variation and evolution + classification and heredity Flashcards
define variation
varation within a species means that successful inbreeding organisms produce individuals with different characteristics
give two types of variation
inherited variation and aquired variation
define inherited variation
a characteristic that is controlled by genes e.g eye colour /hair colour
define aquired variation
a characteristic that is learned through life e.g piercings
define heredity
the passing on of features to offspring by means of genes
what is a gene
a section of DNA that causes the production of a protein- they are units of inheritance
what is gene expression
the way in which genetic information in a gene is decoded and used to make a protein
what is a somatic cell
refers to every cell in the body apart from egg and sperm cells
what is a mutation
a change in the amount of structure of DNA . can be extremely harmful if the mutation occurs in a gamete.
what are mutagens
agents that cause mutations, for example ionizing radiation or chemicals such as alcohol
what is a spontaneous mutation
wrong base sequence due to faulty DNA replication
what is a gene mutation
occur in a single gene, can be passed to offspring e.g cystic fibrosis
what is a chromosome mutation
large changes in the structure or number of one or more chromosomes e.g down syndrome is caused by 3 number 21 chromosomes
define evolution
the way in whch living things change genetically to produce new forms of life over a long period of time
what two scientists worked on evolution
darwin and wallace
what is natural selection
the fittest survive in passing a variation onto the next variation
what 3 observations did darwin make while studying evolution
overbreeding-organisms produce large numbers, population remains constant, inherited variations occur in populations
what evidence of evolution do we have
fossils
what do fossil evidences indicate
modern species are more complex, life has changed over time
