Word Definition
Unicellular Consists of one cell
Multicellular Made of many cells
Bacteria Simple organisms consisting of one cell that does not contain a nucleus.
Nucleus The control centre of a cell
Autotrophic Make food from small molecules using an energy source, such as light in photosynthesis
Photosynthesis Set of chemical reactions in plants that allow them to produce their own food (glucose) using water, carbon dioxide and light releasing oxygen.
Heterotrophic Getting food by eating and digesting the tissues of other organisms.
Saprophytic Getting food by digesting the tissues of other organisms outside the body.
Species The member of a species can reproduce with each other to produce offspring that will also be able to reproduce.
Homeotherms An animal that keeps its body temperature more constant than the surroundings, and often warmer, by releasing heat from reactions in its body.
Chordate Has a rod/spinal column supporting the body
Non-chordate No rod/spinal column supporting the body
Poikilotherms An animal whose body temperature varies with the temperature of the environment around it.
Oviparous Offspring that develop in eggs, as in birds. vivaparous Mother gives birth to live young, as in mammals.
Interbreed Reproduce with other members of the same group.
Hybrid An organism that is the result of breeding together two different species. A hybrid had characteristics form each species.
Ring species A ring of populations, in which neighbouring populations that can interbreed but the populations at the two ends of the chain cannot (despite the fact they might live in the same area).
Binominal system System of naming organisms using two Latin words.
Variation Differences between characteristics in different organisms.
Biodiversity A variety of species of plants and animals.
Discontinuous variation When a variable cannot have a continuous range of options, for example shoe sizes, days of the week.
Continuous variation When a variable can have any numerical value. Human height is a continuous variable.
Adaption Organisms have certain characteristics that allow them to survive in particular places. These characteristics are called adaptations.
Genetic variation Variation in characteristics caused by the instructions in cells (genes).
Normal distribution Bell-shaped curve shows most values are in the middle, and a few at the extreme values.
Acquired characteristic A characteristic that is changed by the environment rather than inherited form your parents.
Environmental variation Differences between the characteristics of organisms caused by their environment.
Competition When organisms need the same resources as each other, they struggle against each other to get those resources.
Natural selection A process in which organisms that are best suited to the conditions in their habitats are more likely to survive.
Evolution Gradual change of a species over a period of time.
Extinct The dying out of a species so that it no longer exists.
Resistant An organism that has evolved so that it is not affected by substances that would normally kill it.
Speciation Formation of a new species, such as when populations of a species are separated geographically and evolve until they are no longer capable of interbreeding.
Inherited variation Variation caused by genes.
Allele Different form of the same gene.
Cell membrane Thin layer around the cell that contains what goes in and out of cells.
Cytoplasm Jelly-like part inside a cell where the cells activities happen.
Chromosome A long thread of a molecule called DNA. Each chromosome contains a series of genes along its length.
DNA Deoxyribose nucleic acid, chemical that makes up genes and chromosomes; the instructions for a cell’s growth and activity.
Gene A section of DNA that carries the instructions for a characteristic.
Gamete Male and female sex cells
Sperm cell The male gamete in animals.
Egg cell