SCI definitions

Only the definitions required for the Y10 exam.

Gas Exchange

The movement of oxygen and carbon dioxide between the bloodstream and the alveoli (alternatively, between the capillaries and cells)

Breathing

The process of taking air in (inhalation) and out of the lungs (exhalation)

Cellular Respiration

Process in a cell that converts glucose and oxygen to create energy

(carbon dioxide and water are also given off)

Alveoli

Small air sacs where gas exchange occurs in the lungs

Artery

A blood vessel that carries mostly oxygenated blood away from the heart

Vein

A blood vessel that carries mostly deoxygenated blood towards the heart

Capillary

Very thin blood vessel that allows for passage of water, oxygen, nutrients, waste products between the bloodstream and cells

Red Blood Cell

A cell in the blood that carries oxygen and carbon dioxide throughout the body

White Blood Cell

Cells found in blood that help defend it from infection such as bacteria and viruses

Pulmonary

Relating to the lungs. E.g. Pulmonary artery carries blood to the lungs

DNA

The molecule that carries the genetic instructions

Chromosome

Threadlike structures that contain long lengths of DNA that holds many genes.

Gene

Section of a chromosome that codes for one trait e.g. eye colour

Allele

The different forms of a gene e.g. blue eyes

Gamete

A sex cell

Fertilisation

The fusion of two gametes

Zygote

A fertilised egg cell

Embryo

A ball of cells formed from the zygote by cell division.

Foetus

An unborn or unhatched offspring that has developed beyond an embryo.

Meiosis

The type of cell division that gametes are made by.

Mitosis

The type of cell division that body cells are made by.

Sexual reproduction

Reproduction that involves two individuals contributing genetically to offspring.

Variation

The differences (in DNA) of individuals in a population/species

Genotype

The alleles an individual has for a trait

Phenotype

The physical expression of the gene

Homozygous

Genotype with two of the same alleles

Heterozygous

Genotype with one dominant and one recessive allele

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Chemical change

When a new substance forms during a chemical reaction due to bond breaking and forming.

Physical change

A change of state, between solid, liquid or gas, or a change of shape and no new substance is formed.

Atom

Smallest complete particle of matter.

Atomic number

Number of protons inside the nucleus of an atom.

Proton

The positively charged subatomic particle found in the nucleus of an atom

Electron

The negatively charged subatomic particle, found in the orbitals surrounding the nucleus.

Ion

An atom or molecule that has gained or lost electrons and now has a positive or negative charge.

Valence shell

The outermost electron orbital of an atom

Ionic bonding

An electrostatic force of attraction between cations and anions

Covalent bonding

A shared pair of electrons between two or more non-metal elements.

Valence electron

The electron(s) found in the outermost electron shell of atoms or ions.

Electron arrangement /configuration

A shorthand notation which symbolises the number of electrons in each electron shell for an atom or ion.

Diatomic element

Two atoms of the same element held together by a covalent bond. eg Br 2 , Cl 2

Acid

A substance that donates H + ions to water.

Alkali

A soluble base.

Base

A substance that accepts H + ions from water (forms OH - ions).

Concentration

The measure of the amount of dissolved solute in a given volume of solvent measured in gL -1 .

Red litmus

An indicator that turns blue in a basic solution

Blue Litmus

An indicator that turns red in an acidic solution

Universal indicator

Indicator that gives an indication of the pH of a solution

pH scale

0 – 14 scale of the concentration of H + ions.

0 = high concentration of H + ions and low concentration of OH - ions

7 = same concentrations of H + and OH - ions

14 = high concentration OH - ions and low concentration of H + ions

Reaction: acid + base

When an acid reacts with a base, the products are a salt and water.

Limewater

A solution that turns cloudy white when carbon dioxide is bubbled through it

Pop test

A test for the presence of hydrogen gas

Force

A push or pull on an object that can cause a change in speed, direction or shape measured in Newtons (N)

Contact force

Force between two objects that are touching e.g. friction

Non-contact force

Force between two objects that are not touching e.g. gravity

Resultant force

(net force)

The overall force acting on an object.

Friction

Force that always acts to oppose motion or attempted motion.

Air resistance

(drag)

Friction force caused when an object moves through air

Average speed

The rate of change of distance travelled OR how fast you change your distance

travelled in a certain amount of time (m/s or ms -1 )

Acceleration

The rate of change of speed OR how fast you change your speed in a certain

amount of time. (m/s 2 or ms -2 )

Weight

The downward force caused by gravity on an object, measured in Newtons (N).

Mass

The amount of matter that makes up an object, measured in kilograms (kg).

Series circuit

Circuit where current flows through all components in one pathway.

Parallel circuit

Circuit where current flows through more than one pathway through components.

Fuse

A thin piece of wire that will melt when the current increases above a certain level. A safety component in a circuit.

Circuit breaker

An automatic switch that stops the flow of electric current in a suddenly overloaded electric circuit.

Current

The rate of flow of electrical charge, measured in amperes (A)

Voltage

The electrical potential energy per unit charge, measured in Volts (V). Also known as potential difference.

Resistance

The measure of how much a material reduces the flow of current through it. Measured in Ohms (Ω)

Power

The energy transformed per second by a component in a circuit, measured in Watts (W) and calculated using P = I x V