B16-18 Definitions Flashcards
Reproduction - Inheritance - Variation & Selection
Asexual reproduction
A process resulting in the production of genetically identical offspring from one parent
Sexual reproduction
A process involving the fusion of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other
Fertilisation
The fusion of gamete nuclei
Pollination
The transfer of pollen grains from the anther to the stigma
Self-pollination
The transfer of pollen grains from the anther of a flower to the stigma of the same flower or different flower on the same plant
Cross-pollination
The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
Sexually transmitted infection
An infection that is transmitted via body fluids through sexual contact
Inheritance
The transmission of genetic information from generation to generation
Chromosome
A thread-like structure of DNA, carrying genetic information in the form of genes
Gene
A length of DNA that codes for a protein
Allele
A version of a gene
Haploid nucleus
A nucleus containing a single set of unpaired chromosomes, eg. in gametes
Diploid nucleus
A nucleus containing two sets of chromosomes, eg. in body cells
Mitosis
Nuclear division giving rise to genetically identical cells
Meiosis
Reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells
Genotype
The genetic make-up of an organism in terms of the alleles present
Phenotype
The observable features of an organism
Homozygous
Having two identical alleles of a particular gene
Heterozygous
Having two different alleles of a particular gene
Dominant
An allele that is expressed if it is present
Recessive
An allele that is only expressed when there is no dominant allele of the gene present
Sex-linked characteristic
A characteristic in which the gene responsible is located on a sex chromosome and that this makes it more common in one sex than in the other
Variation
Differences between individuals of the same species
Mutation
Genetic change
Gene mutation
A change in the base sequence of DNA
Adaptive feature
The inherited functional features of an organism that increase its fitness
Fitness
The probability of an organism surviving and reproducing in the environment in which it is found
Process of adaptation
The process, resulting from natural selection, by which populations become more suited to their environment over many generations
