Containing the full set of chromosome pairs, as in body cells.
Containing only half the normal number of chromosomes (one of each pair), as in gametes.
A haploid cell capable of fusion with another haploid cell to form a zygote; sperm and egg cells.
Diploid cell resulting from the fusion of an egg and sperm; the first stage of a unique new organism.
The various stages through which an organism passes during its life.
Penetration of egg by sperm and fusion of the egg and sperm nuclei. Union of gametes.
Fertilisation that takes place outside the body, in the external environment.
-In plants, having both stamens and carpels in the same flower.
-In animals, producing both male and female gemetes.
Relatively abrupt transistion from one developmental stage of an animal into another, usually from larva into adult.
Development of an animal that involves an intermediate free-living larval form before the adult form is reached.
Pattern of animals develoment in which an individual is hatched ot born in an essentially adult form.
Mammal in which oestrus and ovulation occurs only once during the breeding season, usually triggered by environmental conditions.
An animal in which ovulation is controlled by hormones release within the body.
An animal in which ovulation is stimulated by an external factor, such as courtship and mating.
Chemical agent that carries a message from one individual to another of the same species. e.g between males and females, signalling sexual receptiveness or reproductive state.
Protection and nourishment of offspring provided by one or both parents enhancing the chances of survival.
In vitro fertilisation
The fertilisation of an ovum outside the body, in laboratory glassware. IVF is used particulary if normal fertilisation cannot occur.
The taking of a sample of amniotic fluid, containing fetal cels, at about 14-15 weeks pregnancy. The fluid nd fetal cells are tested to detect abnormalities such a Down syndrome.
In vertebrates, the membrane forming the fluid-filled sac (amniotic cavity) surrounding the developing embryo.
Chorionic villus sampling
Method of obtaining fetal cells early in pregnancy (around 10 weeks) for analysis. Cells are taken from the outer membrabe, the chorion, which will later contribute to the placenta.
cell, encases in a protective coat that enables it to survive in unfavourable environments, which can give rise to a new individual upon germination. In plants, spores are the haploid products of meiosis.
The gamete-forming haploid stage in the life cycle of a plant.
Diploid stage in the life-cycle of a plant resulting from the fusion of gametes.
In flowering plants, smaller spores produced by meiosis that give rise to male gametophytes, which produce sperm.
In flowering plants, larger spores produced by meiosis that give rise o female gamaetophyes, which bear egg cells.
In harmaphrodites, fertilisation of eggs by sperm produced in the same individual.
A form of asexual reproduction in plants where a megaspore mother cell (2n) simply divides by mitosis to produce a new plant that is a genetic clonne.
In plants, a state of reduced metabolism, such as occurs in seed and deciduous plants during winter.
Store of food in animal egg that nourishes the developing embryo.
Juvenile form of an organism that undergoes a change in form to reach adulthood, eg. caterpillar is the larva form of moth.