ESTAS 3 Flashcards
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 (the way in which new alleles are formed)
gene mutation
a change in the base sequence of DNA
adaptive feature
an inherited feature that helps an organism to survive and reproduce in its environment
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
food chain
chain showing the transfer of
energy from one organism to the next, beginning with a producer
trophic level
the position of an
organism in a food chain, food web, pyramid of
numbers or pyramid of biomass
food web
a network of interconnected
food chains
producer
an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
consumer
an organism that gets its energy by feeding on other organisms
herbivore
an animal that gets its energy by eating plants
carnivore
an animal that gets its energy by eating other animals
decomposer
an organism that gets its energy from dead or waste organic material
population
a group of organisms of one species, living in the same area, at the same time
community
all of the populations of different species in an ecosystem
ecosystem
a unit containing the
community of organisms and their environment,
interacting together, e.g. a decomposing log, or a lake
