PSLE Science Summary Notes PDF

PSLE SCIENCE SUMMARY NOTES (TOP school summary)  Topics Matter 5 Materials...

PSLE SCIENCE SUMMARY NOTES (TOP school summary)  Topics Matter 5 Materials 6 Cells 7 Processes 9 Systems 10 Adaptations 14 Reproduction 22 Environmental Interactions 28 Life Cycles 31 Heat 32 Energy 35 Forces 39 Electricity 43 Light 45 Magnets 48 Water and Changes of State 50 Man and the Environment 52 Definitions 57 Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 2 TIPS For questions which involve a table of results or an experiment, you can use a structure which includes… ANSWER Answer the question first, with a yes or no, or an A or a B, etc. when the question requires you to do so. This should also include some information from the question or the experiment such as, “Towel B had the smallest mass at the end of the experiment” Then insert the reasoning behind your answer which has to be backed by a scientific topic such as reproduction. You then sum up the entire answer by linking it to the initial answer by saying something along the lines of “Hence, this is why Material Z is the best conductor of electricity” Note: Be sure to use the correct comparison words. For example, if there are only two set-ups then use “better” but if there are more than two set-ups, use “best”. Sample Answer: Towel B is the most absorbent material. Towel B had the greatest change in mass at the end of the experiment from 20g to 50g showing that it had absorbed the most amount of water from the beaker. Hence, Towel B is the most absorbent material. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 3 Types of Questions Aim ↬ To find out if/how/which independent variable affects the measured variable Control Set Up ↬ The set-up is a control set-up to compare and confirm that any difference in the dependent is solely due to the (DV) Controlled Variable ↬ This prevents the (inferred factor) from affecting the (inferred DV), ensuring that any difference in the (DV) is solely due to the (IV). External factor (e.g. Experiment carried out in a dark room, layer of oil added etc.) ↬ This prevents (inferred external factor doing_ _), ensuring that any difference in the results is solely due to the (DV). Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 4 Matter ↬ matter is anything that has mass ↬ mass is the measure of the amount of matter in an object ↬ when matter gains heat, it: expands occupies more space, becoming bigger increases in volume remains the same in mass ↬ when matter loses heat, it contracts occupies less space, becoming smaller decreases in volume remains the same in mass Types of matter Solids ↬ has a definite shape and will not change in shape unless a force is applied ↬ has a definite volume ↬ cannot be compressed Liquids ↬ does not have a definite shape and takes the shape of its container ↬ has a definite volume and cannot be compressed ↬ the water level is always parallel to the floor Gases ↬ does not have a definite shape ↬ has no definite volume and can be compressed ↬ has definite mass meaning if you pump more air into a container, the mass will increase ↬ will occupy all the available space in the container Displacement ↬ occurs when matter occupies space previously occupied by another type of matter Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 5 Materials Properties Strength To be strong is to be able to withstand great amounts of force Hardness To be hard is to have the ability to withstand being scratched and indented Flexibility To be flexible is to be able to bend without breaking Waterproof To be waterproof is to not absorb water Elasticity To be elastic is to have the ability to return to the object’s original size/shape after forces are applied to it Durability To be durable is to be able to remain its condition in spite of potential damage Example questions Q: State 2 properties needed for a plate A: Rigid and waterproof. Note: When answering questions regarding something that should not be flexible do not answer saying flexibility and _. This answer could also refer to the object being flexible which is incorrect, so choose to say rigid instead. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 6 Cells A cell is the basic unit of life for all organisms Parts and Functions ↪ Nucleus ↬ Contains genetic information (DNA) ↬ Controls all activities in the cell, such as Cell division Cell repair ↬ Most cells have a nucleus ↪ Cytoplasm ↬ The place where chemical reactions or cell activities take place ↬ Transports substances within the cell ↬ Present in all cells ↪ Cell membrane ↬ Selectively permeable ↬ Controls flow of substances in and out of the cell ↬ Present in all cells ↪ Cell wall (plant cells) ↬ Supports the plant and gives it a regular shape ↬ Prevents cell from bursting when too much water enters ↬ Not present in animal cells ↬ Fully permeable, meaning most substances will pass through ↪ Chloroplast ↬ Present in green leaves and stem cells ↬ Contains chlorophyll to trap light to make food via photosynthesis ↪ Vacuole* (do not need to learn now) ↬ Stores water for cell Common Questions Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 7 Is Organism X (Euglena above) more like an animal cell or plant cell? EITHER It is more like an animal cell, as it does not have a cell wall. All plant cells have a cell wall and animal cells do not. Hence, Organism X is more like an animal cell. ORIt is more like a plant cell because it has a chloroplast. Only plant cells have a chloroplast. Hence, Organism X is more like a plant cell. Q:When exposed to starch, the iodine solution turns dark blue and its original colour is yellowish-brown. The Visking tube is a material similar to the cell membrane and has properties similar to it as well. What happens after 30 minutes? A: The iodine solution in the container remains yellow-ish brown and the mixture inside the Visking tubing turns dark blue. This is because the Visking tubing is selectively permeable, similar to the cell membrane. The Visking tubing only allowed the iodine solution to enter it but not the mixture in the tubing to exit the tubing. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 8 Processes Photosynthesis ↬ needs sunlight, carbon dioxide and water ↬ produces oxygen and glucose (not starch) ↬ chlorophyll in chloroplasts in the leaf trap light to make food for the plant through photosynthesis ↬ Helps the plant make food During photosynthesis, the plant takes in carbon dioxide and water and converts them to glucose and oxygen. It can only photosynthesise in the presence of sunlight. Excessive glucose (interchangeable with sugar and food), is stored in fruits, storage roots, or storage stems as starch. Starch can be tested for with iodine solution. DO NOTsay that photosynthesis produces starch, instead, it’s sugar or glucose. Respiration ↬ the production of energy, occurring usually concurrently with gaseous exchange ↬ the process is when oxygen is absorbed into the bloodstream while carbon dioxide is expelled from it Note: Not only animals can respire. In fact, plants, fungi and bacteria can too. Well, every living organism does too! Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 9 Systems A system is made up of two or more parts that function together. All plants and animals have systems. Plants have transportation systems while humans have respiratory, circulatory, skeletal, muscular, digestive, urinary, nervous etc. systems. Respiratory, Circulatory and Digestive Systems are commonly tested, though it is possible that they will test muscular or skeletal systems. Human System Parts Functions Mouth ↬Teeth chew food into smaller pieces, increasing the surface area of food that digestive juices can act on, digesting the food faster ↬ Saliva is mixed with food to make the food wet and soft so that it can be swallowed easily and to break down some food into simpler substances as saliva contains digestive enzymes Gullet/Oesophagus Transport food from the mouth to the stomach Stomach Breaks down food into simpler substances with digestive enzymes in the stomach Small intestine ↬ Completes digestion ↬ Blood vessels around it absorb digested food and nutrients into the bloodstream to be transported to the rest of the body Large intestine The location where water and other substances are absorbed from undigested food into the bloodstream Rectum A temporary storage site for faeces Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 10  Nose ↬Oxygen is taken in and carbon dioxide is expelled ↬ Hairs in the nose help trap unwanted substances and filters air Windpipe ↬ is a wide, hollow tube that connects the nose to lungs Lungs ↬ contain air sacs that increase the exposed surface area of the blood vessels to the air in the lungs, increasing the rate of gaseous exchange in which oxygen is absorbed into the bloodstream and carbon dioxide is expelled Diaphragm ↬a thin layer of musclethat sits at the base of the chest and separates the abdomen from the chest. ↬ It contracts and flattens when you inhale. When you exhale, the diaphragm relaxes. Veins and Arteries ↬ Veins carry blood to the heart ↬ Veins carry waste materials like carbon dioxide away from different parts of the body to the lungs to be removed. ↬ Arteries carry blood from the heart to the rest of the body ↬ Arteries transport oxygen, digested food, nutrients and water to different parts of the body to be used for respiration in the cells Heart ↬ pumps blood around the body Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 11  Ribcage ↬ supports the body and gives it its shape ↬ protects delicate organs like the heart and lungs Skull ↬forms the head of the human skeleton ↬supports the structures of the face ↬protects the brain from injury ↬ ↬The long stretch of bone which Backbone connects the skull, ribcage and hip all together, as well as other bones. ↬ protects the spinal cord, which is a nerve and keeps the regular shape of your back. Inhalation Exhalation Movement of ribs Upwards and outwards Inwards and downwards Movement of diaphragm Contracts and moves down Relaxes and curves up Size of chest cavity/ Increases Decreases ribcage Movement of air In Out Note that the skeletal, muscular and respiratory all are involved in the process of breathing in and out. Q: Why does X’s heart beat faster when she plays tag? A: So that her heart can pump oxygenated blood with digested food faster to the different parts of the body to release energy faster to run during respiration. The heart also pumps faster to transport deoxygenated blood to the lungs to remove Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 12 carbon dioxide and take in oxygen through gaseous exchange between the air in the lungs and the bloodstream faster. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 13  Adaptations Adaptations allow animals to survive better in their natural habitat by allowing them to: ↬ Obtain air, water, food and nutrients for survival ↬ Stay safe from predators ↬ Undergo reproduction ↬ Changes in surroundings ↬ Cope with physical conditions (e.g temperature, light intensity and availability of water) Adaptations can be split into two different groups, structural adaptationsand behavioural adaptations. Structural adaptations are the specific physical characteristics which enable an organism to increase its chances of survival. This can be things like one’s blood, type of outer covering and size, and is represented in the tables with “[S]” While behavioural adaptations are specific methods a living creature behaves in order to increase its chances of survival. For example, by hibernating in winter. It is represented in the tables as “[B]” Staying warm in the cold Adaptations Purpose Example(s) Warmed-blooded [S] Enables animals to generate enough heat Mammals and to keep themselves warm. They can also Birds maintain a consistent body temperature no matter the temperature of the surroundings. Hence, warm-blooded animals are able to stay warm and still be active during the cold winters. Thick fur or feathers There are many spaces in between the Arctic Fox, [S] fur/feathers. They trap air, which is a poor Penguin conductor of heat, close to the animal’s skin, causing the rate of heat loss from its body to surrounding air to decrease, allowing it to keep more of its body heat and stay warm. Black skin [S] To absorb (not conduct!) more heat from Polar bear the Sun to stay warm Blubber [S] Blubber is essentially a thick layer of fat, Whale, Seal, which is a poor conductor of heat. This Walrus, Sea Lion then causes the rate of heat loss from the Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 14  animal’s body to the surrounding air to decrease. Small ears [S] Small ears naturally have a smaller Arctic Fox exposed surface area of the animal’s ears to the cold surroundings. With smaller exposed surface area comes a lower rate of heat loss from the animal’s body to the surroundings. FUN FACT: The ears are extremely susceptible and vulnerable to the cold. Having small ears could reduce the chances of frostbite, which could potentially cause the ears to fall off. A layer of oil [S] Oil is immiscible with water. Hence, it Penguin helps to repel and prevent cold water from collecting on the skin of the animal. Hence, the animal will not lose heat to the water, keeping it warm Antifreeze substance To prevent plant cells from freezing even Winter Rye in plants [S] in winter Antifreeze substance These substances are mostly made in in animals [S] animals that have no other way to protect themselves from freezing. Antifreeze does exactly what its name implies, preventing their cells from freezing. Migrating [B] Animals migrate from cold places to Goose, Duck, warmer places during winter to escape the Humpback whale, cold and find food and water more easily Crane Fluffing of feathers [B] Similar to having thick fur or feathers, this European robin, action traps more air, which is a poor Blue jay conductor, in the spaces between the feathers. This helps to reduce the rate of heat loss from its body to the cold surroundings Shivering [B] When shivering, your muscles actually Bees, Dragonflies begin to contract and expand, creating warmth for your body by expending energy Huddling together [B] By keeping close together, the animal has Emperor a smaller surface area exposed to the Penguins, Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 15  surroundings. This, in turn, causes the Puppies rate of heat loss from the animal’s body to the surroundings to decrease as well. This also allows them to share their body warmth among one another. Hibernating [B] When hibernating, animals become less Grizzly Bear, active, life processes slow down and are Squirrel, basically a state of inactivity. The animal is Hedgehogs, Bats then able to save energy which is produced from food, especially when there is a lack of it in winter. Staying cool in the summer Adaptations Purpose Example(s) Large ears [S] Large ears help to increase the exposed Fennec Fox, surface area of the ears, increasing the Hares, Elephants rate of heat loss from its body to the surrounding air. Thus, this helps in keeping the animal cool. Hairs on feet [S] Similar to thick feathers and furs, the hairs Fennec Fox trap air, which is a poor conductor of heat, thus reducing heat gain by the feet from the hot ground. Long legs [S] The longer the legs, the further the main Camel body is from the ground which has been scorched by the sun. Hence, the animal is able to stay cooler by reducing the amount of heat gain via the legs. Reflective coat [S] Since a reflective coat is unable to absorb Camel heat, the animal stays cooler and is protected from the warmth of the sun. Bushy Tails [S] With that bushy tail, animals can use it as Kalahari ground a sort of umbrella to shield it from the sun squirrels and stay cool. Behavioural Purpose Example(s) Adaptation Nocturnal (active at Since at night, the sun is no longer there Kit Fox, Coyote, night) [B] to terrorise the animals with neverending Badger, Gopher heat, only coming out at night is a smart Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 16  method to escape the warmest part of the day. Burrowing into the Many desert animals live in burrows or Kangaroo Rat, sand/dirt [B] shelters underground where the soil is Golden Mole, cool which help them to stay out of view of Gerbil the sun and stay cool. This also gives them a good hiding spot from predators. Aestivation [B] Basically a process like hibernation except Jerboa, done in warm areas to keep cool. This water-holding allows the animals to conserve energy frogs, California which can easily be lost when it is hot. red-legged frogs Panting [B] Since some animals, unfortunately, do not Dogs, Cats and have sweat glands, they relieve heat by even some desert panting which helps to reduce their body birds! temperature. Spreading liquids on By spreading liquids such as urine, saliva Vulture, Red the body [B] or the scarce water they find on their body, Kangaroo, Owl, a process called evaporative cooling takes Elephants place where the animal’s body loses heat to the water, allowing the water to evaporate and the animal to cool down at the same time. Adaptations of plants Adaptation Purpose Examples Tendrils/vines/thorns These plants tend to have weak stems Cucumber, Pumpkin, that climb upwards [S] that are unable to support the rest of the Kiwifruit, Tomatoes, plant by themselves and as such rely on Common Ivy other objects/parts of the plant. By spreading themselves out or reaching Clasping roots that upwards, the leaves are able to be climb upwards [S] exposed to more sunlight which helps the plant absorb more light to undergo a greater rate of photosynthesis. Hence, Vines that creep along they are able to produce more food and a flat surface [S] grow better. [Summary: to obtain more light] Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 17 Large leaves [S] Large leaves increase the exposed Canna, Elephant’s Ear, surface area of the chlorophyll in the Persian Ivy, Ginger Lily leaves to the surroundings, allowing them to trap more light, undergo a greater rate of photosynthesis and make more food to grow better. Closing the stomata Since during the day there is more Plants in general, during the day but sunlight, by closing their stomata, this especially in the desert opening it at night [B] prevents water in the plant from evaporating allowing the plant to have more water to photosynthesise. While at night, there is no light and is cool so water in the plant will not evaporate. At the same time, the plant can take this chance to take in more carbon dioxide for photosynthesis. Hairs on leaves that The air in these plants are less dense Water Lettuce trap air [S] than water and as such enable the plant to float on water. Allowing them to trap sunlight more easily to make more food Swollen leaf stems and grow better. Water Hyacinth that are filled with air [S] Large leaves that float This allows the plant to trap more light Water Lily, Lotus on water [S] compared to fully submerged leaves to photosynthesise more to make more food. Long roots or spread This increases the exposed surface Most plants out roots [S] area of roots allowing the plant to absorb more water via the roots. Small leaves [S] Less exposed surface area of leaves Mimosa reduce water loss through transpiration Hairy leaf surfaces [S] The hair on the leaves reduces the Magnolia, Sycamore trees exposed surface area of the leaves to the surrounding, reducing the amount of water loss from the stomata through transpiration Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 18 Swollen stem [S] The stem is used to store water in Cactus cases where there is scarce water supply Adaptations of animals Adaptation Purpose Examples Big eyes and night Since most of these animals hunt primarily Owl, Cat, Possum, vision [S] at night, large eyes allow more light to Raccoon enter the animals’ eyes making it easier for them to make their way around in the dark and catch their prey. Good sense of hearing Instead of relying on their eyes, these Wolves, Owl, Bat or smell [S] animals rely on their nose to sense their prey. Echolocation [S] Echolocation allows these animals to find Bat, Dolphin their prey, their fellow species and also obstructions in their way. Nocturnal [S] Since there are fewer animals at night, Snakes, Scorpion, Bat there is less competition between animals for food. Furthermore, it is harder for their prey to spot them at night. Streamlined This allows the animals to cut through air Fishes and birds bodies/shape [S] and water faster and easier to reach their desired location sooner. Fins and Tails [S] This helps the animal propel themselves Most fish easier in water so they can travel faster. Webbed feet [S] Ducks and frogs Oar-like legs [S] Water boatman Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 19 Gills [S] Gills help fish to breathe in water as water Fish enters the gills and the dissolved-oxygen enters the gills and into the blood circulating around the gills. Air sacs [S] Air sacs help increase the exposed surface Mammals area of our lungs to take in more air. Moist skin [S] Moist skin allows some animals to breathe Some amphibians through their skin when in water Breathing tubes [S] These help bugs to take in oxygen whether Mosquito Larvae directly from the surface or by storing air Air bubbles [S] Water spiders Blowholes [S] This allows mammals who are underwater Whales and dolphins to take in oxygen Produce own light [B] These fish produce their own light not only Pony fish and Flashlight to allow themselves to see but also to fish attract prey. Wings [S] Flying Most birds, Bats Hollow bones [S] This reduces the overall mass of the Birds such as Ostriches animal so it requires less energy for the and Emus animal to move or take flight. Claws and sharp teeth This allows animals to catch and consume Carnivores like lions [S] their prey easier by having a good grip on and wolves the animal and also tearing up its flesh. Camouflage/mimicry Camouflage refers to blending in with one’s Owl butterfly, [B] surroundings while mimicry refers to chameleon pretending to be something else other than your actual identity. This allows both prey and predators to hide from their predator and prey respectively. Types of camouflage/mimicry: Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 20  1. Eyespots which make the animal appear larger than how it actually it 2. Having a similar colour to its surroundings Hunting in groups [B] This makes the animal appear more Lions, Killer whales intimidating and also makes it easier to catch their prey. Staying in groups [B] This often helps to intimidate predators so Zebras, Deer they are less likely to be eaten. This also confuses the predator when having to chase the prey as there are many to chase after. Long tubular beak [S] This beak can be used to stick into flowers Hummingbird to drink nectar Hooked beaks [S] This is used to crack open nuts and seeds Parrots, Eagles, Owls for food but can also be used to tear flesh. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 21 Reproduction Animals Parts of the female animal reproductive system and functions (from lowest to highest): ↪ Vagina ↬ Where the baby comes out from during natural birth ↪ Uterus ↬ where the embryo usually develops ↪ Fallopian tubes/Oviduct ↬ where egg cell meets sperm ↬ where the egg cell is fertilised ↪ Ovaries ↬ where egg cells are stored Fertilisation ↬ For fertilisation to occur, ovaries and fallopian tubes must be intact. ↬ Fertilisation requires the egg cell and the sperm cell’s respective nuclei to fuse together. If either is not present, fertilisation will not occur. ↬ There are two types of fertilisation Internal fertilisation is when the sperm and egg cell are contained in the female organism’s body External fertilisation is when sperm and egg cells are released into the surroundings (usually water) to move freely and can be separated by the water current. Only Amphibians and fish do this. Developing The organs involved are: ↬ Umbilical cord Contain blood vessels that transport oxygen and digested food to the foetus and remove carbon dioxide from the foetus’ body. It is connected to the placenta ↬ Placenta Is a flattened circular organ at the surface of the womb, that contains nutritious substances for the foetus to grow healthily that are from the mother’s body. It MUST be removed from the mother’s body during birth or it will decompose in the womb, spreading bacteria, which would cause death. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 22  Water bags that contain the foetus, hence the phrase “my water broke”. ↬ FUN FACT: Mammals’ eggs are smaller than birds’ eggs because the egg of a mammal continues to develop within the mother’s womb and obtains both digested food and oxygen directly from the mother, whereas a bird’s egg is larger to store the food needed to develop the chicks outside the mother’s body. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 23  Reproduction (Plants) Plants reproduce to ensure the continuity of their species. Plants produce flowers that: ↬ have either male or female parts (unisexual) ↬ have both female or male parts (bisexual) ↬ don’t need female/male parts. Examples include ginger. (asexual) Part of flower Characteristics and functions Anther ↬ found at the tip of the filament ↬ produces and store pollen grains ↬ each pollen grain contains male reproductive cell Male Part ↬ releases many pollen grains to increase the (Stamen) chances of a successful pollination Filament ↬ the long stalk that holds the anther in a suitable position to hold the pollen grains Stigma ↬ found at the top of the style ↬ receivespollen grains Style ↬ the long stalk that holds the stigma in a suitable Female position to receive pollen grains Part (Pistil) Ovary ↬ contains the ovule(s) ↬ develops into fruit after pollination and fertilisation Ovule ↬ contains the female reproductive cell ↬ the site where fertilisation occurs ↬ develops into a seed after pollination and fertilisation Stages of reproduction in plants: Pollination → Fertilisation → Seed Dispersal → Germination Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 24  Pollination ↬ Is the transfer of pollen grains of the same species from the ripe anther to the stigma ↪ Self-pollination ↬ takes place within the same flower or flowers of the same plant ↪ Cross-pollination ↬ occurs between different flowers of different plants of the same species Insect-pollinated Flowers Wind-pollinated flowers Flowers are large, brightly-coloured and Flowers are smaller and scentless with scented dull coloured petals Nectar present Nectar absent Stamens and stigma within petals, Stamens and stigma hang out of the filaments not hanging loosely flower. Filaments are long and big and hang loosely Stigma is sticky so that pollen grains Stigma is larger with featherybranches land and do not fall off for catching pollen grains. Not sticky at all Pollen grains are large and heavy with a Pollen grains are smaller, smoother and rough and sticky surface for sticking to light, easily carried by the wind. animals’ bodies. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 25  Fertilisation ↬ the process in which the nucleus of the male reproductive cell fuses with the nucleus of the female reproductive cell ↬ takes place in the ovary of the plant ↬ requires the stigma and the ovary (which contains ovule(s) and pollen grain) Part of flower Development after fertilisation Petals Anther Wither and fall off Filament Stigma Style Ovule Develops into seed Ovary Swells and becomes the fruit Dispersal Dispersal reduces the competition between the parent plant and the child plant for water, light and mineral salts in the soil. NOTE:For seed dispersal questions, only mention competition for air when the plant is an aquatic plant and in that case, also remove the competition for water. Wind dispersal ↬ These plants’ seeds are light, have feathery hair-like structures and wing-like structures to help them be carried over long distances Splitting ↬ The seeds are stored inside ‘pods’ that become dry once the seeds are ripe. Once the pods dry, the seeds automatically “explode” from the inside and the seeds disperse around the parent plant. Water dispersal ↬ The seeds of fruits that are dispersed by water are waterproof and usually have fibrous husks to ensure that water cannot enter the fruit Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 26  and that it floats. Examples include coconut. They are found along the coasts and banks of water bodies, downstream from the adult plant. Animal dispersal ↬ The fruit has many hair-like / hook-like structures so that it can cling to mammal’s fur. After the animal has moved a distance away, the fruit drops off, hence they can travel further distances. Examples include mimosa. ↬ The animal eats the fruit, and after a while, the seed passes out with its undigested food a distance away. The seed is tiny so that the animal would be able to swallow it and indigestible so that the animal cannot digest it and will be passed out with the animal’s faeces, which also serves as nutrients for the plant. These can also travel longer distances from the adult plant ↬ Sometimes the fruit is relatively large and cannot be swallowed by the animal and after the animal eats the fruit, it leaves the seed at the foot of the tree or near it. Germination ↬ The process in which a seed emerges from dormancy and starts to develop into a young plant or seedling ↬ Moisture, oxygen and warmth are needed ↬ Light is not needed ↬ Roots emerge first before the seedling NOTE:Boiled seeds are dead and cannot germinate. They will end up decomposing. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 27 Environmental Interactions Food Chains/Food Webs Important: When drawing food chains, always use a ruler and pencil, arrowheads pointing to the predator. Likewise with light drawings. ↬ food chains show the transfer of energythrough an ecosystem ↬ food webs are formed by linkingmultiple food webstogether ↬ all food chains and food webs begin with a food produceror basically a self-sustaining plant ↬ primary consumers may be herbivores(plant-eaters) or omnivores (plant and animal eaters) ↬ secondary consumers can be carnivores(meat-eaters) or omnivores (plant and meat-eaters) NOTE:Predators can only be animals that eat other animals and NOT SOLELY PLANTS, meaning that herbivores cannot possibly be predators. Plants can also not be prey. Transfer of Energy ↬ the Sun is the main source of energy for all life on Earth Ecological Balance ↬ The ecological balance of the ecosystem relies on consistent and reasonable numbers of each consumer in the food chain. ↬ the population size of an organism can be affected by various factors such as natural disasters or a growth in the number of predators ↬ An increase in the number of any organism in the food chain will immediately cause a discrepancy in the ecological balance. ↪ Changes in population size of prey and predators ↬ when the population size of predator decreases, there will be fewer predators to consume/feed on its prey, causing the population size of its prey to increase Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 28  ↬ when the population size of prey decreases, there will be less food for its predators, causing the population size of the predator to decrease. ↬ when the population size of the prey decreases and the predator has more than one food source, the predator will feed on the other food source(s) to make up for the lack of this particular prey, causing the population sizes of the other prey to decrease ↬ when the population size of the prey decreases and the predator only has one food source, the predator will not have enough prey to feed on and compete against each other for food, eventually dying of starvation, so the population size of the predator will decrease ↬ when a new organism is added into the food chain/web, it will compete with other organisms for food and cause the population size of the prey to decrease as there are twice as many organisms feeding on it ↬ naturally, the population of the predator lags behind the prey because digestion of prey and obtaining sufficient energy for reproduction takes time. Note that population size is the number of organisms (young + adults) excluding eggs. Different types of relationships Type of relationship Description Example Producer-consumer* One organism eats and the other Grass ↬Deer ↬Lion Predator-prey* gets eaten Mutualism Both organisms benefit from the Plant pollinators obtain food relationship from nectar while at the same time the plant also gets pollinated Parasitism The parasite benefits from the Mosquitoes feed on the blood relationship while the host is of humans and at the same harmed. time transmit diseases to us Competition Both organisms are harmed as they Woodpeckers and squirrels compete for limited resources often compete for nesting spaces * try not to use these phrases during PSLE as it tends to be vague as to which organism is the predator/prey, so you may be marked wrong. Instead, use _ is the predator of. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 29 Decomposition ↬ The breaking down of dead matter into simple substances such as mineral salts and nutrients ↬ Decomposition requires moisture, oxygen and warmth ↬ decomposition produces heat and carbon dioxide, besides the simple substances ↬ Only fungi and bacteria are decomposers ↪ Importance of Decomposition ↬ Through decomposition, simpler substances like mineral salts and nutrients are produced to be absorbed by plants for better growth and also helps to enrich the soil ↬ Helps to prevent animal waste and dead matter from piling up ↪ Detritivores/Animals that feed on dead matter ↬ Examples include vultures and earthworms etc. ↬ Helps to increase the rate of decomposition by breaking up the dead matter into smaller pieces, so there is more exposed surface area of the dead matter exposed to the decomposers, increasing rate of decomposition ↬ are NOT decomposers NOTE: make sure you write “breaking up” instead of breaking down and “smaller pieces” instead of “simpler substances” Example Question Q:How does toasting bread help prevent the growth of mould on the bread? A: Toasting the bread removes moisture from the bread, so there is no more water in the bread which then removes one of the factors essential for the survival of the mould: water. Hence, mould will no longer be able to survive on the bread. Q: Vultures were observed to be feeding on a carcass of a zebra, explain how this benefits decomposition. A: Vultures help to break up the zebra carcass into smaller pieces, which increases the exposed surface area of the carcass to decomposers, increasing the rate of decomposition of the carcass. Hence, the carcass will decompose faster. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 30 Life Cycles A life cycle is a pattern that repeats the series of changes in an organism’s life from birth to adulthood. All stages are related to one another. ↳ 3-stage life cycle ↬ Young of animal looks similar to adult (exceptions include frogs) ↬ Common stages are egg, nymph and adult ↬ Common examples are dragonfly and grasshoppers ↳ 4-stage life-cycle ↬ Metamorphosis occurs ↬ Young of animal looks different from adult ↬ Stages are egg, larva, pupa and adult → Egg stage ↣ After the period of incubation, it hatches to becomes a larva → Larval stage ↣ The animal is usually the most active during this stage ↣ It feeds and ingests a lot of food, allowing it to grow rapidly → Pupal stage ↣ Protects itself in a cocoon or a hard casing ↣ Complete transformation occurs of the animal’s appearance occur ↣ No food is consumed at all and very little movement occurs → Adult stage ↣ The stage where reproduction occurs ↣ Last stage of the life cycle ↬ Common examples include: butterfly, beetle, mosquito Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 31 Heat Difference between heat & temperature: ↬ heat is a form of energy ↬ temperature is a measurement of how hot an object or substance is In our simple, P6 energy-conversion words, heat is a form of energy and travels from a region of higher temperature to one of lower temperature until both are the same temperature. It is NOT temperature. (please note that in thermodynamics, heat and heat energy are two different things) Properties of Heat: the amount of heat energyan object has is dependent on its mass and temperature Factors affecting heat transfer ↬ Good & poor conductors of heat metals, in general, are good conductors of heat most nonmetals are poor conductors of heat when asked to state poor conductors of heat, styrofoam is the safest option ↬ Surface area the greater the exposed surface area, the greater the rate of heat loss/gain Effects of heat ↬ Changes in state Solid to liquid (heat gain) Liquid to gas (heat gain) Gas to liquid (heat loss) liquid to solid (heat loss) ↬ Expansion and contraction expansion (gain heat) contraction (heat loss) Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 32 Absorption of heat ↬ the colour of an object affects the amount of heat absorbed by the object ↬ darker the colour, the more heat is absorbed ***Absorption is different from conducting heat. Conducting is transferring the heat away from the object but absorbing is for the object to be able to gain more heat for itself. Common Questions Q:Chris poured steaming hot coffee into two cups, one metal cup and another ceramic mug. Which coffee will reach room temperature first? A: The coffee in the metal cup. Metal is a better conductor of heat than ceramic and so it will conduct heat from the coffee to the surroundings faster than the ceramic mug. Hence, the coffee in the metal cup will lose heat faster and reach room temperature first. (Concept: Materials, Heat) Q: Look at the fox named Svenin the picture below, his ears are small. How does this help him survive in his cold environment? A: Having small ears reduces the surface area of ears exposed to the surroundings, so Sven loses less heat to the surroundings and stays warm in its cold environment. (Concept: Adaptations, Heat) Q: Kelly packed a tank with a cap not airtight full to the brim with Gatorade However, Kelly left the tank under the hot sun. After 4 hours, she found that some of the Gatorade in the tank had seeped out. Why was this so? Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 33  A:Gatorade in the tank gained heat from the sun and expanded to occupy more space but since the tank was filled to the brim, there was no more space in the tank to occupy. Hence, the Gatorade seeped out of the tank. (Concept: Matter, Heat) Q: Why does a thick glass cup crack when boiling water is poured into it? A: There is an uneven expansion of the glass in the glass cup [when hot water is poured into it]*. Glass is a poor conductor of heat and the inner layer of glass in contact with the boiling water will conduct heat from the hot water to the outer layer slowly, causing the inner layer to gain heat and expand more quickly than the outer layer of glass. NOTE: frequently remind yourself to write these “prepositional phrases” (i say time prepositions because it resembles actual prepositional phrases but at the same time is not a prepositional phrase). These indicate when something happens. for example, adding “when he fell down” to “he scraped his knee” tells you when he scraped his knee and how he scraped his knee. a “science prepositional phrase” would be “when the ball rolled down the slope”. Q: Why are telephone lines hung loosely from the poles? A: Telephone lines are hung loosely to allow them to lose heat to the surroundings in cold weather and contract to become shorter without snapping. Q:Why did a laundry line snap in winter? A: The laundry line lost heat to the cooler surroundings in winter, causing it to contract and become shorter. However, since the laundry line was not hung loosely, it became too short and snapped. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 34  Energy ↬ Cannot be created or destroyed ↬ Can be converted from one form to another or transferred to other objects ↬ NOT THE SAME AS FORCES ↬ Non-matter Sources of Energy ↬ Renewable The Sun Wind Water stored behind a dam Biomass Earth (Geothermal) ↬ Non-renewable Fossil fuel Nuclear fuel Advantage Disadvantage Sun ↬ Renewable source ↬ Solar panels are expensive (however ↬ Doesn’t cause pollution thankfully prices of solar panels are decreasing as technology improves!) ↬ Energy can only be harnessed when the Sun is present ↬ Requires a lot of space/surface area as solar panels cannot be stacked on top of one another Water ↬ Renewable source ↬ Blocks light from reaching plants in water ↬ Doesn’t cause pollution bodies (and other consequences and problems that arise from that such as less oxygen being produced which may lead to fish in those bodies of water dying) ↬ Requires a lot of space and is expensive Wind ↬ Renewable source ↬ Energy can only be harnessed when wind is ↬ Doesn’t cause pollution present ↬ Requires space to harness sufficient energy as they can’t block each other ↬ Large structures so they cannot be built in countries where there is a lack of space like Singapore Fossil fuel ↬ Cheap ↬ Will eventually run out (non-renewable) ↬ Easy to use, transport and ↬ Releases carbon dioxide when burnt distribute ↬ Contributes to global warming and air pollution Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 35 Geothermal ↬ Renewable source ↬ Might cause surface issues such as energy ↬ Doesn’t cause pollution earthquakes ↬ Expensive ↬ Location-specific (can only be used in certain locations) Biomass ↬ Renewable source ↬ Still causes some carbon emissions due to energy ↬ Carbon neutral having to still burn trash ↬ Less expensive than fossil fuels ↬ Less garbage in landfills Types of Energy (those tested, at least) ↬ Potential Energy Gravitational potential energy Chemical potential energy Elastic potential energy ↬ Kinetic energy ↬ Heat energy ↬ Sound energy ↬ Light energy ↬ Electrical energy Gravitational Potential Energy ↬ is the stored energy an object has due to its position above the ground and only possessed by objects above ground/a surface ↬ the greater the mass of the object, the more gravitational potential energy it has ↬ meaning if you had 2 prisms of equal height off the ground but one was 50g while the other was 20g, the 50g prism would have more gravitational potential energy ↬ the greater the height of the object above the ground, the more gravitational potential energy it possesses ↬ meaning that if you had 2 blocks both weighing 100g, block A that is 10cm from the ground would have a lower gravitational potential energy than block B which is 5cm from the ground Elastic Potential Energy ↬ the stored energy that an elastic object has when stretched or compressed ↬ the greater the extent to which an elastic object is stretched or compressed, the more elastic potential energy it possesses ↬ the thicker the elastic object, the more elastic potential energy it possesses Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 36  ↬ when more elastic objects are used, they have more overall elastic potential energy when they are stretched or compressed. ↬ meaning, if you had 3 hair ties, if you stretched one of the hair ties with a certain amount of force, it would be able to be stretched further than if you were to stretch 2 hair ties at once with the same amount of force ↬ NOTE:elastic potential energyis the energy in a stretched/compressed spring, whereas elastic spring forceis the forcetrying to return the spring to its original length (these are easily confusable so please be careful) Kinetic energy ↬ the energy that moving objects possess and only when an object is moving, it can have kinetic energy ↬ the greater the speed of the object, the more kinetic energy it has ↬ meaning, if you were to compare an object that is travelling at 10km/h versus an object that is travelling at 15km/h, the latter would have greater kinetic energy ↬ the greater the mass of the object, the more kinetic energy it has ↬ meaning, if you had 2 cars of different models both travelling at 80km/h and one of the cars was 100kg while the other was 150kg, the 150kg car would have more kinetic energy Common question: The classic damquestion Q:Would more, less or the same amount of electricity be produced when the dam is situated higher? A:More electricity would be generated. When the dam is situated higher up, the water in the dam would possess a greater amount of gravitational potential energy, which would be converted to more kinetic energy of the falling waterwhen the dam is released. Hence, more kinetic energy would be converted to more electrical energy. NOTE: remember to put “of [what]” when writing about the kinetic energy of an object and also make sure the [what] mentions a movement like a “moving car”! Also take note of consistently using comparative terms in the answer. Q:Julie turned the key of a musical box and observed the ballerina in the musical box start to turn and dance. He then measured the time taken for the ballerina to stop dancing. Why would the ballerina eventually stop dancing? A:All kinetic energyof the dancing ballerina is converted to sound energyand heat energy due to friction between the air and the dancing ballerina(air resistance), leaving no kinetic energy of the ballerina left for movement, thus it stops dancing after some time. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 37 Q: Oscar places two blocks of equal size 20cm above a table. Block A weighs 100g while Block B weighs 50g. 1) Which of the blocks has a greater amount of gravitational potential energy? 2) Which of the blocks would reach the table faster? A1: Block A has a greater amount of gravitational potential energy. It has a greater mass than Block B and as such possesses more gravitational potential energy than Block B. A2: Block A would reach the table faster. This is because Block A has a greater amount of gravitational potential energy which is converted to more kinetic energy of the falling block. Hence, it would reach the ground faster. Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 38 Forces Forcescan ↬ move a stationary object ↬ stop a moving object in its tracks ↬ change the speed of a moving object ↬ change the direction of a moving object ↬ change the shape and size of a moving object The standard unit of measurement for force is the newton (N). A stationary object will remain stationary if ↬ there are no forces acting on the object (only applicable in space) ↬ the forces acting on the object balance each other out Types of forces ↪ Non-contact forces ↬ A non-contact (or acting-at-a-distance) force exists when the objects are not in contact/touching. For example, gravitational force and magnetic force are non-contact forces. Magnetic force ↬ Gravitational Force ↪ Contact forces ↬ A contact force exists only when the objects are in physical contact with each other/touching. Examples include frictional force and elastic spring force. Frictional force Air resistance Water resistance Elastic spring force Magnetic force ↬ is the force of attraction and repulsion exerted by a magnet ↬ can act on magnetic materials ↬ can act from a distance ↬ always the strongest at the poles of the magnet. (North and South) ↬ cannotpass through magnetic materials but can pass through non-magnetic materials (to a certain thickness). ↬ both magnetic forces of attraction and repulsion are useful Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 39  Gravitational force ↬ is the force of attraction that exists between two objects that have mass ↬ amount of gravitational force depends on the mass of objects and distance between them ↬ weight is a measure of the amount of gravitational force acting on an object and is not equivalent to the mass (weight basically is a force) ↬ Gravitational force is constant wherever you go on Earth (‘s surface) and will change when you go to other planets/the moon Weight (W) Mass (m) Definition The measurement of the The amount of matter in pull of gravity acting on an an object object Unit of measurement Newton (N) Kilogram (kg)/ Gram (g) Measurement Measured using a spring Measured using a beam balance balance Dependence on the pull The greater the pull of Independent of the pull of of gravity gravity acting on an gravity acting on an object object, the greater the (does not affect) object’s weight **WHEN DRAWING GRAVITATIONAL FORCE LINES, START FROM THE MIDDLE OF THE OBJECT OR THE BOTTOM AND GO DOWNWARDS AS IT IS A PULL Frictional force ↬ resists motion between two surfaces that are in contactwith each other ↬ acts in the direction opposite to motion and opposes motion ↬ is present onlywhen motion is present* ↬ increases along with mass ↬ increases along with the angle of inclination meaning, if you had an object that is on a slope of a hill that has a steepness of n while another object is on a slope of a hill that has a steepness of 2n. The object on the hill that has a steepness of 2n would have a greater amount of friction between it and the ground. ↬ the rougher the surface texture, the more friction Disclaimer: the information in this document is intended solely for the personal non-profit use of the user who accepts full responsibility for its use. Distribution and/or selling this document is not allowed. While we have taken every precaution to ensure the information here is current and accurate, errors may occur. 40  ↬ contact surface area does notaffect the amount of frictional force meaning, if you take 2 objects of the same mass but with different amounts of exposed surface area to the ground. The two objects would have the same amount of frictional force when moving at the same speed. however, air and water resistance are affected by surface area Advantages of friction Disadvantages of friction ↬ allows us to grip onto items ↬ causes wear and tear, which is why after some time, the soles of your shoes ↬ allows us to walk without slipping become thinner and thinner ↬ produces heat, which allows us to stay ↬ opposes motion and causes objects to warm or produce fires slow down or come to a stop ↬ allows us to stop objects unnecessarily ↬ if we had no friction, we would not be ↬ can cause fires or cause things to able to stop moving and not be able to overheat and break down walk either! *however, if an object is on a slope and it does not move downwards, friction is present but it is equal/more than the gravitational force acting on the object ↪ Air resistance ↬ is the frictional force between the object and the air as the object falls through the air ↬ an object experiencing air resistance will move slower through the air ↬ the greater the surface area of the object exposed to the air, the greater the air resistance it encounters and the longer it takes to reach the ground from a height ↬ can be reduced by having a streamlined shape, as streamlined shapes reduce the drag, or resistance to motion through the air, by causing the air around to move in definite patterns called streamlines ↪ Water resistance ↬ is the frictional force between the object and the water as the object moves through the water ↬ slows the movement of the object in water ↬ the greater the surface area of the object exposed to the water, the greater water resistance it encounters and the longer it takes to move through the water ↬ can be reduced by having a streamlined shape, as streamlined shapes reduce the surface area for water to act on ↪ Lubricants