All Biology Definitions

Ecology

Is the scientific study of the interactions of organisms in their environment

Ecosystem

Community of organisms and their environment e.g. seashore ecosystem

Biosphere

The part of the earth where organisms can live

Habitat

Part of an ecosystem where organisms live

Community

The different groups of organisms living in an ecosystem

Niche

The role of an organism in an ecosystem

Abiotic Factors

Non - living features of the environment that affect the community e.g. aspect

Biotic Factors

Living factors of the environment that affect the community e.g. food

Food Web

The interconnection between two or more food chains

Food Chain

Pathway along which energy is passed from one organism to another

Trophic Level

Feeding stage in a food chain

Pyramid of numbers

Diagram that shows the number of organisms at each trophic level

Competition

When organisms in an ecosystem struggle for a resource that is in short supply

Contest Competition

A physical confrontation between two organisms and only one can win the resource

Scramble Competition

A struggle for a resource in an ecosystem with all the organisms obtaining a small amount of the resource

Predation

The killing , catching and eating of another animal

Parasitism

When one organism live in or on a second organism from a different species , feeding on it and causing it harm

Symbiosis

When two organisms , from different species lives together and at least one benefits

Mutualism

When two organisms from different species live together and both benefit e.g. clover and rhizobium

Commensalism

When two organisms from different species live together and one benefits and the other neither benefits or is harmed e.g. birds nest in a tree

Conservation

The wise management of the environment and its resources

Pollution

The addition of anything harmful to the environment e.g. gases from burning fossil fuels

Eutrophication

When nutrients run off from the land into a lake / river which causes the dense growth of plants in the water and the death of fish and other organisms

Decomposers

Microorganisms and other organisms that return nutrients to the environment by death and decay

Hypothesis

An educated guess

Experiment

Designed to test the hypothesis

Control

Used to compare the results of an experiment

Data

The collection of observations and results

Replicate

A repeat of the experiment

Theory

A hypothesis supported by results gathered over a long period of time

Double - blind Testing

Neither the experimenter nor the test group know the treatment that is being given

Observation

Taking in information about the natural world

Law / Principle

A definite and factual explanation

Random Selection

Choosing without a method or conscious choice

Placebo

A substance used as a control in an experiment

Diversity

The large variety of organisms on earth

Cell

The basic unit of structure and function in an organism

Tissue

A group of cells specialised for a particular function e.g. connective tissue

Organ

A group of tissues working together for a particular function e.g. heart

Tissue Culture

The growth of cells in a sterile nutrient medium

Prokaryotic

Do not have a membrane bound nucleus or membrane bound organelles

Eukaryotic

Have a membrane bound nucleus and membrane bound organelles

Diffusion

The movement of a substance from an area of high concentration to an area of low concentration along a concentration gradient

Osmosis

Is the movement of water molecules from an area of high concentration to an area of low concentration across a selectively permeable membrane

Active Transport

The movement of a substance from an area of low concentration to an area of high concentration against a concentration gradient . It requires ATP ( energy )

Turgor

The pressure of the cell contents against the cell wall

Plasmolysis

The shrinkage of a plant cell due to the loss of water by osmosis

Selectively Permeable

Only allows some substance to pass through the cells membranes

Substrate

Substances on which an enzyme acts

Enzyme

A biological catalyst which is made of protein

Denaturation

The change in the structure of the active site preventing the enzyme from bonding with a specific substrate

Immobilised Enzymes

Enzymes that are fixed in an inert material

Metabolism

The sum of all the chemical reactions in a living organism

Optimum Activity

Enzymes working at its most efficient and best rate

Specific

Each enzyme only acts on a particular substrate

Anabolism

When small molecules are built into larger molecules using energy e.g. Photosynthesis

Catabolism

When big molecules are broken down into smaller molecules releasing energy e.g. Respiration

Cell Continuity

The ability of cells to divide and survive

Somatic Cells

All the normal body cells that are not gametes

Cancer

When normal cells lose control of the rate and number of mitotic divisions

Cleavage Furrow

Is the separation of two identical nuclei during mitosis to form one cell each

Alleles

Alternative form of a gene e.g. T and t

Chromosome

A thread like structure made up of DNA and proteins containing genes , found in the nucleus

Dominant

The gene that is expressed in the phenotype of the heterozygous condition e.q. Tt , T is dominant

Recessive

The gene that is masked in the phenotype by the dominant allele e.g. Tt , t is recessive

Fertilisation

The fusion of two haploid gametes to form a diploid zygote

Gamete

A haploid sex cell capable of fusion

Genes

Unit of heredity made up of DNA that codes for one trait

Genotype

The genetic makeup of an organism

Heterozygous

When two different alleles of a gene control the same trait e.g. Tt

Homozygous

When two identical alleles control the same trait e.g. TT

Mitosis

Cell division where two cells are produced each with the same number of chromosomes

Incomplete Dominance

When neither allele is completely expressed in the phenotype of the heterozygous condition e.g. Roan breed of cattle

Phenotype

The physical appearance of an organism

Meiosis

Cell division which produces 4 cells . Each cell has half the number of chromosomes as the parent cell

Homologous Chromosomes

Pairs of chromosomes that contain genes that control the same characteristics

Sex Chromosomes

A pair of chromosomes that determine the sex of the individual e.g. XX \= female or XY \= male in humans

Sex Linkage

When genes are carried on the sex chromosomes ( X or Y ) e.g. haemophilia

Linkage

When genes are present on the same chromosome

Autosomes

The 22 pairs of chromosomes that are not sex linked

Mendel's Law of Segregation

Traits are controlled by a pair of factors . Only one of any pair can enter a gamete

Mendel's Law of Independent Assortment

When gametes are formed , either a pair of alleles can enter a gamete with either of another pair

DNA Profiling

The examination of a sample of DNA for a pattern or band to compare

Non - coding DNA

Does not carry the information to make a protein

Genetic Engineering

Them manipulation and alteration of genes or genotype to give valuable traits to the organism

Genetic Screening

Testing for the presence or absence of genes

Evolution

Inheritable change within a species overtime in response to the change of their environment and by natural selection

Mutation

A change in the DNA that alters the genetic code

Species

A group of organisms capable of interbreeding to produce fertile offspring

Variation

Differences within a population or species

Heredity

Genetic inheritance from parents to offspring

Complimentary base pairs

Each base has a corresponding base / pair e.g. Cytosine and Guanine are complimentary pairs

Translation

Translating the genetic code of mRNA in the cytoplasm to make a specific sequence of amino acids

Transcription

Transferring the genetic code from DNA to mRNA in the nucleus

DNA Deoxyribonucleic Acid )

Located in the nucleus and makes up genes and chromosomes . Forms a double helix and its base sequence forms the genetic code

Bioprocessing

Using microorganisms to form single celled protein

Binary Fission

The reproduction of bacteria asexually . Two genetically identical cells are produced

Plasmid

A loop of bacteria within a bacterium which can code for antibiotic resistance

Endospore

Produced by bacteria when under unfavourable conditions as a survival method

Chemosynthetic

Use the energy released from chemical reactions to make food e.g. rhizobium