Physics

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... that were created by a few of my classmates and I on Facebook when we were in .... Why are boiling stones / porcelai
These were notes that were created by a few of my classmates and I on Facebook when we were in Sec 2. We... did not complete it. Nevertheless, we hope this last-minute work (then) will help you as you prepare for the exam through the process of revision. The LSS syllabus for Sec 1 and Sec 2 respectively may have changed, so some of the following may not be relevant to you. Use of the following is completely at your own risk. We will not be responsible in any incompleteness of your answers in the actual exam.

Physics 

ENERGY

1. State the principle of conservation of energy? Ans: Energy cannot be created nor destroyed, but can be converted from one form to another or transferred from one body to another while total energy remains constant. 2. Springs always exert their force downwards. Ans: True 3. The rebound height of a ball is always less than the initial dropped height. Explain why. Ans: When the ball rebounds, some kinetic energy is converted to heat and sound energy.



LIGHT AND COLOUR

1. What are the two laws of reflection? The normal, incident ray and the reflected ray both lie on the same plane. The angle of incidence is equal to the angle of reflection. 2. Angle of incidence is equal to angle of emergence. Ans: True 3. Third class lever has the effort in the middle while first class lever has the fulcrum in the middle. Ans: True 4. What are the characteristics of an image of a plane mirror? Ans: Virtual, Laterally inverted, Upright, Same size, Same distance away from the mirror 5. What is the difference between a real and virtual image? Ans: A real image can be projected on a screen while a virtual image cannot be projected on a screen. 6. What are the characteristics of a convex and concave mirror? Ans: A convex mirror bends towards the object while a concave mirror bends away from the object. 7. Where are convex mirrors used? Ans: Car side mirrors / Security mirrors in a shop 8. Where are concave mirrors used? Ans: Dentist mirrors / Cosmetic mirrors / Car headlights / Torchlights 9. What are the features of an image of a convex mirror? Ans: Diminished, Virtual, Upright, Wider scope of view 10. What are the features of a near image of a concave mirror? Ans: Diminished, Inverted, Real

11. What are the features of a far image of a concave mirror? Ans: Magnified, Upright, Virtual 12. What is refraction and why does it occur? Ans: Refraction is the bending of light rays and the change of the speed of light when it passes from one transparent medium to another of different optical densities. 13. Why does a swimming pool full of water will appear shallower than it actually is? Ans: The optical density of air is lower than the optical density of water. When light rays travels from the air to water, light will bend towards the normal, hence the bottom of the pool appears higher. 14. What should you look out for when drawing a ray diagram? Ans: Draw a dotted line to represent the normal and indicate that the normal is perpendicular to the mirror surface. 15. What primary colours form the secondary colours? Ans: Red (highest wavelength), Orange, Yellow, Green, Blue, Indigo and Violet (lowest wavelength). 16. What is dispersion? Ans: It is the separation of white light into its seven colurs. 17. What type of colour is reflected when coloured light is shone onto an object? Ans: The similar colour of the light and object will be reflected while the different colours are absorbed by the object. 18. What type of colour is passes through coloured filter paper? Ans: The similar colour of the light and filter paper will pass through while the different colours are absorbed by the filter paper.



TURNING EFFECTS

1. State the principle of moments? When an object is in equilibrium, the total clockwise moments about a pivot are equal to the total anti-clockwise moments about the same pivot. 2. Define moment? Moment is defined as the product of the force and the perpendicular distance from the line of action of force to the pivot. 3. How would a force produce a zero turning effect? A force produces zero turning effect when the force is exerted on the pivot. 4. How would a force produce a maximum turning effect? A force produces maximum turning effect when the force is exerted as far away from the pivot as possible.



ELECTRICITY

1. How is current measured and where is the meter placed? Ans: Current is measured by an ammeter and it is placed in a series arrangement.

2. How is potential difference measured and where is the meter placed? Ans: Potential difference is measured by a voltmeter and it is placed in a parallel arrangement. 3. Define current? Ans: Current is the amount of charge carried by each electron when they flow through a wire per second. 4. Define potential difference? Ans: Potential difference is the amount of electrical energy converted to other forms of energy per unit of charge flow. 5. Define resistance? Ans: Resistance is the ratio of the amount of potential difference across a component to the amount of current flowing through it. 6. What is Ohm’s Law? Ans: V = I R 7. How is resistance measured in a series and parallel arrangement? Ans: Series: R (eff.) = R (1) + R (2) Parallel: [1 / R (eff.)] = [1 / R (1)] + [1 / R (2)] 8. How is potential difference measured in a series and parallel arrangement? Ans: Series: V (total) = V (1) + V (2) Parallel: V (total) = V (1) = V (2) 9. How is current measured in a series and parallel arrangement? Ans: Series: I (total) = I (1) = I (2) Parallel: I (total) = I (1) + I (2) 10. Explain change in current when a pathway for current to flow through increases or decreases. Ans: When the pathway for current to flow through increases, current is being divided in a parallel circuit. Current decreases. When the pathway for current to flow through decreases, there is one pathway for current to flow through. It becomes a series circuit. As resistance increases, current decreases.

Chemistry 

MIXTURES AND COMPOUNDS

1. Define mixture and compound. Ans: Mixture is 2 or more substances that are not chemically combined and not in fixed proportion. Compound is 2 or more substances chemically combined in a fixed ratio. 2. What are the differences between a mixture and a compound? Ans: Compound is a pure substance. Mixture is not pure. Compound is in fixed proportion. Mixture is not in fixed proportion. 3. Define solution. Ans: A solution is a mixture consisting of one or more dissolved substances in a liquid. (Note: A solution may be either a mixture of solid and liquid or two liquids.) 4. What are the properties of a solution? Ans: Clear, Homogeneous, Solute particles do not sink to the bottom, Solute particles do not get left behind as residue.

5. Define saturated solution. Ans: A solution with the max amount of solute in the solution 6. What is the difference between a concentrated and saturated solution? Ans: A concentrated solution contains a high amount of solute while a saturated solution contains a maximum amount of solute. 7. What is the difference between solubility and rate of dissolving? 8. Name the factors affecting solubility. Ans: Type of Solute, Type of solvent and temperature. 9. Explain how they are able to affect solubility. Ans: Diff types of solute are soluble in Diff types of Solvent( answers 2 question) And a higher temp will make the the Solvent particles expand and able to have more solute 10. Name the factors affecting rate of dissolving. Ans: Stirring, Temp and surface area 11. Explain how they are able to affect rate of dissolving. Ans: Higher temperatures gives solvent particles energy causing higher speed collisions that are able to produce a reaction quickly. Stirring provides more energy to the solvent and solute particles. They hit onto one another with stronger forces. Higher surface area brings about more contact between the solute and solvent. Hence powdered solids dissolve faster than lumps of solids.



SOLUBILITY

1. Distinguish between a soluble and insoluble substance. 2. List the reactivity series of metals.



ACIDS AND BASES

1. What is an acid? Ans: An acid is a substance that produces hydrogen ions in water. 2. What is a base and what is an alkali? Ans: A base is a metal oxide or metal hydroxide that reacts with acids to produce salt and water only. An alkali is a soluble base that produces hydroxide ions in water. 3. What are the differences between an acid and an alkali? Ans: An acid is produces hydrogen ions in water while an alkali produces hydroxide ions in water. An acid has a sour taste while an alkali has a bitter taste 4. What happens when an acid reacts with a metal, carbonate and base? Ans: An acid reacts with a metal to form salt and hydrogen. An acid reacts with a carbonate to form salt, water and carbon dioxide. An acid reacts with a base to form salt and water only. 5. What happens when a base reacts with an acid and an ammonium salt? Ans: A base reacts with an acid to form salt and water only. A base reacts with ammonium salts to form ammonia gas, water and salt.

6. How would you test for the presence of hydrogen? Ans: Place a lighted splint in the gas. A pop sound is heard and the splint is extinguished. 7. How would you test for the presence of carbon dioxide? Ans: Bubble the gas into limewater. A white precipitate would be formed. 8. How would you test for the presence of oxygen? Ans: Place a glowing splint in the gas. The splint would be relighted. 9. How would you test for the presence of ammonia? Ans: Place a moist red litmus paper in the gas. The moist red litmus paper will turn blue. 10. What is a strong acid? Ans: A strong acid is an acid that completely ionises in water. 10. What is a weak acid? Ans: A weak acid is an acid that only ionises to a slight extent in water. 11. How do acids and alkalis affect the universal indicator? Ans: An acid will change the universal indicator from green to red while an alkali will change the universal indicator from green to purple. 12. How do acids and alkali affect phenolphthalein? Ans: An acid will not change phenolphthalein’s colourless colour while an alkali will change the phenolphthalein colour from colourless to pink.



SEPARATION TECHNIQUES

1. Describe Filtration. Ans: Place a piece of filter paper in a filter funnel. Position a beaker under the filter funnel and pour the mixture into the filter funnel. The filtrate will be collected in the beaker and the residue remains on the filter paper. Wash the residue with distilled water and let it dry. 2. Why must the residue be washed with distilled water and left to dry? Ans: Some of the solute is absorbed on the surfaces of the residue. Washing the residue with the water would help to flush down the solute into the filtrate, ensuring that the residue is cleaner. 4. What will you obtain as the end product in Evaporation and/or Crystillisation? Ans: The solute of the original solution 5. Describe the process of Crystallisation. Ans: Dissolve the substance with water and filter the solution. The residue and the filtrate will be separated. Heat the filtrate to half volume and allow the hot saturated solution to cool down. Recover the crystals via filtration. Dry the crystals by pressing them between sheets of filter paper. 6. What is the difference between crystallisation and evaporation? Ans: Crystallisation applies to all substances while evaporation only applies to substances that do not decompose when heated strongly. 8. What will you obtain as the end product of distillation? Ans: The pure solvent of the original solution. 9. Why are boiling stones / porcelain chips added into the distillation flask? Ans: To ensure smooth boiling and prevent too much bubbling. 10. Why must the bulb of the thermometer placed beside the sidearm of the distillation flask? Ans: To measure the temperature of the vapour to be condensed in the Liebig condenser.

11. Why must a Liebig condenser be placed in the experiment? Ans: It is used to condense the vapour and change it into a liquid form. 12. Why should cold water enter through the bottom and warm water leave through the top of the Liebig condenser? Ans: It is to maintain a gradual drop in the temperature of the water in the condenser so as to ensure effective cooling of the vapour. 13. Describe the function of Fractional Distillation. Ans: It is used to separate a solution of liquids with different boiling points. 15. Why must you draw the starting line in pencil instead of pen? Ans: The dyes in the ink of a pen may be soluble in the solvent and interfere with the chromatogram. 16. Why must you apply only a small spot of the tested ink to the pencil line? Ans: To prevent spreading of dyes sideways and thereby getting mixed up with other nearby spots. 17. Why must ensure that the solvent does not touch the starting line? Ans: The substance will dissolve into the solvent rather than travelling up the chromatogram. 18. Why must the solvent be in a beaker and covered with a lid? Ans: It is to prevent the solvent to evaporate away from the chromatogram too quickly and result in an incomplete experiment. 19. Explain why should the solvent front be as high as possible? 21. Describe Sublimation. Ans: Place the mixture in an evaporating dish. Position the dish under a bunsen burner. Place an inverted funnel just above the dish. The substance with high melting point would be left on the dish. 24. Explain the difference in the properties of the substances that is used in the above separation techniques. 25. How do impurities affect melting and boiling points of substances? Ans: Impurities lower the melting point of a substance and increase the boiling point of the substance. They are not fixed and occur over a range of temperatures.

Biology 

DIFFUSION AND OSMOSIS

1. What is diffusion? Ans: It is the movement of molecules from a region of higher concentration to a region of lower concentration. 2. What is osmosis? Ans: It is the movement of water molecules from a region of higher concentration to a region of lower concentration through a partially permeable membrane. 3. What are the differences between diffusion and osmosis? Ans: Diffusion refers to the movement of molecules while osmosis refers to the movement of water molecules. Diffusion does not require a partially permeable membrane while osmosis does.

4. What happens to an animal cell when placed in a diluted solution? Ans: The water potential in the animal cell is less than that of the diluted solution. Water will diffuse from the diluted solution into the animal cell. The animal cell will swell up and later break apart. 5. What happens to an animal cell when placed in a concentrated solution? Ans: The water potential in the animal cell is more than that of the concentrated solution. Water will diffuse from the animal cell into the concentrated solution. The animal cell will turn flaccid and decrease in mass. 6. What happens to a plant cell when placed in a diluted solution? Ans: The water potential in the animal cell is less than that of the diluted solution. Water will diffuse from the diluted solution into the animal cell. The plant cell will turn turgid and the mass of the cell decreases. 7. What happens to a plant cell when placed in a concentrated solution? Ans: The water potential in the animal cell is more than that of the diluted solution. Water will diffuse from the animal cell into the concentrated solution. Crenation occurs and the plant cell will turn flaccid. The mass of the cell decreases.



PLANT TRANSPORT

1. Why must multicellular organisms have a transport system while unicellular organisms do not? Ans: Unicellular organisms are able to transport materials like food, water and urea in and out of their bodies easily by diffusion and osmosis. However, the cells of multicellular organisms are too far away from the surface of their bodies. A transport system is required to transport materials around the body. 2. Describe the function of xylem and phloem tubes in a plant? Ans: Xylem conducts water and mineral salts from the roots to all parts of the plant, and provides mechanical support to the plant. Phloem transports organic materials / food up and down the body (translocation). 3. What does a vascular bundle consist of? Ans: Xylem tissues, phloem tissues and cambium (divides to form new xylem and phloem tissues) 4. Where are xylem and phloem tissues found in the stem, root and leaf? Ans: The xylem is always found on the interior / at the top. The phloem is always found on the exterior / at the bottom. 5. What are the functions of the xylem tissues? Ans: (same question as question 2) 6. How are xylem tissues formed? Ans: (You will not need to know this in the exam) 7. How are xylem tissues adapted for their functions? Ans: Has a dead empty tube to maintain a continuous lumen for water and mineral salts to be transported easily. Also has lignified walls to support the plant and prevent the xylem from collapsing. 8. How are phloem tissues adapted for their functions? Ans: Sieve cells are elongated and arranged end to end to conduct food. Also have companion cells to assist the sieve cells in the transport of food. 9. Draw and label a root hair cell. Ans: (How do I do this…? As in draw… ok study the Biology workbook :D)

10. What is the root hair cell’s function? Ans: The root hair cell provides support to the plant and keeps it upright. It also helps the plant absorb water and mineral salts efficiently. 11. How is root hair cell adapted for their functions? Ans: Has a large vacuole to create a steeper concentration gradient and has finger-like extensions to increase surface area to volume ratio and absorb water and mineral salts faster. 12. What are the forces that cause water movement in the plant? Ans: Root pressure (continuous movement of water through roots hair cells), capillary action (conduction of water of xylem) and transpiration pull (evaporation of water through the leaves to push the water and nitrate ions up the stem). 14. What is the function of transpiration pull? Ans: Ensures a constant flow of water to be taken from the soil to the leaves and enables photosynthesis to occur. 15. How is rate of transpiration affected? Ans: Rate of transpiration increases when: Humidity of air is low Temperature of environment is high Speed of wind is high Light intensity is high 16. How is the plant affected when light is absent? Ans: When light is absent, photosynthesis does not occur. The plant loses more water and the guard cells turn flaccid. This would cause stomata to close and transpiration decreases.



TRANSPORT IN HUMANS

1. Describe the adaptations of the heart. Has valves to prevent the backflow of oxygenated and deoxygenated blood in the right and left side of the heart. Has specialised muscles to ensure constant contraction and relaxation of the heart. Consists of two chambers separated by a septum to enable double circulation, maintain pressure and prevent deoxygenated and oxygenated blood from mixing 3. Describe the circulation of blood in the body from the heart Body Cells -> Vena Cava -> Pulmonary Artery (deoxygenated blood) -> Lungs -> Pulmonary Vein -> Aorta 4. Why do humans require double circulation? Blood goes through the heart twice in a single circulation. This is important as blood loses pressure after taking up oxygen in the lungs. Hence, it is sent back to the heart to be re-pumped. 5. What does blood consist of? Red blood cells, white blood cells, plasma and platelets. 6. What are the functions of blood? -Transport oxygen from lungs to tissues. -Transport carbon dioxide from tissues to lungs -Transport of digested food and mineral salts from the digestive tract to the other parts of the body -Transport of excretory waste products from the tissues to the lungs, skin and kidney -Transport of hormones from the endocrine glands to the parts of the body which need them. -Distribution of heat to help maintain body heat -Removal of pathogens(bacteria) and dead cells by phagocytosis -Production of antibodies

7. How is the red blood cell adapted to its function? -Minute, circular and biconcave. This increases their surface area, thus increasing the efficiency of diffusion of gases across the membrane. 8. What are the functions of the two types of white blood cells? - Phagocytes: engulf and ingest foreign bodies -Lymphocytes: Produce antibodies which cause the bacteria clump together, making them easy to be ingested 9. Draw out the two types of white blood cells and describe their shape. Lymphocyte - Round - has a large nucleus Phagocyte - Irregular - Lobed Nucleus - Granular cytoplasm 10. What is the function of platelets? Aid in the blood clotting process. 11. What is the function of plasma? Carries proteins, dissolved materials, carbon dioxide, hormones, urea, etc around the body 12. Describe the properties of an artery. -Present thick layer -Muscular, elastic wall -Fast flow of blood in lumen -High blood pressure -Low blood volume -Not permeable -Valves absent -Carry oxygenated blood 13. Describe the properties of a vein. -Thinner muscular wall -Elastic, very thin layer -High blood volume -Slow at low pressure -Not permeable -Valves present -Transports blood towards heart under low pressure 14. Describe the adaptations of capillaries. -One cell thick walls -Non-muscular -Non-elastic -Low blood pressure -Slow blood flow in lumen -Slightly less volume than in artery -Partially permeable -Valves absent -Function is for exchange of materials



REPRODUCTION IN HUMANS

1. Define sexual reproduction. Ans: Sexual reproduction is the reproduction involving the fusion of the male and female sex cells in an animal.

2. What are male and female gametes called and where are they produced? Ans: Male gametes are called sperms and are produced in the testes. The female gamete is called an ovum and is produced in the ovaries. 3. What is the sex chromosome number found in the nucleus of the male and female gametes? Ans: 23 4. Label the parts of an sperm. (can’t draw, so I’ll tell you the parts of the sperm) Ans: Head (contains digestive enzymes to break down cell membrane of ovum), Middle piece (contains mitochondria to produce energy for movement) and Tail (for effective swimming) 5. How is the sperm adapted to its function? The sperm has a tail and a streamlined body shape to enable the sperm to swim efficiently. The sperm is light and small to enable fast movement 6. Why must the scrotum be found outside the body? The body’s temperature is too high for the production of sperms in the testes and requires a lower temperature to produce quality sperms. 7. Label the parts of an ovum. Ans: Cytoplasm (Storage of food to enable ovum to survive while awaiting fertilisation), Nucleus and Cell membrane (Hardens after one sperm has penetrated to prevent multiple fertilisation) 8. How is the ovum adapted to its function? Ans: Has a large size to enable sufficient food storage and maximise chances of fertilisation. It also has a cell membrane enables certain materials into the cell. 9. Tabulate the differences between a sperm and an ovum. 10. How are a sperm and an ovum similar? 11. Name the main parts of the male reproductive system. 12. Describe the route a sperm takes to reach the ovum of the female reproductive system? 13. Define puberty. Ans: It is the stage of human growth when a person develops and becomes physically mature. 14. When does puberty usually start for boys and girls respectively? Ans: Begins at 11 for girls and 14 for boys 15. What physical changes take place when a boy undergoes puberty? Ans: Facial hair, armpit hair and pubic hair starts to grow Voice box enlarges and voice deepens Penis and testes increase in size 16. What physical changes take place when a girl undergoes puberty? Ans: Pubic hair and armpit hair starts to grow Breasts and uterus enlarge while hips broaden 17. What is menstruation? Ans: It is the monthly discharge of blood from the uterus via the vagina. (It is part of the menstrual cycle and occurs for the first five days.)

18. What four processes occur during the menstrual cycle and when do the processes occur in the cycle? Ans: Approximate days: Day 1 to 5 – Menstruation (uterine lining is discharged and broken down) Day 6 to 10 – Growth, Thickening and repair of the uterine lining Day 11 to 17 – Fertile period (sperms likely to cause fertilisation) Day 13 to 15 – Ovulation (ovum is released into the fallopian tube from ovary) 20. Outline the events that occur after the menstrual cycle. Ans: Ovulation occurs and mature eggs are released. One ovum fuses with sperm to form zygote through fertilisation Embryo is formed and later implanted onto the uterine lining Placenta, amniotic fluids and the umbilical cord form after implantation 21. What are the functions of amniotic fluids, placenta and the umbilical cord? Ans: Amniotic fluid – Supports and protects the embryo Placenta – Allows diffusion of oxygen, food substances and excretory products to and from embryo’s and mother’s blood Umbilical cord – Transports deoxygenated blood from embryo to placenta and food substances from placenta to embryo 22. What happens when fertilisation does not occur after the menstrual cycle? Ans: The ovum breaks down together with the uterine lining on the 28th day. The ovum is discharged with the blood in menstruation through the vagina and the cycle repeats.



ISSUES ON SEX

1. What are contraception methods classified as physical (or barrier), chemical (or hormonal) and permanent (surgical). Ans: (Look at questions 2,3,4,5,6,7,8,9,10) 2. How is a male condom used and what does it do? Ans: The male condom is a sheath, usually made of rubber, that is worn over the penis during sexual intercourse. The sheath prevents sperms from being deposited in the vagina, thus preventing fertilization. Condoms are 88% to 98% effective for prevention of pregnancy if used correctly. It is only used once, then disposed. 3. How is a female condom used and what does it do? Ans: A female condom is inserted into the vagina. It prevents fertilization by setting up a barrier between sperms and egg. It is 79% to 95% effective. It is only used once, then discarded. 4. What is a diaphragm and how does it work? Ans: It is a round piece of rubber or plastic that is inserted through the vagina to cover the cervix. The diaphragm must be inserted prior to intercourse and needs to stay in place for at least 6 hours after intercourse(no longer than 24 hours). Used with spermicide for greater effectiveness. If used with spermicide it is about 83% effective. 5. How is an interline uterine device used and what does it do? Ans: It is an instrument that is inserted into the uterus. It works by preventing implantation of a fertilized egg. I must be inserted or removed by a doctor under sterile conditions and can be left in the body for up to 10 years. It is 98% to 99.4% effective. 6. What does hormone pill injection do and how does it work? Ans: It is made of female sex hormones that prevent ovulation. Without an egg fertilization cannot take place. Must be taken daily. If taken according to instructions, it is 99.5% effective.

7. What do spermicides do and how does it work? Ans: They are chemicals that kill sperms. There are different types of spermicides such as creams, jellies, foams and suppository inserts. Must be inserted into the vagina 15-30 minutes before sexual intercourse and can be used together with different forms of contraceptives. Spermicide is 79% effective if used without a condom. 8. How is vasectomy used and what does it do? Ans: It is a minor surgical procedure where the sperm ducts are cut and tied. After vasectomy, sperms are still produced but cannot travel to the uretha. The sperms will be reabsorbed by the body with no harmful effects. It is hard to reverse, but it is possible to be done. 9. How is tubal ligation used and what does it do? Ans: It is a surgical procedure where the fallopian tubes are cut and tied this prevents eggs from meeting sperms thus fertilization cannot occur. Surgery to reverse ligation is not always effective. 10. What are causes and symptoms of Gonorrhea? Ans: It is a bacterial infection passed through sexual contact. Some do not show any symptoms while others may have painful urination, sore throat, fever and discharge from sexual organs. Symptoms may show 1 -14 days after infection. 11. What are causes and symptoms of Syphilis? Ans: It is a bacterial infection passed through sexual contact. About 21 days after infection, painless sores will appear on sexual organs or other parts of the body. 3-6 weeks after appearance of sores, non-itchy rash will appear on the body. Will experience tiredness and loss of appetite. Also, swollen nymph lodes will appear. 10 years after infection, paralysis, blindness, heart damage, nerve damage and brain damage will appear. 12. What are causes and symptoms of AIDs? Ans: AIDS is caused by the Human Immunodeficiency Virus (HIV). The virus damages the persons immune system and makes the person vulnerable to infections and certain cancers. HIV infected person may not show symptoms for many years. The infected person will eventually fall ill from other sicknesses due to a weakened immune system. At this time the person is said to have full blown AIDS. Infected people are especially prone to Kaposi’s sarcoma, severe weight loss, brain infection, tuberculosis affecting many organs at the same time. There is no cure for AIDS, antiviral drugs may be taken to slow down the onset of AIDS. A person with full blown AIDS will most usually die within 2 years. 13. What treatment is given to Gonorrhea and what happens if left untreated? Ans: The treatment to Gonorrhea is with antibiotics. The disease may be cured if treated at early stages. If left untreated it may cause sterility in both men and women. 14. What treatment is given to Syphilis and what happens if left untreated? Ans: The main treatment is with antibiotics. The disease may be cured if treated at early stages. If left untreated if may cause sterility in both men and women. 15. How can one prevent the spread of HIV? Ans: (For all STDs) The best way to prevent STDs is to practice safe sex. A person should avoid promiscuous behavior and stick to one partner. Condoms can prevent STDs. Needles used for tattooing, acupuncture or ear-piercing should be properly sterilized to prevent AIDS. 16. What are some of the reasons for abortion? 17. What are some of the side effects of abortion?