James Ang's Really Useful PSLE Science Word-list

No.

Words

Meaning

Related Words

1

Absorber

A material that takes in water or other things such as energy and radiation.

2

Acid

A chemical with a sour taste which turns blue litmus paper red.

3

Adaptation

Animals and plants survive in nature due to their special characteristics and natural protective mechanisms.

4

Alkali

A chemical with a bitter taste which turns red litmus paper blue.

5

Alloy

A material usually made from the mixtures of two or more metals.

6

Amoeba

A unicellular micro-organism that can carry out its own life functions.

7

Amphibian

An amphibian is an animal that can live in both land and water. An example is the frog.

8

Anther

The male part of a flower which produces pollen grains.

Stigma

9

Antiseptic

Substance that kills germs that may be found in cuts and wounds.

10

Artery

A blood vessel that carries blood rich in oxygen away from the heart to the other parts of the body.

Vein; capillaries

11

Atmosphere

The air that surrounds planet Earth.

12

Atom

The smallest particle in an element. Each atom has a nucleus in the middle and one or more electrons orbiting around it.

13

Axis

The axis of the Earth is an imaginary line through the Earth from North to South pole which causes day and night when the Earth rotates around its axis

14

Bacteria

Tiny organisms which are made up of one cell, many which cause diseases.

Bacterium (Singular)

15

Ball and socket joint

A type of connection between two bones that allows rotational movement. An example is the neck joint.

16

Biodegradable

Biodegradable materials can be broken down naturally by decomposers such as bacteria or fungi.

17

Biotechnology

The study of living things to produce benefits to ensure the survival of the human species.

Life science

18

Bladder

An organ in the abdomen which stores urine before it is released outside of the body.

19

Blood

Blood is the red liquid that is pumped around our body by the heart. It transports oxygen, food, water to all parts of our body.

20

Boiling point

The temperature at which a liquid changes to a gas.

21

Budding

A method of reproduction in which a new cell is formed by growing out from a part of the parent cell. Micro-organisms such as yeast reproduced by budding.

22

Camouflage

Protection mechanisms due to the colour, marking or animal shape that help living things to blend with its surroundings.

23

Capillaries

Capillaries are narrow blood vessels that connect arteries to veins in order for substances to be transported to and away from the body cells.

Capillary (singular)

24

Carbohydrates

Carbohydrates are foods that give us energy.

Starch

25

Carbon cycle

The process by which carbon in the atmosphere is converted from one form to another and back again in a continuous manner.

26

Carbon dioxide

A colourless and odourless gas which makes up 0.03% of air. It can trap heat and cause greenhouse effect. It is taken in by green plants during photosynthesis and given out by living things during respiration and given off during decomposition.

Greenhouse effect

27

Carnivore

An animal that only feeds on other animals

28

Catalyst

A catalyst speeds up the rate of a reaction without itself being changed in the process.

29

Cell

The smallest unit of life. All living things are made up of cells.

30

Cell division

The process whereby one cell splits to produce two new, identical cells.

31

Cell membrane

The thin and soft layer that surrounds the cytoplasm of a cell which controls the materials moving into and out of the cell. It is semi-permeable in that it allows some substances to pass through but not others.

32

Cell sap

The liquid found in a plant cell which keeps the cell firm.

33

Cell wall

A thick layer around the plant cell that is made up of cellulose and helps maintain the shape of the plant cell.

34

Centre of gravity

The point at which the mass of an object appears to act on.

35

Ceramic

A hard and strong material which is made from sand or clay.

36

Characteristics

Properties or qualities used to describe or distinguish a thing or group of things.

37

Chemical change

A change which had taken place which cannot be changed back to it original form without employing the use of chemical means. Example is the burning of paper.

Irreversible change

38

Chemical energy

A form of energy that is stored in chemical forms waiting to be used. Examples are candles, food and batteries.

39

Chlorophyll

The green pigment found in plants that enables photosynthesis to take place.

Chloroplasts

40

Chloroplasts

Tiny discs found in plant cells containing chlorophyll.

41

Chromosome

Thread like structures that have genes and control what a living thing looks like and how it functions.

42

Circuit

The path though which electricity flows from the battery through wires and devices before returning back to the power source.

43

Circuit breaker

A device that automatically breaks the flow of electricity in a circuit when there is a surge of electric current caused by faulty appliances or short circuit.

44

Circulatory system

It is made up of the heart, blood vessels and blood to carry food, water, oxygen and waste materials within the body.

45

Classification

A system of organising and arranging things that are related and/or share similar characteristics or nature. Helps to make the information more useful and easy to understand and remember.

Dichotomous key

46

Closed circuit

A closed circuit allows electricity to flow through.

47

Combustion

The burning through the action of heat on certain materials.

48

Community

It is made up of all the populations of living things that lives together in a habitat.

49

Condensation

The process in which a gas changes to a liquid upon cooling.

Evaporation

50

Conduction

A method of heat or electricity transfer which usually takes place in a solid object.

51

Conductor

A material that allows heat or electricity to pass through it easily. Most metals such as copper and silver are good conductors.

Insulator

52

Conservation

Protection and preservation of the environment and natural resources.

53

Constriction

A small bend found in the clinical thermometer to prevent the mercury from flowing back to the bulb.

54

Consumer

An animal that eats plants or other animals to derive energy.

55

Contraction

A decrease in size or volume due to heat loss.

Expansion

56

Control experiment

An experiment that is set up to be use for comparison to identify the effect or observation made due to a change of a condition or variable in the experiment.

57

Convection

A method of heat transfer that usually occurs in gases or liquids.

58

Criteria

The valid and necessary conditions.

Criterion (singular)

59

Current

A flow of electricity in a circuit. Current is measured in Amperes.

60

Cytoplasm

Jelly-like substance containing chemicals where chemical reactions of the cell take place.

61

Decomposer

An organism that breaks down dead or decaying materials into simple forms. Carbon dioxide is produced in the process. Examples are bacteria and fungi.

62

Definition

A statement of the meaning of a word, word group or a process.

63

Deforestation

The indiscriminate cutting down or burning of trees for mankind related development.

64

Density

A measure of the mass of an object per unit volume. Materials with a high density are heavy for their size while materials with a low density are light for their size.

65

Deoxyribonucleic Acid (DNA)

The molecules of DNA contain the information for cells to reproduce correctly. 

66

Diaphragm

A dome-shaped sheet of muscle that supports and separates the chest from the abdomen.

67

Dichotomous key

A classification used to identify living things by dividing the group into two smaller groups each time.

68

Digestion

The process by which food is broken down into simpler forms for adsorption into the blood stream to be transported to the other parts of the body.

Enzyme

69

Dispersal

The scattering of fruits and seeds for reproduction of plants to take place in a favourable environment.

70

Diversity

The variety of living and non-living things that have different characteristics.

71

Dynamo

A device that converts kinetic energy to generate electricity to power appliances and households.

Generator

72

Ecosystem

The living environment of a community of organisms.

73

Efficiency

The ratio of the Output energy over the Input energy.

74

Effort

The amount of force to be exerted on the body.

75

Elastic energy

A form of potential energy stored due to the compression or stretching of an elastic material.

76

Electrical energy

A form of energy caused by the flow of electrons through an electrical conductor.

77

Electricity

The flow of electrical energy through an electrical conductor.

78

Electromagnet

A magnet that is made by passing an electric current though a solenoid (a wire coil) around a piece of soft iron core.

Solenoid; permanent magnet

79

Electron

A negatively charged particle found inside an atom and which orbit around the nucleus.

80

Element

An element is a substance that cannot be broken down into simpler substances by any chemical method.

Atom

81

Embryo

An unborn offspring of an animal that is formed inside the animal or an egg.

82

Energy

Energy is the capacity to do work.

83

Environment

The living and non-living things that affect the organism in its habitat.

84

Enzyme

Enzymes are organic catalysts which speed up the rate of reactions. Examples are digestive enzymes such as amylase and protease.

85

Evaporation

The process in which a liquid changes to a gas or vapour. The rate of evaporation depends on humidity, wind, temperature and the size of exposed surface area.

Condensation

86

Exhale

To give or breathe out air.

87

Expansion

An increase in size or volume due to heat gain

contraction

88

Experiment

A scientific method use to test out an idea or demonstrate the effect of an action.

89

Extinct

The state of being no longer in existence.

90

Fats

Fats found in animals are reserves for when food is scarce. Fats are solids while oil is liquid.

91

Fermentation

A process where sugar or carbohydrates are changed into alcohol and carbon dioxide due to the action of yeast which is a fungus. Fermentation is used in the making of bread and the production of beer and wine.

92

Fertilisation

The process in which the male cell meets the female cell and fuses together.

Reproduction

93

Filament

The filament is a male part of the flower which holds up the anther.

94

Filter

A technique of separating a soluble substance from a insoluble substance by means of a filter paper.

95

Filtrate

The clear part of substance that has passed through the filter paper.

96

Flexibility

The ability of a material to be bent easily without breaking or damaging it. An example of a flexible material is rubber.

97

Food chain

A food chain shows the food relationship and the transfer of energy among organisms.

98

Food pyramid

A food pyramid shows food relationship, size of populations and relative amount of food each consumer needs for survival.

99

Food web

A food web is made up of a series of food chains that are interconnected.

100

Force

A push or a pull. It can affect the motion and also change the shape of an object.

101

Freezing point

The temperature at which a liquid changes to a solid.

102

Frequency

The number of complete cycles per unit time.

103

Friction

A rubbing force which slows down moving objects.

104

Fuel

Anything that produces heat and light energy when burnt.

105

Fulcrum

The point at which a lever is supported. Also known as a pivot, hinge or knife edge.

106

Full moon

The moon with the whole disk illuminated by the Sun.

107

Fungi

A group of non-green living things that reproduce by spores and cannot make its own food. They live on other living things and organic materials such as sawdust for their nutrition. Examples are mushrooms, yeast and mould.

Fungus (singular); skin infections

108

Gear

A wheel which has toothed edges and can be used to transfer motion.

109

Gene

A part of a chromosome which controls the characteristics in an organism.

110

Genetic engineering

Techniques used in the alteration (by adding or removal) of an organism's genetic make-up.

111

Genetic selection

The selection of desirable gene for mass reproduction.

112

Germination

The initial growth of a seed or spore in a conducive environment.

113

Global warming

An increase in the Earth's atmospheric temperature due to ecological changes.

Greenhouse effect

114

Glucose

A form of simple sugar that is carried in the blood stream and used during respiration to produce energy to do work and keep the body warm.

115

Gravitation potential energy

Energy stored in a body as a result of its position due to height. Magnitude of gravitational potential energy depends on the mass, gravitational acceleration and height.

116

Gravity

Force of attraction that pulls all objects towards the Earth.

117

Greenhouse effect

Atmospheric gases such as carbon dioxide trap heat and cause an overall global warming effect.

Global warming

118

Habitat

The place or home of an organism.

119

Hardness

The ability of a material to withstand scratches. An example is of a hard material is diamond which is the hardest naturally occurring material.

120

Heat

A form of energy that causes a change to the temperature of an object and its surroundings. Heat has no mass and does not occupy space.

121

Herbivore

An animal that only feeds on plants.

122

Hinge joint

A type of connection between two bones that allows forward and backward movement. An example is the elbow joint.

123

Homo sapiens

The scientific name for mankind.

124

Humidity

The "wetness" or the amount of water vapour contained in the air.

125

Hydroelectric energy

A form of electrical energy produced when water at great heights is used to move the generator turbines.

126

Hydrogen

A colourless and odourless gas which is the lightest gas in the world. It is explosive when in contact with a naked flame.

127

Hypothesis

An idea that is derived from observation but which has not been scientifically proven to be correct and valid.

128

Inclined plane

A surface that has been raised on one end.

129

Indicator

An indicator is a substance which changes colour depending on whether the solution to be tested is acidic or alkaline.

130

Infer

To provide an explanation about or to derive a conclusion based on certain observations.

131

Inhale

To take or breathe in air.

132

Inheritance

Characteristics which are passed down from the genes of the parents.

DNA

133

Insect

An insect is an animal that has three parts to its body and also has six legs. An example is housefly. But a spider is not a insect because it has 8 legs.

134

Insulator

A material that prevents heat or electricity to pass through. Most non-metals such as air and plastics are insulators.

135

Interdependent

A relationship in which organisms depend on one another for survival.

136

Invertebrate

Animal without backbone.

137

Iodine solution

A solution used to test for the presence of starch. Turns from brown to blue in presence of starch.

138

Irreversible change

A change which had taken place which cannot be changed back to it original form without employing the use of chemical means. Example is the burning of paper.

Chemical change

139

Kinetic energy

A form of energy due to the motion of a body.

Movement energy

140

Laboratory

The place where scientists conduct experiments to further the discovery of science. Chemicals and apparatus are found in a laboratory.

141

Large intestine

The part of the digestive system that absorbs water and mineral salts. This section is after the small intestine and before the rectum.

142

Larva

The young of an insect that has been hatched from an egg and which has a 4-stage life cycle. The larva does not resemble the adult.

Larvae (plural); pupa

143

Lever

A simple machine which is made up of a strong rigid bar supported on a fulcrum.

144

Life cycle

Natural stages of growth that an organism must pass through from the time it is born or hatched until it dies.

145

Life science

The study of living things to produce benefits to ensure the survival of the human species.

Biotechnology

146

Light

A form of energy we can detect with our eyes to allow us to see. White light can be split into a spectrum of colours. Light has no mass and does not occupy space.

147

Limewater

A solution used to test for the presence of carbon dioxide gas. Limewater turns milky (or chalky) when carbon dioxide is passed through it.

148

Load

The work that is to be done or carried out.

149

Luminous

Being able to be seen by the naked eye.

150

Magnet

An object that can exert a magnetic push or pull on other magnetic objects that are made of iron, steel, nickel or cobalt.

151

Magnetism

An invisible force that acts on magnetic materials such as iron, steel, nickel and cobalt.

152

Magnitude

The size and amount of a certain quantity.

153

Mammal

An animal that has hair. The female gives birth to its young and produces milk to feed them. Examples are human beings, apes, whale and dolphin.

154

Mass

The amount of matter in the object. Mass is measured in grams and kilograms.

155

Material

Any matter such as glass, wood, ceramic and plastics from which things are made from.

Natural material; synthetic material

156

Matter

Any object that has weight and occupies space.

157

Maximum

The biggest or highest amount of a quantity.

158

Melting point

The temperature at which a solid changes to a liquid.

159

Membrane

A thin and soft layer which allows some substances to pass through it but not others.

160

Mercury

A liquid metal commonly used in a clinical thermometer. Also a name for a planet in the Solar system.

161

Micro-organism

A tiny living thing that cannot normally be seen by the naked human eye but can be observed under a microscope. Examples are bacteria and germs.

Microscope

162

Microscope

An instrument used to observe micro-organisms by magnifying them.

163

Mineral salts

Chemicals that occur naturally and a small amount is required for overall good health.

164

Minimum

The smallest or lowest amount of a quantity.

165

Momentum

The product of the mass and velocity of a moving object.

166

Moon

A natural satellite that revolves around Earth or any other planets. The moon does not give off its own light but reflects the light it gets from the Sun.

167

Motion

An act, process or instance of moving.

Movement

168

Motor

A device that converts chemical or electrical energy to kinetic energy.

Engine

169

Moult

The shedding of skin by insects such as cockroach when they outgrow the skin.

170

Movement energy

A form of energy due to the motion of a body.

Kinetic energy

171

Multicellular

Organisms that are made of more than one cell are called multicellular organisms.

172

Muscle

A thick, stretchy tissue that is attached to the bones to control the body parts movements.

173

Muscular system

It is made up of all the muscles in the body to enable movement of various body parts to take place.

174

Natural material

Materials that occur naturally such as rubber, wood, cotton.

175

Nerve

A body tissue that transmit messages from one part of the body to another.

176

Neutron

A particle found inside the nucleus of an atom and which does not carry any charge.

177

Nitrogen

A colourless, odourless and inert (unreactive) gas which makes up 78% of air.

178

Nitrogen cycle

The process by which nitrogen in the atmosphere is converted from one form to another and back again in a continuous manner.

179

Non renewable

Not replaceable. Take a long time to be replaced naturally. An example is crude oil.

180

Nuclear fusion

The fusing or combining of two atoms to form a larger one.

181

Nuclear fission

The splitting of an unstable atom into two or more smaller particles. During the process enormous amount of energy is given off.

182

Nucleus

A small structure which contains chromosomes and controls the chemical reactions of the cell.

183

Nutrients

Substances that enable plant and animal growth.

184

Nutrition

The process of taking in food to get energy and for growth and repair.

185

Nymph

The young of an insect that has been hatched from an egg and which resembles the adult. An example is the cockroach.

186

Oesophagus (gullet)

The part of the digestive system that passes food from the mouth to the stomach.

187

Omnivore

An animal that feeds on both plants and animals.

188

Opaque

Does not allow any light to pass through it. One is unable to see through an opaque object. An example is cardboard.

transparent; translucent

189

Open circuit

An open circuit does not allow electricity to pass through.

190

Orbit

The circular path through which an object moves around another object in space.

satellite

191

Organ

A group of tissues organised to perform a particular function. Examples are kidney, heart and the stomach

192

Organ system

A group of organs organised to perform a particular function. Examples are digestive system, circulatory system.

193

Organisms

All living things are organisms.

194

Ovary

The female part of a plant or an animal which contains the ovules (plant) and the eggs (animal).

195

Ovule

The female part of a plant which contains the egg cell or seed.

196

Oxygen

A colourless and odourless gas which is required by all living things in order to stay alive. It makes up 20% of air and supports combustion (burning).

Respiration

197

Ozone layer

A layer of ozone found in the Earth's atmosphere which protects the living things from harmful ultraviolet radiation of the Sun.

198

Parasite

An organism that depends or lives on other living organisms for food and nutrition.

199

Perpendicular

A line which forms a right angle with the original line.

200

Phloem

The outer tube in a plant that transports food from the leaves to other parts of the plant.

Xylem

201

Photosynthesis

The process by which green plants make food from water and carbon dioxide in the presence of light. Oxygen is produced during photosynthesis.

202

Physical change

A change which had taken place which can be easily changed back to its original form by the use of physical means. Example is the change in states of water.

Reversible change

203

Planet

A large object that revolves around the Sun. The nine planets in the Solar System are; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

204

Plastic

A man-made material which is cheap, durable and waterproof and is derived from the refining of petroleum. It does not break down easily and can cause pollution. Recycling and reuse of plastics help to reduce environmental pollution.

205

Pollen grains

The male cells of a flower that is used to pollinate the flower.

206

Pollination

The movement of pollens from the anther of a flower to reach the stigma so that reproduction can take place.

207

Pollution

Actions and activities that causes the environment to become dirty and unsuitable for living.

208

Population

A group of living things of the same kind living together and reproducing themselves in a particular habitat.

209

Potential energy

A form of energy that is stored for the purpose of being used later.

Stored energy

210

Predator

An animal that hunts for other animals for food. Most carnivores are predators.

Prey

211

Predict

To forecast or make a guess based on what is known or observed.

212

Pressure

Pressure is the force pressing on a given area.

213

Prey

An animal that is eaten by other animals. All herbivores are prey.

214

Primary colours

Red, blue and green colours are primary colours.

215

Prism

A prism is a shaped piece of glass which can split white light into the colour of a spectrum or a rainbow.

216

Producer

Green plants that can make their own food by photosynthesis.

217

Protein

Protein helps build the body's tissue for growth and repair.

218

Proton

A positively charged particle found inside the nucleus of an atom.

219

Puberty

The stage in mankind where the reproductive organs are being developed.

220

Pulley

A simple machine which is made up of a rope wound around a supported wheel.

221

Pulse

The rate of heart beats which can be felt in the arteries.

222

Pupa

The stage of growth between the larva and the adult of an insect of a 4-stage life cycle.

Pupae (plural)

223

Radiation

A method of heat transfer that does not required a medium for it to take place.

224

Rainbow

A rainbow is a natural phenomenon and is formed when sunlight passes through drops of rain.

225

Rate

A measure of quantity in relation to time.

226

Reaction

When chemicals react they combine together in different ways or splits apart to form simpler substances.

227

Recycle

To be used again through a cycle of changes or treatment. An example is plastics which can be recycled.

228

Reflection

The process by which light and sound waves get bounced off when they strike a surface.

229

Reflector

A material that causes light energy or other form of radiation to bounce off a smooth surface.

230

Renewable

Can be replaced naturally. An example of renewable resource is trees.

231

Reproduction

The process by which living things produce more of their own kind to ensure the survival of the species.

232

Reptile

Reptiles are cold blooded animals which have dry and scaly skins. An example is crocodile.

233

Residue

The part remaining after another part has been filtered away by filtration method.

234

Respiration

The process by which living things take in oxygen to break down food to produce energy to do work and keep the body warm. Carbon dioxide is given off during respiration.

235

Respiratory system

It is made up of nose, mouth, windpipe, lungs and diaphragm working together to exchange gases with the surroundings.

236

Retina

The part of the eye which captures the image a person sees.

237

Reversible change

A change which had taken place which can be easily changed back to its original form by the use of physical means. Example is the change in states of water.

Physical change

238

Revolution

One revolution is a complete round of movement about an object.

239

Ribcage

The part of the skeleton that protects the lungs and heart.

240

Rotation

The process of turning or spinning on its own axis in a circular motion.

241

Satellite

An object that revolves around another object in space.

orbit

242

Scavenger

A scavenger does not hunt for its own prey but feeds on dead animals left behind by other predators.

243

Science

Science is the study or natural things around us.

244

Scientific method

The way scientists go about finding out things.

245

Seed leaf

The part of a seed that protects the baby plant and provides it with food during germination stage.

246

Seedling

A young plant made of few roots and leaves.

247

Semi permeable membrane

A thin and soft layer which allows some substances to pass through it but not others. 

248

Shadow

The darkened parts formed when light is blocked by an opaque object. Shadow has no mass and does not occupy space.

249

Skeletal system

It is made up of all the bones in the body to support the body to give it a structure and to protect the delicate body organs.

250

Skeleton

The supporting framework of the body of most animals.

Vertebrate; invertebrate

251

Small intestine

The part of the digestive system where most of the digestion of food takes place. This section is after the stomach and before the large intestine.

252

Soil erosion

The removal of top soil by wind or water and which will lead to environmental problems.

253

Solar energy

A form of light and heat energy that comes from the Sun.

254

Solar system

The Solar System comprises the Sun. the planets that revolves around it and the moons.

255

Solution

A mixture of a liquid with a dissolved solid or gas.

256

Sound

A form of energy produced as a result of vibration and which can be audible (heard) by living things.

257

Species

A group of living things of the same kind that can reproduce to continue their existence.

258

Speed

How fast an object moves. That is the rate of change of distance moved.

259

Sperm

A male reproductive cell that that is produced by the testis of the male animal.

260

Spore

Produced by fungi, ferns, moss and bacteria for reproduction.

261

Star

An object in space which gives off its own light and heat. The Sun is the most important star in the Solar system.

262

Starch

Starch is food that gives us energy. Examples are bread, pasta and potatoes which contain starch.

Carbohydrates

263

Steam

Water vapour form from boiling of water at 100 degrees Celsius.

264

Stigma

The female part of a flower which receives the pollen grains.

265

Stomata

Tiny openings on the surface of a leaf which allow exchange of gases and water vapour. Stomata are found mostly on the underside of the leaf.

Stoma (singular)

266

Stored energy

A form of energy that is stored for the purpose of being used later.

Potential energy

267

Streamline

A shape or form which allows air and water to slip through easily.

268

Strength

The amount of force which can be applied to a material without breaking it. Example of a strong material is iron or steel.

269

Style

The style is a female part of a flower which connects the stigma and the ovary.

270

Sundial

A olden day instrument used to tell the time of the day by measuring the length of a shadow caused by the sun's rays.

271

Switch

A switch is used to start or stop an electric current flowing in a circuit.

272

Synthetic material

Materials that are man-made and which does not occur naturally, such as plastics, PVC, styrofoam, nylon.

273

System

A group of related parts working together to perform a function. Usually include inputs, process and outputs.

274

Telecommunications

The use of radio waves to send and receive signals for communication purposes.

275

Temperature

The degree of hotness or coldness of a body.

276

Testis

The reproductive organ of the male animal which produces sperm.

Testes (plural)

277

Texture

The way a material feels when it is touched. Example the surface of glass is smooth.

278

Thermometer

An instrument used to measure the temperature of a body.

279

Time

A duration for which an event occurs. Time is measured in seconds, minutes and hours within a day.

280

Tissue

A group of cells organised to perform a particular function. Examples are skin tissue and muscular tissue.

281

Translucent

Allows some light to pass through. One can see through a translucent object but not very clearly. An example is frosted glass.

282

Transparent

Allows most light to pass through it. One can see through a transparent material very clearly. An example is clear window glass.

283

Transpiration

A process where water is drawn up by roots of a plant when water vapour evaporates from the leaves.

284

Umbilical cord

A tube that conveys food, oxygen and blood from the mother to the baby and removes waste products from the baby.

285

Unicellular

Organisms that are made of one cell are called unicellular organisms.

286

Variable

A factor that can be changed to determine the resultant effect on an experiment. Examples are the temperature or light conditions.

287

Vein

A blood vessel that carries blood rich in carbon dioxide away from all parts of the body back to the heart.

288

Vertebrate

Animal with backbone.

289

Vibration

The movement to and fro about a fixed position.

290

Volume

The amount of space taken up by an object.

291

Water vapour

Water that is in gaseous state.

292

Wheel and axle

A simple machine which is made from having a bigger wheel joined to a smaller axle.

293

Windpipe

The passage in the respiratory system that transfer air from the nose to the lungs.

294

Womb

The organ in females where the baby develops and grows.

295

Work done

The amount of work done is calculated by the product of Force and distance moved in the direction of the force. When a force is exerted on the wall which does not move at all, there is no work done!

296

Xylem

The inner tube in a plant that transports water and mineral salts from the roots to the other parts of the plant.

297

Yeast

A unicellular micro-organism that is commonly used in the fermentation process and in the making of bread.

Fermentation