NCEA Level 1 Biology
Gene
A lenght of DNA that codes for a particular trait.
Gametic mutation
A mutation that can be passed down because it accurrs in a germ-line cell (gamete).
Somatic mutation
A mutation that cannot be inherited because it occurrs in a non-germ-line cell.
Homologous Chromosomes
A pair of chromosomes, one from each parent, that re the same in length, shape and size, and contain the same genes.
Gametes
Sex cells (sperm or eggs).
Evolution
Changes in the iherited traits of a population throughout time.
DNA
Deoxyribonucleic acid, the hereditary material that contains genetic instructions. *Double helix
Zygote
First cell of a new organism.
Dominant
An allele that will always be expressed, whether one or two are present.
Recessive
An allele which is only expressed if the organism contains two copies.
Allele
An alternative from of a gene.
Pure breeding
An organism that is homozygous for the desired trait. e.g. TT or tt
Meiosis
Cell division for the production of gametes (sex cells).
Mutation
Permanent chnages to the genetic material (DNA/RNA) of a cell.
Random fertilisation
Sperm fertilises eggs randomly which means that the number of offspring showing a particular trait will not always match the probability predicted by a Punnet Square, unless the number of offspring is large.
Homozygous
The 2 alleles for a trait are identical. e.g. tt or TT
Phenotype
The appearance or physical expression of a trait. e.g. Blue eyes
Fertilisation
The fusion of an egg and a sperm, resulting in a zygote.
Natural selection
The process by which traits become more or less common in a population due to differences in survival and/or reproductive success.
Genotype
The two alleles an organism possesses for a trait. e.g. tt, TT or Tt
Heterozygous
The two alleles for a trait are different. e.g. Tt
Genetic variation
The variety of different genotypes for a particular trait within a population.
Chromosome
Threadlike strucure of DNA that contains genes. *Nucleotides - phosphates, sugars and bases