P5 Science Topical Notes (Latest MOE PSLE Syllabus)
Updated: Mar 21
Primary 5 Science builds on foundational inquiry skills by focusing on two core themes: Systems and Cycles. In Systems, students investigate plant transport systems for water and food, human respiratory and circulatory systems (including nose, lungs, heart, blood vessels, and their roles), and how these integrate with digestion. They separately explore electrical systems, including circuits, conductors/insulators, and effects of adding components like batteries or bulbs. In Cycles, students study plant and animal reproduction (pollination, fertilisation, seed/fruit dispersal, germination, and human fertilisation basics), water's states and changes (melting, evaporation), the water cycle, and factors affecting evaporation rates. These topics sharpen observation, explanation, and real-world application skills essential for PSLE success.
Last updated 20 January 2026
Chapter 1: Reproduction in Plants and Animals [Cycles]
A cell is a basic unit of life.
The nucleus in a living cell contains genetic information that is passed down from parent to offspring. Heredity is the passing on of traits (characteristics) of an organism.
Purpose of reproduction
Living things reproduce to ensure continuity of their kind.
Types of reproduction:
Sexual reproduction | Asexual reproduction |
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Reproduction in Flowering Plants
Flowering plants carry out sexual reproduction and reproduce from seeds
4 key processes: pollination, fertilisation (seed production), seed dispersal, germination
Parts of a flower
Anther: produces and store pollen grains which contains the male reproductive cells
Filament: holds the anther in a suitable position to store pollen grains
Stigma: receives pollen grains
Style: holds the stigma in a suitable position to receive pollen grains
Ovary: protects the ovule and develops into fruit after fertilisation
Ovule: develops into seed after fertilisation, contains the female reproductive cell
Pollination
Pollination is the transfer of pollen grains from the anther of one flower to the stigma of the same/ another flower of the same kind.
Insect-pollinated flower | Wind-pollinated flower |
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By removing either the stigma/ ovary / ovule/ style, fertilisation cannot occur and the ovary will not develop into a fruit.
Fertilisation
Fertilisation occurs when a male reproductive cell fuses with a female reproductive cell.
For plants, fertilisation occurs in the ovary.
Each pollen grain develops a pollen tube inside the style.
The male reproductive cell will travel down the tube and enters the ovule
Male and female reproductive cell fuses in the ovule
After fertilisation, the petals, style, stigma, anther, filament will wither and drop off.
Ovules develop into seeds
Ovary swells and becomes the fruit
By removing either the stigma/ ovary / ovule/ style, fertilisation cannot occur and the ovary will not develop into a fruit.
Seed dispersal
Purpose of seed dispersal:
Seeds have to be dispersed further away to reduce overcrowding and the competition between the young plant and parent plant for light, water, space and mineral salts.
Animal dispersal
The juicy/fleshy/fragrant fruits attract animals and the
hook-like structure/ stiff hairs help the fruits to attach to the animal’s fur or skin so it will be carried by the animal away from the parent plant
The small indigestible seeds are swallowed by the animal together with the fruit and is passed out in the animal's droppings after the it has travelled and carried the seed further away from the parent plant
the animal droppings provide nutrients for plants to take in and grow more healthily
Wind dispersal
The wing-like/ hair-like/ feather-like/ parachute-like structures helps the seed float in the air so the wind can carry the seeds further away from the parent plant in the direction of the wind.
Water dispersal
Waterproof outer layer
The fibrous husk helps trap air so the fruit can float in water. Thus, the water can carry the fruit and the seeds further away from the parent plant in the direction of the water current
Explosive action/ Splitting
The pod-like structure that dry up and split open forcefully, scattering the seeds around the parent plant
Germination
Germination occurs when the seed gets oxygen, water and warmth.
A seed does not need light to germinate
A root emerges first, then the shoot
The stored food in the seed leaves provide nutrients for the germinating seed
Non-flowering plants reproduce from spores, without fertilisation (do not produce seeds)
Spores are dispersed by the wind as they are light
Spores germinate and grow into plant
Reproduction in Humans
Testes develop and produce male reproductive cells (sperms)
Penis helps to transfer the sperms into the female vagina during mating.
Ovaries develop and produce female reproductive cells (eggs)
Womb: is where fertilised egg develops into a baby
Vagina: is where sperms are released into the female body
An egg is released by one of the ovaries.
Fertilisation occurs when a sperm fuses with an egg.
Only one sperm fuse with one egg, the rest of the sperms will die
Fertilisation occurs in the fallopian tube
The fertilised egg develops into a foetus in the womb
If both the fallopian tubes were cut, the woman cannot get pregnant. The eggs produced by the ovaries cannot travel down the fallopian tube to fuse with the sperms so fertilisation cannot occur
Similarity in sexual reproduction of flowering plants and humans:
Similarity: Sexual reproduction in flowering plants and humans involves the fusion of the male and female reproductive cells during fertilisation.
Chapter 2: Water Cycles [Cycles]
Water is a matter (has mass and occupies space).
Water can exist in 3 states of matter:
Solid: Ice
Liquid: Water
Gaseous: Water vapour/ Steam
Heat gain/loss will result in change in state of matter:
From | To | Process | |
Heat gain | solid | liquid | Melting |
liquid | gas | Boiling/ Evaporation | |
Heat loss | gas | liquid | Condensation |
liquid | solid | Freezing |
Melting, Freezing, Boiling occurs at a fixed temperature.
Freezing point is the temperature at which a liquid loses heat and changes to a solid state.
Melting point is the temperature at which a solid gains heat and changes to a liquid state.
Boiling point is the temperature at which a liquid gains heat and changes to a gaseous state.
Melting/ Freezing point of water is 0°C
Boiling point of water is 100°C
Steam is water vapour at 100°C
Example: Some ice cubes were being heated up for 60 minutes
From 0 to 5 minutes:
Ice gains heat from the flame and increases in temperature to 0°C
From 0 to 15 minutes (melting):
Heat is still being gained but the temperature remains constant.
Ice is turning into water, it is a mixture of ice and water
temperature of water and ice is at 0°C
At 15th minute, all the ice has completely melted into water
From 15 to 40 minute:
Heat is gained by the water and the temperature increases
From 40 to 50 minutes (boiling):
Heat is still being gained but the temperature remains constant.
Water is turning into water vapour (steam)
At 50th minute, all the liquid has completely turned into steam
*When there is a change in state (melting/boiling), the temperature remains constant but heat is still gained.
Evaporation is the process where liquid gains heat and changes into gas.
Factors affecting rate of evaporation:
Presence of Wind/ wind speed
Temperature
Exposed surface area
The higher the temperature, the higher the rate of evaporation
The stronger the wind, the higher the rate of evaporation
The greater the area of exposed surface, the higher the rate of evaporation
Boiling | Evaporation |
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Condensation is the change in state of a liquid from a gas due to heat loss.
Evaporation and Condensation occurs at any temperature
Water Cycle (Water cycle: Water - water vapour - clouds - rain)
Evaporation and condensation are two processes that allows water cycle to continue.
The water cycle is the only natural way to refresh water and ensures a constant supply of fresh water.
All living things need water to survive. Plants need water for photosynthesis, germination and plant transport system
Clouds, mist: condensed water droplets
Steam: hot water vapour
Water pollution
Cause of water pollution: littering, dumping of waste, oil spills, deforestation
Impact of water pollution: water no longer safe to use so there will be less usable water
Chapter 3: Plant System (Plant Transport System) [Systems]
Transport System in Plants:
Water-carrying tubes transport water and mineral salts from the roots to other parts of the plant
Food-carrying tubes transport food made by the leaves to other parts of the plant
*The tubes are separated from one another
When food-carrying tubes are removed, food made in the leaves cannot be transported beyond the cut to the roots. Hence, excess food will be accumulated above the cut and causes it to swell.
the excess food can be transported to the fruits and store in them. Hence, causing bigger fruits to be grown.
Chapter 4: Human System (Respiratory and Circulatory systems) [Systems]
Respiratory System
Air is a mixture of gases (nitrogen, oxygen, carbon dioxide and other gases such as water vapour).
Respiration occurs in all living things. Respiration is the process of releasing energy from food for organism to carry out their activities.
Respiration:
Need
Food
Oxygen
Water
Produces:
Carbon dioxide
Water
Energy
Human respiratory system: Nose, Windpipe, Lungs
Nose: Air containing oxygen is entered through the nose. Hairs in the nose help to trap unwanted substances and filters the air
Windpipe is a hollow tube that transports the air from the nose to the lungs
Lungs contain air sacs that increase the exposed surface area of blood vessels to the air in the lungs, increase rate of gaseous exchange in which oxygen is absorbed into the bloodstream and carbon dioxide is expelled
Circulatory System
Human circulatory system: Blood, Blood vessels, Heart
Circulatory system transport oxygen, digested food and water to all parts of the body Heart: An organ that pumps blood around the body
Blood vessels: are tubes through which blood flows. Some carry blood from our heat to all parts of the body while some carry blood from other parts of our body back to the heart Blood: Digested food, oxygen, water to the cells of the body
Blood: Carbon dioxide and other waste materials away from cells to lungs
Heart rate increase when exercising
During exercise, the heart beats faster in order to pump more blood that is rich in oxygen and digested food to the muscles so the muscles can produce more energy through respiration and to pump more blood that is rich in carbon dioxide away from the muscles
The human’s circulatory system is in two directions while the fish’s circulatory system is in one direction.
Plants: tubes that transport food made by the leaves and water and mineral salts from the roots.
Humans: blood vessels that transport blood containing digested food, oxygen and carbon dioxide.
Chapter 5: Electricity [System]
Electricity is a form of energy.
The path through which electricity flows is the electric circuit. An electric circuit consist of:
Battery (an energy source)
Other circuit components:
Wires (made of copper covered with plastic/rubber)
Bulb
Switch
The metal tip and metal casing of the bulb should be connected to different ends of the battery in order for bulb to light up.
A series circuit is a circuit with only one path for electric current to flow through.
A parallel circuit is a circuit with multiple paths for electric current to flow through.
When the switch was closed, it forms a closed circuit and electric current could flow through the circuit (lightning the bulb/turning the iron rod into an electromagnet/etc.)
A material is an electrical conductor/insulator
Most metals are electrical conductors Glass, Air, plastic, wood, paper are electrical insulators
The bulb will be brighter if more batteries arranged in series were added to the circuit.
More batteries in series mean more electric current flows through the bulb
A bulb will fuse if too much electric current flows through it (filament melts)
Advantage of bulbs in series: Batteries will last a longer period of time compared to bulbs in parallel.
Disadvantage of bulbs in series:
The brightness of each bulb decreases as more bulbs are added to the circuit
Bulbs are dimmer than ones in parallel
Break in circuit when one bulb fuses and no other bulbs will light up
Bulbs in series cannot be controlled individually
Advantage of bulbs in parallel:
Brightness of each bulb remains the same when more bulbs are added to the circuit
Other bulbs will stay lit even if one bulb fuses
Switches can control each series of light bulbs individually
Disadvantage of bulbs in parallel: Batteries will last a shorter time
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