Junior Secondary Science Vocabulary Flashcards

Comprehensive vocabulary flashcards covering key terms and definitions across Form 1, Form 2, and Form 3 Science lecture notes.

Science

The study of everything around us using our 5 senses, made up of biology, chemistry, and physics.

Biology

The study of living things, including plants and animals.

Chemistry

The study of changes that happen to matter.

Physics

The deal with the study of matter and energy.

Technology

The use of knowledge, skills, and information from science to make items that make our lives easier.

Hypothesis

A possible answer or explanation to a scientific question, or an intelligent guess.

Fair test

An experiment in which only one factor is changed so that the results are valid and unquestionable.

Independent variable

The factor that is intentionally changed in an investigation.

Dependent variable

The variable that is affected by the change in the independent variable.

Control group

The group in an experiment used for comparison where no change to the independent variable is made.

Scalar

A physical quantity that has magnitude (size) only, such as time, temperature, volume, and density.

Vector

A physical quantity that has both size (magnitude) and direction, such as acceleration, velocity, and force.

Length

The shortest distance between two points, with the standard unit of meter ($m$).

Area

A measure of the size of the surface of something, calculated as $\text{length} \times \text{width}$ with standard unit square meter ($m^2$).

Volume

The amount of space occupied by an object, with the standard unit of cubic meter ($m^3$).

Mass

The amount of matter contained in an object, with the standard unit of kilogram ($kg$).

Density

The mass per unit volume of a material, calculated as $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$.

Buoyancy

The upward force acting on an object in a liquid.

Temperature

The degree of how hot or cold an object is, measured using a thermometer with the standard unit Kelvin ($K$).

Endoskeleton

A supporting structure made of bones located inside the body of an animal.

Exoskeleton

A hard outer supporting structure found outside the body of an animal, such as the cuticle in insects.

Vertebrates

Animals that possess a backbone or vertebral column.

Invertebrates

Animals that do not have a backbone.

Dicotyledonous plants

Flowering plants whose seeds contain two cotyledons for storing food.

Monocotyledonous plants

Flowering plants whose seeds contain only one cotyledon.

Cell

The basic unit of life that forms the structural building blocks of all living organisms.

Nucleus

The cell structure that controls all reactions and activities taking place within the cell.

Cytoplasm

The fluid inside the cell membrane where substances dissolve and which gives the cell its shape.

Cell membrane

A selectively permeable layer enclosing the cell contents that controls movement of substances into and out of the cell.

Cell wall

A rigid outer structure in plant cells that is freely permeable and provides shape.

Chloroplasts

Plant cell organelles containing the green pigment chlorophyll that enable food production via photosynthesis.

Tissue

A group of similar cells working together to carry out a specific function.

Organ

A body structure made of several types of tissues grouped together to carry out a special function.

Photosynthesis

The process whereby green plants use sunlight, water, and carbon dioxide in the presence of chlorophyll to produce glucose and oxygen.

Stomata

Tiny pores on the surface of leaves flanked by guard cells that allow gases to enter and leave.

Respiration

The cellular process in which glucose and oxygen are used to release energy, water, and carbon dioxide.

Transpiration

The loss of water vapour from plant leaves through the stomata.

Atom

The smallest particle of matter that can exist on its own or take part in a chemical reaction.

Proton

A positively charged subatomic particle located in the nucleus of an atom.

Electron

A negatively charged subatomic particle located in shells orbiting the nucleus of an atom.

Neutron

A neutrally charged subatomic particle located in the nucleus of an atom.

Diffusion

The movement of particles from an area of higher concentration to an area of lower concentration until evenly distributed.

Anomalous expansion of water

The unique property of water where it contracts when cooled down to $4^\text{o}C$, but expands as it cools further down to $0^\text{o}C$.

Acid

A substance that dissolves in water to release hydrogen ions and give a pH of less than 7.

Base

A metal oxide or metal hydroxide that neutralizes an acid to produce salt and water only, having a pH greater than 7.

Alkali

A base that is soluble in water.

Frequency

The number of sound or wave vibrations produced per second.

Amplitude

The maximum displacement of a wave from its rest position.

Echo

A reflected sound wave caused by an obstacle such as a large wall or cliff.

Longitudinal wave

A wave in which particles of the medium move parallel to the direction of wave movement.

Transverse wave

A wave in which particles of the medium move perpendicular ($90^\text{o}$ angle) to the direction of wave movement.

Enzyme

A biological catalyst that speeds up chemical reactions in living organisms.

Gene

The smallest unit of inheritance located on a chromosome that controls cellular activities and physical traits.

Genetic engineering

The technique of manipulating and combining genetic materials from different organisms to achieve specific traits.

Ecosystem

A biological community of interacting living organisms and their non-living physical environment.

Symbiosis

A close ecological relationship between two different organisms where both individuals benefit.

Parasitism

A relationship between two organisms where one (the parasite) benefits at the expense of the other (the host).

Pollination

The transfer of pollen grains from the anther to the stigma of a flowering plant.

Lithosphere

The Earth's solid outer subsystem consisting of the crust, semi-solid mantle, and core.

Hydrosphere

The subsystem containing all of Earth's solid, liquid, and gaseous water.

Biosphere

The Earth's subsystem that encompasses all living organisms, including plants, animals, and microorganisms.

Atmosphere

The layer of air surrounding the planet Earth extending from the surface up to over 10,000 kilometers.

Ohm's Law

States that the potential difference ($V$) across a conductor is directly proportional to the current ($I$) flowing through it, provided temperature remains constant.