Revision Science Document

Acceleration

Acceleration

Any change in velocity

Air resistance

A force that resists an object's motion through air

Applied force

A type of force exerted by a person, animal or machine

Balanced force

A force with an equal and opposite force acting on the same object

Collision force

A contact force that acts on an object when it hits another object

Contact force

Any force that can only occur when two objects are touching

First law of motion

An object has a constant velocity unless acted on by a net force

Force

A push or pull

Free body diagram

A representation of all the forces acting on an object

Friction

A force that resists an object's motion

Gravity

The attractive force between any two objects that have mass

Inertia

The natural tendency of an object to maintain a constant velocity

Mass

The amount of matter in an object

Net force

The overall force on an object

Newton

The standard unit of force

Non-contact force

Any force that can occur even when two objects are not touching

Reaction force

The force that is paired with another force by the third law of motion

Second law of motion

An object's acceleration is directly proportional to the net force acting on it, and inversely proportional to its mass.

Speed

The rate of change of an object's position

Support force

An upward force exerted on an object by a solid surface

Tension

A force that pulls inward when a solid object is stretched

Third law of motion

Every force has an equal and opposite reaction force

Thrust

A force that acts on an object when it shoots out a jet of liquid or gas

Unbalanced force

A force without an equal and opposite force acting on the same object

Velocity

The speed of an object in a certain direction

Water resistance

A force that resists an object's motion through water

Weight

The force of gravity on an object

Abiotic factor

A non-living thing in an ecosystem

Biodiversity

The variety of living things in a particular area

Biotic factor

A living thing in an ecosystem

Carbon cycle

The continual movement of carbon through ecosystems

Cellular respiration

The reaction in living cells that releases energy for life processes

Chemical energy

The energy stored in molecules

Commensal

Benefiting one species while the other species is not affected

Consumer

An organism that gets its food by eating other organisms

Contaminant

A harmful substance in the environment or in living things

Decomposer

An organism that breaks down dead matter by releasing chemicals

Ecology

The scientific study of ecosystems, a branch of biology

Ecosystem

A collection of organisms interacting with each other and their environment

Energy

The ability to move, grow and function

Food chain

One pathway of energy transfer between organisms

Food web

Connected pathways of energy transfer between organisms

Matter

Any substance that takes up space and has mass

Mutualistic

Benefiting both species

Parasitic

Benefiting one species while the other species is harmed

Photosynthesis

The reaction in producers that transforms light energy into chemical energy

Producer

An organism that makes its own food by harnessing sunlight energy

Resilience

The ability to recover after a change

Species

A group of similar organisms that can breed with each other

Symbiosis

A long-term relationship between species where at least one benefits

Acquired trait

A feature that is gained during an individual's lifetime

Adaptation

A genetic trait that helps an organism survive in its environment

Antibiotic

A medicine that kills bacteria or prevents their growth

Antibiotic-resistant

Able to survive in the presence of antibiotics

Behavioural adaptation

A behaviour or action that helps an organism survive

Common ancestor

A species that two or more other species have evolved from

Competition

The struggle between organisms for resources, such as food or mates

DNA

A molecule that contains genetic information

Ecosystem

A collection of organisms interacting with each other and their environment

Evolution

A change in the genetic traits in a population over many generations

Evolutionary tree

A diagram that shows how species are related

Extinction

The dying out or complete disappearance of a species

Gene

A unit of genetic information

Genetic diversity

The amount of genetic variation in a population

Genetic trait

A feature that can be passed down by genes to the next generation

Inheritance

The passing down of traits via genes from one generation to the next

Mutation

A small random change in an organism's DNA

Natural selection

The survival of organisms that are better adapted to their environment

Population

A group of organisms of the same species living in the same place

Selection pressure

A challenge that affects an organism's ability to survive and reproduce

Speciation

The formation of a new species

Species

A group of similar organisms that can breed to produce fertile offspring

Structural adaptation

A physical feature of the body that helps an organism survive

Trait

A feature of an organism

Variation

A difference in traits between individuals of the same species

Adenine

One of the four nucleotide bases in DNA, pairs with thymine.

Base pair

Two bases joined together

Allele

A version of a gene

Amino acid

A small molecule that joins with others to form proteins

Anaphase

A stage of cell division in which the chromosomes separate

Base

Part of a DNA molecule that comes in four types:A, C, G and T

Cell cycle

The repeated process of cell growth and division

Cell division

The splitting of a cell to form new cells

Chromosome

A DNA molecule that condenses during cell division

Crossing over

The swapping of genes between chromosomes in a homologous pair

Cytosine

The base that combines with guanine to form a base pair

Daughter cell

Any new cell formed by cell division

DNA

A molecule that contains genetic information

Dominant allele

A version of a gene that is expressed even when only one copy is present

Dominant trait

A feature that appears when at least one allele is present

Fertilization

The joining of an egg and a sperm to form a new organism

Gene

A unit of genetic information

Generation

Members of a family that are born and live at about the same time

Genotype

A pair of alleles that influence the appearance of a particular trait

Guanine

The base that combines with cytosine to form a base pair

Heterozygous

A genotype in which the two alleles are different

Homologous pair

Two chromosomes that contain versions of the same genes

Homozygous

A genotype in which the two alleles are the same

Inheritance

The passing down of traits via genes from one generation to the next

Interphase

The stage of the cell cycle in which a cell grows and copies its DNA