contraceptives can be divided into four groups; 1. Natural 2. Hormonal/chemical 3. Physical/mechaical 4. Surgical methods 1. Natural methods Method advantages Disadvantages Abstinence: no sexual intercourse at  100% effective against pregnancy o No disadvantage all. and STDs Withdraw (Coitus interruptus);  Purely natural and does not depend o Highly unreliable as there is a pre-ejaculation fluid penis withdrawn from the vagina on artificial devices. which can be secreted and contains sperms and it before ejaculation is not easy for the man to withdraw his penis as he will be at the peak of pleasure. o There is high pregnancy risk. o STDs are spread with this method. Rhythm (safe period): sexual  Acceptable in most religions. o It is unreliable because keeping track of ovulation intercourse done only during the safe  Can be effective against pregnancy if can be difficult as it can change any time and it is periods and avoided during fertile the dates are noted well. difficult t be certain about the safe period length. periods (when fertilization is likely to o Encourages the spread of STDs lead to pregnancy). Uses the mucus, calendar and temperature method. Prolonged breastfeeding (cultural  Very effective against pregnancy. o No disadvantage method)  100% effective against STDs 33  2. Hormonal/chemical methods Method advantages Disadvantages Pill e.g. RU486: two kinds mini-pill  Easy to use. o Does to prevent STDs. (contains progesterone which causes  Reversible o Must be taken daily. changes in the uterus lining  Does not interfere with sexual o Have side effects to women’s health; breast preventing implantation) and activity. swelling, cervical cancer, nausea, diarrhoea and combined pill (contains Oestrogen  99% safe at preventing ovulation weight gain. and progesterone and this prevents and pregnancy. ovulation)  Can be administered by individuals Spermicides: kills sperms, must be  Kill sperms. o Must be applied before every sexual activity. applied inside the vagina as far up as  Effective when used with the o It is messy. possible ten minutes before sexual diaphragm o Unreliable when used alone. intercourse.  Serves as a lubricant for the o Does not prevent STDs. vagina. o Has to be used with the diaphragm.  Easy to be used/applied. Injection (Depo-Provera): injected  Reversible. o Can lead to sterility. into the body every 3 months. Stops  99% effective against pregnancy. o Administered by a doctor. ovulation by preventing formation of o Causes abnormalities in the period. ova in the ovaries. o Can lead to heavy menstrual bleeding. o Have side effects like; dizziness, weight gain. o Does not protect against STDs. Morning-after pill: Used after  Effective against pregnancy if o Only prescribed by a doctor in case of risk it is not intercourse has taken place. Contains taken before 3 days of sexual act. for regular use. hormones which cause lining of the o Therefore not easily accessible. uterus to be shed. It is to be taken 48-72 hours after sexual intercourse especially if pregnancy poses a risk. 3. Physical/mechanical/barrier Methods Method advantages Disadvantages Condom sheath (male: thin rubber  99 % effective in preventing o Allergy of the lubricant or latex. covering fitted on an erect penis. Has pregnancy and STDs o Improper use can result leading to the spread of a bulb to collect sperms after  Easily available, accessible STDs. ejaculation. Femidom/female  No need for medical assistance o There is a possibility of bursting in case of too condom: thin sheath which lines the needed. mush friction during sexual act vagina prevents entry of sperms.  Can be used with Spermicides Diaphragm/cap: it is a dome shaped  Fairly effective (98%) in blocking o High risk of infections. piece of rubber with a piece of metal the sperms. o Has to be used with other methods e.g. worn by women fitted on the cervix  Does not have any side effects. Spermicides. opening to prevent sperms from o Possibility of discomfort if not inserted properly. reaching the uterus. o In rare cases may lead to irritation to the penis or vagina. o Has to inserted by a physician o Correct size must be fitted Intra-Uterine Device (IUD)/Loop:  Reliable for women who already o Has to be inserted by a qualified doctor. small objects (spiral, loop, ring) has children and those who do not o There is need for pelvic examination to determine made of steel or plastic which is live far from the health facilities the size of the cervix. inserted by a physician into the  Stops implantation. o Can cause excessive bleeding. uterus. Fitted by straightening in a  Reversible. o Do not protect against STDs. tube like instrument, pushing this  Long term contraception through the cervix then pushing the IUD out at the tube’s end. The IUD interferes with implantation of the embryo) 34  4. Surgical methods Method advantages Disadvantages Vasectomy and Laparatomy  Permanent and 100 % effective. o Does not prevent STDs (tubal ligation): in men sperm duct  Safe and simple out patient o Irreversible is cut and tied to prevent sperms operation. o Has to be done at a hospital. from passing to the urethra. In  Sexual characteristics are not o Pains can be experienced after surgery. women (laparatomy) oviduct cut and affected as the individual can still o Not suitable for young people but for people who tied to prevent the sperms from ejaculate (men) already have children reaching the egg in the oviduct. SEXUAL TRANSMITTED DISEASES Sexual intercourse involves very intimate contact between human beings, such contact can lead to STDs. Sexually transmitted diseases are those diseases that can be passed on from one person to the other through sexual contact. It is important to note that the chance of getting STDs is increased by having sexual intercourse with many partners. All STDs are very dangerous when if not treated. STDs include; Gonorrhoea, syphilis, AIDS/HIV, Genital herpes and warts, Candida, Chlamydia, Chanchroid, Vaginal Thrush, hepatitis B. STD & Cause Transmission Symptoms Effects Treatment Control 1. Gonorrhoea  Unprotected Symptoms appear 4  Can lead to use of  Infected person should caused by a bacteria sexual days after infection. blockage of antibiotics refrain from intercourse. (Neisseria intercourse o In men, there is a the urethra e.g.  Using a condom every time gonorrhoeae) with an yellowish discharge in men. penicillin, when having sexual infected of pus due to  Can lead to tetracyclin intercourse. person, inflammation of the sterility  Discouraging multiple sexual urethra.  Can cause partners (being faithful) o Burning sensation blindness in  Abstaining when urinating. newly born o Narrowing of the babies. urethra may lead to  Bladder may difficulty in be affected urinating. (cystitis). o Sore throat  Infections of o Rectal infection in the sperm both males and duct and females. prostrate o In Women, no signs gland may at the early stages , lead to o In the later stages the sterility. infection may spread from the urethra and vagina to the uterus and fallopian tubes leading to sterility. 2. Syphilis caused  Unprotected o Stage 1/Primary: after  Insanity if use of  Same as of gonorrhoea by bacteria sexual 1-3 weeks of the central antibiotics Treponema pallidum intercourse infection, painless nervous such as which is a  During sore/chancre appears system tetracycline spirochatae pregnancy on the penis and becomes and (from mother vagina or cervix. A affected. Pennicillin to child) lump/ulcer develops  Bacteria on the penis or causes vulva. The signs inflammatio disappear without n leaving a scar. everywhere o Secondary stage/stage in the body. 2: about 2-6 months  Can lead to 35  non-itchy skin rash paralysis develops, sores on  The bacteria the mouth, throat and can pass genitals. Lymph through the glands become placenta and swollen. Symptoms affect the disappear again unborn o Tertiary stage/stage 3: baby. occurs after 2-4 years, damage to internal organs occurs, the liver, heart, spinal cord and brain (paralysis result after this), insanity and death result. 3. Acquired Immune  Unprotected o Prolonged and  death There is  Abstinence Deficiency sexual unexplained  insanity can currently no  Condom use Syndrome (AIDS)/ intercourse tiredness. result treatment or  Being faithful HIV (Human  During birth. o Swollen glands  There can be cure for this  Avoid infection and sharing Immunodeficiency  Breast (lymph nodes) a severe disease. needles Virus feeding o Fever lasting for weight loss. But there are  Acquired: obtained  Sharing more than ten days. some AZT from somewhere sharp objects o Chills and ARV Immune: defense (syringes or o Excessive sweating drugs that against infection needles) with especially at night. are used to Deficiency: Lack of an infected o Mouth lesions suppress the Syndrome: many person including yeast virus symptoms  Exchange of lesions and painful increasing fluids like, swollen gums. the lifespan Caused by a vaginal o Sore throat. of the retrovirus HIV fluids, blood, o Cough and patient but semen tuberculosis this has to o Shortness of breath be given o Changes in bowel after habits including undergoing constipation. an HIV test. o Frequent diarrhoea o Opportunistic infection (such as pneumonia, Candida) o Tumour (Kaposi sarcoma) o Skin rashes and skin cancer o Severe weight loss o headache ENERGY FORMS AND ENERGY SOURCES Fossil fuels: these are the remains of dead plants and animals that have been buried underground for millions of years. Examples of fossil fuels include; coal, natural gas, petrol, diesel and oil. IMPORTANCE OF FOSSIL FUELS They are a source of energy e.g. - heat energy - used to heat water that turns turbines to produce electricity - used as a fuel in transport 36 RENEWABLE AND NON – RENEWABLE ENERGY SOURCES RENEWABLE SOURCES – these are sources that can RENEWABLE ENERGY SOURCES – these are be replaced sources that cannot be replaced once they are used up. Biomass (wood, dung, etc) Oil The sun (solar energy) Coal Moving water(hydroelectric energy) Gas The heat of the earth(geothermal energy) Energy from radioactive material( nuclear energy) ALTENATIVE ENERGY SOURCES AND THEIR AVAILABILITY IN BOTSWANA Form of energy Formation Availability in Botswana Solar Created from heat and light of the sun. Available Hydroelectric Produced when running or falling water is used to turn Not available turbines. Wind When blow, it is used to turn large propellers which Available turbines to turn. Biomass Produced when bacteria and chemical process change Available waste matter to fuel. Nuclear Is generated when atoms undergo fusion.fusion takes Not available place when the nucleus of an atom splits,during this