A3 PSLE Science Notes (2023) Annotated PDF

Characteristics of living things 4 processes in sexual reproduction of ֍ plants Melting point of ice /Freezing pt of water: 0 °C 3. The digestive system consists of the mouth, Compare how plants, fish and humans take in 1. Ne...

Characteristics of living things 4 processes in sexual reproduction of ֍ plants Melting point of ice /Freezing pt of water: 0 °C 3. The digestive system consists of the mouth, Compare how plants, fish and humans take in 1. Need Food, Air & Water to survive When ice is heated, it gains heat & melts to become gullet, stomach, small intestine, large intestine oxygen & give out carbon dioxide. 2. Grow pollination water at 0 °C. When water is cooled, it loses heat & and anus. 3. Reproduce germination fertilisation (seed production) freezes to become ice at 0 °C. It breaks down food into simple substances. 4. Respond (to changes around them) seed dispersal Boiling point of water: 100 °C It absorbs these substances so that they can be When water is heated, it boils & changes to steam at used by the body. Some groups of living things: Note: Seed dispersal usually happens before 100 °C. When steam is cooled, it condenses to water 1. Plants germination (but a mangrove seed germinates while it at 100 °C. Flowering OR Non-flowering e.g. moss / fern is attached to the parent plant). 2. Animals Why do we see mist? Amphibians/Birds/Fish/Insects/Mammals/Reptiles Parts of a flower: When the warm water vapour (of boiling/hot water) A – moist skin (frog) Male: Filament, Anther comes into contact with the cooler air, it loses heat & B – feathers (chicken, eagle) Female: Stigma, Style, Ovary, Ovule condenses to form water droplets which are seen as F – gills, scales (goldfish, guppy) Brightly coloured petals can attract pollinators. mist. I – 3 body parts, 6 legs, hard body covering Ovules → seeds, Ovary → fruit (cockroach, When the warm water vapour of the surrounding air M – hair/fur, gives birth to young, adult females Physical characteristics of FLOWERS for pollination comes into contact with the cooler air (around the ice produce milk (cow, goat, squirrel, rabbit, bat) cube), it loses heat & condenses to form water Fish: Gills → Other parts → Heart → Gills again R – scales, with or without shells (snake, tortoise, Wind → dull-coloured, no scent, stigmas/anthers droplets which are seen as mist. lizard) hanging out, no nectar - The exchange of gases in the human lungs WATER CYCLE: Heat from the Sun causes water All animal groups lay eggs except mammals 4. The skeletal system consists of the skull, rib and take place between the air sacs and the from water bodies to gain heat and evaporate to form 3. Fungi (mould, mushroom, yeast) Animal → Brightly-coloured petals, with backbone. blood vessels. water vapour. As the water vapour rises, it loses heat 4. Bacteria scent/smell, with nectar Water containing dissolved oxygen enters and condenses to form water droplets which gather It supports the body. - through the mouth and passes through the Physical characteristics of fruits/seeds for dispersal to form clouds. When the water droplets become too It gives the body shape. gills of the fish. The oxygen enters the blood Materials Physical properties heavy, they fall down as rain. It protects the organs in the body. in the gills and is transported to different parts 1. Ceramic 1. Strength (strong, not strong) 2. Flexibility (flexible, not flexible) Water: fibrous husk that traps air, able to float on No Evaporation → Water cannot become water of the fish. As water flows out from under the 2. Fabric 5. The muscular system consists of muscles. gill covers, carbon dioxide is removed. 3. Waterproof or not (absorbs water or not) water, waterproof covering vapour & water cycle cannot go on. 3. Glass (young plants along river banks, seaside etc.) It helps different parts of the body to move. - The exchange of gases with the surroundings 4. Transparency (allows all/most/some/no 4. Metal light to pass through) No Condensation → No clouds formed, no rainfall. takes place through tiny openings (stomata) Wind: feathery/hair/wing-like structure. (young plants Water vapour remains in air & cannot return to Earth Human respiratory system found mainly on (underside of) leaves. 5. Plastic 5. Ability to float/sink in water 6. Elasticity in direction of wind from ___ to ___) for water cycle to repeat itself. Organ Functions 6. Rubber Nose Air enters the body through the nose and Air is a mixture of gases such as nitrogen, 7. Magnetic (Iron/Steel) or not Living things need water & the water cycle provides 7. Wood Animal: 1. Hooks/bristles attach/stick to fur the hairs in the nostrils remove dust from carbon dioxide, oxygen & water vapour. 8. Good conductor of heat (Metals)/ them with a continuous supply of water. 2. Fleshy, juicy fruit/ Big seeds/ hard or the air breathed in. Poor conductor of heat (Non-metals) indigestible seeds which can be passed out in waste Air also leaves the body through the Compare how substances are transported 9. Conductor of electricity (Metals)/ Water is important to life processes nose when we breathe out. within: (young plants randomly spaced out) Insulator of electricity (Non-metals) 1. Digestion Wind The air travels between the nose and the - plants: tubes that transport food and water 2. Transport of substances in circulatory system pipe air tubes through the windpipe. Both the Splitting: dry pod which curls back when “ripe”, - humans: blood vessels that transport digested Some definitions 3. Germination & Growth of plants windpipe and the air tubes transport the scattering seeds on it’s own (with force) food, oxygen and carbon dioxide 1. “strength” → ability to be subjected to loads 4. Photosynthesis air to and from the lungs. (young plants around parent plant) Lungs Each air tube leads to one of the lungs. without breaking. 5. Transport of minerals & food in plants Plant transport system: 2. “flexibility” → ability to bend without breaking. The lungs help the body to take in 3. “waterproof” → does not absorb water/allow Process of fertilisation in the human reproduction Impact of water pollution on Earth's water resources oxygen and remove carbon dioxide. Part Function 1. Fertilisation occurs when a sperm fuses with an (rainwater, rivers, sea). When the air reaches the lungs, oxygen Water-carrying Carry water & minerals from water to pass through. passes into the blood. tubes the roots to all parts of plant. 4. “transparency” → whether material allows most/ egg. 2. The fertilised egg develops in the womb. E.g. When the sea is polluted by oil spills, animals (The blood transports the oxygen to all and plants living in the sea may not be able to Food-carrying Carry food (sugar) from the some or no light to pass through. parts of the body.) tubes. leaves to all parts of plant. 5. “elasticity” → ability to return to its original shape/ Note: Ovaries produce eggs, testes produce sperms. survive. Water sources / food sources will be reduced. At the same time, the blood transports length when applied force is removed. Plants can reproduce by spores or seeds. Clean water is a limited natural resource → need to carbon dioxide to the lungs. The carbon 6. *Magnetic → Can / will be attracted to magnets conserve (save) water. dioxide is removed from the body when 7. *Good conductor of heat → Allows heat to be Similarity in terms of fertilisation in the sexual 3Rs: Reduce, Reuse, Recycle – treating used water we breathe out. transferred/gained/lost more easily / quickly by removing harmful substances using advanced (In the lungs, the air tubes branch into reproduction of flowering plants & humans. tiny tubes that end in air sacs. The air 8. *Conductor of electricity → Allows electric current -------------------------------------------------------------------- technologies so it can be reused. sacs are surrounded by blood vessels. to flow through. Matter is anything that has mass & occupies space. The exchange of gases in the lungs take A cell is a basic unit of life. Factors which affect rate of evaporation CELL part Function Animal Plant place between the air sacs and the blood Mass is measured using electronic mass balance. 1. Wind (Speed / Strength / presence) vessels.) 1. Nucleus See below. √ √ Different living things have different life cycles 2. Exposed surface area of liquid Volume of liquid → measuring cylinder/syringe 2. Cytoplasm √ √ Adult plant (beaker is not so suitable – intervals are too large) 3. Temperature of surroundings 3. Cell membrane √ √ Human circulatory system Volume of regular solids →calculation 4. Temperature of liquid Organ Functions 4. Cell wall - √ 5. *Humidity (Amount of water vapour in air) 5. Chloroplast - √ (~leaf) Seed → Young plant Volume of gas → syringe Blood - transports oxygen, digested State of matter Definite volume Definite shape food and water to all parts of the CELL parts & Functions body 3 stages 4 stages Solid √ √ *Identify human organ systems (digestive, skeletal, Nucleus - Controls all the activities in a cell. - transports carbon dioxide & - Contains information that is (egg, nymph, adult) (egg, larva, pupa, adult) Liquid √ X respiratory, circulatory, muscular) & state functions. other waste materials away from 1) Butterfly passed on from parents to young. 1) Grasshopper Gas X X various parts of our body. Cytoplasm (jelly-like substance) which allows 2) Cockroach 2) Beetle 1. The respiratory system consists of the nose, cell activities to take place in it windpipe and lungs. Blood (tubes that) transport blood to all 3) Mosquito Note: Air has no definite volume/ can be Controls the movement of (egg, young, adult) vessels parts of our body. Cell Note: The young/larva of COMPRESSED. It takes air into the body. membrane substances in and out of the cell. 3) Chicken insects eats a lot and moults Heart pumps blood through blood ” Empty space ” → There’s AIR. It removes air from the body. vessels to all parts of the body all Cell wall supports & gives the plant cell its 4) Frog several times. shape. 5 Changes of state (Temperature stays constant) the time. Chloroplast structures that contain chlorophyll, 2. The circulatory system consists of the heart and Living things reproduce to ensure continuity of their (the green pigment) that traps Heat gained/needed Heat lost blood in blood vessels. Digestive, respiratory & circulatory systems sunlight to make food for the plant. kind and that many characteristics of an organism 1. Melting (S → L) 4. Condensation (G → L) It carries digested food, water and oxygen in the work together to carry out life processes. are passed on from parents to offspring. 2. Evaporation / 5. Freezing (L → S) blood to all parts of the body Note: Some animal cells may have chloroplasts & no cell 3. Boiling (L → G) It carries waste materials away from different parts walls. Some animal cells like blood cells adapt to have no nucleus, so they cannot reproduce & have limited functions. of the body. Cells in stems or fruits can have chloroplasts too.  PLANT part Function A magnet can exert a push or a pull. Friction causes wear & tear. Without friction, we Positive Decomposers obtain energy/food by breaking Roots 1.Absorb water & minerals from soil may slip/cannot hold objects. 1) Conservation (3Rs of materials/water, down dead (plant/animal) matter and animal 2.Hold plant firmly to soil Characteristics of magnets: Reduce pollution, Protect wildlife) waste into simple substances which are 1) Magnets can be made of iron or steel To reduce friction: 2) Reforestation (Planting to replace trees returned to the soil as minerals to be used by Leaves 1. Make food (sugar) for plant. 1. Apply lubricant like oil, grease on moving parts or 2. Exchange gases with surroundings 2) Magnets have two poles: North & South removed, new trees take in CO2, reduce CO2 plants again. between surfaces in contact → less wear & tear/ Stem 1. Hold the plant upright so leaves can 3) A freely suspended bar magnet comes to rest in air, reduces effects of global warming) Decomposers ensure that the Earth will not be overheating between parts. get sunlight to make food for plant. pointing in a North-South direction covered with dead matter & animal waste. Or smoothen surfaces with sandpaper etc. 2. Transport water & minerals from … 4) Unlike poles facing each other attract & Negative -------------------------------------------------- Some fungi and bacteria are decomposers & some 2. Rollers and wheels makes it easier to move heavy to…/Transport food from … to … of them can cause diseases which can wipe out a like poles facing each other repel objects.(e.g. Using trolleys) 1) Global warming whole group of plants or animals as a result of Flower/ For reproduction (pollination/fertilisation) 5) Magnets attract magnetic materials - Average temperature of Earth rises diseases. Fruit For reproduction (seed dispersal) 6) Strongest magnetic pull at poles Effects of forces on springs - Due to more CO2 in air, more heat trapped Animals obtain energy by consuming other Compare magnets, non-magnets & magnetic Elastic spring force (exerted BY spring) allows a - Ice melts, sea levels rises, floods, loss of organisms. An electric circuit has an energy source materials. stretched / compressed spring to return to its habitats Plants obtain energy from the food they make. (battery) & other circuit components (e.g. A original length when the applied force is - Weather changes →Little/Heavy Rain → wire, bulb, switch). removed. Droughts/Floods →Plants destroyed → Food Requirements for photosynthesis A current can only flow in a closed / Elastic s. force is DIFFERENT fr. applied force shortages. 1. Water 2. Carbon dioxide complete circuit. 3. Light energy (trapped by chlorophyll) Factors affecting survival of organism/ 2) Pollution (L/A/W) **Photosynthesis produces sugar & oxygen. Electrical conductors: Metals e.g. copper characteristics of environment (LOWFATS) - Land (waste takes up space) A plant respires (takes in O2, produces CO2 all day) (usually used in wires), aluminium, iron, steel Physical - (Temperature, Light, Air, Water, Soil) - Air (haze, smell, chemicals, dust, acid rain) Electrical insulators: Non-metals e.g. rubber, - availability of Food - Water (oil spills, harmful chemicals from 6 Types/forms of energy: (KS HELP) wood, plastic, glass etc. - types of other Organisms present (producers, - Kinetic energy - Electrical energy factories) magnet can attract objects made of magnetic consumers, decomposers) - Sound energy - Light energy E.g. of circuit diagrams: series/parallel materials AND it can attract the unlike pole - Heat energy - Potential energy (G, C, E) Effect of variables on current When environment becomes unfavourable, organisms 3) Depleting natural resources (facing it) / repel the like pole of another magnet. adapt & survive; migrate or die. - Fossil fuels (non-renewable) - No. of batteries (arranged in series) Sources of energy: Sun; Wind; Running water & - No. of bulbs (arranged in series / parallel) - Materials - Over-mining/Cutting down trees fossil fuels – coal, oil, natural gas; Fuels e.g. An object made of magnetic material can be A food chain contains at least 3 organisms, - Food sources (overfishing etc.) wood, Battery, Food etc. attracted by magnets (either pole). starts with producer/plant & shows energy An object that is not made of magnetic material transfer from one organism to another E.g. of Energy conversion from one form to 4) Deforestation cannot be attracted or repelled. organism. another. - Loss of habitats, extinction, population decline (Energy flow diagrams can show from sun → 1. Solar Cell (LIGHT from Sun → Elect.) A magnet made using electricity is called an - Dry land → less rainfall plant → organisms). - CO2 increases as less trees take in CO2 during electromagnet. It can attract magnetic objects 2. Roller Coaster (KE, GPE) only if it is connected to a battery or energy A food web consists of at least 2 food chains. photosynthesis 3. Pendulum or swing (KE, GPE) source. When removed, it will lose its - Soil erosion due to wind/water → muddy rivers magnetism. A prey is an animal that is hunted,killed & eaten. 4. Lighting circuit (PE from battery → Elect. in A predator is an animal that hunts & kills other wires → Light + Heat of bulb) Make magnets by “Stroke”/Electrical method An object can be seen IF it reflects light OR is a * If from mains, it is electrical energy animals for food. Stroke method: An organism is a living thing. light source. A shadow is formed when light is 4. Ball stops: KE of ball → Heat (ball/ground) 1) Stroke the iron nail a few times with one end completely or partially blocked by an object. of a bar magnet (as shown in the diagram). A population is a group of organisms of the 5. Cycling up a slope (PE from food eaten → \ 2) Test to see if the iron nail can attract any same kind, living & reproducing at a given place KE + GPE of cyclist) Property: Light travels in straight lines. small magnetic object. & time. 6. Hydroelectric power station: GPE of water → 3) Continue to stroke the iron nail until it A community consists of many different Variables that affect shadows: KE of flowing water → KE of turbine → becomes a magnet. populations living together in a particular place. - shape, size & position of object(s) Electrical energy in generator → The magnetic object is stroked many A habitat is a place where an organism/ 7. Steam-powered power station: PE of fossil times in the same direction with the same community lives. - dist btw light source-object & object-screen pole of a magnet each time. A habitat provides food, air, water, shelter, fuels → Heat energy of fuels/water → KE of space & protection. (FAWSSP) S. Bigger Smaller B. steam → KE of turbine → Elect in generator Electrical method:  T →  O →  S → 1) Coil a long piece of wire around the iron nail Different habitats support different communities (garden, field, pond, seashore, tree*, mangrove Need to conserve energy usage in our at least 20 times. Sources of heat: Sun, fire, lighted candle/bulb Advantages of connecting in parallel: 2) Connect both ends of the wire to a battery. swamp) everyday life. (See previous notes of Electricity) 1. When one bulb blows, the other(s) remain lit. *Temperature (of object/substance) is a 2. Can switch on and off individually and save 3) Test to see if the iron nail can attract any small magnetic object. *Can have tree community within a garden community measurement of its degree of hotness. electricity. but organisms of tree community usu. stay on the tree. 3. Bulbs in parallel brighter than in series (same → A wire is coiled many times around the *Heat is a form of energy. number of batteries) magnetic object, with the ends of the wire If same temp → More mass, contains more heat. connected to a battery/power supply. Adaptations serve to enhance survival & can be If same mass → Higher temp means more heat. Need to conserve electricity/use wisely List some uses of magnets: E.g. magnetic Structural (physical characteristics) or Generating electricity is costly and uses up chess board, compass, doorstopper, Behavioural (how organism acts). Heat flows from a hotter to a colder object/ precious fossil fuels which can eventually run - cope with physical factors, obtain food, escape refrigerator, Maglev train & rollercoaster region until both reach same temperature. out. We need to conserve electricity so that the predators, reproduce by finding & attracting A change in temp. is due to gain/loss of heat. fuels on earth will last longer. (Both use electromagnets) etc mates/ dispersing seeds/fruits Use energy saving bulbs and turn off all Effects of a force which is a push/pull: Effects of heat gain / loss electrical appliances when not in use. 1. can move a stationary object (Super President Donald T.R.U.M.P.) 1) temperature rise/fall 2. can speed up motion 2) contraction / expansion of objects (S, L, G) Proper use & handling of electricity 3. slow down motion S – obtaining Sunlight 3) change in state of matter (temp. constant) If we are not careful when we use electricity, 4. change the direction of motion 5. can stop a moving object P – chasing Prey electric shocks can hurt us or even cause death. Good conductors of heat: metals 6. may change the shape/size of an object D – coping with Darkness a) Do not put too many plugs into one socket. Poor conductors of heat: wood, plastics, air The plugs may get too hot and start a fire. T – coping with extreme Temperatures Types of forces: Light intensity & temperature can be b) Never touch switches with wet hands. - Gravitational force (Thus, objects have weight) R – Reproduction (mates, pollination, dispersal) measured by datalogger with light/temperature c) When using electrical appliances, hold onto - Elastic spring force / elastic force sensors. A thermometer measures temperature. the plastic or wooden handles. - Frictional force U – breathing Underwater d) Check electrical appliances regularly for - Magnetic force M – Movement (streamlined body shape…) Living things need energy to carry out life processes. exposed wires. e) Never try to repair any electrical equipment Friction opposes motion & causes objects to P – escaping from Predators The Sun is our primary source of energy (light and yourself. Ask an adult /an electrician for help. slow down. KE→heat heat) & energy from most of our energy resources is Man’s impact on environment. obtained in some ways from the Sun.