Definitions

• Genetics

  The study of inheritance
• Species


  Group of organisms that can interbreed and produce fertile offspring
• Inheritance/heredity

  The passing on of traits from one generation to the next
• Traits

  Physical/chemical characteristics that a living organism possesses
• Gamete

  Haploid sex cell capable of fusion
• Gene

  A piece of DNA that contains instructions to make a protein
• Locus

  The position of a gene on a chromosome
• Alleles

  Alternative forms of a gene
• Homozygous chromosomes

  Two alleles are the same
• Heterozygous chromosomes

  Two alleles are different
• Genotype

  The genetic make up of an organism
• Phenotype

  The physical make up of an organism (result of the interaction of genotype with the environment)
• Dominant

  The trait that is shown in the f1 generation. It represents the working of the recessive allele
• Recessive

  Means that the gene does not work in the presence of a dominant allele
• Incomplete dominance

  Neither gene is dominant or recessive in the presence of a dominant allele
• Progeny

  The offspring that is produced
• Cell continuity

  Ability of cells to divide and survive from one generation to the next
• Mendel's 1st law (law of segregation)


  Traits are controlled by pairs of alleles. These alleles separate at gamete formation, with each receiving one allele from each parent
• Mendel's 2nd law (law of independent assortment)


  When gametes are formed, either allele is equally likely to combine with either member of another pair of alleles
• Linkage (genetics)

  Both genes are present on the same chromosome
• Sex linkage

  Genes that are carried on the X or Y chromosome
• DNA replication

  Process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules
• Heredity /genetic inheritance

  The passing on of characteristics from one generation to the next
• Gene

  Section of DNA that codes/contains genetic code for protein
• Gene expression

  The process by which the code in DNA is used to make protein. It is the expression of genes that produce the characteristics that are inherited
• Osmoregulation

  The active regulation of the osmotic pressure of an organism's body fluids, to maintain the homeostasis of the organism's water content
• Turgor pressure (osmosis and diffusion)

  The force of the cell contents against the cell wall in the plant cell
• Active transport (osmosis+diffusion)

  The process where chemicals are taken into a cell against the diffusion gradient
• Osmosis

  The movement of water from an area of high concentration to an area of lower concentration across a semi-permeable membrane
• Diffusion

  The movement of molecules from areas of high concentration to areas of lower concentration across a selectively permeable membrane
• Transpiration (plant)

  Loss of water off leaves
• Venation

  The pattern of veins in a leaf
• Transpiration

  The loss of water vapour from the leaves and other aerial parts of the plant by evaporation
• Asepsis

  Removing unwanted microorganisms (prevent contamination)
• Sterile

  An object or environment free of contaminating microorganisms
• Chromosome mutation

  Large changes of base pairs in the structure or number of one or more chromosomes eg Downs syndrome caused by extra chromosome (3 at 21st chromosome - Trisomy 21)
• Gene mutation

  Changes in a single base pair within a gene e.g cystic fibrosis / haemophilia
• Evolution

  The genetic change that occurs in organisms over a long period of time in response to the environment
• Dispersal

  The transfer of fruit or seed as far away as possible from the parent plant
• Dormancy (seeds)

  A resting phase of reduced metabolic activity where the seeds undergo no growth