P6 Science Mindmap Created by Kagi inc. est. 69
P6 Science Mindmap
Created by Kagi
inc. est. 69
Human Body as a System
What is a System?
A system is made of two or more parts that function together
If one part is damaged or unable to work properly, the system will not be able to function properly
Systems can be man-made and natural
Manmade - e.g. a torch is a system in which if the bulb or battery is spoilt, the torch will not produce light
Living things are natural systems that have parts that work together to keep living thing alive and healthy
When are some organ systems in the human body?
The human body is made up of multiple organ systems
Each organ system is made of different parts with different functions
Parts: Mouth, Gullet, Stomach. Small Intestine, Large Intestine, Anus
Breaks down food into simpler substances
Absorbs digested food, nutrients, minerals and water to be used by the body
Stores undigested food until it is passed out
Parts: Nose, Windpipe, Lungs
Takes in oxygen into the body
Removes carbon dioxide from the body
Parts: Blood vessels, Heart, Blood
Transports oxygen, digested food, nutrients, minerals and water
Transports waste materials away from different parts of the body
Supports the body and gives it its shape
Protects delicate organs like the heart and lungs
Enables different parts of the body to move
How do the various organ systems work together?
Our organ systems are interconnected in some ways and work together to enable our bodies to function properly
For example, the digestive system provides digested food that is carried by the circulatory system to all parts of the body.
Failure of a system will result in the failure of other systems
The Digestive System
Why is Digestion important?
We eat food to obtain energy to do work and enable the different systems of our body to function properly
Food must be broken down into simpler substances, before it can be absorbed into the blood and carried to all parts of our body
Digestion is the process by which food is broken down in simpler substances
How is Food Digested?
Food is digested in the digestive system
Digestive juices in some organs of the digestive system act on food and break them down int osimpler substances, allowing it to be absorbed into the bloodstream
How do the different organs in the digestive system work together?
Digestion begins in the mouth
The teeth chew food into smaller pieces which helps to increase the surface area that he digestive juices can act on
The tongue mixes saliva with the food, which will break some of the food down into simpler substances as saliva contains digestive juices. It also makes the food wet and soft so it can be swallowed easily.
The soft chewed food is then rolled into small balls and then swallowed
The gullet is a tube that connects the mouth to the stomach
It has muscles to push the chewed food into the stomach
The stomach is a muscular bag that produces certain digestive juices
Food in the stomach is squeezed and mixed with the digestive juices, breaking down some food into simpler substances
The now liquid-like food moves to the small intestine
The small intestine is a long tube that produces digestive juices. The food is further broken down by teh digestive juices into simpler substances. Food that cannot be broken down into remains undigested.
Digestion is completed in the small intestine
The digested food and other nutrients pass through the walls of the small intestine and into the bloodstream, which carries them to all parts of the body
The undigested food is moved to the large intestine
Water and minerals are absorbed from the undigested food and pass through the walls of the large intestine and into the blood
The remaining undigested food form waste materials which are passed out through the anus
Plants and Their Parts
What are the parts of a plant?
Plants are living things, and like animals, they are made out of many parts - roots, stem, leaves, flowers, fruits
Hold the plant firmly to the soil
Absorb water and minerals from the soil to enable the plant to grow well
The stems of most plants grow above the ground.
Supports the plant
Holds up the leaves to trap sunlight to make food
Some plants have strong stems that grow straight up, and some have weak stems that may climb on other plants for support or creep along the ground
The function of leaves is to make food for the plant by trapping sunlight to make food
They have tiny openings on their underside known as stomata which allow gases to go in and out of the leaves (gaseous exchange)
Most consist of the leaf stalk, leaf blade and veins
Plant Transport System
What is the plant transport system?
The food made by the leaves is transported to the other parts of the other parts of a plant like roots, stem, flowers and the fruits
Water and minerals absorbed by the roots are transported to other parts of the plant
The plant transport system transports these substances to various parts of the plant using two tubes: xylem and phloem
Transport water and minerals
When a stalk of celery is placed in coloured water for some time, the warry-carrying tubes transport the coloured water up the stem.
Air and the Respiratory System
What are the components of air?
There is a layer of gas that surrounds Earth known as the atmosphere
Earth's atmosphere is a mixture of gases called air
Moving air is known as wind
Air is made of about 78% nitrogen, 21% oxygen, 0.03% carbon dioxide, with the rest containing a variable amount of water vapour and other gases
Oxygen is essential to all living things as plants and animals take in oxygen to carry out their life processes
Oxygen is needed for living things to break down food and turn it into energy, also known as respiration
Living things that live in water take in oxygen dissolved in water
Living things that live underground use the oxygen found in the soil
Oxygen is produced when plants make their food by photosynthesis
Oxygen is needed for burning as a burning object combines with the oxygen in the air, thus a continuous supply of oxygen is needed for it to burn
Nitrogen is the most abundant gas in the air
Does not suport burning
Carbon dioxide is given off when living things carry out their life processes
Carbon dioxide is also produced when things burn or decay
Plants use carbon dioxide to make their food during photosynthesis
The exchange of gases happens continuously to maintain a healthy balance of gases in the air
The water vapour in the air is essential in the water cycle and has effect on the weather. Clouds are formed from water vapour
The water vapour returns to Earth as rain,s now or other forms of precipitation
The water vapour is produced when:
Water evaporates into the air
Living things breathe out
The amount of water vapour in the air varies from place to place. Places near the ocean have more water vapour in the air
The noble gases in the air are argon, neon, helium, krypton and xenon.
Breathing V.S. Respiration
Breating is the taking in and giving out of air
Respiration is the reaction in cells where oxygen and nutrients produce carbon dioxide and energy
Parts of the body involved
Breathing: Nose, Mouth, Windpipe, Lungs, Diaphragm
Respiration: All living cells of the body
Role of oxygen
Breathing: Taken in as part of the air breathed in
Respiration: Used to break down food and produce energy
Role of carbon dioxide
Breathing: Given off as part of the air breathed out
Respiration: Produced when food is broken down
Functions of the organs in the Respiratory System
The pathway taking by air in the respiratory system is:
Air -> Nose -> Windpipe -> Air tubes -> Air sacs in lungs
All the cells in our body require oxygen taken from breathing in air
The human respiratory system consists of the nose, windpie, air tubes, air sacs and lungs
Allows air to enter and leave the body
Contains hair and mucus that traps the dirt in the air
Air that passes through is warmed and moistened
Transfers the air from the nose to the air tubes
Windpipe branches into two smaller air tubes
Transport the air to the lungs
Contain air sacs
Allow gaseous exchange in the air sacs
Pick up oxygen from the inhaled air
Pass out carbon dioxide into exhaled air
Have a rich supply of blood vessels which increases the surface area for gaseous exchange
Absorb oxygen which passes through the walls of sacs into the blood vessels
The carbon dioxide passes from the blood vessels and into the air sacs
How do the organs of the Respiratory System work together?
The ribs move out and upwards
The diaphragm moves downwards
The chest expands
Air rushes into the body through the nose and mouth
Air is cleaned, warmed and moistened in the nose
1 more item...
Oxygen from the air breathed in passes through the walls of the air sacs into the blood vessels
Blood carries the oxygen to all parts of the body
Carbon dioxide passes from the blood vessels into the air sacs
The ribs move in and downwards
The diaphragm moves upwards
1 more item...
How do Animals and Plants conduct gaseous exchange?
The respiratory system is responsible for the exchange of gases of living things with the surroundings
Different organs have different parts that make up their respiratory system
Insects / Arachnids
Openings that lead to tubes which carry oxygen to their internal organs
Take in oxygen in the water through their gills
Water containing dissolved oxygen enters the mouth of the fish. It washes over the gills and the oxygen enters the blood in the gills.
As water flows out from under the gill covers, carbondioxide from the blood is carried away
Have lungs and take in air through their nostrils
Have lungs and most take in air through their nostrils
Some mammals such as whales and dolphins also have lungs but their breathe through blowholes on the top of their heads
Some amphibians take in oxygen through their gills
Frogs can breathe through their moist skin when they are underwater instead of their lungs, which they breathe through when they are on land.
Plants have tiny openings known as stomata on the underside of the leaf which is used for gaseous exchange
During respiration throughout the day, plants take in oxygen and produce carbon dioxide
Stomata are commonly found on the underside of leaves, away from direct sunlight to prevent water from evaporating
Breathing In V.S Breathing Out
Not all the oxygen is inhaled by the lungs.
Breathing out: Body gives out carbon dioxide produced during respiration in which the air contains
More Carbon Dioxide
More Water Vapour
Breathing In: Body takes in air for respiration which contains
Less Carbon Dioxide
Less Water Vapour
The Circulatory System
What is it?
The human circulatory system is made up of the heart, blood vessels and blood
The human circulatory system transports oxygen, food and water to all parts of the body
The circulatory systems circulates blood in two parts
Blood is pumped from the heart to all cells in the body before returning to the heart
Blood from all parts of the body is pumped from the heart to the lungs and then back to the heart
Parts of the Circulatory System
The heart is a muscular organ situated near the middle part of our chest, slightly tilted to the left and protected by the ribcage
It is a vital organ that pumps blood all the time to all parts of the body
The heart is made up of special muscles called the heart muscles
We cannot control the movements of the heart muscles
Each heartbeat is a cycle of contraction and relaxation of the heart muscles
The average rate of heartbeat in a hearthy person is 60 to 70 beats per minute
The rate of heartbeat changes with age, health and the type of activity one is doing
With each heartbeat, a pressure wave passes along the blood vessels, pushing the blood through them, also known as the pulse
We take our pulse rate by pressing our fingers on our wrist or neck, and count the number of pulses felt per minute
The normal pulse rate of a healthy young adult is about 60 to 70 times per minute.
The faster the heart beats, the higher the pulse rate
When we exercise, our heart rate increases. This is because our body requires a greater supply of digested food and oxygen that is carried in the blood to all parts of the body. The blood also removes the carbon dioxide produced. Hence, the heart has to pump blood faster throughout the body
The digested food and oxygen are used for respiration to produce enough energy to conduct the activity that is taking place
Blood vessels are tubes through which blood flows
A network of blood vessels connected to the heart is spread throughout the body
Some blood vessels carry blood from our heart to all parts of our body, and vice versa
Blood transports digested food, oxygen, water, carbon dioxide and waste materials to different parts of the body
Carbon dioxide and waste materials are transported away from the cells to the organs that get rid of waste materials like the lungs, kidneys and skin
Digested food, oxygen and water are transported to all cells of our body for respiration
Blood flows through the blood vessels to get to all parts of our body
How do the organs in the Circulatory System work together?
The heart pumps oxygen-rich blood to all parts of the body through the arteries
Blood carries digested food and water from the digestive system to all parts of the body
The arteries branch out intto fine capillaries
The digested food, oxygen and water pass through the thin walls of the capillaries and into the cells of the body
1 more item...
How do the other organ systems work together with the Circulatory System?
Body systems cannot work alone and are interconnected with one another.
Some organs can be part of several systems.
Provides oxygen for the organs that is carried by the red blood cells to all parts of the body
Removes carbon dioxide and water from respiration that the cells produce through exhalation
Provides the heart and other organs in the circulatory system with nutrients from digested food so that he heart can continue beating
Heart muscles pump blood continuously to all parts of the body
Smooth muscles located in veins and arteries push blood through them with every heartbeat
The Unit of Life
What is a cell?
All living things are made of one or more cells.
A cell is the smallest unit of life. It is able to grow, reproduce, take in food and respond to changes in the environment
All living things begin as a single cell
Cells come in different shapes, sizes and structures to suit their specialised functions
Most cells are too small to be seen with the naked eye, only being seen with a microscope
The simplest living organisms have only one cell
Examples of unicelluar organisms are bacteria, yeast and paramecia
Organisms made of many cells are called mutlicellular organisms
The function of a microscope is to help us see objects that are too small to be seen with the naked eye
The common light microscope uses a system of lenses to magnify the specimen, which is the object we wish to see
Eyepiece: Where the eye looks through to observe the specimen
Nosepiece: Can be turned to allow the different objectives to be used
Objectives: Maginify the specimen
Stage: Is where the glass slide is placed
Lamp: Is used to illuminate the specimen
Fine adjustment knob: Makes small adjustments in focusing and has a limited amount of movement
Coarse adjustment knob: Can be turned to raise or lower the body tube or stage, making large adjustments to the focusing
What are the different parts of animal and plant cells?
Animal cell: Nucleus, cytoplasm, cell membrane, vacuole
Plant cell: Nucleus, cytoplasm, cell membrance, chloroplasts, cell wall, vacuole
Functions of cell parts
Cytoplasm: A jelly-like substance that contains many cell parts which allows substances to move around in the cell
Nucleus: A round or oval cell part in the cytoplasm which contains genetic information that is passed down from one generation to another and also controls the activities of the cell
Cell membrane: A thin layer that surrounds the cytoplasm which controls the movement of substances going in and out of the cell
Cell wall: A stiff layer around the cell membrane which supports and gives the cell its shape
Chloroplasts: A tiny dic-like cell part that contains a green pigment called chlorophyll which captures sunlight to make food in a process known as photosynthesis
What is an electrical system?
Electricity is a form of energy which can be used in electrical equipment to produce other forms of energy like heat and light
The path in which electricity flows is the electric circuit
Electrical objects have components in them, making up a electrical system
What is a simple electric circuit made of?
An electric circuit is an electrical system that is made of components like batteries, wires, bulb, switch
A battery has a positive end and a negative end
When the two poles of the battery are connected in a closed electric circuit, electric current flows through the circuit
Batteries are convenient sources of electrical energy that rae used in small electrical appliances like cameras and movile phones
Batteries come in different shapes and sizes
Electric current normally flows through wires
Are made of copper as copper allows electric current to pass through easily
Wires are covered with materials like plastic or rubber to prevent the electric current from leaking out of the circuit. These materials do not allow electric current to pass through them easily.
:A switch is used to control the flow of electric current in a circuit
A switch either breaks or completes a circuit
When th eswitch is open, there is a gap in the electric circuit and thus electric current is unable to flow through and vice versa
A bulb is an electric device often used in a circuit
It shines when its filament gets very hot and begins to give out light
Glass bulb: Prevents filament from being damaged
Wire: Connects filament to metal tip and metal casing
Metal casing: Connected to other components of the electric circuit
Filament: Is made of tungsten and produces light and heat when current passes through
Metal tip: Connected to other components of the electric circuit
How does Electric Current flow in a circuit?
Types of Circuits
Closed and open circuits
Series and parallel circuits
An electric current can only flow in a closed or complete circuit
When the components of the circuit are joined to form a complete path for the electric current to flow it is called a closed circuit
In a closed circuit electric current flows from the battery through the wires to the electrical components and then back into the battery
If any of the components are not properly connected the circuit will not be a closed circuit and electric current will not be able to flow through
When the components of a circuit are not properly connected, there may be a gap in the circuit and electric current is unable to flow through the gap. The path that the current flows through is broken and thus is called an open circuit.
A switch can be used to break or complete a circuit
Connections in a Bulb
A bulb will light up when we use wires to connect it to a working battery
When the metal tip and the metal casing are connected to different ends of the battery the bulb will light up as there is a complete circuit for current to flow through
Series and Parallel Circuits
A series circuit is a circuit that only has one path for electric current to flow through
If a component in the series circuit is not working the current is unable to flow through as the circuit is now open
However a parellel circuit has more than one path for electric current to flow through
Therefore even if a component in the parallel circuit is not working, current can still flow through the other path to form a closed circuit
Electrical Conductors and Insulators
Some materials allow electric current to flow through them and vice versa, which have to be taken into consideration when choosing materials for making electrical appliances and components
Materials that allow electric current to flow through them are electrical conductors
Some electrical conductors conduct electricity better than others are all known as good conductors of electricity
Most metals are good conductors of electricity
Silver is a better electrical conductor than copper but copper is used in current-carrying wires as copper is cheaper than silver
Some liquids also conduct electricity
Mercury is a metal that is liquid at room temperature
Good conductors of electricity are also usually good conductors of heat
MAterials that do not allow electricity to flow through them are called non-conductors of electircity or electrical insulators
Most non-metals are electrical insulators
Most electrical appliances are cased in insulators to prevent electric shocks and wires are covered with plastic or rubber for the same purpose - this is known as insulation.
A circuit tested is used to distinguish between electrical conductors and insulators
A circuit tester is a simple electric circuit with a bulb but it is an open circuit
An object is connected to the circuit to test whether it is a conductor. If it is a conductor, electric current can flow through the circuit and the bulb lights up and vice versa
Variables that affect the electric current in a circuit
The brightness of a bulb depends on 4 variables
Arrangement of Batteries
: The batteries of a circuit may be connected in series or parallel
When the positive end of a battery is connected to the negative end of another battery, the batteries are connected in series.
A parallel circuit will last longer but its bulbs will not shine as brightly as one in a series circuit as they provide less power than the same batteries in circuit. However a series circuit's batteries last shorter than a parallel circuit
Number of Batteries
: When more batteries are connected in series, the bulbs in the circuit shine more brightly as more batteries provide more power to the circuit so more electric current flows through each bulb,
Note: When too many batteries are connected to acircuit, the amount of current flowing through the filament may cause the filament to overheat and melt, causing the bulb to blow.
Number of Bulbs
: When more bulbs are added in series to a circuit, the individual bulbs in the circuits shine less brightly as the amount of electric current flowing through each bulb is decreased
Arrangement of Bulbs
: Bulbs can be arranged in parallel or in series. When it is arranged in parallel, electric current is able to flow through many paths.
When more bulbs are added in parallel to the circuit, they all shine as brightly as before as the electric current flowing through each bulb remains the same.
However to make each bulb shine brighter than a bulb in series more batteries will be needed than the ones needed in series
What is it?
All living things go through changes throughout their lives
The different stages in the life of a living thing make up its life cycle
Adult living things are able to reproduce
The young of living things will go through the same stages as their parents
It is important as it ensures survival and continuity of living things
The young will continue to live when the adults die
Similarities and Differences
Different animals have different stages in their life
The young may look similar or different from the adult
Life cycles of some animals
Begins with fertilised egg which develops into a baby inside a female's body
The female gives birth to a baby which grows into a child that looks like the adult
The child grows into an adult and changes in size. Some features change. The adult can reproduce.
Begins with an egg which was laid by a hen on land. The hard shell of the egg protects the chick growing in it.
The chick hatches from the egg and looks similar to its parents, looking more similar as it grows.
The chick grows into an adult and is able to reproduce
Begins with an egg. Many of these eggs were laid by one female frog to ensure some of its young manage to reach adultood, and are laid in water and surrounded by a jelly-like coating.
The eggs hatch into tadpoles with tails and do not look similar to their parents. They swim in water and feed on tiny plants, breathing with their gills like fish. They begin to develop legs as they grow.
A tadpole develops into an adult frog without tails and gills. It can live in both land and water and can reproduce. It uses its lungs to breathe on land and skin to breathe in water.
Begins with an egg that was laid by a female grasshopper in the soil.
It grows into a nymph that looks like an adult, but smaller and without wings. It moults several times as it grows.
An adult grasshopper has wings, can fly, and can reproduce.
Begins with an egg that was laid by a female butterfly on a suitable plant, to ensure that the young will be able to find food when they hatch from the eggs.
The egg hatch into larvae called caterpillars who feeds on the leaves of the plant, eating a lot so that it can grow. As it grows, it moults several times.
The caterpillar spins a case around its body and stays in the case. During this stage, it does not feed and develops inside it.
Once it is fully developed, it will break open the case and emerge as an adult butterfly. It spreads and dries before flying off and is able to reproduce.
Begins with an egg that was laid by an adult mosquito in still water.
The eggs hatch into larvae called wrigglers and hangs on the water surface. It moves around around to feed on the tiny organisms and food particles in the water. As it grows, it moults a few times.
After its final moult, the larva develops into a pupa. The pupa stays near the water surface and does not feed. It develops into an adult inside the case.
Once it is fully developed, it will break open the case and behold emerges an adult mosquito, who will then spread and dry its wings before flying off. It is able to reproduce.
Begins with an egg that the female lays on leaves.
The larva lives on plants and eats a lot, moulting several times.
The larva develops into a pupa and attaches itself to a plant, and stops feeding, developing into an adult in the pupal case.
The pupal case breaks open, giving wayt o the adult beetle. It spreads and dries its wings before flying off and is able to reproduce.
Life cycles of most plants
Most plants grow from seeds.
The root grows out of the seed, followed by the shoot.
The seed grows into a young plant that begins making its own food.
As the plant grows, more leaves develop to make more food, and more roots grow to absorb more water from the soil. Flowering plants develop flowers that develop into fruits with seeds. The seeds grow into new plants.
Matter and its Three States
What is it?
All living things around us are made of matter.
It is anything that has mass and takes up space.
Measuring mass and volume?
It is the amount of matter in a body or object
It is measured in grams (g) or kilograms (kg)
A balance can be used to measure the mass of an object or compare masses of two or more objects
An electronic balance can also be used, giving you a more precise result
The amount of space than an object occupies
Measured in cm3, m3, ml, or litres.
An object has to be removed before another can occupy its space
Is air matter?
Air is invisible matter but has mass and occupies space, so it is still matter
Three States of Matter and its Properties
Has a definite shape and volume.
Cannot be compressed.
Has no definite shape but has a definite volume
Cannot be compressed
Has no definite shape and volume
Can be compressed
Finding the volumes of each state
Step 3. Lower the solid in the water
Step 2. Record the volume of the water
Step 1. Fill half a measuring cylinder with water
Use measuring cylinders to measure the volume of water by reading the markings on it.
From Parents to Young
Why do Living Things reproduce?
All can reproduce.
All have a limited life span which may vary in length. All of them will die one day.
All may die due to old age, illnesses, accidents or attacks by predators.
Reproduction helps their own kind to continue to exist.
What is heredity?
Family members share similarities in characteristics or traits
Traits are controlled by genes in nucleus of cells
Genes carry info in living things
Parents pass characteristics or traits to their young when they reproduce
Heredity is the passing of traits from the parents to young. The young inherit these traits from the parents.
Some are obvious like:
Ability to roll tongue
Some are less obvious like:
Some traits are unique like:
Development traits rely on environmental factors and genes like:
Height affected by diet
Some are not inherited from parents like:
Length of hair
Length of fingernails
Shows the relationships within and beyond family
Hereditary disorders can be traced through the trees because several people in the family could be affected due to an abnormal gene
Reproduction in Plants
How do plants reproduce?
Plants can reproduce by many ways like seeds, spores etc
Plant parts like flowers are part of reproduction and are called reproductive structures
How do flowering plants reproduce?
Reproduction through Seeds
Flowering plants carry out sexual reproduction with seeds
There are four processes in the life cycle of a flowering plant:
Adult plants produce flowers which are pollinated
The female reproductive cells are fertilised by the male reproductive cells
The flowers turn into fruits with seeds that are dispersed
The seeds germinate to grow new plants which grow into adult plants and the cycle repeats
Structure of a flower
Flower helps flowering plants to produce seeds when pollinated
Some plants have different ways to reproduce:
Some have both male and female parts
Some have male and female parts on different plants
Some have male and female parts on seperate flowers
Anther: Produces pollen for pollination and stores them in pollen sacs
Filament: Holds the anther up
Stigma: Receives pollen grains
Style: Connects the stigma to the ovary
Ovary: Protects the ovule and becomes the fruit after fertilization
Petal: Attracts pollinators for pollination to the flower
Flower stalk: Holds up the flower so it can be easily detected by pollinators
Pollination occurs when pollen grains are transferred from the anther to the stigma
Birds, insects or the wind help in the transfer of pollen grains
Flowers are usually large, brightly coloured and scented attract insects
Anthers do not hang out of the flowers
Stigma is sticky in order to catch pollen grains
When an insect visits a flower to eed on the nectar, pollen grains from the anther stick to the insect's hairy body
The pollen grains are brushed off onto the stigma of the same flower or another flower that the insect visit
Flowers are usually small and dull coloured with no scent
Anthers hang out of the flowers so that pollen grains are easily shaken free and carried by the wind
Stigma is large and feathery in order to catch pollen grains floating in the air
The filament sways in the slightest wind and pollen grains are shaken free
The pollen grains are carried by the wind and land on the stifma of another flower
Fertilisation is the process in which a male reproductive cell fuses with a female reproductive cell
During pollination, pollen grains are transferred to the stigma
Each pollen grain produces a pollen tube. The male reproductive cells are found inside the tip of the pollen tube.
The pollen tube enters the ovule that contains an egg cell. Fertilisation occurs when the male and female reproductive cells fuse.
Formation of fruits and seeds
After fertilisation, most of the flower parts such as the petals, style and stigma usually wither and drop off, except the ovary
The ovules in the ovary start to develop into seeds
The ovary enlarges and gradually becomes the fruit
When the ovary is ready to release the seeds in it, it is said to have ripened
Dispersal of fruits and seeds
Seeds need to be dispersed or scattered away from the parent plants to: prevent overcrowding which can lead to competition for food, water, light, and space and so that they can grow in a more suitable and favourable environment
Since plants cannot move about, their fruits and seeds have special characteristics or adaptations to help their dispersal by animals, wind, water or explosive action
Juicy, fragrant, sweet or brightly coloured fruit with hard seedsand have hooks or still hair
Dry, light, small, have wing-like or parachute-like structures that allow them to be easily carried by the wind
Have waterproof outer layer or fibrous husks to allow them to stay afloat on water
Have fruit walls that split open with a sudden force when ripe, shooting out the seeds in different directions
Germination is the first stage in the development of a plant to a seed
Seeds need not germinate immediately after being dispersed and formed
Seeds can remain dormant for a long time before germinating when they are in favourable conditions
If a seed is not dead, it will germinate when it gets sufficient air, water and warmth - note: light NOT needed
When a root grows out of a seed, the seed has germinated
The germination of a seed is a part of the plant's life cycle thus it will continue to grow and complete its life cycle
The root appears first once it has germinated to allow more water to be absorbed and provide support as the young plant begins to grow. At this stage, the young plant uses food from its seed leaves for energy
The shoot appears after the root
When the first leaves of the shoot open, the young plant can carry out photosynthesis to make food
How do non-flowering plants reproduce?
Besides sexual reproduction, some plants can also reproduce without fertilisation
Non-flowering plants like ferns do not produce seeds and reproduce using spores
Fern: Spores are found in spore bags located on the underside of mature leaves
Moss: Spores are found spore bags at the ends of stalks
Spores are tiny and can only be seen under a microscope
Spores are generally dispersed by the wind because they are light
Spores will germinate when their conditions are favourable
Reproduction in Humans
How do Humans Reproduce?
Humans produce their young by the process of sexual reproduction involving a male and female
In sexual repdocution, the male and female mate and their reproductive cells meet
The organs involved in reproduction form the reproductive system
Sexual reproduction can occur when the reproductive system is fully developed
Human Reproductive Systems
Testes develop and produce male reproductive cells called sperms
The penis helps to transfer the sperms into the female body
Ovaries develop and produce female reproductive cells known as egg cells
An egg is usually released from one of the ovaries each month
The womb is where a fertilised egg develops
The vagina is a muscular tube leading from the womb out of the female body
A baby's reproductive system is relatively inactive during childhood
When the male reaches maturity, his testes will begin to develop and produce sperms
When the female reaches maturity, the eggs that are already present in her ovaries will begin to mature
The sperm and egg contain hereditary information that is passed on from the parents to young
What happens during and after fertilisation?
During mating, sperms from the male testes are released into the female vagina through the penis
The sperms travel through the egg by swimming with their tails
Only one sperm will fuse with one egg and the remaining ones will eventually die
After the sperm fuses with the egg the egg is said to be fertilised
The fertilised egg is divided to form many cells
A baby is developed from these cells in the mother's womb and stays inside for about nine months until it is fully grown and its organs are present and well developed.
The developing baby is connected to the mother through the umbilical cord which
supplies nourishment and oxygen to the baby
removes waste products from the baby's body
Water and Changes in State
What is Water?
Water is the most common liquid found on Earth, being found in oceans, rivers, air, etc
Water is matter because it has mass and occupies space
Liquid water has a definite shape but not a definite volume
Water is colourless and transparent
What are the three states of water?
Water can exist in three interchangeable states:
Solid: ice, snow
Gas: Steam, water vapour
How does water change its state?
Water is able to change from one state to another by gaining or losing heat
Heat Loss - Freezing (Liquid to Solid)
When water loses heat, its temperature drops
Tempeemperature is a measure of how hot or cold something is.
The freezing point of water is the temperature at which the water changes from a liquid state to a soil state due to heat loss
The freezing point of water is 0C
Heat Loss - Condensation (Gas to Liquid
Condensation is the change in state of water from a gas to a liquid due to heat loss. It can occur at any temperature.
Steam is water vapour at 100C. Like water vapour at any temperature, it condenses when it meets a cooler surface
Heat Gain - Melting (Solid to Liquid
Melting is the change from a solid to a liquid due to heat gain
The temperature in which a substance melts is called the melting point, which for water is 0C
Heat Gain - Boiling (Liquid to Gas)
When water gains heat, its temperature rises
Boiling is the change in state of water from a liquid to a gas due to heat gain
The temperature in which a liquid boils is called the boiling point, which is 100C
Heat Gain - Evaporation (Liquid to Gas)
Evaporation is the change in state of water from a liquid to a gas due to heat gain
Unlike boiling, evaporation occurs all the time at any temperature below boiling point
Produces a cooling effect, as when water evaporates, it gains heat from its surroundings so the surroundings lose heat and cooling is experienced
Evaporation can be used to dry clothes and separate salt from water
The rate of evaporation indicates how fast or slow evaporation is taking place
The factors affecting the rate of evaporation are temperature, presence of wind, area of exposed surface and humidity of the air
The temperature of the water and its surroundings affect the rate of evaporation.
The higher the temperature, the higher the rate of evaporation
Presence of Wind
When water evaporates, the water vapour it forms usually collects just above the water surface
When wind blows, it takes away the water vapour and creates space for more water vapour to form
Thus, the stronger the wind, the higher the rate of evaporation
Area of Exposed Surface
The area of exposed surface is the surface that is exposed to air
Water vapour forms at this surface
The greater the exposed surface, the higher the rate of evaporation
Humidity of the Air
Humidity is the measure of the amount of water vapour in the air
The lower the humidity of the air, the higher the rate of evaporation
On a dry day, humidity is low and there is little water vapour in the air, making it easy for water to evaporate, and vice versa
The Water Cycle
What is it?
Evaporation and condensation enable the water cycle to take place
Heat energy from the sun causes water on the Earth to evaporate, forming water vapour
This water vapour loses heat to the cooler air and condenses into tiny water droplets, forming clouds
Water evaporates from the ground and water bodies. Living things like plants and animals also release water vapour into the air
It is the continuous movement of water from the earth, sky and back to the earth. It can occur because water can change states
When the water droplets get big and heavy they fall from the clouds as rain, snow or hail
Clouds provide us with rain, snow or hail which are forms of fresh water.
Help to reduce the effect of the Sun's direct rays on the earth
Snow is made out of snowflakes
When the air temperature drops below freezing point, the water droplets in clouds freeze into ice crystals
The ice crystals collide with one another and more water vapour condenses on it, eventually forming snowflakes
Hail is frozen rain or hailstones
The temperature near the top of colouds is low so water droplets freeze when carried to the top
Air movements in the clouds carry the frozen water droplets up and down many times and each time they rise, another layer of ice forms around them
This continues until frozen water droplets are too heavy and fall
When the temperature of the ground is below freezing point, the air above or around it becomes very cold
Water vapour in the air freezes into tiny crystals, which form a sparkling white coat of frost on the ground and on trees
Rain falls onto the earth as fresh water. Some of it falls onto the ground and into water bodies.
Importance of the Water Cycle
All living things need water to stay alive
The water cycle is the only natural way to refresh water and provide a constant supply of fresh water for living things
Evaporation helps to separate water from dirt and salt
When water falls through the air as rain, it helps to purify the air by removing impurities
Need for Water in Humans
Water makes up 75% of the human body, thus playing an important role in carrying out the functions of body systems
In the digestive system, water is needed to digest food to absorb digested food and pass out waste
In the respiratory system, water is needed for gaseous exchange between the lungs and air we inhale
Air sacs called alveoli are surrounded by a thin layer of water
Oxygen dissolves this layer of water before entering the blood, and the same with carbon dioxide but for exhalation instead
In the circulatory system, water is needed in the blood to carry oxygen and digested food to parts of the body. It also needs to carry away waste materials and carbon dioxide away from the various parts of the body.
Need of Water in Plants
Water plays an important role in carrying out life processes in plants
For germination to occur, a seed needs sufficient water before it will germinate to activate the life processes in it
Plants need water and carbon dioxide in the presence of sunlight to make sugar using photosynthesis
Why is Water a Precious Resource?
Sources of Water
1% of the water is safe for consumption as fresh water
Most water exists in icebergs and glaciers or collected underground as groundwater
Water also exists in the atmosphere as water vapour and in cold regions as ice and snow
Pollution of Water
Occurs when harmful substances get into water and make it unfit for use
Polluted water is to be treated before being used
When the waste decays, harmful substances are produced which make the water dirty, foul-smelling and sometimes poisonous
Untreated chemicals may also suffer the same fate
Can kill the plants and animals living in the water
Oil floating on the water prevents oxygen from dissolving in the water
Without oxygen, the plants and animals will die
Oil may stick to the feathers of birds living near the surface of the water, clumping them together and making them unable to fly, keep warm and swim, eventually resulting in their death
The soil is exposed and rain and wind can move the soil into water bodies and pollute them, which reduces the amount of sunlight that reaches the plants in the water. Without sunlight, plants will be unable to make food and cannot produce oxygen for animals dependent on them and thus the other living things will die
Untreated human waste
Makes water unsafe for consumption and washing which further reduces the already little water on earth fit for human consumption
How can we conserve water?
We have a limited supply of fresh water, so we need to carefully use it to avoid its wastage and ensure that the remaining supply of water lasts longer
3Rs of Water Conservation
Shower instead of bath
Collect water in a basin and wash plates with it instead of a running tap
Turn off the tap while brushing teeth
Use rainwater to wash floors
Use water to wash rice and vegetables to water plants
Use water from washing machines to clean toilets
Treat waste water to make it usable
Can be promoted through campaigns, posters and water rationing exercises
Water rationing is the controlled distribution of water to people when there is a shortage
We no longer get water from our taps and instead have to go to a water distribution centre to collect water using buckets
Each person is only given a set amount of water
Living and Non-living Things
Things around us are grouped into these two
Alive - Living things and vice versa
Living things need air, food and water to survive and will die quickly otherwise and vice versa for the non-living
Living things can grow and vice versa
Living things can respond to changes, and vice versa
Living things can reproduce, and no, your chair is not able to make offspring
Groups of Living Things?
Make their own food
Can move parts by themselves but not from place to place
Eat other living things for food
Can move from place to place
Get food from zombie- uh, the dead, decaying or waste matter
Can move some parts themselves but cannot move from place to place. Sorry. Toad.
According to shape. colour, texture, and properties
Can make their own food
Where do they grow?
Places like fields, forests etc
Can be classified based on this; land and water plants
Produce flowers when they are adult plants
These can produce seeds
May not always bear flowers
Cannot produce flowers
Usually above ground
Have different shapes, sizes and colours
Only on flowering plants (obviously)
Only on flowering plants
Similarities and differences?
Can be similar/different in the following ways:
How are they different in appearance?
This allows us to identify them.
How are they different in outer covering?
Some have hair, scales, feathers, shells etc
Protect body of animals and other purposes
Keeps them warm
Protects from injuries
Protects from predators
Keep the animals warm
Help them to fly
Protects from injuries and predators
How are they different in reproduction?
Some lay eggs
Some give birth to young
Can live on land and in water
Have thin skin to breathe when moist or in water
Breathe with lungs on land
Have feathers to fly and keep warm
Have a beak, 2 wings and 2 legs
Not all can fly
All live in water
Most have scales
Have fins to help them swim and gills to breathe
Have an exoskeleton to give it shape and protect its soft body
Body divided into 3 parts
Have 3 legs and 2 feelers
Some have wings to fly while some do not
Reproduce by laying eggs
Most give birth to their young
The young feed on their mother's milk
Most live on land
Dry skin with scales
Breathe using lungs
Some have shells for protection
Fungi and Bacteria
What is Fungi?
Fungi is a group of living things found in many places that are cool and moist
Some are very tiny and cannot be seen by the naked eye whilst others are large enough to be seen
Feed on other living things, dead or alive as they break down the matter into simple substances and absorb them
Reproduce through tiny and light spores that are carried by wind
Fungi being useful/harmful to us?
Some mushrooms can be eaten
Yeast is used to make food like bread
Some moulds can be used to make cheese
Penicillin, an antibiotic, derives from Penicillium, a type of mould
Can cause things to spoil
Can grow on living things
What are Bacteria?
Large group of living things that feed on dead or alive living things
Bacteria being useful/harmful to us?
Used to make cheese or yogurt
Can grow on food and spoil it
Can make us ill
Materials are used to make objects around us
Materials are obtained from natural sources like plants
Ability to support a heavy load without breaking or tearing
Can be tested by: trying to break the material with loads or hands
Ability to bend without breaking
Can be tested by: Trying to bend the material with hands
Ability to float or sink in water
Can be tested by: Pushing an object into water and seeing if it sinks or floats
Does not absorb water
Can be tested by: Dipping the material in water and observe if it has absorbed water
Ability to allow light to pass through
Can be tested by: Shining light at one side of the object and observing how much light can be seen on the other
Choosing the right material?
Use different materials to make different objects
Some have properties that make them suitable to be used to make certain objects
The properties and uses of the material and object respectively must be known to choose the right material
Different materials can be used to make one object
Different materials can be used to make different parts of one object
What are magnets?
Magnets are special objects that attract or pull objects made of metals like iron and steel
Magnets can come in different shapes and sizes
What are the Characteristics of a Magnet?
A magnet can attract magnetic materials
A magnet is able to attract some metals like iron and steel which are considered magnetic
However some metals like aluminium and copper are unable to be attracted to a magnet and are considered as non-magnetic
All non metals like glass, wood are non-magnetic
A magnet has two poles
The ends of a magnet are called poles
All magnets have two poles even if they are button magnets or horseshoe magnets - north pole and south pole
The attraction of me, uh i meant the magnet is strongest at its poles
A freely suspended magnet points in the North-South direction
A compass is an instrument that can help to identify the poles of a magnet
A freely suspended magnet points in the North-South direction when it comes to a rest
A magnet can attract and repel another magnet
When two magnets are placed near each other, they will either attract or repel each other
Like poles repel and unlike poles attract
Testing the strength of magnets
Some magnets are stronger than others
One way to find out which magnet is stronger is by measuring how many thumbtacks made of a magnetic material each magnet can attract
How can we make magnets?
Some magnets exist naturally in nature while some can be made from magnetic materials
When a magnetic object is made into a magnet it is magnetised
There are two methods to make a magnet
Stroke the iron rod with one pole of the magnet
Repeat the stroking process a few times using the same pole in the same direction
Bring the iron rod near some steel clips, if it attracts the steel clips, it has been magnetised
Coil the electrical wire as many times around the nail
Proceed to connect the ends of the wires to the ends of the battery
Bring the iron nail near some steel clips - it is now an electromagnet and will attract the steel clips as it is now magnetised. However once the nail is seperated from the wire it is no longer a magnet as it is only a temporary magnet
An electromagnet can be made stronger by increasing the number of turns of wire around the nail or by increasing the number of batteries used
What is a force?
A force is a push or pull that one object exerts on another
When we apply a force in a direction towards our body, it is a pull, and vice versa
Forces help us to do a lot of things in our daily lives like rowing and sweeping the floor
The actions of twisting and turning are the results of a combination of pushing and pulling forces
What are the effects of a force?
Forces cannot be seen but their effects can be seen and felt
A force can start or stop the motion of an object
A force can change direction of a moving object
A force can change the size or shape of an object
A force can increase or decrease the speed of a moving object
A force can make a stationary object:
Start moving - the larger the force applied the greater the distance and speed that it will move
Change its shape
A force can make a moving object
Move faster or slower
Change its direction of movement
Change its shape
What are the different types of forces around us?
Friction / Frictional Force
Elastic Spring Force
Gravity / Gravitational Force
What is Friction?
Friction is a force that exists between two surfaces rubbing against each other
Friction opposes motion and acts to reduce the speed of a moving object and to change its direction opposite to the direction the object is moving
Friction produces heat
Friction between rougher surfaces is greater and produces more heat than friction between smoother surfaces
What is Elastic Spring Force?
Elastic objects change shape when a force acts on them but retain to their original shape once the force is removed
When an elastic object is stretched or compressed, it exerts a force on the object compressing or stretching it. This force is known as Elastic Spring Force
What is Gravitational Force?
Gravity is the force of attraction that exists between things that have mass
Gravity depends on the the mass and distance of objects:
The larger the mass of objects, the larger the gravitational force between them
The closer the distance between objects, the larger the gravitational force between them
When we refer to an object's gravity, we usually mean the force between the Earth and the object. Earth has a very large mass and we are on it, so it exerts a strong gravitational pull on us and objects on it.
Objects further away from Earth experience a weaker gravitational pull which is how astronauts float in space without getting pulled back to Earth
Weight tells us how heavy an object is and is the amount of gravitational force acting on an object
Objects on Earth have weight because of the gravitational force between them and Earth
Obviously, an object with a smaller mass will have less weight than one with a larger mass
What is Magnetic Force?
A megnetic force is a force exerted by magnets on magnetic materials
Magnetic force is responsible for the action of magents on magnetic materials: the magnetic force of attraction and repulsion
What is an organism?
An organism is a living thing
What is a population?
A population consists of all the organisms of the same kind that live and reproduce in a particular place
The population size is the total number of live organisms in a poplulation
What is a habitat?
A habitat is a place where a population of organisms lives.
A habitat is a place where the organisms find everything they need such as food, water, air, space and shelter to live and reproduce
There are different habitats for various organisms like pond, rainforest etc
The living conditions are different in different habitats, so the types of organisms found in one habitat will be different in the other
Habitats can be natural or artificial
Man-made habitats are called artificial habitats
How are the different populations in a habitat interdependent?
Populations of several kinds of organisms may be found in any one habitat
All the populations living in a habitat are linked together and may depend on one another for survival or for completing their life cycle
Populations l;iving in the same habitat are therefore said to be interdependent
What is a community?
A community consists of differnet populations of organisms living together and interacting in a single habitat
The populations in a community are said to be interdependent as they rely on each other for survival
Different communities can be found in different habitats
Different types of communities and their features
A seashore habitat consists of the land near the sea
May have sandy soil and/or large rocks
The seashore is flooded with seawater during high tide and vice versa
Crab, clam, coral, snail, sea star, sea urchin, mudskipper, and seagrass all live on the sandy beach near the sea and are regularly flooded by waves
Sea star and mussels cling to the rocks on the shore near to the sea in which are regularly flooded at high tide
Anemone, clam, sea urchin, mosses, and jellyfish live in the pools of water between rocks on the shore near to the sea in which are regularly flooded at high tide
Bacteria, fungi and seaweed live in both locations
Mangrove Swamp Community
Mangrove swamps are muddy areas that are flooded when the tide comes in
They are commonly found near the mouths of rivers
A mangrove swamp serves as a habitat for many unique plants and animals
Plants found in mangrove swamps have special roots that can survive the flooding by seawater and also provide support to the plant in the soft mud
Animals like frogs and prawns are found in these areas. Mudskippers are fish that can survive out of water for a short amount of time
A pond is an aquatic habitat
Has floating aquatic plants that float freely on the surface of the water
Has partially-submerged aquatic plants that have their roots rooted to the soil but has its leaves, flowers, fruits and seeds on or above the surface of the water
Has totally-submerged plants that are totally submerged in the water, obviously
Some fungi like toadstool grow on fallen leaves on the banks of the pond
Algae are usually found beneath the surface of water while amoebae are found in the pond water
Many different plant and animal populations make up a field community
The leaf litter community can be a part of this community
Has plants like vemonia and lalang
Has bacteria, fungi and other microorganisms that can be found in or on soil, in or on plants, or in or on animals
Has animals that either live in soil like the termite or live among plants like the bee and lizard
Gardens at home or at school provide a habitat for many different populations of organisms
A leaf litter community may be a part of this community depending on whether fallen leaves and dead plant are cleared from the garden
Has bacteria with some being found in the garden soil
Has plant like ferns and trees
Has fungi like moulds and mushrooms
Has animals like sparrow and butterfly
A Single Plant Community can be found inside other larger communities like a garden community as smaller communities can often be found in larger communities. This habitat can serve as a habitat for plants and animals
Leaf Litter Community
Leaf litter forms from fallen leaves, bits of bark and dead plant matter and is usually found where there are lots of plants
A leaf litter habitat is made up of leaf litter and the soil below the leaves and is dark and warm, with little air movement. It is also damp.
Earthworms, ants, snails, millipedes, and grasshoppers feed on leaf litter and break it into smaller pieces so that it is easier for bacteria and fungi to grow on and also are eaten by other animal populations
Beetles feed on leaf litter or on microorganisms and small insects and are eaten by lizard and spider populations
Centipedes feed on the millipedes
Spiders and lizards feed on other animal populations like the ants and grasshoppers
Fungi and bacteria feed on leaf litter by digesting it as they grow on it and make it softer and easier for some animals to eat
Is often part of larger communities like a field community
A forest habitat is very large and thus many populations of plants and animals live there
Plants like trees, ferns and mosses can be found in a forest
Animals like tigers, rabbits, bees and snakes can be found there
Smaller communities like the rotting log community, the single plant community, the tree community and the leaf litter community can be found in there
Rotting Log Community
A log is a large part of the trunk of a tree that is formed when a tree falls down and dies
A log that is still being digested by fungi and bacteria is known as a rotting log
Fungi and bacteria decompose the log and release nutrients and also decompose the waste of organisms living there
It is a dark and damp habitat and thus provides food and shelter to many populations of organisms
Mosses and ferns can grow on the log
Other populations either feed on the rotting woof or feed on the insects and worms living under the rotting log
What is an Environment?
Organisms are affected by conditions in their surroundings
The environment of an organism in made of living and non-living things that affect the organism, known as living and non-living factors which affect the survival of the living things found in the environment
The non-living factors of an environment include: light, temperature, air, water and soil
The living factors of an environment are all the living things that the organism interacts with, which includes: availibility of food and the kinds of organisms present
How do non-living factors in an environment affect the living things?
The amount of light from the sun affects the temperature of the environment
Plants need light energy to carry out photosynthesis. Some plants have different light requirements - some are shade-loving and some are sun-loving. If they are not in their suitable conditions, they may die
Light helps predators like eagles to see their prey
Some prey only come out at night to avoid their predators like mice and moles
Animals like beetles avoid light as they cannot survive bright conditions for a long time. This is due to the fact that the amount of sunlight affects the temperature in a habitat - more sunlight means a higher temperature
The amount of light can be measured by using a light sensor connected to a datalogger - the unit for measuring light is lux
Most organisms are adapted to live within a particular temperature range and cannot survive out of this range
The temperature of an environment can be measured using a laboratory thermometer or with a temperature sensor connected to a datalogger - the unit for measuing temperature is C
Organisms need water to carry out life processes, and the temperature of the environment affects the amount of water available to them
Below 0C, water freezes and the amount of liquid water decreases as more water freezes into ice
Above 0C, water evaporates and the rate of evaporation increases as the temperature increases and thus the amount of liquid water decreases as more liquid water evaporates and becomes water vapour
Air is a very important component in the environment as it affects the survival of an organisms
Few organisms can survive in the presence of low oxygen levels
Air is important to most living organisms because organisms need oxygen to carry out respiration and will die if sufficient oxygen is not available to them and plants need carbon dioxide to carry out photosynthesis to produce oxygen and make food
Less air is available to places that are higher up, like on mountains
The amount of air can be measured by using an oxygen sensor connected to a datalogger. The unit for measuring oxygen is parts per hundred or parts per thousand,
Air is needed in soil by roots of plants and burrowing animals for respiration. Oxygen is increased by burrowing animals as they mix air with soil as they burrow.
Air is needed on land by plants, animals and other organisms for respiration. Plants also need it for photosynthesis. Plants increase the oxygen in the air as they photosynthesise.
Air is needed in the water by plants and algae, who need it for both respiration and photosynthesis, and animals who need it for respiration. Plants increase the oxygen by photosynthesis. Algae grow close to the surface and block out light, resulting in the plants being less able to photosynthesize and thus produce lesser oxygen
Organisms need water in order to carry out life processes such as respiration and photosynthesis
Water is used to transport dissolved gases, food and waste through the bodies of organisms
Some organisms such as fish can only live and breathe in water
Some organisms need water to help them complete their life cycle.
Some organisms have mechanisms for storing water when it is available to them like the cactus and camel
Water in the liquid state is measured using a measuring cylinder and is measured in millilitres and litres
When there is little water, the soil is extremely dry. Thus, plants wilt as they are unable to get enough water to conduct respiration and photosysnthesis and animals will dehydrate as they also do not have enough water for respiration.
Lots of available water, the soil is waterlogged and the plant roots are unable to breathe. The burrowing animals may too be unable to breathe in soil and have to come out else they'd drown. Animals on land may also drown.
Some plants need soil to grow. The types of plants that can grow in a habitat depend on the type of soil in the habitat
Plants get water and minerals from the soil.
Plant roots grow into the soil and hold onto it tightly in order to support the plant
Animals such as earthworms and ants make their home in soil. Soil provides protection from heat, light and predators
How do the living factors in an environment affect the living things?
The availability of food can affect the survival of an organism
Food provides living things with energy to carry out their life processes to do work
Plants can make their own food using light energy, carbon dioxide and water during photosynthesis. They connot make their own food if the materials needed to make food are not available
Other organisms depend directly or indirectly on the food made by plants
Organisms that can find their food easily are more likely to stay alive than organisms that have to search for food
Organisms interact with other organisms living in the same habitat and this can help or harm the organisms
Some animals feed on plants, plants and animals, or plants only
Some bacteria and fungi are decomposers. They get their food by breaking down dead organisms and animal waste into simple substances which serve as nutrients in the soil and are used up by plants.
Some organisms like bacteria and fungi cause diseases
What are adaptations?
An organism that is
to its environment in its natural habitat can survive there.
Organisms often have special characteristics or features called
that help them to
in their natural habitats and
Classifications of Adaptations
behave in certain ways
that help survive or reproduce. These are
Organisms may be structurally and/or behaviourally adapted
How do living things adapt in order to survive?
An organism can be adapted to its environment for:
Movement, breathing, dealing with physical conditions
(like extreme temperatures)
, getting food, protection, reproduction, and making food.
Food Chains and Food Webs
Where do organisms get their energy from?
Only plants can trap energy from the sun directly - thus they are called producers
Animals that eat plants and/or other animals get their energy from the sun indirectly
Energy in all organisms can be traced back to the sun.
What are producers and consumers?
Organisms can be classified according to how they get their food
Producers are organisms that can make their own food.
Consumers are organisms that cannot make their own food and have to feed on plants and other consumers to get food to survive
What are prey and predators?
An animal that is being hunted and eaten by another animal is called a prey
An animal that hunts and eats other animals (not plants) is called a predator
Herbivores are prey and carnivores and omnivores are predators but can also be prey
What is a food chain?
Food chains show the predator-prey relationship between organisms
Food chains begin with a producer, i.e. a plant. The plant converts light energy into chemical energy stored in the food they make. The energy is passed on to herbivores and omvivores and then passed on to other omnivores and carnivores
Food chains are also energy chains because they show the transfew of energy between organisms. All energy begins from the sun.
What is a food web?
Organisms can belong to more than one food chain as consumers can eat more than one prey
Organisms can also be eaten by more than one prey
Predators may also be prey to other organisms
Food chains can be linked to form a food web.
The food web all start from a producer which gets its energy directly from the sun. Thus, all energy in a food web comes from the sun
Food chains in one community can be combined into a food web
How does the predator-prey relationship affect the population size?
Predators control the number of prey in a community by killing them. Prey control the number of predators as if the predators get too numerous they will eat too many prey and will be unable to sustain their high population. The population sizes thus stay balanced in a community.
Removing or adding a new population of organisms will affect the balance in the food web
Light and Shadows
What is Light?
Light is a form of energy
We need light to see things
What are some sources of light?
Objects that give off light are called sources of light
The sun is our main source of light during the day
All stars including the sun give off light on their own
Some animals such as fireflies give off light on their own
Fuels like coal and wood and bulbs and lamps give off light
How does light help us see?
We are able to see an object when light from the object enters our eyes. This happens when the object is a source of light or reflects light from a source of light
How much light can pass through different types of materials?
Different materials allow different amounts of light to pass through them
There are different types of materials: Opaque, Translucent and Transparent.
Opaque > Do not allow light to pass through, we cannot see through them
Translucent > Allow some light to pass through, cannot see through them clearly
Transparent > Allow most light to pass through, can see through them clearly
How are shadows formed?
Light travels in straight lines. Shadows are formed when light is blocked by an object.
A shadow always forms on the opposite side of the light source
The shape of the shadow is similar to the shape of the object
How can we change the shapes and sizes of shadows?
An object can have shadows of different shapes depending
The size of an object's shadow depends on the positions of the object, the light source and the screen
When the object is nearer the light source or further from the screen the shadow is bigger and vice versa
Heat and Temperature
What is Heat?
Heat is a form of energy that makes things hot
We cannot see heat but we can feel its effects. Heat can be felt by our sense of touch
What are some sources of heat?
Things that produce heat are known as sources of heat
Heat from the sun keeps Earth warm
Heat can be obtained from burning fuels like wood and coal
Many electrical appliances give off heat like stove and oven.
Sources of light can also be sources of heat
What is the difference between heat and temperature?
Heat is a form of energy and it makes things hot (like me). Temperature is the measurement of the degree of hotness of an object or place
The higher the temperature of an object is, the hotter it is
Our sense of touch lets us know roughly how hot or cold something is. However, we cannot measure the degree of hotness accurately and to do so we can use a laboratory thermometer (for objects) or a clinical thermometer (for our body)
We use Celsius (C) to measure temperature
What are some effects of heat gain and heat loss in our daily lives?
When an object gains heat, its temperature increases.
When an object loses heat, its temperature decreases.
When an object gains or loses heat, it can change state.
Matter can expand or become bigger when it gains heat.
Matter can contract or become smaller when it loses heat.
How does heat flow?
Heat always flows from a hotter to a colder place until they reach the same temperature
What are good and poor conductors of heat?
When two objects of different temperatures touch each other, heat flows from the hotter object to the cooler object.
of heat allow heat to flow through them easily.
of heat do not allow heat to flow through them easily.
Energy in Food
Why do Living Things need food?
All living things need food because they need to utilise the energy stored in food for all their activities
Living things also need energy to carry out life processes
Food that is eaten needs to be digested or broken down into glucose before they can be used to provide energy
The energy stored in food is released during respiration
How do plants make their own food?
The sun gives off light and heat energy
Light energy allows green plants to make food during photosynthesis and heat energy keeps the things and organisms on Earth warm
Plants obtain energy from the sun but cannot make use of the energy from the sun directly
Plants have chlorophyll that capture light energy from the sun to make food using carbon dioxide and water through photosynthesis
Water is absorbed by the roots and through the leaves. Carbon dioxide enters the leaves through the stomata
The food can be broken down in respiration to provide energy for life processes
The oxygen produced during photosynthesis is given out into the environment
Excess sugar produced is stored as starch in various parts of the plant
When a part of a plant is growing, it will need more energy. So the starch in the storage parts will be converted into glucose and transported to that part of the plant
How do animals obtain energy?
Animals cannot make their own food.
Animals satisfy their energy needs by eating other organisms to get the energy stored inside of them.
There are 3 types of animals: Herbivores, Carnivores, and Omnivores
Herbivores > Eat only plants.
Carnivores > Eat only animals.
Omnivores > Eat plants
Why is the sun important to living things on Earth?
The sun is our primary source of energy, providing us with both heat, and light.
We need light to see and heat for our bodies to function
Energy from the Sun is passed on to plants during Photosynthesis, and from plants and animals to us when eat them. All the energy in our food can be traced back to the Sun.
No sun > No light > No photosynthesis > No oxygen > Oh shit can't breathe > humanity dies
Forms and Uses of Energy
What is energy?
Energy is the ability to do work.
We can our energy from sources like food
Energy can get things to move or change in state
We need energy to stay alive as all parts of our body need energy to function. This energy is gotten from the food we eat
Energy is neither created nor destroyed. When we use energy, it is converted into other forms of energy
What are the different forms of energy around us?
Heat, electrical, light, kinetic, potential and sound
What is light energy?
Light energy is a form of energy that enables us to see
Light energy from the sun enables plants to make food
Objects can be seen if they give off or reflect light
What is heat energy?
Heat energy is a form of energy that makes things warm or hot
Heat energy from the sun keeps things warm so that organisms can survive
Heat energy is also produced through friction
What is sound energy?
Sound is a form of energy produced by vibrating objects
Sound travels outwards from the object producing it towards our ears. It requires a medium to flow through
Sound can travel in solids, liquids and gases but cannot travel through empty space
What is kinetic energy?
Kinetic energy is the energy that moving objects have
It can be found in all things
The faster an object moves the more kinetic energy it has
The amount of kinetic energy that an object has depends on the mass of the object and the speed of the object
An object at rest has no kinetic energy
What is electrical energy?
Electrical energy aka electricity, is a form of energy that can be carried along wires.
Electricity is usually generated in power stations
Energy stored as (Chemical Potential energy) in batteries or solar cells can be changed to electricity
Electrical energy is a very useful form of energy as it can be easily changed to other forms of electricity.
What is potential energy?
Potential energy is stored energy that can be converted into other forms of energy
There are 3 types - chemical, gravitational and elastic
Chemical potential energy is stored in food, fuel and batteries
The stored energy can be released as usable energy
Gravitational potential energy is present in any object above the ground
The gravitational potential energy of an object depends on its mass and distance away from the ground
Elastic potential energy is the energy an object has when it is stretched or compressed
Once released, the elastic potential energy converts back into kinetic energy and the object returns to its original shape
The more an object is stretched or compressed, the more elastic potential energy it has